Drawbored Loose Tenons for Edge Joining

[Stanley Covington]

Richard Maguire posted an article on his website The English Woodworker about his mistrust of edge joints that rely solely on glue, and how he prefers to add drawbored loose tenons in addition to glue to reinforce such joints.

I will not post the excellent pictures from his webpage to this post, but urge you to take a gander at the article.

http://www.theenglishwoodworker.com/trust-or-reinforce/

It looks like a solid and even decorative way to edge join largish planks, such as thick tabletops, benchtops, and perhaps even some exposed structural applications. The latter is my primary interest.

I have used dowels, biscuits, slips, and even nails for the same purpose, but never a drawbored tenon, and am curious about several points, including splitting, potential difficulty in aligning the plank's top faces, and most importantly, the possibility of such large cross-grain tenons causing the joint to fail with dimensional changes to the boards due to humidity swings and exposure to rain.

Anyone have experience with this interesting joint?

Do you know if it used for shipbuilding?

Stan

[steven c newman]

The Greeks used for their ships.......

[Stanley Covington]

The Greeks used for their ships.......

Steve:

Thanks. Any idea where I can find a reference?

BTW, I used to live in Ohio, and it was said you could stand on a tuna fish can and view the entire state with a strong telescope. Where is the "Peak of Ohio?"

Stan

[steven c newman]

Look up the ships called Tiremes ( sp).....as in the navy from Athens that beat the Persians. There is now a replica of one of their ships in a museum.

Campbell Hill in Logan County, OH. Mad River Mountain Ski Resort is just south of there. I'm in Bellefontaine, OH. You can see quite a ways, from the JVS School located on that hill. Was the site of an Air Force Radar station, and I think one or two of the old Radome bases are still there.

[Stanley Covington]

I will look up the ships. Thanks.

I have been through Bellfontaine a few times. Nice town.

I used to live in Dublin, and later in Galena, a couple of hundred yards East of Alum Creek Reservoir. I wish I was there now to see the dazzling Autumn colors on Africa Road.

Stan

[Derek Cohen]

Stan

My concern with this approach is the introduction of additional stresses into the joining boards. The drawbore will pull the seams together. In a mortice and tenon, this is end grain to face/edge grain. On a tabletop it is edge-to-edge grain. Where there is not a good fit, and the drawbore pulls the seams together, will this introduce stresses that will be forced to escape elsewhere? I ask the question - I do not know.

Usually, when biscuits or Dominos or splines are used to align boards, my practice has been to glue just glue the one side, not both. Dovetails are used to stabilise, not pull together.

Lastly, is there any historical evidence of a drawbored, loose tenon tabletop?

Regards from Perth

Derek

[Stanley Covington]

Stan

My concern with this approach is the introduction of additional stresses into the joining boards. The drawbore will pull the seams together. In a mortice and tenon, this is end grain to face/edge grain. On a tabletop it is edge-to-edge grain. Where there is not a good fit, and the drawbore pulls the seams together, will this introduce stresses that will be forced to escape elsewhere? I ask the question - I do not know.

Usually, when biscuits or Dominos or splines are used to align boards, my practice has been to glue just glue the one side, not both. Dovetails are used to stabilise, not pull together.

Lastly, is there any historical evidence of a drawbored, loose tenon tabletop?

Regards from Perth

Derek

Thanks for the observations, Derek.

If the board's edges are not planed to match for a tight fit, or if the boards were sprung a great deal, then it seems clear the stresses you mentioned might be a fatal problem because the stresses on the pins close to the board's edges will tend to split the boards, especially if there is a gap between the boards that would allow the cracked edge to expand into relieving the stresses.

But if we assume both edges are planed to close tightly, as a good edge-to-edge joint should be, glue is used, and the loose tenons are only reinforcement perhaps intended to keep the boards tightly joined even if the glue fails, then it seems that the stresses might work. And if the drawbore work is done precisely, it seems that would not be a big problem since there would be no large space for the cracked edge to expand into since opposing edges would tend to contain any cracking induced expansion. Does that make sense?

Re historical examples of tabletops, I don't know of any, But I have seen large and heavy oak doors in cathedrals in Europe made of multiple shiplap boards joined with a rectangular cross section wooden stick, as long as the door is wide, and penetrating all the way through each board through aligned mortises/slots cut entirely through each board. The one I recall had 5 or 6 of these horizontal sticks (long, full-length, through tenons?) holding the door together, and pinned at their ends. As a matter of fact, there is a BBC program with Ruth Goodman about building a castle (Guidelon?) in France that shows part of the process of making such a door.

