Dowel Jig Question [Archive] - Sawmill Creek Woodworking Community

Peter Quinn

12-16-2012, 8:50 PM

I have the original "dowel it" self centering jig, similar to the one Mike linked visually, but just four different sized holes. Got it from my Dad when he retired. Works great. Its pretty accurate, easy enough to use, though I honestly use it only very occasionally. There are other more expensive jigs that would let you do frameless cab type joints more easily if that is in your future. This type of jig only does end to edge joints or edge to edge joints, not edge to face. I'd agree with Mike that there are stronger joints, but a good dowel joint is no shame and a lot quicker to make than anything nearly as strong. Well, you could dump $2K on a domino XL set up, and or another $1200 on the regular domino, that would be a bit quicker, but then you would have to make a lot of mortises to justify that. Nice if you are prepared to go that route. Dowels get you a certain combination of cheap, strong and quick and accurate that works for some people in some situations.

Last weekend I made a pair of 8'X5' barn doors using stub tenons and dowel joints. Its a fast and dirty temporary door but it still has to look decent and last several years. I have a slot mortiser with doweling function that sure makes big dowels and alignment easy on multiples, but I was moving 100MPH to get these things made in a single day, had to go in before christmas! So the hand held jig gives real easy set up. No time to invest in setting up a machine for 4 stiles. I'm using 5 1/2" maple pins, fit like a glove even at over 3" deep!

Without seeing the plans your working on its hard to envision what you actually need dowels for on a folding table. I've had better success on edge grain glue ups using cauls and careful clamping, usually a bit of card scraping is all thats required to level the surfaces.

Dan Rude

12-17-2012, 12:16 AM

I have the Jig others are showing, but mine has the fixed holes. I also have the simple Rockler Jigs http://www.rockler.com/product.cfm?page=18059&site=ROCKLER that work very well for the money. That being said I'm tempted this Christmas to buy the new Jessm Jig at http://www.jessemdirect.com/JessEm_Dowelling_Jig_p/08350.htm it is on special now. I know Bill Huber reviewed the more expensive model and liked it so much he sold his "Dowel it". This model is supposed to work even better.
Dan

mreza Salav

12-17-2012, 1:55 AM

The best built and very good quality doweling jigs are dowelmax (at around $320) and the ones from Jessem (at around $230) http://www.jessem.com/DOWELING_JIG.html

Jessem has recently come up with a new that looks eqaully good at an attractive price of $160 (it was on sale for $99 a few weeks ago) http://www.jessemdirect.com/JessEm_Dowelling_Jig_Master_Kit_p/08350-master-kit.htm

I have the bigger Jessem jig and am quite happy with it.

HANK METZ

12-17-2012, 7:41 AM

The Dowel- It jig works as well as any out there for your purpose, but before I put any money on the table and since your need is currently for one project, I'd play with shop-made (https://www.google.com/search?q=home+made+dowel+jigs&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=5hHPUIC7EJKw8ATw-4DQCg&biw=1276&bih=890&sei=6hHPUPqiFJCc8gTpoYGIBA) jigs first.

- Beachside Hank
Improvise, adapt, overcome; the essence of true craftsmanship.

Bill Huber

12-17-2012, 9:13 AM

I guess the first question I have is will this be the only project you plan to use it on?
If so then just about any of the Dowel It type jigs will work just fine, now if you plan to use it for a lot of different projects then a better jig would be the best.

I have had the DowelMax and now have the Jessem, I like using dowels and for me the Jessem was much better and easier to work with. Both jigs work about the same way but the DowelMax requires shims were the Jessem does not when using different thickness of wood, which I really like.

Both jigs use a reference end and surface for placing the jig which is very accurate.

I will have to disagree with Mike on dowels, I think they are very good for all types of joinery and for panels when used with a good jig are great for alignment, spot on every time. Dowels are much faster then other methods and the strengths is just about as good, from the testing that I have seen.

Here is my write up on the Jessem. http://www.sawmillcreek.org/showthread.php?140404-Jessem-s-new-dowel-jig-WOW!!!!&highlight=Jessem+doweling+jig

pat warner

12-17-2012, 1:37 PM

Moreover, Bill, my hero, Krenov, used them. They must be good!

Myk Rian

12-17-2012, 1:45 PM

A question comes up, why do you want a dowel jig? For joinery, dowels are inferior to other techniques such as M&T or loose tenons.
It doesn't matter the "Why". Just which one.

The Dowel- It jig works as well as any out there for your purpose,
I have one. It works well, and is USA Michigan made.

Mike Henderson

12-17-2012, 1:48 PM

I will have to disagree with Mike on dowels, I think they are very good for all types of joinery and for panels when used with a good jig are great for alignment, spot on every time. Dowels are much faster then other methods and the strengths is just about as good, from the testing that I have seen.
The problem with dowels for alignment when gluing up a panel is that the dowels have to all be perfectly aligned. If one dowel is just a fraction of an inch displaced (sideways) in one board, the two boards will not go together. Biscuits and Dominos allow you to make the slot a bit wider so that when to go to put the boards together they will still fit even if one or more of the slots or mortises are just a bit offset to the side.

Dowel joints are not as strong as M&T joints that will fit into the same space. You can easily calculate the equivalent long grain-to-long grain surface area between a dowel joint and an M&T joint and see that the M&T joint has greater long grain-to-long grain surface area (I've done this in previous postings here about the strength of dowel joints). Finally, many people have had lots of experience with chairs that came apart at the back of the seat because the dowels used came loose. I've repaired many, many of those chairs, but never a chair with a M&T joint.

I think a better statement might be that dowels can provide acceptable strength in certain joints, but not will not be as strong as a M&T joint.

Mike

Prashun Patel

12-17-2012, 2:08 PM

I owned the Dowelmax and it was worth the price. If I were to buy a new doweling jig, I'd get the Jessem. The Dowelmax was incredibly accurate. It is so well machined, the alignment problems Mike notes were never an issue - even when gluing up wide panels with dowels indexed every 6" over a 3-4 foot range.

If you have the money, a Domino is worthy of consideration. It can do everything the dowel jigs and a biscuit joiner can do. It's a lot of money, but it's more flexible and faster (you don't have to commandeer your drill, and the depth and angle stops are integrated and pre-set.

I will say that I found the dowelmax marginally even more accurate than the Domino. When gluing up panels, the dowelmax locked them in perfectly. With the Domino, there is some (very) minor slop that still benefits from vertical clamping over the joint. I never had to do that with the Dowelmax. I chalk this up to the fact that a drill and very good brad point bit are cleaner and gentler to bore than the wider mortises of a Domino or Mortisepal.

Bill Huber

12-17-2012, 2:45 PM

The problem with dowels for alignment when gluing up a panel is that the dowels have to all be perfectly aligned. If one dowel is just a fraction of an inch displaced (sideways) in one board, the two boards will not go together.
Mike

Have you ever use a DowelMax or the Jessem jig, they both are very very accurate. I have made some large panels, 20" wide with 5 boards and never had to sand them down to a misalignment.

When I look at things I have use my doweling jigs on I just can not see doing it any better with M&T or biscuits.

As to the strength that is a debate that will go on forever, I think it is all in how the test are done and who does them.

Mike Henderson

12-17-2012, 4:25 PM

Have you ever use a DowelMax or the Jessem jig, they both are very very accurate. I have make some large panels, 20" wide with 5 boards and never had to sand them down to a misalignment.

When I look at things I have use my doweling jigs on I just can not see doing it any better with M&T or biscuits.

As to the strength that is a debate that will go on forever, I think it is all in how the test are done and who does them.
The misalignment is not in the vertical direction, it's in the horizontal direction. The cheapest self centering dowel jig can center a dowel so that the boards will be aligned (flat) when you glue up. The problem is in the other direction. If one dowel hole is out of place in the horizontal direction, the two boards will not go together. Other techniques for aligning boards allow for horizontal misalignment. For example, when you use a Domino, most people will put one domino in without widening the mortises. This domino is the alignment (horizontal) domino. All of the other mortises are a bit wider than the loose tenon so that if you were just a bit off when you made the mortise, the two boards will still go together.

