Power Hammer Forging Tenons

[iron quake]

I’m making .38 round tenons on .75 square bars. I made a spring tool from 4140 and heat treated it. It’s a progressive .43, .38, .31, .25. I made it for tenons and drawing out long round sections. The holes are relived on the sides where the two halves come together so I don’t get over lap and shunts. I’d say it works ok such as it is The issue is, I’ve been reducing the .75 bar to .50 square before sticking it in the spring tool but I get a lot non square shoulder to fix because of the radiuses on the edge on my main die set. I fix this with my own version of monkey block mounted to a 3” steel plate on the floor so I can really beat the hell out of it to square it up. This works but I need something better than this. How much improvement will I get if I shoulder first with a shouldering spring tool? I’ll be making a larger tenon tool, one that goes from .75 to .38 in five steps. I’m not sure if I’d be better off making a shoulder tool first. What say you master smiths!

[John B]

Are you using a power hammer or by hand?

Similar technique in both cases different style of tooling.

Butcher in all round to isolate end to be worked, it is important to get a clean edge correctly lined up, on all four sides

Side set down to just plus of finished diameter required from each opposing side

Use your reducing dies/swages to bring to size,

Then you should only have to use a monkey tool lightly or not at all,

I can't get pictures to post, but there is a guide to making tenons #5 on http://www.iforgeiron.com/topic/21343-joining-methods-course-last-weekend-april-2011/ (square in this case but tooling is similar except replace square block/anvil edge with round swaging tools) in the Blacksmiths Guild UK section of the Groups forum

Edited March 11, 2012 by John B

[bigfootnampa]

I am not sure what you mean by "shoulder tool" but if you mean a butcher or side set tool I think that would be a good idea. I also think that you'd be more successful with a standard monkey tool for refining your tenons than with the floor mounted version that you are using. The mass of your bars is working against you as you are doing it now whereas by hammering on the monkey tool instead of the far end of the bar you'd be able to use it to your advantage. You want to get your hammer working as close to the area that needs shaping as possible for the most efficient delivery of force. As you are now working you are wasting most of your hammer force in deforming the cold end of your bars which is why you have to work so very much harder to get your real work done.

[peacock]

Yes, use a butcher or something of that type to set the shoulder then draw down. Now remember when you wanted to upset bars? Use the lesson learned on that here. Make a monkey tool for your 6x air riveter and square up the shoulder. Let the mass of the bar become is't own anvil as Bigfoot just stated.

[JNewman]

A shouldering/butchering tool will make a big difference. Look at the tool Grant was using in this videohttp://www.youtube.com/watch?v=CFqGzYvwdX4&list=UUHM4D8_ih1OdIK9iSZQl9UQ&index=10&feature=plcp with going from 3/4" to 3/8" you may need 2 stages in the butchering. Your butchering should not go right to 3/8" although it is easier to open the butcher up than close it while making it. Once you have it butchered roughing it down to 3/8" square then octagon on your flat dies using a stopper is the quickest way to get it to size. You can then go straight to your 3/8" swage. I have a tool I make that has a 4" long 3/4" shank coming out of a 1 3/4"x1" bar. I do these this way, butchering the bar to just over 3/4" round, taking the butcher off the hammer drawing it to 3/4" square then octagon, then swaging them.

A trick for monkeying the tenons is to use a monkey tool made for a air chisel. I have used the common muffler gun type on 1/4"and 5/16" tenons on 1/2"and 5/8" bar and it works amazingly well. I am not sure they would have enough power with the 3/4" bar but you could buy a larger .680 shank tool if you are making a lot of these tenons. It would be worth trying with the muffler gun type as it is a pretty easy tool to make.

[iron quake]

The input from you folks is just invaluable to me, I can’t thank you enough. I gleaned several knowledge nuggets from this post. The shoulder tool will be very helpful and the video of Grant RIP, gives me the idea of placing a removable collar on long parts to get them located into the dies accurately every time. I need to buy a chipping hammer as my 6X rivet hammer is a little too weenie for a lot of things and the shank it too small to machine parts with a larger end mass for doing things like those mentioned above.

For any of you using these chipping hammers or pneumatic tools for forming hot what’s the best alloy to machine these from? I like S7 a lot and have been making tools from that for 30 years but not hot work tools. How about H10 11 or H13? Thanks again.

[JNewman]

It has been a while since I used pneumatic tools for chiseling and I mostly just reworked commercially made tools for that. Most of the monkey tools I made from just mild steel but the last one I made that had to upset 50 5/8" bars I used 4140. S or H series steel would probably been better but more expensive.

[KjZitur]

This is one way of doing tenons. 3 stage tool to forge tenon and upset with a monkey tool in a zip gun and finish with monkey tool by hand........it's an old video but it might give you some ideas...

tenon.wmv

[MOblacksmith0530]

I just finished some 1/2 inch square tennons on 1" bar and I used a smithing magician with butcher tools in it to set the shoulder and then drew them down on the power hammer using sizing stops on flat dies then finished them with a monkey tool. Pretty simple to do and easier if you are doing round. It is really important in my mind to start with butcheres shoulders or you will have a lot of monkey tool work to do.