Not sure if they were drawbored or not. Not the same thing as what Mr. Maguire uses, but there are some similarities.

I have always thought it would make a cool table, but the chance has not presented itself. The loose tenons Mr. Maguire uses seem like an interesting alternative.

Stan

[Wayne Lomman]

This is a good concept. It doesn't introduce any different stresses that clamping and gluing any misaligned joint would have anyway. If done poorly, of course it will cause problems, the same way as poor work causes problems everywhere. I'll give it a go for sure. It's the first decent alternative to glue I have come across. Cheers

[Patrick Chase]

The Greeks used for their ships.......

Makes sense as they lacked waterproof adhesives back then. I'm less convinced that it makes sense now, or for less demanding applications like furniture.

[Pat Barry]

A variation on this technique works great for breadboard ends but is totally unnecessary for edge glued boards.

[Patrick Chase]

Richard Maguire posted an article on his website The English Woodworker about his mistrust of edge joints that rely solely on glue, and how he prefers to add drawbored loose tenons in addition to glue to reinforce such joints.

I think that the question one has to ask here is whether his mistrust is well-founded or even remotely rational.

Edge joints consist of a very large long-grain to long-grain interface with ~identical direction. Long<->long grain is basically the poster child application for glue, in the sense that it's the one and only case where it actually performs as claimed/advertised. The fact that the directions are the same (as opposed to something like the cheek interface of an M&T, which is also long-to-long but where they're at 90 deg) means that you don't have internal stresses that accumulate as the wood tries to differentially expand/contract with moisture changes.

His comparison to apron end-grain joints is irrelevant and specious, because such joints are worse in both respects: First, they're end-grain to long-grain, meaning that the glue's bond strength is greatly reduced. Second, the bonded surfaces have different grain direction, meaning that they build up internal stresses as moisture content changes. A purely glued apron joint is vastly weaker than a purely glued edge joint, and that's why we reinforce them as he describes.

I note with interest that the one thing he doesn't say in the article is that he's actually seen a properly glued edge joint fail. This appears to me to be a case of irrational paranoia.

One thing he didn't go into but that is a valid concern IMO is the longevity of common wood glues (PVA) in particular. As I understand it there are concerns about what happens to those after, say, a century or two. If I were going to be paranoid about edge joints I'd worry about glue selection rather than about mechanical reinforcement.

[Stanley Covington]

A variation on this technique works great for breadboard ends but is totally unnecessary for edge glued boards.

Pat:

I don't mean to be confrontational, but is this just your opinion, or have you tried loose, drawbored tenons for edge-joined boards before? If you have experience using this technique, how did it fail to meet your expectations?

Thanks.

Stan

[brian zawatsky]

This technique works great for breadboard ends but is totally unnecessary for edge glued boards.

I agree. Seems like a lot of totally unnecessary work where a glued joint would more than suffice, although I suppose that would depend upon the application.
In shipbuilding perhaps necessary, in furniture way overkill.
I suppose if one had way too much time on one's hands and wanted to make a simple glued panel joint take 5 times longer and much more difficult, this would be the way to go.

[Patrick Chase]

Lastly, is there any historical evidence of a drawbored, loose tenon tabletop?


More to the point is there historical evidence of glued edge joints failing in significant numbers?

Smart and experienced people do irrational stuff all the time - It's sort of a fundamental trait of humanity, from which all of us suffer in varying ways. Historical evidence of drawbored joints therefore doesn't tell us anything about a rational need to use them (after all, there's historical evidence of the extraordinarily high value of both Dutch Tulips and low-tranche mortgage-backed securities). We'd need to have evidence that the glued sort actually fail to justify that.

[Patrick Chase]

Pat:

I don't mean to be confrontational, but is this just your opinion, or have you tried loose, drawbored tenons for edge-joined boards before? If you have experience using this technique, how did it fail to meet your expectations?

Thanks.

Stan

When you're talking about doing additional work above baseline, "will it work" isn't the relevant question. Of course it will. You don't want to overdo the tension when drawing cross-grain, for the reasons Derek outlined, but other than that it's a well-proven technique.

The question to ask is "does it fix a real problem", and that's where I think Richard's piece is extremely weak.