The only people who can believe that dowels are as strong as a M&T joint are those who have drunk the dowel KoolAid (are religious about it). It's pretty easy to prove mathematically that you have more long grain-to-long grain surface area with a M&T joint. And long experience with both dowels and M&T joints have shown the relative strength of the two joints.

Mike

Bill Huber

12-17-2012, 4:35 PM

The misalignment is not in the vertical direction, it's in the horizontal direction. The cheapest self centering dowel jig can center a dowel so that the boards will be aligned (flat) when you glue up. The problem is in the other direction. If one dowel hole is out of place in the horizontal direction, the two boards will not go together. Other techniques for aligning boards allow for horizontal misalignment. For example, when you use a Domino, most people will put one domino in without widening the mortises. This domino is the alignment (horizontal) domino. All of the other mortises are a bit wider than the loose tenon so that if you were just a bit off when you made the mortise, the two boards will still go together.

The only people who can believe that dowels are as strong as a M&T joint are those who have drunk the dowel KoolAid (are religious about it). It's pretty easy to prove mathematically that you have more long grain-to-long grain surface area with a M&T joint. And long experience with both dowels and M&T joints have shown the relative strength of the two joints.

Mike

I will ask the same question I ask in the other reply, Have you ever tried one of the jigs, the DowelMax or the Jessem?

I can understand that with a jig like you are talking about the spacing could be off really easy but with jigs I am talking about they are spot on.

Mike Henderson

12-17-2012, 4:37 PM

For the mathematics, check post 21 in this thread (http://www.sawmillcreek.org/showthread.php?184381-Doweling-Jig-Recommendations-Please&highlight=dowels).

Mike

Ray Newman

12-17-2012, 4:37 PM

Like most of us, I also have a dowel boring guide. Have not the slightest idea when I last utilized it and it must be almost 30 years old.

Having said that, I re-read your post as it rang a bell in my memory bank.

Thinking out loud here:

Wood swells with humidity and dampness. What you want to do might work well as long as there is no humidity. Dry weather, the legs fold easily and the dowels lined up the top well. Humid weather and things did not work as well. Plus wood dowels can break off or otherwise become deformed.

Possibly brass rod of the appropriate length and diameter with a tapered end to align the tops and as the pivots for the folding legs?

Might be appropriate for what you are doing. Here, the local hardware has brass rod of various length and diameter. Or, a local machine shop or machine shop supply house stocks it.

Fabricate the taper by gluing emery paper to a board; hold it against the brass dowel chucked in an electric drill?

mreza Salav

12-17-2012, 7:37 PM

The misalignment is not in the vertical direction, it's in the horizontal direction. The cheapest self centering dowel jig can center a dowel so that the boards will be aligned (flat) when you glue up. The problem is in the other direction. If one dowel hole is out of place in the horizontal direction, the two boards will not go together. Other techniques for aligning boards allow for horizontal misalignment. For example, when you use a Domino, most people will put one domino in without widening the mortises. This domino is the alignment (horizontal) domino. All of the other mortises are a bit wider than the loose tenon so that if you were just a bit off when you made the mortise, the two boards will still go together.

The only people who can believe that dowels are as strong as a M&T joint are those who have drunk the dowel KoolAid (are religious about it). It's pretty easy to prove mathematically that you have more long grain-to-long grain surface area with a M&T joint. And long experience with both dowels and M&T joints have shown the relative strength of the two joints.

Mike

I am not attached to any of these methods. I use traditional M&T, loose tenon (using a jig on the router), and sometimes use dowels. I do agree that M&T are the strongest but in many (I'd say most) applications the difference (which I think is in the order of 10-20% difference in strength) is a real non issue.

As for the alignment problem you are talking about: I fully understand what you are trying to say but I have never ever had that issue, as long as you are careful in your work.
Of all the methods above (plus perhaps biscuits) I prefer dowels for aligning panels the most.

Matt Day

12-17-2012, 8:41 PM

Mike Henderson

12-17-2012, 10:21 PM

My personal opinion is that for most hobbiest projects dowels are just fine compared to M&T. If I was building a bed, I'd use M&T; side table, dowels would be fine.

Lets not get personal ( or religious?) about this, it's not a Sawstop thread! :-).
I agree that for some construction (meaning projects) dowels will provide very adequate strength, and I said so in an earlier post. However, there's no question that M&T is a stronger joint.

Mike

Alan Wright

12-17-2012, 10:26 PM

Bill, I couldn't agree more with all you've said. I have a domino, and a biscuit joiner, and a jessum dowling jig (I purchased it largely based on your review... Thanks). There are so many ways to skin a cat, but we all tend to go with what is easiest. If I have any doubts abougt joint strenght, I use the domino. However, for gluing up panels, I almost always grab the jessum. Until you've used one, it's difficult to understand just how accurate it is an how easy it is to get the alignments spot on, both vertical and horizontally. Therer is a jig attachment that comes with the Jessum Jig that is specifically designed to get the spacing down the length of two corresponding board faces to be exact mirror images of each other. When you plug in the dowels and join the boards, the surfaces are just about dead on.... Much much more accurate than a biscuit (my biscuit jouner sits on a shelf).

When using a domino (in my experience) and for joining panel edges, you get significant strength when using the largest floating tenons, but you also have a much bigger hole to drill out and the domino shakes a bit and it is more difficult (though not impossible) to get an exact veretical vertical alligment. Using the smaller Domino tenons makes it much easier to get the precision, but then you give up strength. Again, lots of ways to join wood. For me it all comes down to the strength needed, the ease of the process, and the accurcy of the results. I use my Jessum and I use my Domino both, but in a perfect world, having both is very helpful, and I definately see a place in my shop for a QUALITY dowling jig.

Jack Lemley

12-18-2012, 9:13 AM

I agree that for some construction (meaning projects) dowels will provide very adequate strength, and I said so in an earlier post. However, there's no question that M&T is a stronger joint.

Mike

Mike,

I agree that a M&T done properly is strong than a dowel. However, with a Dowel Max it's pretty hard not to get the dowel joint right and not so much with a M&T. I have been a hobbiest now for 30 years and a screwed a few M&T joints in my time. I am not a purist either way. Time, convenience, strength needed, quality requirements of project all come into play when I make my joint decisions.

Jack

Phil Thien

12-18-2012, 9:24 AM

Mike,

I agree that a M&T done properly is strong than a dowel. However, with a Dowel Max it's pretty hard not to get the dowel joint right and not so much with a M&T. I have been a hobbiest now for 30 years and a screwed a few M&T joints in my time. I am not a purist either way. Time, convenience, strength needed, quality requirements of project all come into play when I make my joint decisions.

Jack

Agree 100%.

I enjoy watching the Woodsmith Shop show (I think that is the name, I should really know it). On occasion they will show a mortise/tenon or stub tenon joint that they've just made, as they insert the tenon into the mortise.

What I've noticed is that, quite often, the fit is way too loose. Too much of a gap for normal PVA glue's to hold tight. A properly executed joint made with dowels would be substantially stronger. And a properly made doweled joint IS much easier to achieve than a well-fitting mortise and tenon.

I have tested old dowel joints to destruction. These are projects made when I was a kid, thirty years ago. When I cut through the joint so I can see a cross-section of the dowels in the holes, I see that the dowels are still round (haven't run into any oval ones, as one magazine writer said they all become out of round). In fact, I'd have to say if anything, the dowels had swollen and made better contact with the walls of the holes during the glue-up than even I had expected.

Mike Henderson

12-18-2012, 10:21 AM

Mike,

I agree that a M&T done properly is strong than a dowel. However, with a Dowel Max it's pretty hard not to get the dowel joint right and not so much with a M&T. I have been a hobbiest now for 30 years and a screwed a few M&T joints in my time. I am not a purist either way. Time, convenience, strength needed, quality requirements of project all come into play when I make my joint decisions.

