I’m finishing a chest that has a couple dozen M/T joints that I want to pin. I was thinking of doing square pins, but I’m looking for an easier way than marking out and cutting them with a regular chisel.
The mortises were cut using my drill press and mortising attachment, and I got to thinking, If I drive a square chisel into the wood with the drill press, why not use the chisel piece as a hand tool and gently tap it with a mallet to drive square holes (after pre-drilling round ones, slightly smaller than the square)?
Anyone think this would ruin the mortising chisel?
Just to be clear, the steps I’m thinking of would be:
1) assemble chest
2) drill 3/8″ round holes, pin tenons with 3/8″ dowels, but leave top 1/4″ of the hole empty
3) Tap a 7/16″ mortise chisel over the pinned joint to cut a square hole centered on the pin
4) Plug square holes with 7/16″ square plugs.
[And yes, I know I could make single pins that are mostly round along the length except for a square end, but it’s easy for me to make dowel and adding plugs is easier. The stock is 1.375″ thick red oak, so pins will be strong even with the top 1/4″ missing.]
Paul
Replies
I do this all the time with my motising chisels. I just used my 1/2 inch to make square holes in my assembly tables 2 inch thick oak edge to accept 1/2 inch bench dogs i made from oak. Those chisels are tuff, they have to be with all the pressure applied to them.
Garry
http://www.superwoodworks.com
You could just use the top quarter inch. Unless your M&T joints are really sloppy they are likely to be plenty strong. Pins of 3/8" diameter are pretty large--certainly not needed for structure. You may want the 7/16" size for esthetic reasons, but you could easily go down to 1/4" pins with 5/16" square caps if you want.
The pins are really for decorative purposes only. The M/T joints all fit tight without having to hammer them together, but I wanted to dress up the piece a little. I felt the 1/4" plugs would get lost on a bench chest that is 46w x 18d x 22h, all frame & panel construction where rails and stiles are 3" wide with 2.5" wide mullions.Recommending the use of "Hide Signatures" option under "My Preferences" since 2005
Why mess around with pinning with a dowel, making a countersunk mortise and then covering the dowel with a square plug? I just drill the same size hole as the mortise bit that I will use, tap the mortise bit in with a wooden mallet (you may want to do this in a few stages so it doesn't get wedged tight) and then drive in a square peg, full depth. No chance that way of the plug coming loose later and saves a step. If you want to leave the pegs proud, you need to put a tape depth guage on the drill and mortise bits and be a little more careful about the pin lengths. Try it in a scrap and I think you'll see it's simple.
Mike Hennessy
Thanks for the suggestion, I'll try it on scrap--but for a 3/8" hole, I suspect that there is too much extra wood on a square pin to be forced in, without damaging the tenon. Maybe for smaller plugs it's OK, but on a 3/8" plug there is almost 1/8" of square corner to squeeze into each round hole.
Still, I'll give it a try.Recommending the use of "Hide Signatures" option under "My Preferences" since 2005
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