If you like the decorative aspects then you're using it to fix a different problem (appearance rather than strength) and I would have no qualms about that.

[Stanley Covington]

I think that the question one has to ask here is whether his mistrust is well-founded or even remotely rational.

Edge joints consist of a very large long-grain to long-grain interface with ~identical direction. Long<->long grain is basically the poster child application for glue, in the sense that it's the one and only case where it actually performs as claimed/advertised. The fact that the directions are the same (as opposed to something like the cheek interface of an M&T, which is also long-to-long but where they're at 90 deg) means that you don't have internal stresses that accumulate as the wood tries to differentially expand/contract with moisture changes.

His comparison to apron end-grain joints is irrelevant and specious, because such joints are worse in both respects: First, they're end-grain to long-grain, meaning that the glue's bond strength is greatly reduced. Second, the bonded surfaces have different grain direction, meaning that they build up internal stresses as moisture content changes. A purely glued apron joint is vastly weaker than a purely glued edge joint, and that's why we reinforce them as he describes.

I note with interest that the one thing he doesn't say in the article is that he's actually seen a properly glued edge joint fail. This appears to me to be a case of irrational paranoia.

One thing he didn't go into but that is a valid concern IMO is the longevity of common wood glues (PVA) in particular. As I understand it there are concerns about what happens to those after, say, a century or two. If I were going to be paranoid about edge joints I'd worry about glue selection rather than about mechanical reinforcement.

One man's paranoia is another man's due caution. Belt and suspenders. Knocking on a stone bridge before crossing.

I am more concerned about the potential downsides to this technique, rather than its practical necessity.

Stan

[Art Mann]

Sounds like a solution still looking for a problem to solve to me.

[Pat Barry]

Pat:

I don't mean to be confrontational, but is this just your opinion, or have you tried loose, drawbored tenons for edge-joined boards before? If you have experience using this technique, how did it fail to meet your expectations?

Thanks.

Stan
No, never tried it. Never occurred to me to try it. Now that I've heard of it and thought it over I see no benefit. If, on the other hand, you were making some ginormous table top (very thick), and you has no glue to work with, and didn't want to use battens, and wanted to do a huge amount of extra work to create all the needed mortises, then I suppose you could make some strong connections. I'd still rather use glue and a traditional edge glued joint though.

[Wayne Lomman]

Doing extra work for just for the sake of it is a sin? Am I actually in the right forum? If that is the standard by which all techniques are measured, then throw away your hand tools because machining is quicker. It is a possible solution to a problem, not a panacea. If you don't have a use for it, don't use it. If you don't buy his paranoia, ignore it. And since when were synthetic glues traditional? Myself, I now see a way to make a table entirely glue free regardless of the ideology of the person who introduced me to the concept. Cheers!

[steven c newman]

They built these ships this way, due to a lack of glue that was waterproof. The ships were built fast, were made light, and not much draft. Never really left the sight of land, because, come nightfall, those lightweight ships were dragged ashore by their crews. The loose tenons and pins....as soon as the wood planks they held together get wet.....the planks would swell, and the joints pulled tight together, held by those pins. They MAY have added some fibre caulking between the planks, the rest of the "sea-worthy-ness" was due to the pinned tenons. These were the ships that featured three levels of rowers on each side. and a ram on the prow with enough Bronze to make L-N jealous...

[Stanley Covington]

Doing extra work for just for the sake of it is a sin? Am I actually in the right forum? If that is the standard by which all techniques are measured, then throw away your hand tools because machining is quicker. It is a possible solution to a problem, not a panacea. If you don't have a use for it, don't use it. If you don't buy his paranoia, ignore it. And since when were synthetic glues traditional? Myself, I now see a way to make a table entirely glue free regardless of the ideology of the person who introduced me to the concept. Cheers!

Thanks, Wayne. My thoughts exactly.

I don't know if I will ever use this technique, but it is another way to get the job done, and even though it takes more work, and certainly would not be called for most of the time, it seems to add value. That makes it worth looking into, IMO.

I am dissapointed that so many seem to lack curiosity about an ancient, time-tested technique, one that humans used to trust with their very lives.

Stan

[Pat Barry]

Thanks, Wayne. My thoughts exactly.

I don't know if I will ever use this technique, but it is another way to get the job done, and even though it takes more work, and certainly would not be called for most of the time, it seems to add value. That makes it worth looking into, IMO.

