Using Hollow Punch

All,
Having never used a hollow punch before and needing to make bur-free 5/32" holes in 16 gauge sheet metal . . . is it as simple as whacking
it down with a hammer? (As it would appear.)
After you wipe away your tears a simple yes/no will do fine.
Thx!
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b_t snipped-for-privacy@hotmail.com wrote:

Suggest you invest in a hand punch, one of the Whitney No. 5 Jr. clones. You can't put a hole too far from an edge, but they work just dandy. The HF unit has metric sized punches, but 5/32" isn't too different from 4mm. See: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?ItemnumberD060
or ebay item 200071575071
GWE
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Hollow punches are for leather. Or for punching holes in canvas to put grommets in.
As grant says, for sheet metal, a Roper Whitney No. 5 junior cant be beat. I have had mine for close to 30 years now, and it still works great.
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IIRC we used to use a solid, square ended (slightly tapered) punch on sheet metal to make holes for rivets. Place the sheet over a block of lead (or end grain hardwood, but lead is better), place punch on mark and strike smartly with a hammer, the slug is driven into the lead block and gets liberated upon re-casting. Gerry :-)} London, Canada
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Thanks for all the suggestions (now regretting getting too excited and purchasing hollow punch set online).
I also have a need for a sheet metal disc of variable diameters. I tried cutting one using a hole saw with my drill press but found the 2" disc it cut to be basically 'torn out' of the sheet (one big bur). Is this due to a lack of WD40 oil while I cut it? Did I try to cut it too fast? Is there something better to use for cleaner discs than a hole saw?
How can I get nice clean sheet metal discs?
(I'm trying to make my own sprockets by using layered sheet metal.)
Thanks again, -Bkennedy
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b_t snipped-for-privacy@hotmail.com wrote:

You are learning! Your design idea which sounded simple, might not be .. you may have to go back to the drawing board. To cut discs cleanly on a drill press (don't even think about a hand drill) you would need a flycutter and a specially ground HSS bit called a "trepanning bit". To cut discs cleanly in industry is done with big punching machines, faster than you can even think.
WD-40 is worthless as a cutting oil on steel. It might work OK on aluminum, being largely kerosene.
Grant
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On 23 Jan 2007 19:51:09 -0800, b_t snipped-for-privacy@hotmail.com penned the following well considered thoughts to the readers of rec.crafts.metalworking:

Find a circle shear...
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16 ga.? That ain't gonna' happen! 16 thousandths - OK.
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Layered sheet metal is not a very cheap, or easy way to make a sprocket. Or much of anything. They use the technique to make transformers, but for totally different reasons.
I would be slicing the final thickness you want off of round bar, with a small 4x6 horizontal bandsaw- its gonna be cheaper and quicker in the long run, and the bandsaw is good for a million other things.
Yes, you could cut circles in 16ga with a flycutter- but to do it in much quantity, you would probably want a milling machine, with a collet system that actually locks in place with a drawbar- nothing quite as exciting as when you flycutter overpowers the friction fit of your morse taper drill chuck, and decides to go for a spin around the shop.
2" circles are usually stamped on a punch press. And you can buy em cheaply from companies that do this by the thousand. Like Wagner- http://www.jgbraun.com/site/viewer.aspx?iid 73&mname=article&rpidW0
The tonnage required to punch a 2" circle from 16 ga is more than you would think- probably around 12 tons. Can you hit a hammer that hard?
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