Tenons & Cold Shuts

[Firegirl]

Hi Everybody,

I am making a table (pictures when it's finished) and I'm having trouble avoiding cold shuts on the tenons. I only have hand tools, an anvil, and a swage block...no nifty toys or power tools. Any suggestions????? Thanks :)

[easilyconfused]

Have you chamfered all sharp edges? Sharp edges are usually a major cause of cold shuts. A round file to clean up sharp edges and radius the corners of the tenon might help. Any more info you could give us on the tools and technique you're using, including photos, would be helpful to isolate the problem.:)

[Mark Aspery]

Generally when I have this happening to me, it is because I have made a mistake when I was butchering the material - isolating the mass for the tenon.

As I travel a lot to smith, I take a butcher edged hand chisel for my tenons. If I could have my preference, I would take a butcher edged hardy cut-off tool.

I know that the closest that I can work to the end of the stock is half its thickness from the end. If I work any closer than that I will peel off the end rather than butcher the material.

I forge out the tenon using a guillotine tool made from 1 1/4 inch square tubing with some 1 inch bar inside.

This can be two bits of the tubing welded to a piece of angle iron that will fit into your hardy hole.

The shoulder (only) is finished with a monkey tool.

[Gobae]

Where on the tenon? The shoulder or the shaft proper, or the end? Each area can have different causes and cures.

But regardless of the specifics, I would definitely suggest making yourself a "monkey tool" to help with the shouldering. A monkey tool is essentially a chunk of metal with a hole drilled in it (the size of the tenon shaft) that can be hammered down the shaft. This will square up the shoulder and the shaft.

[dimenickel]

very nice pictures ... thanks

[Alwin]

With hand tools and without a guillotine tool, I might recommend using a butcher with a rounded edge on top instead of a sharp chisel. It means you're fullering instead of cutting and will prevent cold shuts while you are improving your skills. Your butcher should be flat on one side and the angle that it slopes down on the other side makes a difference. If it has a very steep slope and you aren't very accurate with your hammer when shaping the tenon, you can push some of the metal in the tenon side back into the shoulder creating an overlap. A more gradual slope on the tenon side of the butcher will mean that it takes longer to get the tenon to size but it will decrease the risks of a cold shut. As you get better and improve tooling, a sharp butcher and guillotine tool will make it much faster. It may also be that a little practice with a sharp butcher is all you need. When forging a tenon by hand it is very helpful to hit a few times on one side then flip 180 degrees and hit a few times on the opposite side, then turn 90 degrees and do the same.

[Mark Aspery]

I'm a big fan of the method Mark showed. However, if in spite of all you do, you still end up with the beginnings of a cold shut, stop and rasp it out.


Question for Mark: Do you ever use a side set? Perhaps with larger tenons or do you feel the step is unnecessary.

I used to -as that was the way I was shown. These days I stop and make a monkey tool - even for large tenons such as the heel tenon. If everything has gone wrong, and I have a stepped shoulder across a large tenon (heel tenon) then I will use a side set to help even them up.

I make square monkey tools from round stock with a hole drilled in it.

There is a fashion at the moment to use sockets for a monkey tool for square tenons. I'm fine with that if it is an impact socket and NOT chromed, but the chrome can come off the usual socket set quite fast and it is very sharp (read dangerous). Edited March 12, 2009 by Mark Aspery

[Frosty]

Thanks again Mark. You are filling quite the notebook for me.

Much appreciated.

Frosty

[Pault17]

Mark, Frosty has it exactly right. I wish you lived a little further from the "left" coast on the pacific and closer to the "right" coast over here on the atlantic:D
I would maybe even be able to convince my wife of the benefit gained from your teachings.

thanks for the mini class on tenons

[mcraigl]

OK, my .02. A couple of things. First notice that both of the butchering tools that Mark shows in the picture have a radiused edge on them. Second, and I know it's there even though you can't tell from the picture. When you make your monkey tool, chamfer the mouth of the hole that tenon goes through. Just a bit. You can do it with a bob punch, or with a countersink in a drill. You don't want a sharp corner here either. A couple of other things to think about. Are you working the steel too cold? Are you getting the work done on the tenon with as few heats as possible? Overworking the steel and working it too cold are both sure ways to propogate cold shuts/cracks especially at a square corner (which is why you want a radius on your butcher and a chamfer/radius on your monkey tool).

[Mark Aspery]

OK, my .02. A couple of things. First notice that both of the butchering tools that Mark shows in the picture have a radiused edge on them. Second, and I know it's there even though you can't tell from the picture. When you make your monkey tool, chamfer the mouth of the hole that tenon goes through. Just a bit. You can do it with a bob punch, or with a countersink in a drill. You don't want a sharp corner here either. A couple of other things to think about. Are you working the steel too cold? Are you getting the work done on the tenon with as few heats as possible? Overworking the steel and working it too cold are both sure ways to propogate cold shuts/cracks especially at a square corner (which is why you want a radius on your butcher and a chamfer/radius on your monkey tool).

A very good .02 worth Mike.

[Firegirl]

Thanks for the advice guys, I'm gonna practice for a few days and get back to you :)

[Reid Neilsen]

I agree totally. Sometimes you can get lucky and if you only have to file out a little bit to remove the cold-shut, you can get away with it. I'd use a double fuller/spring fuller/guillotine tool (if you have it) to make your shoulder, forge down the rest of the tenon and clean the shoulder with a file or a monkey tool. OR forge your shoulder for the tenon a bit lower than where it needs to be and remove material until it is exactly where it needs to be. More labor, but you definitely dont want a crack forming at the shoulder of a tenon on a piece that could potentially bear weight (like a table)