I am dissapointed that so many seem to lack curiosity about an ancient, time-tested technique, one that humans used to trust with their very lives.

Stan
steven nailed the rationale for the joint being used in ships. What he presented made perfect sense. Wooden water pails, barrels, etc also rely on the moisture causing the wood to swell and tighten up all the joints and make the pail water tight. I just can't see that sort of thing happening on a table top is all. It sounds like Wayne may be ripe to build one that way though. It would be interesting!

[Wayne Lomman]

I do have a quantity of Huon pine put aside for something special... Cheers

[Derek Cohen]

Hi Wayne

Lucky dog! Huon is very special. Birds Eye Huon is the most prized of Australian timbers.

Here is a bowl in Birds Eye Huon Pine ..

http://i13.photobucket.com/albums/a262/Derek50/Other/HuonPine.jpg

Use your Huon wisely. I would would not add in drawbored anything. The beauty of this wood lies in its simplicity and clarity. Anything else distracts.

Regards from Perth

Derek

[Stanley Covington]

Hi Wayne

Lucky dog! Huon is very special. Birds Eye Huon is the most prized of Australian timbers.

Here is a bowl in Birds Eye Huon Pine ..

http://i13.photobucket.com/albums/a262/Derek50/Other/HuonPine.jpg

Use your Huon wisely. I would would not add in drawbored anything. The beauty of this wood lies in its simplicity and clarity. Anything else distracts.

Regards from Perth

Derek

Beautiful!

[Curt Putnam]

I have long been of the opinion that doing anything to an edge joint (other than jointing it) can only weaken the joint, If one subscribes to the dogma that says glue is stronger than wood, then anything one does to the joint cannot strengthen it; it can only be weakened, or in the best case, a neutral outcome. If you cannot improve it, why go to the effort?

[Stewie Simpson]

A quick glance of Richard Maguire's article and I beginning to visualize the merit of this as an alternate approach to a knock down joint,http://www.technologystudent.com/joints/kdown1.htm. But as I delved much further into the article it dawned on me that Richard was prescribing a permanent glued joint. Based on that value there are better options available such as biscuit and domino, where once the pva glue is applied, swell within their machined slot creating an even stronger bond than a glued line can provide. But it needs to be aligned with the fact there are also much stronger glues available on the market nowadays than pva or traditional hide glue. There are the additional labour costs involved in using this technique, bearing in mind that Richards focus should also be in tune with keeping his labour costs down to remain competitive. The visual interruption the exposed dowels will have on the final appearance of the bench top is also a noteworthy consideration. No details have been provided by Richard on the recommended spacing, or how far in from the edge the drawbore dowels need to be placed to achieve maximum effectiveness. The other noteworthy consideration is the ideal moisture level within these boards prior to permanent bonding.

Putting all that aside, its another option available.

Stewie;

[Eric Brown]

I think that the pins holding the tendons will not grow/shrink at the same rate as the top. This means that sometime the pins may be above or below the top. I want a flat workbench, not one with obstacle's. A better way might be to use threaded rods to put the top together. That would provide a constant force that would keep the top together. With a little creative effort the ends of the rods could be stopped short of the outer edge and a wrench from below can tighten it up.
My maple/walnut bench was glued up using Titebond years ago with just edge joining and I see no issues requiring additional support. I think the "solution" is trying to fix a problem that doesn't exist. Just my 2 cents worth.

[Stanley Covington]

I think that the pins holding the tendons will not grow/shrink at the same rate as the top. This means that sometime the pins may be above or below the top. I want a flat workbench, not one with obstacle's. A better way might be to use threaded rods to put the top together. That would provide a constant force that would keep the top together. With a little creative effort the ends of the rods could be stopped short of the outer edge and a wrench from below can tighten it up.
My maple/walnut bench was glued up using Titebond years ago with just edge joining and I see no issues requiring additional support. I think the "solution" is trying to fix a problem that doesn't exist. Just my 2 cents worth.

I think you make a valid point about the ends of the pins either projecting from, or alternately, being recessed within, the surface of the workbench or table with variations in moisture content. Not really a problem for the rustic furniture and exterior applications I have been considering.

Thanks for the thoughtful insight. This is the sort of useful comment I hoped for.

