Broaches

[mooncoon]

A while ago I posted a thread about making a tapered square broach for cutting the square hole in a hammer for the tumbler shaft. I have used it several times and it cuts the time in fitting a hammer to about 15 minutes from about 45 minutes or more plus does a better job.

A couple of days ago, I finally got around to making a couple of broaches for cutting dovetails. In the past I have milled a square sided slot then filed it to a dovetail using a triangular file with a safe side down. Even so, the bottom of my dovetails tended to be hogbacked. I have not used a 60 degree mill cutter partly because I didn't have one and partly because if I was a smidge large, a sight would be loose and a smidge small and it would not fit.

The first broach was a rapid taper one for opening a 5/16" slot quickly to just under 3/8" dovetail. It tapers from roughly 5/16" wide to almost .5". It is also good for cutting wider dovetails for barrel tenons and also for the little blocks that the forend of a cartridge rifle screw into.

the second broach tapers by roughly .005" per inch and is about 6" long in order to get enough range of cutting width. Other than the fact that I overshot a bit in grinding the 60 degree and filing it to finish, it works like a hot damn and the pair of them cut sight dovetails very quickly plus leave a nice flat bottom to the dovetail

cheers mooncoon

 

[Skinny 1950]

Are you making those out of drill rod then tempering the metal??

 

[NorthCoastBigBore]

Great work as always, thanks for posting. Darn dovetails are tricky, time consuming things by hand.

Great idea.

 

[mooncoon]

these save a lot of time and give an excellent tight fit because you can keep removing just a small amount of metal until you get the fit you are looking for.

I am making them from drill rod and in the case of the long 3/8 slow taper one, I heated the rod red hot and forged it out to a little over 3/8 wide with square sides. Then milled the top and bottom straight and smooth and ground most of the metal off to create the 60 degree side (finished with a file). Teeth are initially cut with a hack saw then filed to shape. I harden the broaches spinning to reduce or prevent warp then draw to brown for a working hardness. Almost forgot, I use a bucket of wood ash for annealing

cheers mooncoon

 

[david doyle]

BUMP for coolness.