Greenlee hole punches

Greetings all: I'd like to generate a bunch of 3 to 4" disks of sheet metal (pretty thin, 20-ish and thinner gauge), and am looking at punches to do the job. Would a Greenlee-type punch preserve the structure of the punch-out (I realize its main purpose is to make the hole, but I'm actually interested in what will be punched out)? Is there some other method that I'm not thinking of (I figure a hole saw is too aggressive and will leave a pretty rough product on both the hole edge and what falls out). Any advice would be appreciated.

Reply to
fura-2
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Unless you use an external press there will be a hole in the middle from the draw stud. The punch is also angled which tends to bend the piece that comes out. I guess you could flatten a twenty gauge disk fairly easily. You would want the old style punches, not the slug busters. What are you going to do with the discs?

Reply to
ATP*

You need a die blanking punch set and a press big enough to do the job. You're barking up the wrong tree with any manual electrician's type punch like Greenlee because they use central holes for a bolt.

When you want the hole sized right, the punch is the right size and the die has clearance. When you want the blank sized right, the die is the right size and the punch has clearance.

Another way is to use a trepanning cutter on a mill or lathe.

GWE

Reply to
Grant Erwin

Greenlee punches require a drilled hole (maybe something like 1/2" for that size, I don't recall) and they cut with a curved edge, so the result is a rather curved slug with a fairly large hole in the middle, probably not what you want.

If a hole in the middle is acceptable, maybe you could stack blanks and turn them on a lathe.

Best regards, Spehro Pefhany

Reply to
Spehro Pefhany

I now it takes all the fun out of it but you can buy these from a trophy/awards supply outfit like Freeman. They come in brass and aluminum with protective paper. They are perfect circles and the edges are smooth. Lots of sizes and finishes. Natural, shiny, blue, red, green, white, black. I have printed thousands of these over the years. Google for trophy supplies. If you want to make them I would suggest a router or you could buy this nice rotary tale I have here and bolt it to your milling machine. Good luck Dan

Reply to
daniel peterman

STOP!!! I punch-out thousands of 19 and other ga. disks that then become wire wheel hubs. (round) how many, what dia. do you want a hole in the middle?

Reply to
Tom Gardner

Thank you. I'd like to make bobeche (wax cups) out of them. I guess bending is what I'd want to do anyway. Thanks.

Reply to
fura-2

You're absolutely right. There will be a hole, and I forgot to take this into account in my post. I guess in the worst-case scenario I could configure things so that I could fill the hole with weld (if I'm good enough).

Reply to
fura-2

It isn't cupping, though, it's bending.

See the photo at the top of this page:

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The slug ends up shaped just like the punch (bottom part), while the chassis ends up flat like the die (top part).

You want to make something like this?

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Best regards, Spehro Pefhany

Reply to
Spehro Pefhany

According to fura-2 :

Hmm ... you *could* mount the halves of a Greenlee punch in a hydraulic press, and punch holes without a center hole. But they

*still* would come out shaped like a Pringles artificial (reconstituted) potato chip. :-)

Enjoy, DoN.

Reply to
DoN. Nichols

Thanks very much for the links. The punch is indeed what I was inquiring about, but as has been pointed out by others I guess I don't necessarily want the hole in the middle. The detail of the bobeche shown in your link it quite a bit greater than I really had in mind, as I'd be happy with simply steel in various shapes.

Reply to
fura-2

Assuming I could weld the hole closed I don't think the hole is too great a problem (and could even come in handy at times). I just tinkering with metal candle holder ideas, just for projects at home. Thanks.

Reply to
fura-2

Excellent idea, thanks very much for the source info.

Reply to
fura-2

I hear what you're saying, but maybe I could just bang 'em back to near-flat or cupped, depending on what looks best. I've got an arbor press -- you think that would give me enough force, esp. if I used a pipe extension on the handle?

Reply to
fura-2

According to fura-2 :

Frankly, I doubt it. (Aside from the problem of maintaining proper alignment.) What tonnage rating of arbor press? I would not try a 1" or larger punch with my 3-ton arbor press -- pipe extension or no.

I remember the effort I had to put onto a 1/2" drive ratchet when punching steel relay rack bottoms with a ball-bearing screw and grease on the threads.

And I remember breaking the drive screw on one of the 1/2" punches. And that is one *tough* screw.

Greenlee sells a hydraulic drive for the bigger punches.

And the amount of force needed on the handles of a Weldon hand punch with 1/4" punch and die installed -- if you are working on steel makes me think that you would need more force for a larger punch than an arbor press is capable of providing.

Although -- if your metal is thin enough and/or soft enough, and the holes are small enough, *maybe* you can get away with it. Make sure that the die is firmly mounted on the anvil, and that the punch does not wiggle far enough to the sides to contact the edges of the die.

Maybe make a fixture to hold the two parts with guide rods and springs to pull the punch back out of the die and the sheet of metal stock which you are using. (But this is pretty close to what you need for a punch and die which will give you flat workpieces.)

Good Luck, DoN.

Reply to
DoN. Nichols

Yeah, I suspected as much (I've a pretty small arbor press) -- time to consider a hydraulic one I guess :). Thanks for the tips.

Reply to
fura-2

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