Stan

[Frederick Skelly]

Lots of interesting discussion here. For me, it's another "tool in the tool kit". I'm glad to be introduced to it, even if I never decide to use it. Thanks guys!
Fred

[Brian Holcombe]

I think there is plenty of validity to method of joining outside of plain glue ups. Take a look a nakashima furniture, they separate the slabs by a slight gap then join them using half lap dovetails. The reason for doing this is, in my opinion, to create a nice edge along two slabs of very inconsistent grain, such a crotch flitches which feature both long grain and end grain along their interior edges.

Stan mentions exterior application and in that application a distrust of glue is plenty valid. I have a table outside that I joined with simple joinery and titebond III. Once it fails I will replace it with a table that uses self locking joinery and while I will probably glue the joints to seal them I will not have them rely upon glue to remain tight, should I recieve a commission for an outdoor table I will also build without reliance upon glue as I guarantee my work.

[Patrick Chase]

I think that the pins holding the tendons will not grow/shrink at the same rate as the top. This means that sometime the pins may be above or below the top. I want a flat workbench, not one with obstacle's. A better way might be to use threaded rods to put the top together. That would provide a constant force that would keep the top together. With a little creative effort the ends of the rods could be stopped short of the outer edge and a wrench from below can tighten it up.
My maple/walnut bench was glued up using Titebond years ago with just edge joining and I see no issues requiring additional support. I think the "solution" is trying to fix a problem that doesn't exist. Just my 2 cents worth.


I think you make a valid point about the ends of the pins either projecting from, or alternately, being recessed within, the surface of the workbench or table with variations in moisture content. Not really a problem for the rustic furniture and exterior applications I have been considering.

Thanks for the thoughtful insight. This is the sort of useful comment I hoped for.

Stan

The peg shouldn't ever extend ("create obstacles") if you use properly dried wood. The peg's long grain is "into" the table, so it will not change length. What you have to worry about is thickness changes of the table surface itself. It will become thicker and cause the peg to recede as it absorbs moisture, and will become thinner and cause the peg to protrude as it dries. If you use dry wood to begin with then the peg shouldn't ever protrude.

Using plainsawn wood for the tabletop will also mitigate the issue (radial shrinkage being less than tangential) but IMO that just moves the problem to other aspects of the design.

On the minus side you also need to worry about the peg taking a compression set along its short axes, as in a chair's round tenons. You can mitigate that somewhat by being careful about peg orientation: If you use a plainsawn tabletop then you'll want to align the peg and top such that their tangential grain axes are the same. If you use a quartersawn tabletop then you'll want to align the peg such that its tangential axis is aligned with the top's radial axis. in both cases the peg's radial axis will be aligned with the top's longitudinal.

EDIT: Of course you can just make the peg shorter than the thickness of the table, and glue a cosmetic plug or cap over it with identical grain orientation to the tabletop. That should fix the cosmetic issues pretty nicely, but seems like a lot of work to undertake to fix a non-problem.

[Patrick Chase]

Stan mentions exterior application and in that application a distrust of glue is plenty valid. I have a table outside that I joined with simple joinery and titebond III. Once it fails I will replace it with a table that uses self locking joinery and while I will probably glue the joints to seal them I will not have them rely upon glue to remain tight, should I recieve a commission for an outdoor table I will also build without reliance upon glue as I guarantee my work.

As I think you know (and as your wording seems calculated to allow), there are a lot of options out there besides simple butt joints and drawbored butt joints.

Techniques that add overlap such as splined joints and T&G don't provide mechanical "locking" but they do provide additional "protected" long grain to long grain glue area.

Then there are ones like sliding dovetails and various keyed spline joints that provide positive mechanical engagement.

Of course you can also simply use a truly water-resistant glue. Titebond III doesn't count IMO. The phenolic (IIRC) adhesives used in Hydrotek and similar high-end marine plys are good enough for boats that spend their entire lives in and around the water, and have also been used for structural members in wooden aircraft. I doubt an outdoor table would present much of a challenge.

[Phil Mueller]

Brian, I am assuming this is what you are referring to?:

347027

[Brian Holcombe]

As I think you know (and as your wording seems calculated to allow), there are a lot of options out there besides simple butt joints and drawbored butt joints.

Techniques that add overlap such as splined joints and T&G don't provide mechanical "locking" but they do provide additional "protected" long grain to long grain glue area.

Then there are ones like sliding dovetails and various keyed spline joints that provide positive mechanical engagement.

