Making Oblong Punches

[stu925]

Ok so I've boogered my last holster belt slot. I've been cutting my 1 3/4" belt slots with a 1/4" punch and a 1 1/2" chisel. Some slots come out ok and then there's the mess I made of one tonight when the chisel went in at an angle. Completely ruined the holster but luckily I cut the slot before I did any stitching. I did some research on a 1 3/4" oblong punch and am not too happy about the prices of them. I've decided to fire up my forge and see if I can make one. So my thought is to use a piece of 1 1/2" black iron pipe and forge it down. I'm sure someone here has made their own oblong punches so any advice I can get here would be appreciated. I can grind the bevel on a 1x30" belt sander and then finish the cutting edge with stones. My question is am I correct in my thinking of using 1 1/2" pipe or should I go smaller 1" or maybe 1 1/4". My next question is will I be able to harden the edge of that black iron? I suspect that it won't harden but I've never tried it. I do enough holsters that the punch will need to hold an edge as I don't want to have to repair the edge every time I use it. Is there a better material to use than black iron? Maybe if all this goes well and I can build it without a significant time investment I can offer them to members here for a reasonable price.

Stu

Edited October 13, 2015 by stu925

[dikman]

I doubt you would be able to harden black pipe as it's unlikely to have enough carbon in it. You could case-harden the edge, but as it will require sharpening from time to time you'll end up removing the case-hardening at the edge, leaving you with a soft cutting edge. One way would be to cut the edge itself from a piece of flat tool steel bar (to give you the correct oval shape), forge your pipe to the correct size/shape, weld the tool steel cutting edge to the pipe then harden and sharpen it.

A fair bit of work, though.

Whatever you do, you'll either have to make the whole thing from high carbon steel, or use high carbon for the cutting edge and weld it to a soft steel body.

[TinkerTailor]

4130 steel bicycle frames yield lots of sizes of tubing. It is stiff and hard enough in its native state to make adequate punches and is usually free. It is not really hardenable, but still works ok. Better than gas pipe that's for sure. The edges don't tend to bend and stay sharp for quite a while if you are careful not to over drive them into the cutting surface. I have a few made this way and they are all good, some with alot of use. I have also sharpened chromoly sockets because sometimes when I am punching holes through multiple layers, I don't want the stretch at the top of the hole a standard punch makes due to the wedge. If you sharpen the inside, you get a straight sided hole. It helps to pre punch the hole a smaller size with a standard punch so the plug doesn't get stuck in the socket.

[stu925]

Ok so further research into this has revealed that Super Quench will harden the black iron somewhat. It won't be as hard as say knife or chisel steel but should help maintain the edge at least a bit better than it would normally. I'm going to try it and see how it goes. Forging a piece of tool steel into a punch would be a great deal of work and may eventually be done as a more permanent solution, for now I'm going black iron and we'll see how that works. I'll update this thread when it's done and tested and let you guys know how it goes.

Stu

[dikman]

It will be an interesting experiment. I remember reading (somewhere!) about Superquench. Apparently the old original formula worked very well, unfortunately it used some toxic materials (of course, that's why it worked so well) so in these OH&S days it's a no-no.

No harm in trying the stuff that's now available, however.

[stu925]

It will be an interesting experiment. I remember reading (somewhere!) about Superquench. Apparently the old original formula worked very well, unfortunately it used some toxic materials (of course, that's why it worked so well) so in these OH&S days it's a no-no.

No harm in trying the stuff that's now available, however.

Looks like I should expect a Rockwell hardness of somewhere between 40-45. Not super high but should be enough for what I need. If it gets me through 3 or 4 holster without needing to be sharpened I'd be happy. I'll be out at the forge tomorrow and hopefully have that tool completed by tomorrow evening or at least completed enough for a test run. I won't be tempering the tool and I'll only be hardening the cutting edge. Bought all the stuff for the Super Quench and the pipe today so we'll see how it goes.

Stu

[TinkerTailor]

4130 steel - 92 rockwell

http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=m4130r

[dikman]

There's any number of steels available that can be hardened, but Stu is trying to do it as simply as possible. Using any of the tool steels to form into a large oblong shape would be a lot of work for most of us amateur blacksmiths, whereas the pipe basically just needs to be shaped and ground.

What are you using to punch on, Stu? That will have a bearing on how long the cutting edge will last (I'm using a hardwood log, as I've found the mass of the thing makes a big difference when punching things).

[TinkerTailor]

Did you miss the part where old bicycle frames are free chromoly tubing? Even the High tensile 1020 tubing of cheap frames is higher in carbon than black iron pipe. It lists as 66 rockwell hot rolled and 72 cold rolled. At 0.20% carbon hi tensile 1020 bike tubes should harden just fine.

These tubes show up in LOTS of sizes. It can be heated and worked. Its also commonly used in race car/offroad/atv/motorcycle chassis shops so cut offs may be available at a fab shop.

I crushed a heated piece of 7/8"d 1/16" wall chromo in a vise and it made a 1 1/8" X 3/16" slot punch. I don't have it in front of me but I think 1 1/8 tubing made a 1-1/2 inch punch 3/16 wide. Only needed a propane torch a vise and alot of filing. Thats as beginner blacksmith as it gets.

http://www.coburnmyers.com/materials-carbon-steel/

http://www.bikeforums.net/classic-vintage/731539-high-tensile-1020-butted-tubing.html

half way down is a post withthe material specs for 4130 and 1020 as used in bicycles.

Edited October 15, 2015 by TinkerTailor

[stu925]

Ok so the black iron was an utter failure. Not because of the hardening issues, it actually hardened up pretty well with the Super Quench but more because of the fact that 1" pipe when forged down to size ends up 1 1/2" and 1 1/4" when forged down to 1 3/4" ends up with a slot almost 1/2" wide, to get a 1/4" wide slot it ends up 2" long. Also because of the thicknes of the wall of the pipe it needs to be heavily tapered or you really need to hammer it to get it through even one piece of 9oz leather, didn't even bother trying 2 layers. So it seems I'm back to the drawing board. I'm thinking I take a 10" sawz-all blade and bend it to shape and then forge weld it. Not exactly sure what I'll do for a handle yet but I'll figure that out after I get the blade bent around a jig. This may be a project for the weekend.

The Super Quench worked as advertised and did harden the iron pipe although I wouldn't ask too much of it. On the other hand I have a Railroad spike knife I made that hardened up really well in the super quench, must have a bit more carbon than the iron pipe. If anyone here is running their own forge and looking to harden mild steel, super quench may be the way to go.

Stu