Jack
My original posting was that dowel joints were inferior to other types of joinery, especially M&T and loose tenon. I don't think anyone who looks at the data with an open mind can doubt the accuracy of that statement. So far, I have not seen any posting that refute that contention, only that certain jigs will make dowel joints with more or less accuracy.

Mike

[Added note: we have history of dowel joinery going back to at least 1900 (repairing old furniture). We do not see failure of joinery such as dovetails or M&T at nearly the rate of failure of dowel joinery.]

[And, come on now, Phil. You're going to justify dowel joints by claiming that M&T joints are not well made and therefore are not as strong as dowel joints???? Using that logic you can justify anything. The only fair test of joinery is to compare two well made joints. And certainly factory made joints, whether M&T or dowels, are going to be well made and well fitted since they're made by machine to very close tolerances. And in those joints we see many more real life failures in the dowel joints than in M&T joints. And it's easy to see why - because dowels do not have as much long grain-to-long grain gluing surface area as M&T joints.]

Mike Henderson

12-18-2012, 12:18 PM

Here's an article (http://www.popularwoodworking.com/techniques/finishing/regluing_doweled_chairs?et_mid=595336&rid=233389068) on the Popular Woodworking site that talks about the strength of dowel joints, and how to repair chairs with them. I agree with his conclusion that you have to disassemble the chair to properly repair such failures. I often re-drill the dowel holes to the next larger size and use larger dowels in the repair. I find that people often wait a long time to get a repair done and there's been a lot of movement in the joint. The dowels actually wear the dowel hole larger so the same size dowel will be loose if you use that in the repair.

If, for some reason, the joint will not come apart, even though it is loose, I'll take a thin saw and cut through the dowels. Then when the joint is apart, I'll drill out the old dowels.

Mike

Martin Jodoin

12-18-2012, 12:43 PM

However, there's no question that M&T is a stronger joint. Mike

Hello Mike, that's your opinion, but here is a quote from Dowelmax folks "... Professionally Test Proven Stronger than Mortise &Tenon".

Before spending 300$ on a dowel jig, i read a lot of reviews and decided to go with the Jessem Model 08300. I found the review of the Jessem jig from Bill Huber very valuable because he used both jigs.
I have a self-centering doweling jig too, but i often do projects with thick stock where the dowels are not to be centered and i was tired of adding shims...
I just received my Jessem jig last week, i did not play with it yet, but this thing is build like a tank. I did some business with Jessem in the past and i am very happy with their customer service.

Mike Henderson

12-18-2012, 12:53 PM

Hello Mike, that's your opinion, but here is a quote from Dowelmax folks "... Professionally Test Proven Stronger than Mortise &Tenon".

Before spending 300$ on a dowel jig, i read a lot of reviews and decided to go with the Jessem Model 08300. I found the review of the Jessem jig from Bill Huber very valuable because he used both jigs.
I have a self-centering doweling jig too, but i often do projects with thick stock where the dowels are not to be centered and i was tired of adding shims...
I just received my Jessem jig last week, i did not play with it yet, but this thing is build like a tank. I did some business with Jessem in the past and i am very happy with their customer service.
I'm sure that anyone who makes a product can find someone who will "prove" that their product is better than the competition. I think most people are a bit more cynical about such marketing claims.

If you want to claim that dowels are as strong as M&T joints you need to point to some reputable testing results, and see that those results have been duplicated by others who perform the same kinds of testing. Also, you need to explain why we find so many failed dowel joints in old furniture, especially chairs, than other types of joinery, especially dovetails and M&T.

Mike

Steve Wurster

12-18-2012, 1:12 PM

Mike Henderson

12-18-2012, 1:46 PM

I believe Matthias Wandel of woodgears fame did a study that showed while M&T is stronger (though not by a "lot"), the failure occurs in the wood, not the glue. I'm betting those old chairs fail because of the glue; modern glue is stronger than wood due to the way it interacts with the wood. Pinned M&T certainly won't have that problem, neither will dovetails where there is obvious mechanical strength even without glue.
R. Bruce Hoadley (of the books "Understanding Wood" and "Identifying Wood") wrote an article in an early FWW magazine where he analyzed the failure of joints, such as the joints on the rear of chairs. His conclusion was that the failure was due to wood failure and not glue failure. That is, the wood separated at the joint - there was a thin layer of wood still attached to the glue (I've seen this in failed joints).

This leads to the conclusion that the greater the effective gluing surface, the stronger the joint. And as shown earlier, most dowel joints do not have as much effective glue surface as a M&T joint. [When a dowel is put into the end of a piece of wood, all of the area is effective gluing surface so this statement applies to dowels that go into the 'side" of another piece of wood, where half of the dowel is facing end grain. So if you wanted to attach two pieces of wood end-to-end, dowels may make the stronger joint.]

Mike

Harvey Miller

12-18-2012, 2:17 PM

If you're interested in a reasonably priced one for your project Rockler sells one for $15 (on sale today for $10). It uses the same face reference style as the Dowelmax and Jessem, but only has dual dowel guides. For the price it's worth trying it out.

http://www.rockler.com/product.cfm?page=18059&site=ROCKLER

Cary Falk

12-18-2012, 3:00 PM

Martin Jodoin

12-18-2012, 3:47 PM

This leads to the conclusion that the greater the effective gluing surface, the stronger the joint. And as shown earlier, most dowel joints do not have as much effective glue surface as a M&T joint. [When a dowel is put into the end of a piece of wood, all of the area is effective gluing surface so this statement applies to dowels that go into the 'side" of another piece of wood, where half of the dowel is facing end grain. So if you wanted to attach two pieces of wood end-to-end, dowels may make the stronger joint.]Mike

Mike, i am not a pro dowels, i still believe a tight M&T joint is stronger. I did some M&T by hand, and some of them were not so nice. I don't have a mortising machine. I am sure you agree that it's easier, for a beginner like me at least, to drill couples holes with a dowel jig (they will be perfect every time) than to cut a tight M&T by hand. I still don't understand the logic about the gluing surface. To me a dowel is just a rounded mini tenon, and a tenon is like a big square dowel, the surface should make a difference, not the shape. If you take a 1/2 inch dowel and sand it down square to 3/8, does it still applies ? I don't understand why we are losing half of the effective gluing surface with a dowel but it does not apply with a tenon. Any picture maybe ?

I totally agree with you btw that more gluing surface = stronger joint.

Cheers

Mike Henderson

12-18-2012, 4:49 PM

Mike, i am not a pro dowels, i still believe a tight M&T joint is stronger. I did some M&T by hand, and some of them were not so nice. I don't have a mortising machine. I am sure you agree that it's easier, for a beginner like me at least, to drill couples holes with a dowel jig (they will be perfect every time) than to cut a tight M&T by hand. I still don't understand the logic about the gluing surface. To me a dowel is just a rounded mini tenon, and a tenon is like a big square dowel, the surface should make a difference, not the shape. If you take a 1/2 inch dowel and sand it down square to 3/8, does it still applies ? I don't understand why we are losing half of the effective gluing surface with a dowel but it does not apply with a tenon. Any picture maybe ?

I totally agree with you btw that more gluing surface = stronger joint.

Cheers
Martin - read post number 21 in the thread at this link (http://www.sawmillcreek.org/showthread.php?184381-Doweling-Jig-Recommendations-Please&highlight=dowels) (click on the word "link"). Hopefully, that will make it clearer. The assumption in that post is that the dowel is going into the "side" of a piece of wood. If the dowel is going into the end of a piece of wood, the dowel is all long grain-to-long grain. On a chair, the dowels that go into the chair rail are going into the end of the wood, but the dowels that go into the chair back are going into the side of the wood so half of the surface area is long grain to end grain.

