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Todd Zucker
03-12-2018, 12:23 PM
In trying to incorporate more hand tools into my projects, I am finding the 3/4-inch-thick mortise and tenon joints on my current garden bench project a little challenging—specifically, gaps where the shoulders meet.

If I were using a Festool Domino and miter saw, it would be fairly easy to cut everything in advance, exactly to length, and get joints where the shoulders meet to all seat properly without gaps. But doing it with marking knives and gauges, chisels and hand saws, even with what looked like properly scribed lines, each joint ends up slightly off, and each joint has slightly different issues (this problem solving and attempt to develop hand skills is part of the fun, of course, and exactly what led me in this direction).

I have been working in pairs, i.e., cutting the tenons and mortises at each end of the front rail, test fitting and trying to get as close as possible, then moving on to the rear rail, then the top rail. But I haven’t been striving for perfection on any particular joint until I am ready to do the final dry fit and can see where the problem areas are. I am wondering if there is a preferable approach in terms of work flow and efficiency. Might it have been better to start by cutting all of the mortises on the project, and then trying to get a perfect fit on each tenon and shoulder before moving onto the next joint. Right now, I am at the point where it looks like a bench, but if I want to refine a particular joint, I am having to disassemble most of the bench.

One other question. Someone mentioned undercutting the rear of the shoulders. Does this refer to undercutting the rear side of the joint itself so that any gap would not be visible from the front or sides of the piece of furniture, or instead, chiseling slightly deeper toward the tenon so that the perimeter of the shoulders seats better on all sides.

John C Cox
03-12-2018, 1:08 PM
Part of what you are seeing is simply having to learn new "tool chops".
Part is things you took for granted - many power saws and big power tools have built in alignment - which keeps cuts square and true... Chisels and hand saws - not so much.. There is a combination of the setup of the tool and your techniques which drive this.. (For example - a dull saw will often cut crooked.. But a sharp saw can cut crooked if your technique is not good).
And the last part is learning the "tricks".

So for example - use some chalk or a 0.003" feeler gage to figure out where your high spots live that are causing your joints not close up properly.. And then carefully pare only the high spots till you get a good flush fit.... That will help you understand where your problems lie and help you think of possible solutions..

Robert Hazelwood
03-12-2018, 1:16 PM
The layout is the most critical part to getting these right. Well, you still have to cut them accurately of course, but if the layout is not spot on then you are fighting uphill the whole way.

The main things to get right in the layout are that the spacing of the mortises along the length of each part, and the tenon shoulder-to shoulder length. In a typical design the important thing is to get these exactly identical. To ensure this I use a lot of transfer marking. So for mortises, I will take one leg and manually measure and layout the length of all the mortises. That will be the master leg from which the others are marked. Pick a convenient indexing point (usually the top or the bottom of the leg) and place the master leg together with the next leg to be marked (clamp if you need to), align the indexing point (e.g. make sure the tops are flush), then use a square to transfer the knife marks from the master leg. You don't have to make a full-length knife mark, you can just transfer a tick onto the new piece- make the full mark once you've separated the two and you can utilize the correct reference faces. Repeat this process for all the legs. This should ensure that all of your mortises start 3.005" (or whatever measurement you actually made on the master leg) from the top of each leg, and are a consistent length.

For the tenon shoulders, I do basically the same thing. It's important to remember that the really critical thing is the distance between the tenon shoulders, and not the overall length of the part or the length of the tenons. This is a little different than power tool methods where you reference from the end of the part. So I take one stretcher and measure and mark both tenon shoulders the desired distance apart, then transfer those to the remaining stretchers. Again, you want to transfer ticks and not full knife lines at this stage. Once each part has knife ticks, then you can mark the full tenon shoulder.

There is a bit of technique to marking tenon shoulders- briefly, the idea is to only ever rest the stock of the square on one of the two reference faces. Having made one line, you flip the part 90 degrees, place the square with the stock on a reference face, place the tip of your marking knife in the end of the first mark on the corner, then slide the square over to meet the knife. With the square in position, make a light mark along the face, then one or two heavier marks. Repeat for the remaining faces, making sure to keep the square stock on a reference face. If you are careful then your knife lines should meet up perfectly around the shoulder.

The widths of the mortise and tenon are set by a mortise gauge, which is simple enough. You just have to make sure to use the same settings on both parts. This is usually the last step in my workflow.

If you get the layout correct then it is just a matter of sawing/chopping/paring to the lines. You might make a mistake in the cut out, but then you'll know why there are gaps because you'll have gone past your line. Of course before the layout can be done properly the parts need to be dimensioned accurately, with square and straight reference faces.

As for undercutting the tenon shoulder, this is usually referring to the making the "face" of the shoulder a bit hollow, so that the outer edges are right on the marked lines, but recessed as you get closer to the tenon. This helps the shoulder line draw up tight since there are no bumps on the shoulder surface to hold up the shoulder line from seating. It is easy to do with a chisel, with the part vertically in the vise, placing the tip of the chisel on the remnant of the tenon shoulder knife line and paring towards the tenon. Don't overdo it (aim for perfectly flat with just a touch of undercut), as it can weaken the joint and if you plane down the part later you might expose the undercutting.