Of course you can also simply use a truly water-resistant glue. Titebond III doesn't count IMO. The phenolic (IIRC) adhesives used in Hydrotek and similar high-end marine plys are good enough for boats that spend their entire lives in and around the water, and have also been used for structural members in wooden aircraft. I doubt an outdoor table would present much of a challenge.

Fair points on the glue and absolutely, I wanted to leave the door open for a host of solutions.

In the Northeast outdoor wooden furniture is really put through the paces, it usually lives a fairly short life. I've studied the points of failure in local park benches and made some mental notes about what I would do or would not do in outdoor furniture. Many do crack at the point where they are draw-bored so I think it is critical to be generous with how much material is left between the pin and the tenon shoulder, or in this case the table edge.

Honestly I have a mind to make the next table in stainless steel and use a granite top, as much as I love wooden furniture it almost feels cruel to put it outside.


Brian, I am assuming this is what you are referring to?:

347027

Exactly right!

[Stanley Covington]

You make some good points, Pat, but I think Eric's point re the tabletop expanding/shrinking in thickness is still 100% valid even if well-dried lumber is used. For example, if the pins were installed flush in a mild Spring, they may well come to project above the tabletop's surface when the local humidity drops for extended periods of time during dry winter months in a heated house, and/or become depressed when local humidity increases for extended periods of time such as during hot, humid Georgia summers.

I have certainly experienced this. The most recent instance was some casework I made in Guam a few years ago from old growth cuban mahogany, a dense, hard, open-grained wood similar to Honduras mahogany but darker and with black pitch pockets. Guam's RH is 85% year round, and the wood, which was harvested 20 years or so ago and stored/misplaced in an enclosed lumber shed, was stabilized at 16%.

I glued a frame and panel lid onto a carcass and added keruing dowels vertically through the face into the carcass's sides as a precaution. Of course, they were flush when I installed them. Now, here in Tokyo and in a house with AC, the dowels are all projecting above the surface of the lid. The wood's MC is 12% in the summer. Easily fixed, but they do get in the way.

Stan

[Gene Davis]

I grew up in Summit county, OH. Don't know whether it was because the highest point in the state was there, or whether it was because the summit of the canal systems was there.

Akron is the county seat.

[Gene Davis]

Yellow glue trumps drawborn tenons, for edge joining. Now, below a waterline, things are different.

[steven c newman]

Spent a couple semesters living in North Hill Akron, and driving to Kent, OH for the weekend Hairy Buffalo.

Trying to drive through Tallemedge was nasty.....way too many speed traps. There was a hill they called Cadilac Hill......one needed an engine that strong to get up the hill. Oh, and you did NOT ever sleep with the windows open at night, or else there would be a fine coating of Carbon Black on the covers. Walking in downtown Akron back then....Quaker Oats was cooking their products.....drowned out the smell out of Firestone and Goodyear plants. I think all three are now elsewhere.

North Hill Akron, right across the Gorge. You were either Italian, or Polish, or an outsider. Never did get to eat at the Brown Derby just off St.Rt. 8.....

[Gene Davis]

My first job was at an Acme supermarket on Tallmadge right near the expressway. Lived over across the gorge in Cuyahoga Falls. Guy I went to h.s. in Akron, his family owned the Brown Derby and he owns the chain now.

[Wayne Lomman]

Derek, I am saving some King Billy pine for a really special job. Don't know what yet. I didn't know I had it for years as it was in the middle of a stack of very ordinary old radiata pine I got in exchange for a favour. Cheers

[Derek Cohen]

Wayne, Tasmania must have the best timber in the world, second to none. The chatoyance of Tasmanian Blackwood is my all time favourite.

Regards from Perth

Derek

[Derek Cohen]

About 20 years ago I did build an outdoor table that utilised pinned loose tenons in mitred joints ...

http://i13.photobucket.com/albums/a262/Derek50/Furniture/TT8.jpg

http://i13.photobucket.com/albums/a262/Derek50/Furniture/Trestletablecompleteddetail.jpg

I miscalculated the amount of expansion in the dry Jarrah top when the rains came in Winter, and they self-destructed! However, the mitred frame remained intact, holding the twisted boards captive. I replaced the boards with increased spacing, and this table continues in use today.

Regards from Perth

Derek

[Wayne Lomman]

I agree with you Derek. My son's house has a solid Blackwood staircase and handrail that has superb timber in it.
I don't use Blackwood much anymore since I found out about the unique dust hazard it has. Think asbestos fibre and that is Blackwood fibre. All the sawmills have to mill it running wet. I don't know what the cabinet shops do.

