Monkey tool, tenon shoulder tools

Hey guys,

I was wondering, for monkey tools or tenon shoulder tools what ratio of tenon diameter to length should be used?

I have a six inch chunk of shaft that I just took to my machinist buddies shop, he is going to face it then we are going to drill holes of different sizes and round over the edges so I can use this like a tenon swage block. Mostly for carpenter’s chisel tangs, but I am drilling holes larger for future needs.

So in traditional joinery is there an advantageous length to make a tenon of a given diameter?

AKA a tenon should be three times s long as the diameter, or what ever the rule may be?

Thanks fellas

Ok, we got it made, just to see how it works…

It’s got 1/4, 3/8, 1/2, 5/8, 3/4, 1" holes the smaller being 2" deep and the larger being 3"

What do you think will it work?


Looks nice! Is the idea that it sits on the anvil and you pound the piece into it to create the shoulder? I’ll try to dig up some photos of the tool I use.

Yeah, that’s what I was shooting for, or maybe it has its own post to set in…once it proves that it can work!

More of a shoulder dresser, and shoulder upsetting, the shoulder will be " made" already if I understand the process right…this will just replace the tube like tool.

Photo of my 1/2 tool. I would like to have a setup like yours but maybe add a stub so it would fit in the hardie hole of my anvil. Let us know how it works!