New source of gas check material for those who roll their own...

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Originally Posted by JIMinPHX

......but the knock out ends up looking like a potato chip.

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Now you have it in a nut shell Jim. You can with a concave punch get enough pressure on a reloading press to cut 0.020 material, but the knock out is what you want to make the check out of and if it is not a near perfect circle with an evenly cut edge it will not form properly. I am never said you couldn't cut it with a reloading press, I said you couldn't cut it and have anything worth making a gas check out of. I just don't see any way around a flat bottom punch cutting out flat circular disks.

Even at the Sierra Plant all of their punches that punch jackets start out and maintain a flat bottom all the way through the drawing out process even on the boat tail bullet the punch has a flat bottom. Round does not work for bullet or boolit bases.

Best wishes from the Boer Ranch,

Joe

Good info, I agree with the quality of the content of this new sorce of GC's. I will also ask my favorite bar maid to keep a few dozen for me. Yhanks for the information!!! SL 45/70:mrgreen:

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I was thinking that the cylindrical relief leaves a good hole, but the knock out ends up looking like a potato chip. That might have something to do with it, but I really don't know. I haven't made many punches. Again, any advice is appreciated.

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Jim,

I would try a cylindrical concave, or just grind a slight (one or two degrees) angle on the punch. Remember; you only need to double the shearing length to reduce the shearing force with 50%. The actually shearing of a stamped part is already done before the punch is halfway through the material! So in theory to cut a .01 disc the punch only need to move .005 into the material.

Again, I wouldn't worry about a slight "potato chip" shaped disc, the disk is still round, and the following draw process will stretch and flatten the disc over the draw punch. But don't take my word for it; try putting a slight curve on a disc and run it through the draw die - I'll be happy to finish off a heaping helping of humble pie if it doesn't works [smilie=1:

As an electrician, I've used the Greenlee knockout cutters. They do cut nice round pieces. Here's a pic of one:http://castboolits.gunloads.com/atta...1&d=1234933026

I know the knockout looks mis-shaped, but I've used these things 100's of times and the cutters do cut nice round holes.
35W

35 Whelen--My dad was an electrician (in Wichita Falls,Texas) and I have his set of Greenlee knockout punches which he had as long as I can remember. Yes, they make a perfect hole, of course for a gas check you are using the material that makes the hole. With the Greenlee you start out with a hole so it would be ruined as a gas check--that's why a press is being used. I've not cut thin aluminum with them but they do require some pretty heavy force. I use them for making the entry doors in purple martin houses and use an impact wrench to drive them.

Ask me nice, and I will tell you all where to get sheet aluminum that mikes a consistent .008" and can usually be had free in reasonable quantities, in large sheets.

Rich
Buff Killer

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Originally Posted by carpetman

35 Whelen--My dad was an electrician (in Wichita Falls,Texas) and I have his set of Greenlee knockout punches which he had as long as I can remember. Yes, they make a perfect hole, of course for a gas check you are using the material that makes the hole. With the Greenlee you start out with a hole so it would be ruined as a gas check--that's why a press is being used. I've not cut thin aluminum with them but they do require some pretty heavy force. I use them for making the entry doors in purple martin houses and use an impact wrench to drive them.

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How long ago was your Dad an electrician? I've lived in Wichita Falls all my life. I may have known him. Regarding the KO cutter, obviously the hole in it negates its use as a gas check punch, but I thought if someone saw the design, they'd understand how a punch might be made.
35W

Question: why would the hole in the middle negate use as a gas check? Ever look at military FMJ slugs? That gray/black stuff at the base is the lead core.

jut curious...

Rich
Buff Killer

And now the $64 dollar answer: go to your newspaper and get a few sheets of the aluminum they use for the printing presses. Used once and discarded.

Rich
Buff Killer

My punchdie cuts .020" copper sheet with little effort with RCBS RC2.
These are .50" disks to make .458" checks.

http://i122.photobucket.com/albums/o...n/IMG_1952.jpg
http://i122.photobucket.com/albums/o...n/IMG_1955.jpg
http://i122.photobucket.com/albums/o...n/IMG_1957.jpg
http://i122.photobucket.com/albums/o...n/IMG_1964.jpg



Kaj

OK, now THAT"S what we're talking about people!

Thank you Kaj!

How about some pictures from a couple different angles?

Your work? Commercially available?

Cheers
Trev

IdahoSharpshooter - I have used these sheets before years ago for other stuff, but didn't think about the thickness until you mentioned it! I think I will go get my hands on 10 sheets or so, and be set for life! (or at least a year or 2).

Kaj,

Your arrangement looks great. Now all you need is a simple guide/stop pin to control the step length via the holes in the strip. Then you can do away with the guide markings, and watch TV while crunching out discs. :-D

I must admit that is a really cool set up, and I will now proceed to insert my foot in my mouth concerning punching material thicker than 10 thou. with a reloading press.


