Newbie notes: Cutting tenons by hand

[Frederick Skelly]

This is another episode in the saga of "Fred Makes Mortise And Tenon Joints". I was going to write this in my personal notebook anyway, so I thought I'd just go ahead and post it to help other hand tool neophytes like me. (Old, skilled hands won't get anything out of this but a chuckle.)

I made 8 machine-cut mortises for a chair. As I mentioned in another post, I didn't get them aligned correctly and had to tune them by hand. As a result, not every mortise was exactly 1/2" wide and centered perfectly. Some were as much as 1/32" wider or slightly offset to one side or the other. (But they were darn sure SQUARE!) Tonight I cut/fit 4 of the tenons. Here are some lessons learned.
1. A sharp marking knife and a good marking gauge make your work fit together better. William Ng was right - a marking knife made a big difference for my accuracy.

2. Mark your tenon to match the individual mortise for which it is intended. Don't just set your marking gauge and lay all the tenons to exactly the same width; i.e., what it's' "supposed to be". Really skilled guys can make perfectly positioned mortises. This newbie can't (yet), not even with a machine (yet). How do you do this? Easy - mark the mortise with a letter to identify it. The first mortise is "A". So is the first tenon. Next, set your marking gauge to match the right side of the mortise A. That's the line for the right side of tenon A, too. Scribe the right line on tenon A. Next set the gauge for the left side of tenon A. If you're good (or lucky), the left side of the mortise is the same offset from the edge as the right side. But if it isn''t, just adjust the marking gauge to match the left side and transfer that to the left side of tenon A.

3. Graham Blackburn recommended cutting the tenon shoulders first. To get a really nice, straight, clean cut, he suggested using a wide chisel to cut a v-groove along the line of that cut, making sure the wall is vertical along the line. I think Chris Schwartz calls this a Class 1 cut - it's gonna show and it has to look good, so you gotta take extra care. Hence chiselling the v-groove. Using this method, and cutting right on the line, I got straight, square shoulders that required very little touchup with the shoulder plane.

4. Next cut the cheeks. I found an LV rip tenon saw does a good job for this -aggressive and controllable. Much better than my smaller LV rip backsaw. Again, cut to the line.

5. Check the fit. Mine were always close but needed some paring with a wide butt chisel. Then they fit well. If you have a rabbett block, that would be a great choice to tune the cheeks. I don't, so I improvised using a combination of my #1 hand plane and a wide chisel (to get right up to the shoulder).

None of this is earth shattering. But it worked for me and the joints fit so well that I feel like I've made a no-kidding breakthrough in my personal skills. So it might work for other newbies. Hope so.

Fred

[Lasse Hilbrandt]

Thanks for good advise

[Derek Cohen]

Hi Fred

There are two strategies I still follow when chopping mortices.

The first is to ensure that the mortice will not wander, and to do this I pare away the top layer within the lines. The slight depression then acts as a guide.



A hole is drilled to aid in removing waste, but this is one of a few methods that works successfully. See my article, here: http://www.inthewoodshop.com/Furnitu...gByChisel.html

The second strategy for square/perpendicular sides is the way you clamp the board to the bench (over the leg). Some prefer to clamp horizontally to a board in the vise. I clamp vertically to the bench as this enables a clamp to act as a visual guide for vertical ...



Regards from Cornwall

Derek

[Steve Voigt]

There are two strategies I still follow when chopping mortices.

The first is to ensure that the mortice will not wander, and to do this I pare away the top layer within the lines. The slight depression then acts as a guide.

…

The second strategy for square/perpendicular sides is the way you clamp the board to the bench (over the leg). Some prefer to clamp horizontally to a board in the vise. I clamp vertically to the bench as this enables a clamp to act as a visual guide for vertical ...

I guess we are off the topic of tenons, but there are some interesting comments on mortising technique, both here and in Ken's thread, that I wanted to add to.

First, I am wondering why more people don't turn the work 90°, so it's parallel to to the ends of the bench. I do this wherever possible; otherwise I do as Ken does and stand at the end of the bench. I prefer the first way because then I can put the work over a bench leg. But the bottom line is that if you can stand directly behind the work, it's much easier to judge vertical, and you don't need visual aids like clamps or whatever.

Second, I have made a lot of mortises by paring away the top layer, as Derek suggests, but I ended up deciding that this method has more negatives than positives. It adds an extra step and extra time. The risk of slipping or blowout as you pare is fairly high. And the floor of the pared-away layer is unlikely to be flat, which actually makes it more difficult to keep the chisel vertical on your first pass.

If you have a firmly struck line on one side of the mortise, it is not hard (with practice) to set the corner of your chisel up against that line with a very high degree of accuracy. The resulting mortise should be as accurate, or more, than with the paring technique. YMMV, of course.

[Derek Cohen]

It adds an extra step and extra time. The risk of slipping or blowout as you pare is fairly high. And the floor of the pared-away layer is unlikely to be flat, which actually makes it more difficult to keep the chisel vertical on your first pass.

Hi Steve

The little extra time is quickly forgotten after the joints are made to one's satisfaction. Poorly done work haunts one forever!