Kees Heiden
03-12-2018, 1:42 PM
On older work, let's say Middle ages to 17th century, a timeframe where a lot of furniture has survived, you wil find that shoulders are severely undercut and the inside, not visible shoulder often doesn't touch at all. Despite the fear that this produces a weak joint, those pieces survived astonishingly well. It seems that such shortcuts are not the reason why furniture falls apart after a while. Shifting fashions, decay in wet environments, a hungry woodstove in grim winters, those are much more dangerous for a piece of furniture then undercut shoulders.

John C Cox
03-12-2018, 2:04 PM
The US FPC did some research into the strength of M&T joints... And given a particular size Tenon - the primary driving factor which determined the strength of the glued joint was the amount of slop on the sides of the tenon in the mortise. The tighter the fit of the sides of the tenon into the mortise - the stronger the joint. And it became massively stronger - not just a little bit...

I have no doubt that if the shoulder was the main contributor, they would have noted that...

I have noticed the same thing incidentally.. M&T joints which fall apart on old furniture tend to be the loose ones.. I have been absolutely horrified at how loose some of the joints I see are.. These loose wonky joints with 1/16" to 1/8" gap on the sides of the tenon (probably for easy assembly) and just fill the whole chasm with glue.. They always come back apart.. And they are a pain to fix right...

Jim Koepke
03-12-2018, 3:33 PM
I have no doubt that if the shoulder was the main contributor, they would have noted that...

The shoulder IS the weak part of the joint since it is end grain to edge grain.

Loose M&T joints fail because most of the traditional glues are not made to fill gaps. Epoxy can fill gaps, but if it doesn't get a good bond from the start, it can also fail.

Just as sharpness fixes many tool problems, the proper fit insures the long life of many joints.

Consider the draw bored M&T. With a proper fitting, it doesn't even need glue to hold together.

jtk

Warren Mickley
03-12-2018, 3:38 PM
If you have only made a dozen or so mortise and tenon joints, the results might show it. Being a beginner is nothing to be ashamed of. If you want to alter your technique to make it look like you have done this a lot, you could end up with more time spent or a weaker joint. If you lay out the shoulder lines all around the joint and they meet nicely after the fourth side, and you saw to the line the joint should seat nicely. If you try for sawing on the line you work will gradually improve and this will pay dividends on other joint making.

On older work I have seen joints where the guy undercut the front and cut the back loose so that the joint can be sloppy and appear fine from the front. I have also seen older work where the tenon shoulders were tight everywhere, which I would expect to be a stronger joint. There is variation in quality in every era.

Mike Cary
03-12-2018, 3:51 PM
I am currently working on a project, my first predominantly hand tool project to be exact. I decided to only use a bandsaw for ripping and a thickness planer.

This project has quite a number of m&t joints. Now I know you got a lot of advice so far, but all my joints fit perfectly and this is how I did it. First I took a marking gauge and set to to exactly 1/3 the distance of the thickness of the...Ah who am I kidding, I cheated and grabbed my Domino!

Simon MacGowen
03-12-2018, 4:15 PM
I am currently working on a project, my first predominantly hand tool project to be exact. I decided to only use a bandsaw for ripping and a thickness planer.

This project has quite a number of m&t joints. Now I know you got a lot of advice so far, but all my joints fit perfectly and this is how I did it. First I took a marking gauge and set to to exactly 1/3 the distance of the thickness of the...Ah who am I kidding, I cheated and grabbed my Domino!

Question: Were you doing a blind or through M&T joint?

I know Glen Huey cheated, too before. Here is proof:

https://www.popularwoodworking.com/article/festool-domino-thinking-outside-the-box


Simon

brian zawatsky
03-12-2018, 4:25 PM
When I have a piece to build with a lot of M&T joints, my workflow is:
Cut all the frame parts to length, mark up for show face & location in the assembly
Lay out all the mortises & cut them
Lay out all the tenons and cut them
Fit & tune mortise/tenons as frame is assembled

Undercut just means to slope the tenon shoulder inwards towards the base of the tenon

Brian Holcombe
03-12-2018, 7:46 PM
I like to create a standard when making multiples by marking out one. I use that to transfer marks to all of the others.

Machine tool method of cutting to length then cutting from the ends to a given length does not transfer well to handtools it just makes for considerable additional work.