Mike

Larry Rasmussen

12-18-2012, 4:49 PM

I also like the Rockler guide Harvey recommends above, it seems to match your intended use and the sale price is frosting. I did have a Dowel Max that I sold a couple years ago, I found it time consuming to align it precisely. Anyway enjoy the project. Larry R, Seattle.

Brian Brightwell

12-18-2012, 7:58 PM

I have the Jessem and agree with you Bill. Actually, I bought it on your recommendation.

Terry Therneau

12-18-2012, 8:50 PM

I have the Dowel Max and agree that it is a great jig. It's not as clear that I would buy it again given the price. I makes perfect edge glue ups easy, and I reach for it for that chore. I've not been as happy with carcass joinery. For longer dowels the angle has not always been perfect --- perhaps it's just me and I'm pushing at an angle with the drill, but it's not perfectly parallel to the face of the board.
I just built a slot mortiser and am now doing my first project with it. Happy so far; if that's still true at the end I'll write up a description.

Terry T.

Phil Thien

12-18-2012, 10:01 PM

[And, come on now, Phil. You're going to justify dowel joints by claiming that M&T joints are not well made and therefore are not as strong as dowel joints???? Using that logic you can justify anything. The only fair test of joinery is to compare two well made joints. And certainly factory made joints, whether M&T or dowels, are going to be well made and well fitted since they're made by machine to very close tolerances. And in those joints we see many more real life failures in the dowel joints than in M&T joints. And it's easy to see why - because dowels do not have as much long grain-to-long grain gluing surface area as M&T joints.]

Interesting. Question:

Is it your feeling that because dowel joints are inadequate where chairs are concerned, that they should be avoided for non-chair projects?

Mike Henderson

12-18-2012, 10:44 PM

Interesting. Question:

Is it your feeling that because dowel joints are inadequate where chairs are concerned, that they should be avoided for non-chair projects?
No, in less stressful joints dowels may provide very adequate strength. Note that my contention has always been that dowel joints are inferior to other types of joinery, not that dowel joints should never be used. We probably do a number of things in woodworking that are not always the "best" but allow us to build something quicker, or with what we have on hand, or for any number of other reasons. If dowels are used with an understanding of their limitations they may provide very adequate service.

But given that, I must admit that I avoid dowels because of their limitations. I do not have to build things fast, nor do I have to sell what I make so I lean towards what I feel is the best way of doing joinery.

Mike

Phil Thien

12-19-2012, 8:57 AM

...Note that my contention has always been that dowel joints are inferior to other types of joinery, not that dowel joints should never be used. If dowels are used with an understanding of their limitations they may provide very adequate service.

Have you seen any of the articles that compare joint strength? My recollection was that dowels compared very favorably to M&T. Do you think the articles are inaccurate, or feel (as some others do) that over time the seasonal movement of wood components compress the dowels to out of round, which compromises joint strength over time?

Terry T. hit on an excellent point I've experienced myself. And that is, even with the best of jigs, the hole is sometimes not perfectly perpendicular to the surface of the wood. This results in a dowel that is slightly angled. In the worst-case scenario, you get two pieces you're trying to join, with holes angled such that the components torque when you try to assemble them.

The solution is to typically use shorter dowels.

I do on occasion remind myself that projects only need to be strong enough for their intended purpose. An end table need not support a strip-dancer unless I'm expecting strip dancers anytime soon.

Bill Huber

12-19-2012, 9:11 AM

Terry T. hit on an excellent point I've experienced myself. And that is, even with the best of jigs, the hole is sometimes not perfectly perpendicular to the surface of the wood. This results in a dowel that is slightly angled. In the worst-case scenario, you get two pieces you're trying to join, with holes angled such that the components torque when you try to assemble them.

I had that problem a little with the angle when I had the DowelMax, it would happen when the nuts would get a little loose on the back side. With the Jessem I have never had it, I think it is the way the reference plate is made. The Jessem is much larger then the DowelMax and it bolted on in a more solid way. I use a lot of 2" dowels with panels and they are flat when assembled.

Steve Wurster

12-19-2012, 9:28 AM

I do on occasion remind myself that projects only need to be strong enough for their intended purpose. An end table need not support a strip-dancer unless I'm expecting strip dancers anytime soon.

Well, that's certainly not happening in my house any time soon, unfortunately. I don't think SWMBO would appreciate it.

On a more relevant note, I just built two side tables for my mother and used M&T construction. I'm not an M&T expert so I had the typical fit problems. I used a router to make the mortises so there was also the rounded ends to deal with (on 32 mortises since each table has a shelf!). About halfway through I wondered why I didn't use my Jessem jig since these are only small side tables and won't be subjected to any kind of beating. They're going to sit on both sides of the couch in the basement and just hold drinks and such; dowels would have been sufficient. I really gotta remember that for next time!

Mike Henderson

12-19-2012, 12:03 PM

Have you seen any of the articles that compare joint strength? My recollection was that dowels compared very favorably to M&T. Do you think the articles are inaccurate, or feel (as some others do) that over time the seasonal movement of wood components compress the dowels to out of round, which compromises joint strength over time?
All of the joinery tests I can recall had results that were in this order of joint strength (for these four options):

1. Standard mortise and tenon
2. Loose tenon
3. Dowels
4. Biscuits

And, of course, we have the observations of those who repair furniture. While not scientific, the anecdotal evidence points to much greater incidence of failure in doweled joints than in standard M&T.

Finally, there is good reason to believe that the amount of effective glue surface in a joint affects the strength of the joint and standard M&T joints have more effective glue surface than dowel joints.

Mike

Brian Brightwell

12-19-2012, 12:36 PM

I saw a test where a bridle joint was actually stronger then a mortise and tendon. Not to many people use a bridle joint.

mreza Salav

12-19-2012, 1:24 PM

All of the joinery tests I can recall had results that were in this order of joint strength (for these four options):

1. Standard mortise and tenon
2. Loose tenon
3. Dowels
4. Biscuits

And, of course, we have the observations of those who repair furniture. While not scientific, the anecdotal evidence points to much greater incidence of failure in doweled joints than in standard M&T.

Finally, there is good reason to believe that the amount of effective glue surface in a joint affects the strength of the joint and standard M&T joints have more effective glue surface than dowel joints.

Mike

I will try to address some of your points as I think they are not quite correct:

- First as I said before I agree M&T is the strongest of the joints *BUT*:
the difference is not substantial w.r.t. dowels. All tests results I have seen rank it only 10-20% higher than dowels. Now keep in mind that
using dowels is a lot easier than traditional M&T so for vast majority of joints one can forgive that extra 10-20% extra strength.

- You keep saying that alignment of dowels in a row is difficult. I understand your concern but it's not that difficult at all. I have built car-cases (cabinets) with dowels and not a single miss-alignment.

- And you say:

"Finally, there is good reason to believe that the amount of effective glue surface in a joint affects the strength of the joint and standard M&T joints have more effective glue surface than dowel joints.

That is not always true again. For example compare the following two:

- two rows of 6 dowels of 3/8", with 3/8" space in between each
- A tenon of size 4.125" wide * 1.125" thick

Note that both give you similar width & thickness. Assuming both are 1" deep, tell me which one has more glue surface area?

Mike Henderson

12-19-2012, 2:19 PM

- And you say:

"Finally, there is good reason to believe that the amount of effective glue surface in a joint affects the strength of the joint and standard M&T joints have more effective glue surface than dowel joints.

That is not always true again. For example compare the following two:

- two rows of 6 dowels of 3/8", with 3/8" space in between each
- A tenon of size 4.125" wide * 1.125" thick

Note that both give you similar width & thickness. Assuming both are 1" deep, tell me which one has more glue surface area?
It's always possible to come up with a configuration that gives dowels an advantage. For example, suppose you compared three rows of dowels to a mortise and single tenon. The dowels would have greater effective gluing surface.

But I can make a double mortise and tenon, just as you can put two rows of dowels in. If I do that, the M&T has approximately twice the effective gluing surface as the dowels.