I have worked a lot with northern nsw timbers. Grey box is sensational but the stuff I had could only be worked with saw and sander. It was absolutely unplanable. Rambling again. Cheers

[Brian Holcombe]

Nicely done Derek. It appears you've also done your table a great service by putting it under an awning.

[Mike Holbrook]

Very nice table Derek!

I have been thinking about making something sort of similar with larger, rougher timber, that I hope to have access to soon. I have been thinking about some sort of retaining frame as well. With your expansion issues noted I may revise my idea to something more similar to yours.

I love the trestle base, very functional. There is a 40' x 10' covered porch over looking the Ellijay river just begging for a similar piece.

[Derek Cohen]

Nicely done Derek. It appears you've also done your table a great service by putting it under an awning.

Not quite an awning, Brian. It's a pergola covered in a grape vine. The table has suffered the West Australian heat and wet for 20 years. Amazed it has survived so well.

Regards from Perth

Derek

[Derek Cohen]

Nicely done Derek. It appears you've also done your table a great service by putting it under an awning.

Not quite an awning, Brian. It's a pergola covered in a grape vine. The table has suffered the West Australian heat and wet for 20 years. Amazed it has survived so well.

Regards from Perth

Derek

[Derek Cohen]

Very nice table Derek!

I have been thinking about making something sort of similar with larger, rougher timber, that I hope to have access to soon. I have been thinking about some sort of retaining frame as well. With your expansion issues noted I may revise my idea to something more similar to yours.

I love the trestle base, very functional. There is a 40' x 10' covered porch over looking the Ellijay river just begging for a similar piece.

Thanks Mike.

A trestle base is a great design for an outdoor table. We get 10 around this table.

I think your river setting definitely wins out as the preferred vista! :) Any pics?

Regards from Perth

Derek

[Pat Barry]

About 20 years ago I did build an outdoor table that utilised pinned loose tenons in mitred joints ...

http://i13.photobucket.com/albums/a262/Derek50/Furniture/TT8.jpg

http://i13.photobucket.com/albums/a262/Derek50/Furniture/Trestletablecompleteddetail.jpg

I miscalculated the amount of expansion in the dry Jarrah top when the rains came in Winter, and they self-destructed! However, the mitred frame remained intact, holding the twisted boards captive. I replaced the boards with increased spacing, and this table continues in use today.

Regards from Perth

DerekNice table Derek. I pictured that the pins would have cause the mitered joints to split open. What actually failed, was that it?

[Patrick Chase]

Nice table Derek. I pictured that the pins would have cause the mitered joints to split open. What actually failed, was that it?

Derek said pretty clearly that the mitered ends held such that he was able to reuse the frame, but that the boards warped within the frame and had to be replaced.

If you look at that design the obvious vulnerability is that the top and bottom frame pieces have longitudinal grain (no expansion) against tangential grain (worst-case expansion) in the boards. I say this because the grain in at least some of the boards looks plainsawn - if they were quartersawn then the mismatch would be about 2/3 as bad (using a 1.5:1 T:R ratio for Jarrah found on the Interwebs). I imagine that the boards swelled in width and then warped to relieve the pressure, which they can do in that design because they aren't tightly constrained in the vertical. This conclusion is supported by Derek's remark that the fix was to leave larger gaps between the boards the second time around.

I think that looking at good designs (which this is IMO) and trying to figure out the tradeoffs is one of the most fun parts of "vicarious woodworking".

Very nice table, Derek!

[Mike Holbrook]

Derek, I will be up at the new place this week end. I will snap a few photos. The old real estate listing pictures are gone since it sold.

I think I see drawbores/wood pins in the ends of the planks making up the table top. I missed those before the close up. So maybe the planks are not even glued together? I am also wondering if this is before the first boards warped or after the new boards were installed?

[Pat Barry]

Derek said pretty clearly that the mitered ends held such that he was able to reuse the frame.
That's why I was asking him to clarify because he said they (meaning what?) self destructed but the mitered frame remained intact. I wasn't sure exactly what it was that self destructed. I would be very surprised to find out that the boards in the field self-destructed.


but that the boards warped within the frame and had to be replaced.
He didn't actually say this

[Derek Cohen]

To clarify .. the boards within warped when they expanded and the frame did not give way. The corner joints were very strong. The frame survived, the boards did not.