Best wishes from the Boer Ranch,

Joe

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Originally Posted by trevj

OK, now THAT"S what we're talking about people!

Thank you Kaj!

How about some pictures from a couple different angles?

Your work? Commercially available?

Cheers
Trev

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Trevj,

Here's few more pictures.
It's all home made and feel free copy it if you like.


Cap'n Morgan,

Don't get me started all over again designing yet another gascheck maker.
This is my third design allready :mrgreen:. (and I'm quite happy with it)


Boerrancher,

And I must admit that I was myself little skeptical about if it will work,but decided to try it anyway:-D.
With tight tolerances and at the top of the stroke,it cuts nice and clean.

http://i122.photobucket.com/albums/o...n/IMG_1969.jpg

http://i122.photobucket.com/albums/o...n/IMG_1979.jpg

http://i122.photobucket.com/albums/o...n/IMG_1985.jpg



Kaj

Per the Freechex information provided on his sales site- the McMasters-Carr catalog pg 2277 has (besides what he recommends) hand punch sets that punch a nice disc from thin stock. I have an old Whitney Metal Co. hand punch (very similar to the small set depicted in the plastic box) that belonged to my grandfather. The 9/32 punch is what Freechex uses to make 22 discs, and a 13/32 for 308 discs. Similar to what is posted in the pic's above, I think you could adapt the hand punch interchangable punch/die idea and scale up the outside of the die to fit a 7/8-14 press hole and adapt the punch to the ram like the Lee push through dies size dies. That could also be reversed so the disc would fall out, too. The hand punches couldn't possibly be anymore difficult to operate than a leveraged reloading press. You might get better usage from your metal with the hand punch too, and not have to cut everything into strips, etc. on the small GC's.

I am considering getting a couple of the Freechex sets (since these are all that seem to be available) and have been studying my various options and things I would need additionally.

Thanks Kaj,

That is an elegant design.

Nice use of the offset bar cut to use for the bulk of the body of the cutting die!

Very clear to see how the ejector for the checks works, too.

I should go rooting through the scrap under my lathe, I guess....

What are you using for a lathe? I've got a Myford here in my basement, but a couple nice "real" lathes at work.

Work goes faster on the big lathes, but it's pretty easy to get lost in the shop, in front of the Myford, too.

Very nice work! You should be very proud of it!

Cheers
Trev

Well, to drag this back to the top, where I can find it again...

I dug up a piece of 17-4 H-1000 or H-900 (unknown for certain) and had at the body of the cutting die.

So far so good.

PITA to get used to a small lathe again. :)

Managed to shoot a drill through the full length of it with the hole running true, not always an easy task, and will take a photo or two.

I'm aiming at a check maker that I can pound out .22 cal checks with, and am deliberating on the sizes and the die design.

Looking at some commercial checks, the material is aprox .010" copper. Figure .050" height more or less, so .214" (the check seat diameter I find published) plus .040" x 2, equals a .294" diameter blank.


At this point, I have settled on a .2145 punch diameter, I think, and am working out my die design so I can have the punch and die align, and still have the finished check eject with a tapered edge on it, so it will form down and grip.

Ponderponderponder....

Been pondering how to make a punch die with interchangeable sizes, too. Thinking drill bushings at this point, but still pondering...


Cheers
Trev

Built this over the last week or so, partly at home in the evening, and partly at lunchtime, at work.

The die body is 17-4. Turns nice, if you are not in too much hurry. Dead easy to get a decent surface finish.

The slot was cut with a 1/32 slitting saw (a device of torment and misery!) because I had one handy. Didnt see much need to go thicker, either.



http://i152.photobucket.com/albums/s...DSCF0080-1.jpg

The hole size was drilled out with a 9/32 long drill, and reamed up to a Letter M size hole (.295", IIRC). The hole had been drilled out from below, to 5/16", to cut down drag and alignment issues.


http://i152.photobucket.com/albums/s...0/DSCF0090.jpg

The punch is built out of some rod that was in the scrap bin. We'll see how it holds up. It's not hardened.

I'll add more info later, gotta go see a movie!

http://i152.photobucket.com/albums/s...0/DSCF0089.jpg

Cheers
Trev

Quote:

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Originally Posted by Boerrancher

Now you have it in a nut shell Jim. You can with a concave punch get enough pressure on a reloading press to cut 0.020 material, but the knock out is what you want to make the check out of and if it is not a near perfect circle with an evenly cut edge it will not form properly. ...

Best wishes from the Boer Ranch,

Joe

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In the case of the Greenlee punch, the female punch is flat & the male punch has the relief cut in it. The hole comes out flat & the slug (disk) comes out like a potato chip. If I were to leave the male punch flat & cut the relief into the female punch, I wonder if the disk would stay flat. I may try that & see what happens.