Todd Zucker
03-12-2018, 8:34 PM
Going from power to hand tools is definitely a learning curve. Lots of new techniques to learn (and hopefully remember, like measuring off of only 2 reference surfaces).
I disassembled and checked everything and did some refining. The shoulder lines were okay, but I had not sawn very close to the line. When I chiseled to the lines, I guess I made some dome shaped shoulders. Things sure can look dead flat until you put a straight edge on them.
That, and I don’t have a 3/4” mortise chisel yet, so a couple of the mortises were not exactly 90 degrees. Tight, but not exactly square.
It is a lot closer to true now, a few mortises are a little looser, and maybe with epoxy and drawboring everything will work out okay. I am going to use some micro balloons in the epoxy in the loose joints to make a thick paste, so hopefully that will get everything solid inside the joints.
I am going to cheat on the armrest-to-back-leg joint and use the domino, as the leg has a 9 degree dog leg, and i don’t want to mess up the armrests. But just on this project. Next one will be full neander, for better or worse. Maybe epoxy. I don’t have to use hide glue to do the Neanderthal thing, right?

James Pallas
03-12-2018, 9:02 PM
The one big thing for me is that thru most of the process the tools are right at hand within reach from your bench. If you find that you have a part that is not suitable for whatever reason you don't have to go reset several machines. Your tools are right there ready to work. If your bench is set up right you can switch from fitting a tenon to chopping the mortise you missed by reaching for another tool. Or pick up a saw to cut something a bit shorter. If possible I always try to have some extra stock prepared planned and ready to go should the need arise.
Jim

Matt Evans
03-13-2018, 8:26 AM
I like to create a standard when making multiples by marking out one. I use that to transfer marks to all of the others.

Machine tool method of cutting to length then cutting from the ends to a given length does not transfer well to handtools it just makes for considerable additional work.

I do this as well.

Also, if you are planing everything to thickness/width with a planer, this may not be an issue, but with hand tools it often is: Make sure you use ONE side for reference on each piece. I mark my reference edges after I plane them, that way I can tell throughout a project where to align my squares and gauges.

Todd Zucker
03-13-2018, 12:16 PM
I think something is starting to click, finally. Maybe because I am actually doing something instead of reading so much about doing it, but these comments certainly help.
With the power tools, the decision is which tool, which brand; maybe which blade; and then watching a video or two. Buy plans. Set up a stop along the fence for repeat cuts, steady hand and everything is hopefully square and true and goes together with a few clamps.
Trying to embrace the simplicity and elegance of hand tools, the decision is which tool; which brand; Western or Japanese; which metallurgy; which bevel angle; flat, hollow or microbevel; which sharpening medium; which grit of each sharpening medium; which flattening stone; whose sharpening technique is best and is it really possible for everyone's technique to be the best; how sharp is sharp enough; when to re-sharpen; strop or not; camber, no camber or just round the corners; mouth width?; cap iron distance; which plane length or chisel width, or mortise chisel; bevel up or bevel down; frog angle; which reference edge(s) to measure from; what the heck are dividers used for and why did I buy them in the first place; do I need two sets of dividers; which marking gauge; single or double bevel marking knife; I'm thinking my next must-have tool is a froe, etc.
It sure is fun, though.

James Waldron
03-13-2018, 12:44 PM
[snip] Next one will be full neander, for better or worse. Maybe epoxy. I don’t have to use hide glue to do the Neanderthal thing, right?

Archeologists have discovered that the Neanderthals discovered the epoxy mines in central Chad, before the desert engulfed the region. When the mines were lost, the use of epoxy was eliminated from Neanderthal society and culture and led to the gradual decline in the population that brought us to today's sad state. Sadly, even with the development of new and seemingly boundless epoxy mines, Neanderthals have never fully recovered their rich tradition of epoxy use and have left epoxy work largely to Homo Sapiens, as a crutch for their use of flat pack furniture and plastic surfaces.

There is a small and declining tribe of Neanderthals who do use epoxy a good bit. They are wooden boat builders. Their existence is threatened by the onslaught of fiberglass boat construction.

John C Cox
03-14-2018, 10:21 AM
....Maybe epoxy. I don’t have to use hide glue to do the Neanderthal thing, right?

Oh my friend - it's worse than that... There are only 2 approved types of Neanderthal wood glue.. Hide glue and fish glue... But to be a "Proper" Neander - you have to MAKE your own hide and fish glue.

;) ;) ;)

Actually - all kidding aside, Hide glue is fantastic stuff in that it is nearly infinitely repairable... One interesting thing about learning to use it is that ALL your joints will be better no matter what glue you use.. Joint prep, setup, clamping, and the like are critical with it - so it forces you to really hone in on the quality of your joint prep and minimizing glue open time... And that pays heavy dividends no matter what glue you use...

For example - with your loose tenon.. With Hide - you would have to glue shims to the tenon and re-fit it to get a good strong joint that won't wobble in a month.... But that would make for a better joint with every glue including wood glue and even epoxy....

Todd Zucker
03-14-2018, 1:39 PM
I thought it was intended to "hide" mistakes, hence the name. At least if I use it I wouldn't need to look for an epoxy mine. That was hilarious.

Brian Holcombe
03-14-2018, 3:21 PM
Hide glue is handy stuff, it lets the joint work together a little easier sometimes so for me I practically require myself to use hide glue in many circumstances. I do use Titebond III still on things like making up panels.

Big downside to liquid hide glue is that you have to wait a full day before you can take the clamps off, not the case for hot hide (as I understand) and Titebond III.