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Punching holes in metals

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Steviegtr02/01/2020 13:57:59
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1233 forum posts
115 photos

Hope this is the right forum area to ask this question. I need to punch holes in copper, nickel, silver & other soft metals. Not in mild or stainless. I need to make some different sizes of punch & dies to use on a press. 1st Q: can I use drill bits with the flute cut off , just leaving the shank as the punch. 2nd Q: The die will be a round washer type that will fit in a jig so I can fit different sizes of punch & die etc. What steel would be the best to make the dies from. Would mild steel drilled & then case hardened work or not. Any suggestions greatly appreciated.

Oldiron02/01/2020 15:09:23
442 forum posts
22 photos

I know nothing apart from the basic engineering principles so I found a video that may answer some of your questions. There are many more video's on YouTube that will help.

Punch & Die

regards

Mick B102/01/2020 15:10:48
1577 forum posts
84 photos

1) There's a small backtaper on drills, so that the diameter's about 0,02 - 0,04 down by the time you get to the runout of the flutes.

How much that matters depends on what's got to fit the hole.

The HSS isn't at full hardness at that point, and how much that matters depends on how many holes you got to pierce and how thick the material is relative to diameter.

2) Traditionally piercing dies might be made from BD3 or equivalent. Case hardened MS would only work for very small quantities.

Silver steel might work well.

 

Edited By Mick B1 on 02/01/2020 15:19:45

SillyOldDuffer02/01/2020 15:21:42
5786 forum posts
1232 photos

Probably a question of what you can get away with rather than producing sooper-dooper tools with the best steel available.

Die and punch both have to be made of something harder and tougher than the metal being punched. Less obviously, the size of the hole, thickness punched and how long the tools are expected to last matter too. A manufacturer might expect to knock out many tens of thousands of holes in difficult material before seeing any wear. Making a suitable die and punch at home to meet a commercial requirement is all but impossible. Don't panic - provided not too many smallish holes are needed, it should be possible to get results.

Mild-steel, case-hardened or not, is unsuitable. It's too soft and plastic. The punch needs to be a close fit to the die, and banging mild-steel soon distorts it. Case-hardening improves the outer wear characteristic of mild-steel, but it's a thin skin that does nothing to stiffen up the insides.

Perhaps best that can be done in a home workshop is grinding blocks of HSS. This is both hard and tough - in a different league entirely from mild steel. Re-using HSS may be possible, but my experience of HSS twist drills is the shanks are much softer than the cutting end. If a shank can be cut or filed, I suggest it's not much good for making a punch. (But might be OK for a few small holes, why not try it.) As HSS is very difficult to heat treat properly (needs to be held close to the correct temperatures for hours), I doubt the soft form can be re-hardened at home - we don't have the necessary equipment.

Tool-steel is a good possibility. You could repurpose a Flymo blade, or old file, car spring, whatever; Tool steels can be softened in a forge, worked to shape whilst soft, and then re-hardened by quenching. The process is simple enough but the operator has to judge metal, temperature and time to get good results. Getting it wrong means the metal may not harden at all, get burnt, crack, or be left as brittle as glass. Skilled work, so practice needed.

Hurrah then for Silver Steel aka Gauge Plate. They are the same metal; Silver Steel comes in ground rods, Gauge Plate in ground slabs. Rods are good for punches, plate good for dies. Silver Steel arrives soft and fairly easy to work. Best of all, it's formulated to be very straightforward to heat treat. Heating to approximately the right temperature and holding for a short time with a blow-lamp before quenching in water or oil usually gets a good result. It's also straightforward to temper the hard item (increase toughness and reduce brittleness) in an ordinary domestic oven. The performance of hardened silver steel won't be the best possible, but it's still pretty good. I've successfully made small marking punches from it, not attempted a die / punch for making big holes in plate.

Dave

Andrew Johnston02/01/2020 15:51:55
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5508 forum posts
647 photos

When I made a punch and die used to punch out an odd shape in brass (so a connector could be snapped in into place) I used silver steel and gauge plate. I left them unhardened. I wouldn't waste my time trying to adapt unsuitable tooling. Just use silver steel for round punches and gauge plate for everything else. For thin material probably not worth hardening, but for material above 10 thou or so I'd harden both punch and die. Silver steel and gauge plate are not quite the same. Silver steel is intended for water/brine quenching while gauge plate has extra alloying elements and is designed for oil hardening. Although of course water is fine for non-critical appllications.

