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Thread: Mortise and tenon questions / musings

  1. #1
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    Mortise and tenon questions / musings

    Been making a lot of m&t's lately and today while I was working several questions / comments occurred to me. First, how anal are you in making the tenons exactly fit the mortise? Not talking about the fit in width, but more in terms of length. I've been trying to be as precise as possible with the layout but at times during assembly I regret it and need to take a skosh off one end or the other to line things up. Usually my m&t's look like this:
    20200808_135611.jpg a tight fit all the way round. Do you leave wiggle room or try for the snug fit in length as well? See advantages in one way or the other?

    I always pare the shoulders down to the tenons. Do you? Is this normal or do you consider it excessive? And if you do pare, do you use a chisel? Or..........
    20200808_143202.jpg

    I've always used a shoulder plane to fiddle the tenons to fit, and to adjust the shoulders if needed. But I started looking at skewed block planes, searched high and low for one and finally got it. Tried it out today and what a difference. Now I know why they are called shoulder planes instead of tenon planes. Since I started as a framer 50 years ago, and moved to roofs, stairs, trim and and the shop , my left hand has always been a clamp, or material feeder, etc. And that made me wonder why there are so many right hand skew planes, and so few left hand ones. I got a left hand one because I can throw the piece on the bench hook, left hand = clamp, and the left skew plane, used in the right hand, pulls the plane up to the shoulder of the tenon. I can't imagine trying to use a right hand skew in the same fashion. I know they sell in pairs, and that there are specialty situations where both are needed. But if you're right handed how do you use a right hand skew? The work must be clamped some how, yes?

    I've also got into the habit - which I think I need to break - of custom fitting tenons to mortises, and labeling them. Not for back slats and such, but for legs and stretchers. Back again to that tight all the way round thing.

    Last comment: I'm working on 2 morris chairs and I gotta say the billiard chairs I made last year were a lot tougher than this. Of course I haven't tried bending the arms yet, so we'll see.
    It's best to fall behind schedule as quickly as possible.
    That way you have more time to make it up.

  2. #2
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    If a tenon is too long to fit in a mortise, I first check that I chopped the mortise to the full planned length of the mortise. Because my work method is to check that detail and confirm that each end of a chopped mortise is indeed pared to at least 90* at the end (and my be slightly undercut to be dead sure) before moving on to the next one, the mortise end is usually on the mark. If the tenon is still too long (width wise) to fit in the mortise, I use a chisel to pare ("take a skosh") a little material off one end of the tenon. I will usually miss the mark on sawing my tenon ends more so than not chop the mortise to the gauged line. I prefer snugly fitted tenons when considering the end fit as well as the cheek fit. Just seems proper in spite of the fact that the glue on the cheek faces is the main strength. Having said that, I do not agonize over tenon end lengths. The majority of my M&T work is done in 3/4" thickness material, so I am usually working with 1/4" tenons.

    I always pare my shoulders down to the tenon because my shoulder sawing always leaves a very slight edge at the gauge line. I usually pare mine down vertically on the shoulders as opposed to the horizontal method you show in photo 2. I used to pare horizontally and use the top edge of my Moxon as a paring platform, but found that I can more easily (and quickly) find the gauge line with the tip of the chisel by dropping it down into the shoulder gauge line. I don't have trouble holding a 90* angle on my chisel as I pare down. Using a diagonal, slicing motion with the chisel instead of paring straight down is better for me. I tend to take only half a chisel width's bite and rotate the chisel down to slice. Sometimes (not very often at all), I drop back to using a shoulder plane to clean up a shoulder line that has gotten completely out of whack or I need to move it beyond the gauge line, but I don't like using a shoulder plane unless something drastic is needed. My medium sized shoulder plane is way bigger than my 1/4" tenon shoulder and (of course) blows out the far end if not stopped and reversed at each end. A chisel is preferred 99% of the time. As long as all of my material was square when the layout was done, tenon shoulders tend to go pretty smooth and trouble free.

    I always label my stiles/legs and rails, so, yes, each mortise-tenon combo is custom fitted. It is not uncommon for me to completely miss the labeling and happily try (or even try to glue) something in the wrong spot and the tenon usually fits OK.
    Last edited by David Eisenhauer; 08-09-2020 at 12:04 AM.
    David

  3. #3

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    I normally make make mortices and tenons with a hollow chisel mortiser and a tenon jig on the table saw, but I always intentionally makes the mortises a little deeper than the tenons, typically about 1/8". If you try to make them exact, the excess glue can sometimes push the tenon out of the mortise on assembly. As far as side fit, I want to feel a little resistance sliding the tenon in, but not a lot. If it is too tight, it can make assembly difficult, especially if there are many pieces to go together, like a panel with a center rail and/or stile.

    When I occasionally do a tenon by hand, I normally just saw the tenon and maybe adjust it with a tad with a chisel. I'm pretty sure that is how hand tool woodworkers 100+ years ago did it. They normally wanted to work as fast as possible using as few tools as possible. I think modern hand tool hobbyists often want to do the opposite. It doesn't help that the interweb is full of "experts" sponsored by hand tool companies.

  4. #4
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    Bill, the sides are what is important, since most strength comes from face-to-face glued connection. Loose tenons need to be shimmed for a slip fit to the sides. Other than epoxy, glue is not gap filling.

    Regards from Perth

    Derek

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    "I've also got into the habit - which I think I need to break - of custom fitting tenons to mortises, and labeling them. Not for back slats and such, but for legs and stretchers. Back again to that tight all the way round thing."

    This is a sensible approach to making things by hand.
    If you did nothing other than bash out mortices, they would approach uniformity.

    I test fit tenons and bridle joints. If they need persuasion to come together, the tenon is too big.

