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Thread: Question on fitting tenon shoulders

  1. #1
    Join Date
    May 2015
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    Question on fitting tenon shoulders

    Curious if anyone has a special technique for fitting shoulders. Do you mark it somehow with a marking knife? Do you fettle and fit, fettle and fit, fettle and fit? The only thing I've found is to eyeball a piece of tape to mark what needs to be planed. But in the end this method resembles the fettle and fit method. Curious how others do it.

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  2. #2
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    One way some folks take care of this is to undercut the shoulder. In other words it is cut in at an angle. This allows the wood to compress as the tenon is clamped or drawn into the joint.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
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  3. #3
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    Everything dead on square ahead of time helps me a bunch Bill. That way when I walk the square around the tenon end for marking, the shoulders are all in the same plane. I saw on a knife wall line, but find I still have a thin-thin shave to take off of the sawn knife line with a chisel to get crisp fit ups. If I am having trouble, I make sure the back (no show) side is the one that is not holding things apart and concentrate on shaving the front side. I also double check the mortised surface to see if it has somehow gotten out-of-flat in the mortise area if something is not lining up. I usually run a smoother across the side that I mortise when I am through chopping the mortise(es) on one side of the equation just to have a flat, smooth face for the tenon shoulders to rest on.
    David

  4. #4
    Join Date
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    Bill, I will echo comments by Jim and David.

    I saw close to the line, since I prefer to use a chisel to finish to the line. This is more accurate than a knife wall to guide the saw, and then sawing to the line. I like a knife wall, nevertheless, but to guide the chisel and, as with dovetails, not allow the blade to be pushed back over the base line. Once all is done, I add a very fine undercut all round to ensure that there are no obstructions when seating the tenon in the mortice.

    Regards from Perth

    Derek

  5. #5
    Join Date
    Dec 2010
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    South Coastal Massachusetts
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    These are chair rails?

    I like wedges tenons in through mortices, to get things tight.
    I find blind mortices difficult, as test fitting is near impossible.

    Using a pair of wedges allows me to make the cheeks snug, but leaves wiggle room to disassemble if adjustments are required.

    The PW article attached specified powered routers for the mortice, but it's essentially the same approach.

    FWIW - I perform similar steps at the same time, but cut each tenon to fit a given mortice (because I'm inconsistent).
    https://www.popularwoodworking.com/p...ise-and-tenon/

  6. #6
    Join Date
    Mar 2015
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    Same here on the techniques already mentioned. Depending on the length of the shoulder, I either pare with a chisel or use a shoulder plane to fine tune to the line, and then undercut with a chisel all the way around.

    When a shoulder doesn’t fit well and I’ve pared accurately to the scribe line, I find it’s usually either something at the bottom of the mortise or something left in the corner of the tenon where the shoulder meets the cheek.

  7. #7
    Join Date
    May 2015
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    Thanks for the suggestions, gents. I cut the tenons in 2 ways for this chair project. The square tenons I cut with my new Bad Axe hybrid saw - what a wonderful tool - and then used a chisel to work to my knife line as Derek described. Same way I do dovetails - I enjoy this work. And I undercut the shoulders with a chisel and all but one of them fit fine. Was very pleased with this part of it. The rails I cut with the tenon jig on the table saw need the most work. The reason I cut them with the jig is that they splay out 7 degrees, and down 12 degrees. (Or the other way round.) I was just more comfortable doing test tenons on the table saw until I got it right. And a good 30% of these 32 tenons need attention. I pre-finished all the pieces so there was a bit of muck from the wipe on to clean up on the shoulders all of them - this was no surprise and was expected. So for these shoulders is there a better way to mark what needs to come off other than what I'm doing with the blue tape? I've got 6 of the 8 sides assembled so It's getting done, it's just a PITA.

    Again - appreciate all the comments. And I'm outta here for the rest of the day - I get to walk my youngest daughter down the aisle. She's getting married to a former Ranger Scout - an absolutely stand up guy. I could not be happier for her.

    And that's a great idea to use a smoother over the mortise - thx.
    If you don't stand for something, you'll fall for anything.

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