Let's look at the mathematics. The surface area of a cylinder (excluding the ends) is 2*pi*r*h, where:

r = radius, which is 3/16" (.1875") in this example.
h = the amount it protrudes into the wood, which is 1" in this example

The area of the dowels will be approximately 14 sq inches, but only half of this is facing long grain, so the effective gluing surface is approximately 7 sq inches.

Six 3/8" dowels with 3/8" between them is 4.125" so one face of a tenon is 4.125 sq inches. Since there are four faces on a double tenon, the total effective gluing surface is approximately 16.5 sq inches.

So the double tenon has approximately twice the effective glue surface of the dowels (actually, a bit more than twice).

Mike

mreza Salav

12-19-2012, 2:51 PM

It's always possible to come up with a configuration that gives dowels an advantage. For example, suppose you compared three rows of dowels to a mortise and single tenon. The dowels would have greater effective gluing surface.

But I can make a double mortise and tenon, just as you can put two rows of dowels in. If I do that, the M&T has approximately twice the effective gluing surface as the dowels.

Let's look at the mathematics. The surface area of a cylinder (excluding the ends) is 2*pi*r*h, where:

r = radius, which is 3/16" (.1875") in this example.
h = the amount it protrudes into the wood, which is 1" in this example

The area of the dowels will be approximately 14 sq inches, but only half of this is facing long grain, so the effective gluing surface is approximately 7 sq inches.

Six 3/8" dowels with 3/8" between them is 4.125" so one face of a tenon is 4.125 sq inches. Since there are four faces on a double tenon, the total effective gluing surface is approximately 16.5 sq inches.

So the double tenon has approximately twice the effective glue surface of the dowels (actually, a bit more than twice).

Mike

- You didn't address the first two points I raised.

- Your math and arguments are flawed. The two settings I described give you the same dimensions, i.e. you can fit them into the same size mortise openning.
If you want to double your tenons side by side you do NOT get 4 face-grain faces, you actually reduce your surface area (do you see this?)
If you are talking about two tenons in the width then go ahead through the pain of making them (and good luck fitting them into the same thickness) just to justify your claims.
I think you also realize that by making multiple smaller tenons you are getting closer to what a dowel is doing.

You first say there are some who are religiously defending dowels yet it seems you are the one who changes the settings to defend your position.
I keep using M&T, loose tenon, and dowels. I really don't see any point debating this anymore.

Mike Henderson

12-19-2012, 3:17 PM

- You didn't address the first two points I raised.

- Your math and arguments are flawed. The two settings I described give you the same dimensions, i.e. you can fit them into the same size mortise openning.
If you want to double your tenons side by side you do NOT get 4 face-grain faces, you actually reduce your surface area (do you see this?)
If you are talking about two tenons in the width then go ahead through the pain of making them (and good luck fitting them into the same thickness) just to justify your claims.
I think you also realize that by making multiple smaller tenons you are getting closer to what a dowel is doing.

You first say there are some who are religiously defending dowels yet it seems you are the one who changes the settings to defend your position.
I keep using M&T, loose tenon, and dowels. I really don't see any point debating this anymore.
One would not put two tenons across the board because the face of the tenons would then be facing end grain.

Mike

Mike Henderson

12-19-2012, 3:27 PM

You first say there are some who are religiously defending dowels yet it seems you are the one who changes the settings to defend your position.
Note that the general rule for tenons is that a single tenon should be about 1/3 of the width of the board. In your example, the tenon is 1.25" thick, implying a board almost 3.5" thick. We don't do much with wood that thick, so your accusation that I'm creating special settings can easily be levied against your example.

And in a board about 3.5" thick, I can put a double tenon.

Mike

Myk Rian

12-19-2012, 5:14 PM

I find it amazing that when someone asks "What doweling jig should I buy", the whole discussion turns into the merits, and flaws of ALL joinery known to man.
Just answer the question.

I made this step ladder for my Wife, using dowels. It shows no signs of breaking into pieces, and crashing down when she uses it.

248417

Mike Henderson

12-19-2012, 5:38 PM

I find it amazing that when someone asks "What doweling jig should I buy", the whole discussion turns into the merits, and flaws of ALL joinery known to man.
I have to agree. I thought my original comment (post #2 in this thread) was not very controversial but a number of people apparently thought it was.

Mike

Matt Day

12-19-2012, 9:51 PM

I have to agree. I thought my original comment (post #2 in this thread) was not very controversial but a number of people apparently thought it was.

Mike

If you agree, how about we all put the keyboards down and stop talking about it? Let's just agree that there are choices to be made with regard to joinery, and personal preferences as to which is best for the appication?

If not, could someone show me how to remove a thread from my view in the forum?

Steve Wurster

12-19-2012, 10:08 PM

If not, could someone show me how to remove a thread from my view in the forum?

Under Thread Tools near the top, select Unsubscribe from this Thread. You'll still see it on the forum page, but you won't get emails any more.

Bas Pluim

12-19-2012, 10:15 PM

I find it amazing that when someone asks "What doweling jig should I buy", the whole discussion turns into the merits, and flaws of ALL joinery known to man.
+1. If you don't like dowels, why bother responding?. Especially if you don't even have one.

BTW, if anyone has a question about finishing cherry, let me know and I'll tell you why you should build your project out of white oak instead.

Mike Henderson

12-19-2012, 10:27 PM

+1. If you don't like dowels, why bother responding?. Especially if you don't even have one.

BTW, if anyone has a question about finishing cherry, let me know and I'll tell you why you should build your project out of white oak instead.
I don't know if you're aiming that comment at me, but I do own a dowel jig and said so in post #2. I think my question in posting #2 was quite reasonable and very much on subject - not a hijack at all. Note that in post #3 the OP answers my question and that would have been the end of it, except that other people started challenging my statement, which I then defended.

Apparently, my position that dowel joinery is inferior to certain other types of joinery is what is so upsetting to some people - they just don't want to hear it, no matter how much data and logic supports it.

Mike

[And according to your logic, Bas, if someone said, "I'm going to build some poplar outdoor furniture, how should I finish it?" No one should point out that poplar is not a good choice for outdoor furniture, and that oak would be a better choice. They should simply reply about how to finish it.]

Dan Lee

12-19-2012, 10:28 PM

LIL
OP asks a question about which dowel jig folks prefer and A fella decides to hijack the thread. I don't get that

Dan Rude

12-20-2012, 1:10 AM

Wow, everyone has given a lot of good information on the benefits of both Dowel and the M & T joints. I hope Brent has decided on what he is going to do. I myself pulled the trigger and ordered the new dowel Jig from Jessem. I have their Zip Slot too, haven’t used it on a major project yet.
Dan

Craig Huenergardt

12-22-2016, 10:44 AM

Just got the Jessem. I am resizing and 5 maple doors I got off craigslist and setting up loose mortises seemed like a lot of work. This thread helped me decide on the Dowell jig and I am using the the 1/2 inch guide.

Carefull not to use too many 1/2 inch dowels. I put 6 in the top rail and the kicker rail and it was hard to close the joint with Bessy clamps with a total of 30 dowels in 3 rails. Had to resort to pony clamps. The dowels were 4 inch fluted by 1/2. Went together very square and flush rail to stile. No way these doors are coming apart.

Changed to 4 dowels in upper and lower rails each side and 3 in the lockset rail the door went together better.

Mike Monroe

12-22-2016, 11:25 AM

Re; the number of dowel to use on door stiles to rails.

I'm re-purposing the wood from interior doors salvaged from a circa 1910's Montgomery Ward kit house. These are all pine 5 panel doors finished with shellac. The rails and stiles on these doors are connected with only two maple 1/2" dowels. The pine in these doors is old growth, has really tight growth rings and machines beautifully - a real pleasure to work with.