    I like to have some adjustment room "North to South" on the tenon. I aim for the thickness of two index cards.

    "East to West" should be snug on assembly. The Japanese technique uses a oval faced hammer to compress one face for assembly like this. I clamp the tenon in my vise until it creaks prior to glue up.

    The Windsor chair makers assure tight fitting tenons with a flared "mortice" foxing wedges and pre-dried male parts.

  6. #6
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    As I expected, the north-south dimension of the tenon is good if it's close, while the sides are critical. I also aim for a press fit. If I need to use a BFH to drive it home, I plane the tenon a bit. So I think I'll start leaving some room on the ends of the tenons.

    I have been using a mortiser and tenon jig as well, but should be getting a new Ron Bontz tenon saw any day now. Really looking forward to cutting the tenons by hand. May have to revisit this from Derek.

    David: "It is not uncommon for me to completely miss the labeling and happily try (or even try to glue) something in the wrong spot and the tenon usually fits OK." Been there and done that. The last set of chairs I made I labeled the legs on the top - 2RF, 2RB, etc. The tops weren't cut to length yet and of course I proceeded to cut the legs to length and forgot to remark the legs. AS you say. most everything fit ok. And I think I'll try the vertical pare you described.

    No comments on using the skew plane to fiddle the tenons?
    It's best to fall behind schedule as quickly as possible.
    That way you have more time to make it up.

  7. #7
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    Like you, I've always used my shoulder plane to fit tenons to the mortise. I don't know about a skew plane, but I've wondered if rabbet block plane would be useful. However, I've always found other things to spend my money on.

  8. #8
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    I use calipers for measuring tenon thickness and pare with a chisel. I never manage to get square tenon's with a plane.

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    I think rabbet planes, shoulder planes, some type of skew planes, files, rasps, floats, etc can all be used successfully to thin a fat cheek down on a tenon, but, FOR ME, a chisel used in a scuffing motion is the quickest/easiest way to go. I run a sharp/fine pencil through my gauge lines and the pencil lines are easy to see while I scuff down to the line. If I have several tenons to create that are of the same dimension and location on several rails or stiles, I may setup a router plane to reference off of the show face of the rail/style to use for final cleanup to final thickness. That works if the initial sawing or subsequent chisel scuffing results in a tenon that is very, very close to final thickness so that the router plane remains setup to the final thickness and never needs intermediate step re adjusting. Constant re adjusting of a router plane depth setting slows things down considerably. I have wondered if folks that own two router planes set both up to work together to bring a tenon down to final thickness. The router plane does bring the tenon cheek flat to the face of the rail/stile. Mainly, I learned how to saw closer to the gauge line and became more willing to occasionally saw one a hair too close as opposed to my death fear of sawing too close to the line. If you never try, you'll never get there. If I have to glue a shim to a tenon on a piece of furniture that is for me or my family only, I can live with that. Doesn't happen often and the tenons are coming to final thickness faster now.
    Last edited by David Eisenhauer; 08-09-2020 at 9:14 PM.
    David

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    One of my mentors used to make gauge blocks for his mortise chisels out of 3/4 or 1/2 material. He would saw the tenon then use his gauge block to check. Cleaned up with chisels. He explained that you could see the whole tenon. If I have many to do I make a block. It only takes a couple of minutes and it works very well.

  11. #11
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    James - I am not clear on what you are describing, but it sounds like something useful. Any way you can show a photo or drawing of the gauge block and it's application? is the gauge block the width of the mortise chisel and 1/2" or 3/4" thick? Is the gauge block laid over the end of the tenon and used as a visual thickness reference for the newly sawn tenon?
    David

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    James may have a different gauge in mind than mine:

    Mortise Gauge Block.jpg

    This was made for a 1"X2"X3" mortise.

    It can also be used to check the squareness of the mortise:

    Mortise Gauge Block in Mortise.jpg

    James mentions using the gauge over the end of the tenon as a visual thickness reference. That sounds like a different animal. For me a caliper works for checking thickness.

    My tendency is to fit the tenon to the mortise then mark each joint separately.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

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    Quote Originally Posted by David Eisenhauer View Post
    James - I am not clear on what you are describing, but it sounds like something useful. Any way you can show a photo or drawing of the gauge block and it's application? is the gauge block the width of the mortise chisel and 1/2" or 3/4" thick? Is the gauge block laid over the end of the tenon and used as a visual thickness reference for the newly sawn tenon?

    James - I'm a bit foggy on what you are doing as well. Any pics you can share?
    It's best to fall behind schedule as quickly as possible.
    That way you have more time to make it up.

  14. #14
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    Quote Originally Posted by Jim Koepke View Post
    James may have a different gauge in mind than mine:

    Mortise Gauge Block.jpg

    ......

    My tendency is to fit the tenon to the mortise then mark each joint separately.

    jtk
    Great idea Jim - I'm gonna try it. Not so much for mortises made on the machine, but hand cut ones for sure.
    It's best to fall behind schedule as quickly as possible.
    That way you have more time to make it up.

  15. #15
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    Quote Originally Posted by Jeff Ranck View Post
    Like you, I've always used my shoulder plane to fit tenons to the mortise. I don't know about a skew plane, but I've wondered if rabbet block plane would be useful. However, I've always found other things to spend my money on.

    I hear you on the money part, but I don't regret this purchase. A left hand skew will pull the plane into the shoulder, and it has a nicker if you need to cut along the shoulder as well. As you can see, the blade is dead even with the side of the plane. It has become my second favorite plane to use.

    20200810_123626.jpg 20200810_123830.jpg 20200810_123813.jpg
    It's best to fall behind schedule as quickly as possible.
    That way you have more time to make it up.

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