Regards from Perth

Derek

[Reinis Kanders]

I have been thinking of making a table similar to Derek's. Here is the original that I liked:
http://www.hasteningantiques.com/wp-content/uploads/2010/10/14-562x750.jpg

How do you think that antique table held for so long? It does not look like inside panels are floating, they just seem to be nailed down.
If I make a table like that it would most likely be for outside.

[Pat Barry]

To clarify .. the boards within warped when they expanded and the frame did not give way. The corner joints were very strong. The frame survived, the boards did not.

Regards from Perth

Derek
Thanks for clarifying. Note - Patrick was correct :)

[Frank Drew]

Returning to our original topic, I'm in the group that considers the draw-bored loose tenon a solution to a problem that doesn't exist, but people are free to use their time as they wish. It's worth noting, however, that Mr.McGuire writes that the impetus for his worries about glue joints didn't involve failing edge joints of the kind we use in tabletops and panels. Rather, "To create a level of consistency and stability within our benches we took the modern approach of creating the tops with face to face laminations. This is more problematic than edge jointing, and it troubled my mind to simply trust the glue..."

Gluing face-to-face laminations being more problematic than edge joints is an understatement and doesn't explain why he decided to re-invent the wheel concerning edge joints, but, whatever, his time to spend as he wishes.

I'd be a bit worried about seasonal movement against the hold of the draw pins causing the wood to crack; a typical table top isn't terribly thick to start with, and the wood on either side of the loose tenon is only a third of that; not much resistance to cracking from stress.


"

[Mike Holbrook]

There may be a few other reasons to consider this system for joining boards for a table. Drawboring might make it easier for those who may not have enough very long clamps to properly glue up a large table. Clamps long enough to do that sort of job are not cheap. Like so many things, if you have all those large clamps, how often will they get used and where might they be stored.

I think Stanley expresses interest in the decorative nature of this joint in his original post.

I am interested in joinery that does not require the use of metal within the wood. Although glue may do the job, Derek's experience with the original boards in his table might suggest that for outdoor applications there may be reasons to use this joinery. In my case, I am thinking about a table sitting outdoors, but under a roof on a screened porch.

Derek, no pictures yet as a 20,000 acre wild fire in the Cohutta Wilderness, some 10-15 miles from our location made clouds of smoke in the area not conducive to wide angle photography. Now about 70% contained.

[Derek Cohen]

I hope you are safe, Mike. Keep in touch.

Regards from Perth

Derek

[Mike Holbrook]

Hmm should have thought about that post a little more. I am in the process of getting our old house ready to sell, in Milton, GA., so we are not living in the new home yet. Kind of irritating to be working on projects at a house for sale instead of the more interesting projects for the new house, but it is what it is. It looks like the fire is contained now, it did make air quality all the way to Atlanta bad for a while.

Record drought here, I am practicing native american rain dances between projects.

[James Pallas]

I have used loose tenon several times for alignment purposes. I bought a biscuit joiner, years ago, a Lamello. Didn't care for it much so gave it away. I also used dowels for same purpose. I never draw bored anything and did not believe it necessary. Did not worry much about glue on the tenons used for alignment either. I have a question for those more experience than myself. If You did draw bore a loose tenon the only tension you would have would be the preload on the pin and the expansion of the wood between the pins which would not be much I don't think. Is my thinking wrong on this?
Jim

[Patrick Chase]

I have used loose tenon several times for alignment purposes. I bought a biscuit joiner, years ago, a Lamello. Didn't care for it much so gave it away. I also used dowels for same purpose. I never draw bored anything and did not believe it necessary. Did not worry much about glue on the tenons used for alignment either. I have a question for those more experience than myself. If You did draw bore a loose tenon the only tension you would have would be the preload on the pin and the expansion of the wood between the pins which would not be much I don't think. Is my thinking wrong on this?
Jim

You're right. Furniture hardwoods typically have tensile strengths on the order of 2 kpsi, so you can apply a pretty decent amount of force that way if your tenons and pins are large enough.

Of course wood glues also have strengths on the order of 2 kpsi, so a tabletop's edge joint has vastly more strength than it needs even without any reinforcement :-).

[Frederick Skelly]

FYI. Just noticed that Richard Maguire has an article on this drawboring apprroach in the current issue of Wood Magazine.

Fred