Art Mann

12-22-2016, 3:02 PM

Having just read through this resurrected old thread, I would like to add my opinion. Using a quality dowel jig like the Jessem or Dowelmax, you can get the same or stronger results than you can with Dominos or several other kinds of joints. My opinion is based on many years of experience and actual evidence rather than speculation on a jig I have never used and don't understand. For anyone who is interested in independent real world testing rather than speculation, I recommend reading the January 2009 issue of Fine Woodworking magazine. They built multiple samples of a wide variety of joints and then used precision instrumentation to test each sample to failure and record the results. Here is a link to the introductory video:

http://www.finewoodworking.com/2009/02/25/joint-strength-test

Here is an interesting observation from the test. The dowel and floating tenon failures were not the result of a failed glue joint. As I expected, the pieces that were joined shattered rather than the glue turning loose. The cross sectional area and placement geometry were much more important than the glue surface area. That contradicts the previously posted mathematical exercise, which was based on an erroneous assumption. The bottom line is that in the Fine Woodworking experiment, the Dowelmax joint required 759 pounds of force to cause failure whereas the Domino joint took only 597 pounds to cause failure. I suppose one could accuse FWW of rigging the test but Festool is a far more important advertiser than Dowelmx. I really can't understand their motive for doing that. I am not claiming that dowel joints will always outperform Dominos but it is obvious to me that both will serve well in the same types of applications.

For more information on the subject, a guy whose work many of you have read, Matthias Wandel, did some experiments comparing various joints. Here are links to his findings:

https://woodgears.ca/joint_strength/index.html

https://woodgears.ca/joint_strength/dowel.html

The Domino wasn't a part of his study but there is a lot of good information on the mechanics of joint failure. The dowel joint turned out to be a very capable performer. The most interesting part is that he describes a measurement methodology that is accurate enough for most purposes using only wood construction and a bathroom scale. I am always amazed at the cleverness of that guy.

Mike Henderson

12-22-2016, 5:57 PM

Art - I've repaired a lot of chairs and it's always the dowel joints that failed. You can do the math and see that dowels do not provide as much long-grain-to-long grain glue surface as a mortise and tenon that can be put in the same area as the dowels. And when those chair joints fail, it's the wood that fails, meaning that the dowel has wood attached to it when you disassemble the joint. It's not a glue failure.

This leads to the conclusion that there's not enough glue surface area to spread the force and the wood, itself, fails. Tenons provide greater long-grain-to-long-grain glue surface area (in the same space as the dowels) and spread the force over a greater surface area, leading to reduced failures.

I've seen many, many chair failures in the back joint where dowels are used. So my experience and the mathematics both say that dowels will not perform as well in that particular joint as mortise and tenon.

Dowels are perfectly adequate in less stressed joints but they do not produce a joint that's as strong as mortise and tenon.

Mike

[Two additional points:
1. When dowels fail in a chair joint, they fail in the back upright back support, not in the seat side rail. The reason is that the dowel in the seat side rail is all long-grain-to-long-grain glue surface so it has twice the long-grain-to-long-grain glue surface area as the back upright support (half of the dowel in that part is facing end grain).

2. When I repair a chair with that kind of joint failure, I replace the dowels with a loose tenon, essentially the same length as the dowels, and epoxy glue. I've never had a chair come back to me.]

[I've posted, a number of times, the mathematics to show that tenons that fit into the same space as dowels have more long-grain-to-long-grain glue surface area, but I'll post it again here if anyone wants me to.]

Art Mann

12-23-2016, 12:36 AM

Jim Dwight

12-23-2016, 9:01 AM

I've reviewed both the FWW and Wood joint strength tests and re-reviewed the Woodgears test this morning. I agree with Mike that the long grain area that is glued to both pieces is the best indicator of strength. I checked a few of the joints in either the FWW or Wood tests (can't remember which) and it explained their results well. The tests are somewhat flawed because they pretend to tell us which joints are best but the contact areas are quite different affecting the tests more than the joint construction. In one of the tests, they used a loose tenon about the same size as the traditional mortise and tenon. It failed at almost exactly the same force as the traditional. But the domino joint failed much earlier because it was much smaller.

Woodgears original result was about 25% less strength in a dowel joint as compared to a mortise and tenon. Then he got leaned on my Dowelmax and retested with a smaller tenon and got closer but the M&T was still stronger. I think 25% is about right. I think Mike is also right that in many cases this won't matter. But for chairs, I wouldn't use dowels. If nobody leans back, the dowel joints will probably work right. But in a light chair, with heavy people that do lean back, I want M&T. I have 4 chairs built this way as does my daughter and they've support 300 lb people with no issue. My son has four that are a little bigger cross section (due to the design he wanted) and they are working well too.

I wouldn't spend $300 on a dowel jig, I spent a little less on a Jet hollow chisel mortiser. With it and a shoulder plane + my table saw I can make M&T joints quickly enough. My lighter chairs actually have mortises made with a plunge router and jig. The routed mortises are nicer but Woodgears also tested M&T joint fit and found it didn't affect strength (within reason).

If you are going to get good at a few joints, M&T seems a better way to go to me than dowels. But if you want to go dowels, just be a little careful in the design. For drawers, I am setup to do machine dovetails because they are the best joint for that application. I doubt I will get good at every joint but I decided to get set up and reasonably proficient at the joints that I think are best.

mreza Salav

12-23-2016, 9:17 AM

Every joint making tool has its own place and applications. I have both version of Jessem doweling jig, have had both versions of Domino, and a tilting head mortiser (sold that one actually). Most often I use Domino but there are situations (like a big entry door) where I'd use a true M/T. I also still use dowels as that gives me the most accurate joint of all IMO (for example, I had to join some walnut plywood in width to get a 80" wide section and dowels gave very flush surface that required no sanding of the seam). For my passage doors I used 1/2"x5" dowels (32 of them in a door) and I think they are as strong as any other joint.

Mike Henderson

12-23-2016, 2:48 PM

Like you, I have repaired several chairs over the years that were doweled together. Perhaps you fix more of that kind of failure because there are so many more chairs built that way. All the failed dowel joints I have fixed were originally constructed using hide glue and undersized and short dowels. What do you think might have happened if those makers had used long large diameter dowels and epoxy or PVA for an adhesive? When I make new furniture, I don't have either of those problems. I just don't think your chair repair experience can be used to conclude that dowel joints are a substandard joinery technique. What do I know? I have only been using dowels to build furniture and cabinets for 40 years without any failures so far. Maybe all that stuff will fall apart tomorrow.

The failures I see are not glue failures - it's the wood that the dowel attaches to that fails. And most of the doweled chairs that I repaired were factory made and the dowels were fully inserted into the holes, and I have no reason to suspect the fit was not good when they were first made.

No matter how you slice it, if you do the math, you'll see that a tenon that fits into the same space as the dowels will have more long-grain-to-long-grain surface area and that's the best indicator of the strength of a stressed joint, such as you see on the back of a chair.

But this is easy for anyone to test for themselves - there are many, many commercially made chairs with two dowels in that joint. Offer to repair one of those chairs for a friend. Take the joint apart and look at the dowel that you pulled out of the hole that failed. It will have wood sticking to the dowel, and the hole will be larger than the dowel because of the wood pulled away from the back support. If you put another dowel of the same size in that hole, it will rattle around.

Make a mortise in that location and in the seat side rail and put in a loose tenon that is as wide as the outside spacing of the two dowels, and as deep as the dowels were. Glue with your choice of glue and return to your friend. I'll bet your friend never brings that chair back to you (but they will bring the rest of the set to you to repair:) ).

Incidentally, the Domino works great for these mortises. If you want a mortise wider than normal for the Domino, just move the tool over and plunge again. You can make your own loose tenons or glue two Dominos together to make a wider tenon.

Mike

[That particular joint on a chair is an excellent "real world" test of joinery in a long-term high stress environment.]

Sean Tracey

12-24-2016, 12:27 AM

Jim Dwight

12-24-2016, 8:15 AM

Another simpler way to look at the strength question is to observe who tells you what. The ONLY people saying dowels are stronger are the companies who sell dowel jigs. The other tests say they are one of the stronger joints but not the strongest. In other words, a pretty good joint.

