Chopping mortises for wedged tenons?

I want to make a wedged through tenon. The mortise is 1/4" wide by 3/4" long, and the thickness of the piece is about 1/2".
I had no trouble chopping the basic through mortise with a 1/4" motrise chisel. Just like a regular mortise, except I kept going :-) The problem is how to cut the angled ends? I tried just paring the square ends with my chisel, but the result was a mess. Any hints for how best to do this?
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I don't have much experience with this, but I found that if you take a scrap block and cut it at the angle you want for the mortise, you can then clamp it to the workpiece and use it as a chisel guide. Scribe lines where you want the new ends of the mortise to be, and clamp your guide on that line. That way you can pare until the chisel "bottoms out" on the guide and you're done.
I think I stole the idea from Ian Kirby.
Chuck Vance
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snipped-for-privacy@swt.edu (Conan the Librarian) wrote:

Sounds reasonable, thanks.
Did you do the paring with the same chisel used to chop the main body of the mortise, or did you switch to something lighter like a bevel-edge chisel for that part of the operation?
What kind of angle did you use? I'm guessing an 8:1 slope, just like on a dovetail, would be about right.
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You're welcome.

IIRC, I switched to a bevel-edge chisel with a lower angle for paring. And it was smaller than the width of the mortise so I had some room to use a slicing cut.

Yeah, I think it was about 8:1.
Since this sounds like your first attempt at doing these, I might as well toss out a couple of potential "gotchas": To reduce the odds of splitting the tenon piece when driving the wedge, drill a hole that's slightly larger than the kerf at its base. And stop your kerf ~1/4" from the shoulder. (Also, choose nice striaght-grained wood for the tenon piece.) When doing double wedges, make sure each wedge is driven home with the angled face towards the end of the mortise/tenon. Otherwise, you risk splitting the wood or actually locking the joint without having it seat all the way to the shoulder of the tenon. (The latter is what happened to me on a mallet.)
Chuck Vance
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snipped-for-privacy@swt.edu (Conan the Librarian) wrote:

Actually, it's my second. My first attempt was a total disaster. I'm hoping to improve on that this time around :-)

Thanks again for the suggestions.
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I'm not sure if you mean the tenon as it extends through the mortise or not. If that is the case, a hand plane will do a good job of making everything flush. On through mortises, I learned to mark both sides of the mortise before chopping. This marking is done with a utility knife in order to define the edges, The mortise is chopped halfway through the piece and then finished from the other side. A mortise chisel is fine, but these mortises can be chopped with a bevel edge chisel. You take smaller chunks out as you go, but this lends itself to producing a cleaner mortise. Of course, you can take smaller cuts with a mortise chisel as well. :-)

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Roy,
I just read your post again, and I may have mis-read it before. If you are talking about a through tenon that sticks through the wood and extends above the wood a small amount and you want to bevel the four edges of the tenon, use a file. a single cut or double cut mill bastard file will suffice. You can also polish the end grain with the file.
Sorry that I missed the thrust of your post, but I tend to be a little dense at times. :-)

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