There is minimal risk of "slipping" if you score the lines around the mortice reasonably deeply (cutting gauge and knife), and use the appropriate size chisel. I even use the mortice chisel since it is sharp enough. I have never experienced any difficulty creating a level floor ... ? What are you doing here?

Regards from cold Cornwall

Derek

[Steve Voigt]

Hi Steve

The little extra time is quickly forgotten after the joints are made to one's satisfaction. Poorly done work haunts one forever!

There is minimal risk of "slipping" if you score the lines around the mortice reasonably deeply (cutting gauge and knife), and use the appropriate size chisel. I even use the mortice chisel since it is sharp enough. I have never experienced any difficulty creating a level floor ... ? What are you doing here?

Regards from cold Cornwall

Derek

Hi Derek,

I'm glad the technique works for you. For me, adding extra steps is something to avoid if possible; even if it's just a minute per mortise, it adds up eventually. And as I said, the resulting quality should be just as good or better.

Looking at your photo, I can see that the floor of your paring is certainly not level, and there is a bit of blow out on the far side. Not a big deal, but I would rather set the tip of my chisel down on a flat, planed surface; it makes it easier for me to keep the chisel square on the 2nd or 3rd blow.

[ken hatch]

Steve,

I agree one deep line from a marking gauge works for me better than any other way, register the edge of the mortice chisel and beaver away. From what I've seen I tend to use lighter hammer hits than most and leaver smaller sized chips. It's counter intuitive but lighter hammer work and smaller chips is usually faster and almost always leaves a better mortice than going for the gold.

ken

[lowell holmes]

Derek,

You did not give him your tip about locating the mortise with a single chisel strike prior to marking the mortise on the wood.
That is my all time favorite of your tips. It's your tip. Maybe you could post it again.

[Derek Cohen]

Hi Lowell

I'm afraid someone will say it causes spelching, or something

It is in the link I provided earlier.

Regards from Cornwall

Derek

[Steve Voigt]

From what I've seen I tend to use lighter hammer hits than most and leaver smaller sized chips. It's counter intuitive but lighter hammer work and smaller chips is usually faster and almost always leaves a better mortice than going for the gold.

Ken, I agree. For me the biggest factor in making mortising go smoothly is taking "goldilocks" chips--not too big, not too small, but just right.

[Stewie Simpson]

Why would you not use a pedestal drill to remove most of waste material. Most workshops have one.

[Patrick Chase]

Hi Steve

The little extra time is quickly forgotten after the joints are made to one's satisfaction. Poorly done work haunts one forever!

There is minimal risk of "slipping" if you score the lines around the mortice reasonably deeply (cutting gauge and knife), and use the appropriate size chisel. I even use the mortice chisel since it is sharp enough. I have never experienced any difficulty creating a level floor ... ? What are you doing here?

Regards from cold Cornwall

Derek

I read your mortising article long ago and found it very useful. I didn't adopt everything you suggested (probably because we have different skillsets, and therefore different "optimal" solutions) but I like the way you present what you do and how you got there.

w.r.t. the chisel-strike for location, I've adopted that and don't see any downsides for most work. it's cross-grain, so I don't see any realistic way that it could spelch or slop over or anything like that. Also, the surface adjacent to the mortise is seldom cosmetic. The only time I wouldn't do that is if the location of the mortise is tightly constrained, for example by a single-shouldered asymmetric tenon.

[ken hatch]

Why would you not use a pedestal drill to remove most of waste material. Most workshops have one.

Stewie,

I've tried drilling and it works but for me it isn't quicker or better than just making a mark and beavering away. Maybe it is lack of drilling skill but my mortices are better with fewer mistakes when just using a pig sticker and chopping to final size vs. drilling and paring to size. Some folks swear by the drill, my guess is it depends on how you learned.

Of course as with all things wood....YMMV.

ken

[Derek Cohen]

I read your mortising article long ago and found it very useful. I didn't adopt everything you suggested (probably because we have different skillsets, and therefore different "optimal" solutions) but I like the way you present what you do and how you got there.

w.r.t. the chisel-strike for location, I've adopted that and don't see any downsides for most work. it's cross-grain, so I don't see any realistic way that it could spelch or slop over or anything like that. Also, the surface adjacent to the mortise is seldom cosmetic. The only time I wouldn't do that is if the location of the mortise is tightly constrained, for example by a single-shouldered asymmetric tenon.

Thanks for the feedback, Patrick. I've not experienced any downsides from this approach, which is hardly original (I just do not know whom to offer as an influence). The example in the photo was taken from something I was working on at the time, and the wood is Tasmanian Oak, which is stringy and difficult to cut cleanly. It is inclined to crumble at edges. Probably not the best choice to illustrate with.

Regards from Cornwall (will be driving up the coast today)

Derek

[Derek Cohen]

Steve,

I agree one deep line from a marking gauge works for me better than any other way, register the edge of the mortice chisel and beaver away. From what I've seen I tend to use lighter hammer hits than most and leaver smaller sized chips. It's counter intuitive but lighter hammer work and smaller chips is usually faster and almost always leaves a better mortice than going for the gold.

ken

I have two mallets I use for morticing. One is 20 oz, which is for softer woods (such as the Tasmanian Oak in the photo shown earlier), and the other weighs 36oz, which is used for hard woods, such as Jarrah.

What do you use?

Regards drom Cornwall

Derek