Roger Marty

12-24-2016, 9:05 AM

I have this Woodcraft jig and I think it is great:

http://www.woodcraft.com/product/124315/premium-doweling-jig.aspx

As far as doweling vs. M&T-- I love the ease and speed of dowel joints. I made 12 web stretcher frames using dowel joints since to me it seemed like the extra strength of M&T didn't matter (and they were then dadoed into a solid carcass). But for a post-and-panel dresser I'm starting, I'll go with M&T because those joints will bear the full weight of the drawers.

Sean Tracey

12-24-2016, 2:47 PM

R. Bruce Hoadley (of the books "Understanding Wood" and "Identifying Wood") wrote an article in an early FWW magazine where he analyzed the failure of joints, such as the joints on the rear of chairs. His conclusion was that the failure was due to wood failure and not glue failure. That is, the wood separated at the joint - there was a thin layer of wood still attached to the glue (I've seen this in failed joints).

This leads to the conclusion that the greater the effective gluing surface, the stronger the joint. And as shown earlier, most dowel joints do not have as much effective glue surface as a M&T joint. [When a dowel is put into the end of a piece of wood, all of the area is effective gluing surface so this statement applies to dowels that go into the 'side" of another piece of wood, where half of the dowel is facing end grain. So if you wanted to attach two pieces of wood end-to-end, dowels may make the stronger joint.]

Mike

I think you reached a conclusion that is not always correct. The wood failed, not the glue. So you propose to add more glue area. The glue area was obviously large enough that the wood itself broke somewhere. When you make a mortise and tenon joint in wood, you reach a point where the tenon is so large that it weakens the joint because the walls of the mortise are too thin. Conversely, you can make a mortise and tenon joint where the walls of the mortise are quite strong but the tenon is not strong enough. Since wood is not a homogenous material and since different loads will cause vastly different breaking strenghts depending on load type and direction, there is a lot of variability in what makes a given joint the strongest. Proportions and wood grain can cause unexpected results.
l
In general, Mortise and tenon are quite strong joints. However, Dowel joints are easy to make with the new jigs from Jessem and Dowelmax. I've made cabinets with strings of dowels several feet long and every single one of them fit perfectly. Dowel joints are very useful in casework where the alignment they provide is a huge benefit. Dowelmax and Jessem can be used to position the dowel holes in both directions to extreme accuracy due to repeater bars and positioning the next set of dowel holes incrementally off the last set. You can use these jigs to replicate the work of a multi-spindle drilling machine used to make cabinet case work.

As a young man, I learned the importance of roundness and precision location. My boss had designed a metal stamping die that did not use dowels to locate the parts of the die. Instead it used the outside of the die parts which were sort of trapezoidal to fit in a trapezoidal mortise to high precision. It was damn near impossible to assemble. Had it been made with dowel positions, it would be much easier to align the parts of the die and press them together with a lower likelihood of cocking the parts.

Dowels add a mechanical lock due to the swelling of the compressed material while mortise and tenons have clearance and no compression as cut. So a straight mathematical calculation of glue joint surface area doesn't tell you the complete picture.

So as far as joints go, dowels, loose tenons, and M&T all have their place and dowels may surprise you in strength compared to loose tenons and M&T depending on the joint and the particular pieces of wood being joined. I can definitely see a well designed dowel joint beating loose tenons and M&T joints at least occasionaly depending on the joint and wood involved.

John Lankers

12-24-2016, 4:16 PM

Mike, Art, I think you both are raising valid points here. A m/t joint is usually laid out and executed with great care and a dowel joint, which can also be very strong when done properly, is often chosen to save time and it is easier to do for lesser skilled workers in a factory setting.
However, when I picture a 2 x 4 and a 2" dowel, which could be compared to a tenon and a dowel in furniture construction, the 2 x 4 would be much stronger than the 2" dowel when used as a lever.

jack duren

12-24-2016, 10:43 PM

I started using dowels in a cabinet shop in 83. Love em, but I know better in certain situations. Anyone can argue but experience tells you whether this or that is appropriate especially when it comes to keeping a roof overhead.

I still to this day, use my trusty Craftsman dowel jig. It was used when I bought it from an old woodworker when he died in 83 and his family sold off his shop. If you want one on the cheap these work fine. I use to use the doweling machine in the day. Like to have one...
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Mike Henderson

12-25-2016, 12:18 AM

I think you reached a conclusion that is not always correct. The wood failed, not the glue. So you propose to add more glue area. The glue area was obviously large enough that the wood itself broke somewhere. When you make a mortise and tenon joint in wood, you reach a point where the tenon is so large that it weakens the joint because the walls of the mortise are too thin. Conversely, you can make a mortise and tenon joint where the walls of the mortise are quite strong but the tenon is not strong enough. Since wood is not a homogenous material and since different loads will cause vastly different breaking strenghts depending on load type and direction, there is a lot of variability in what makes a given joint the strongest. Proportions and wood grain can cause unexpected results.
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In general, Mortise and tenon are quite strong joints. However, Dowel joints are easy to make with the new jigs from Jessem and Dowelmax. I've made cabinets with strings of dowels several feet long and every single one of them fit perfectly. Dowel joints are very useful in casework where the alignment they provide is a huge benefit. Dowelmax and Jessem can be used to position the dowel holes in both directions to extreme accuracy due to repeater bars and positioning the next set of dowel holes incrementally off the last set. You can use these jigs to replicate the work of a multi-spindle drilling machine used to make cabinet case work.

As a young man, I learned the importance of roundness and precision location. My boss had designed a metal stamping die that did not use dowels to locate the parts of the die. Instead it used the outside of the die parts which were sort of trapezoidal to fit in a trapezoidal mortise to high precision. It was damn near impossible to assemble. Had it been made with dowel positions, it would be much easier to align the parts of the die and press them together with a lower likelihood of cocking the parts.

Dowels add a mechanical lock due to the swelling of the compressed material while mortise and tenons have clearance and no compression as cut. So a straight mathematical calculation of glue joint surface area doesn't tell you the complete picture.

So as far as joints go, dowels, loose tenons, and M&T all have their place and dowels may surprise you in strength compared to loose tenons and M&T depending on the joint and the particular pieces of wood being joined. I can definitely see a well designed dowel joint beating loose tenons and M&T joints at least occasionaly depending on the joint and wood involved.
Well, you can believe what you want but on chairs, in that back joint, doweled joints fail on a regular basis, and loose tenon (or full M&T) joints rarely fail. I haven't had to repair a chair with a M&T joint in that location but part of the reason is that there are few commercial chairs that are made with M&T joinery there.

As I've said many times earlier in this thread, dowel joints can be used quite successfully in many places in furniture making - but M&T joints are stronger and should be chosen for high stress locations. Specifically, the back joint on a chair and the attachment of the legs to the apron on a table (people grab a table and drag it to a new location. The length of the leg causes great stress to the joint where the leg joins the apron.)

Mike

[It's unlikely that you would "weaken" the joinery members by putting in a M&T. In a chair, for example, the back member will be over an inch wide and we usually put in a 3/8" thick tenon. Additionally, for most M&T joinery, we do not go completely through the member. And, in any case, we do not see joinery failure in chairs and tables where the joinery member breaks. For chairs with dowels, we see the dowels pull out of the back member. For chairs with M&T, I haven't seen any failures in that joint but neither have I seen a chair back break off, leaving a stool.

For tables, the legs are generally much larger, perhaps as much as 4" at the top. The apron is generally 3/4" material and the tenon is again generally 3/8" thick. I've never seen a leg break off from the mortise "weakening" the leg, but I have seen dowels pulled out of the leg.

Your concept of a mortise "weakening" a joint by putting a mortise into it simply does not hold water. We just don't see joinery members breaking because of well made M&T joinery.]

Brian Brightwell

12-25-2016, 11:09 AM

Good write up Sean.

jack duren

12-25-2016, 11:14 AM

Good write up Sean.

Really....I'll side with Mike on this one..

Let the party begin..............
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Glenn de Souza

12-25-2016, 12:02 PM

When you make a mortise and tenon joint in wood, you reach a point where the tenon is so large that it weakens the joint because the walls of the mortise are too thin. Conversely, you can make a mortise and tenon joint where the walls of the mortise are quite strong but the tenon is not strong enough. Since wood is not a homogenous material and since different loads will cause vastly different breaking strengths depending on load type and direction, there is a lot of variability in what makes a given joint the strongest. Proportions and wood grain can cause unexpected results.

You've touched on an interesting and valid point. When joining two members, there is a balancing act between the size of the joint and the weakening consequence of removing wood to make way for the joint. This doesn't have to do with the dowel vs. M&T debate that is going on here but has to do with optimal joint design using either approach, or any joinery method for that matter. The 1/3 thickness tenon rule was mentioned earlier in this thread which is a good rule for M&T.

I enjoy seeing these tests that measure the lever force exerted on a right angle joint to see where the breaking point occurs. However it's important to remember that a properly designed piece of furniture will create an assembly that should not be exposed to bare levered force like that. Even a table apron without a stretcher is secured in two directions (planes) so it would need to break in two places at least, and maybe three or more. This is not to mention the incidental racking support of the top which is secured to the apron/leg assembly using your attachment method of choice (although I will agree, the chair back situation that Mike is referencing is a particularly stressful joint).

This is why both joinery methods if well made and properly glued should be more than adequate for most appropriate applications. This is also why I believe design has more to do with failure than joinery method unless the joinery method really violates rules and good sense. Otherwise we are probably splitting hairs between each other in terms of strength.

I like using conventional M&T, loose tenon M&T,and I happen to have a Jessem Dowel jig which I think is unbelievably accurate and efficient to use. I've never seen one of my dowel joints fail, but then I've never seen one of my own M&T joints fail either. Everyone is entitled to their personal favorite method. Some prefer Ferraris, some prefer Corvettes. They're both pretty fast.

Since the original post has to do with dowels and dowel jigs, here's a question that I've always wondered about - Which situation would be better/stronger? Using fewer longer or larger dowels, or using more smaller dowels? For example, in a joining two 3/4" thick pieces, if you had the choice of four 3/8" diameter dowels in a row vs seven 1/4" diameter dowels staggered in two rows like Jessem shows, which would be your choice?

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Jerome Stanek

12-25-2016, 3:25 PM

I have the one like the Wood Craft one and when was out of town I needed it but left it home. I went to Harbor Freight and they had the same kind but for about $15 instead of the $66 that works just as good. That is the one I carried when I traveled

Art Mann

12-25-2016, 8:22 PM

I think it is time to put this thread into perspective. The original poster, wherever he may be 4 years later, asked which is the best dowel jig to buy. He was not looking for anyone's opinion on whether dowels were a good method of furniture construction. Nevertheless, Mike Henderson and a few others felt it necessary to make comments that cast doubt on dowel joinery. Other people attempted to refute those comments. Some of them have been woodworking a very long time and are not exactly what you would call questionable sources of information.

A few people questioned the ability of these jigs to line up dowel holes properly in challenging situations. They obviously had not tried any of the recommended ones or they wouldn't have even asked the question. People who want to really be informed should watch the demonstration videos on the manufacturer's website. Uninformed opinions sometimes just make people who offer them look uninformed.

At one point, Mike offers "proof" that dowels are not good because he has repaired a lot chairs with failed dowel joints. This sounds to me like coming to the conclusion that Toyota Camrys are unreliable because so many of them have to be repaired. Could it not be that more Camrys (or dowel joints) had to be repaired because there is a higher percentage of them. I don't know the answer to that but it is possible. The few doweled together chairs I have worked on were around 100 years old. The failure of the dowel joints was due to small and short dowels and the failure of the hide glue. I fixed at least one I remember by drilling out the dowel holes to a larger bore and inserting new ones. It has been a long time now and I haven't heard any complaints.

Mike and others just assumed that the mode of failure for typical wooden joints is glue failure. I disagreed with that assertion and pointed out a couple of reliable sources that contradict this opinion. At least one person didn't see the point. Anyone who is interested can read the information, look at the photos and judge for themselves. I posted links. There are many other sources if you dig for them. Joint integrity is a much more complex subject than just declaring one type of joint is always decidedly inferior and another is always the best.

Some people offered the opinion that mortise and tenon joints are stronger than dowels. I have never said otherwise, although there are a few special circumstances where this has been the case. My comments don't refer to M&T. I used to use it fairly often until I began failure testing dowel construction for the same applications using a Dowelmax jig. My experience showed that dowels were more than adequate for my purposes. I sold my hollow chisel mortiser and began using dowels instead in order to get more work done. I have yet to receive a complaint and I don't regret my decision.

At some point, the Domino machine came out and people started claiming that the joints are stronger than dowels without offering experimental evidence. For the most part, anecdotes are useless. I personally can't say for sure because, as someone pointed out, the geometry of the joint makes a big difference in which construction is more appropriate. I think it could go either way depending on the circumstances. My conclusion is that either method is more than adequate in most applications. M&T joints just aren't worth the effort if the joint isn't going to fail anyway. With the limited amount of this type of joinery I do, I just can't justify a Domino machine at way more than twice the price of the dowel solution, especially since I already own a Dowelmax. I like the concept and maybe some day I will get annoyed enough to buy a Domino. Right now, I am contemplating buying the Jessem jig because it does offer some advantages over the Dowelmax.

Mike Henderson

12-25-2016, 9:50 PM

Art - I never, ever, said that the failure mode for doweled joints in chairs was glue failure. In fact, I said the opposite. The glue does not fail, the wood fails. It's really true that glue is stronger than the wood.

My comments are based on observation as well as mathematical analysis. I've shown that a tenon that fits into the same space as dowels will have significantly greater long-grain-to-long-grain glue surface area. My contention is that, based on the observations I've made of the failure of the wood in high stressed dowel joints, the reason for the failure is because the wood attached to the dowel fails. I've pointed out that when the joint is disassembled I find wood still attached to the dowel and the dowel hole is larger than the dowel.

I've also pointed out that when these chairs are repaired with a loose tenon that is the width of the location of the two dowels, and the same thickness as the dowels, I do not have any failures reported to me.

If someone else would like to offer a good logical explanation of why they think dowels are as strong as M&T, and especially if they could back their explanation with a mathematical basis for their explanation, I'd like to hear it.

And I would contend that observations from real world joinery failure in long term high stress conditions are more valid than any short term test. The short term tests are actually attempting to duplicate the things we see in the real world and may, or may not, do a good job of duplicating those conditions.

I'm quite convinced that M&T joinery is stronger than dowels and is the joinery of choice for high stress locations, such as chair back to seat attachment or for attaching legs to aprons on tables.

Mike

[Also, my observations are subject to checking by any one of you. There are many, many failed dining room chairs in the US. Ask around and you'll get lots of offers if you say you'll fix one. Take it apart and observe for yourself the condition of the dowels and the holes for the dowels - and which member the dowel failed in: the back leg or the seat side rail. I think you'll find what I described above. Repair it with a loose tenon of the proper size and see if it comes back to you.

If you go to repair a doweled joint you may have a problem extracting the dowel from the hole, even though the dowel is loose in the hole - which means you can't easily get the joint apart. I discovered the reason is that the wood in the rear of the dowel sometimes breaks with larger pieces attached to the dowel than in the front of the dowel. So the dowel hole is larger in the rear than at the surface of the wood. In those cases, you'll have to disassemble the joint by using a thin saw (I use a Japanese saw) to cut the dowels and get the joint apart. Then, you may have to drill out the dowel (jam it first to keep it from spinning). Use a smaller drill bit and then break the dowel into pieces to extract it. When you extract the pieces you'll see the wood attached to the back of the dowel.

An additional comment is that we've had many comments about failed dowel joints in this thread but no one reported a failed M&T joint during this discussion.]