The punch needs to be slightly smaller than the die. The thicker the material to be punched the smaller the die needs to be.

Andrew

Jeff Dayman02/01/2020 15:58:37
1818 forum posts
45 photos

Fundamentals of punch and die hole formation at link below.

**LINK**

Useful hand punch tool for light sheetmetal at link below. Had one for years, works really well.

**LINK**

David George 102/01/2020 17:00:18
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1226 forum posts
415 photos

Hi I have some screw type punches bought for jewelry making. I have also made similar from silver steel and a bolt with a hardened dowel inserted with a slight angle ground on the end to help the cutting procces.

Impressart 2 Hole Punch 1.6mm And 2.4mm Pierces

999_ia68_12 (2).jpg

I hope this will help

David

David Jupp02/01/2020 17:23:27
730 forum posts
17 photos

If the holes happen to be a standard size, hole punches used when building control panels can be surprisingly inexpensive (e.g. Q Max brand).

Steviegtr02/01/2020 19:15:10
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1233 forum posts
115 photos

Thanks for replies. Looks like Silver steel & gauge plate. You are a clever lot on here. The sizes will be roughly 3/8", 1/2", 5/8" & 3/4". Jewellery mainly. I have a set I bought from ebay but have trouble centering the work piece. Hence to make something better. Has this page got some sort of weird spellcheck. Tried to change centering to centring. Which would make it usa.

Howard Lewis02/01/2020 19:54:48
3276 forum posts
2 photos

For the sizes that you quote, I think that you will find that Arc Euro do a set that covers from 1/8" up to 3/4".

Just checked the latest catalogue; price is £51.13, plus £3.60 postage. Stock code is 100-192-00700

I have used my set fairly often, on shim steel, tin plate, and rubber or joint materials, with no sign of deterioration yet evident, so fairly long lasting.

HTH

Howard

not done it yet02/01/2020 21:22:39
4648 forum posts
16 photos

Just a question of interest. Are you wanting the holes or the discs?

Steviegtr02/01/2020 21:43:10
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1233 forum posts
115 photos

I want to punch holes in old coins dead centre. There are ones for sale self centering but expensive. So the reason to have a go at making one myself. Don't need the bit from centre unless they are silver.

James Alford02/01/2020 22:06:27
377 forum posts
73 photos

I have done some punching out of copper sheet: it is not a nice metal for this. The metal tears, rather than shears, unless the punch and die are well-matched and receive a sharp, heavy blow to operate them. Even then, using professionally made dies in a fly-press, I still encountered tearing.

Jamie.

Steviegtr02/01/2020 23:13:18
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1233 forum posts
115 photos

The one at the bottom is what I have. The 1st pic is what I would like to make. They are a fortune from America. Better punch

punch

Michael Gilligan02/01/2020 23:39:06
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15735 forum posts
687 photos
Posted by Steviegtr on 02/01/2020 23:13:18:

[…]

The 1st pic is what I would like to make. They are a fortune from America.

.

dont know Interesting

I’ve just found a video to watch tomorrow : **LINK**

https://youtu.be/GIkQy1H6MiI

MichaelG.

Steviegtr02/01/2020 23:47:42
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1233 forum posts
115 photos

Yes that's the one. Going to base something along those lines. No patent on that part but would not matter I will argue my grandad was Chinese.

Michael Gilligan02/01/2020 23:59:11
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15735 forum posts
687 photos

The main body looks suspiciously like a pipe connector of some sort

... might be worth visiting your local supplier of big hydraulics

MichaelG.

Steviegtr03/01/2020 00:10:04
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1233 forum posts
115 photos

20200103_000026.jpgThe 1st thought I had when I saw it was a 2" bsp stainless fitting. It is not out of the question I may take that route. It's the tapered internals that hold the ring central that is important. I have ran off with both of my 1st attempts at rings. A bit naff but now I have the tapered cones & going to make some white acetol pushers once the lathe is up & running, so as to not damage the print. The copper one made my finger green in 1 day ha ha. Thought about clear lacquer on the inside but it will wear of quickly. 20200102_235957.jpg

Edited By Steviegtr on 03/01/2020 00:12:03

Hopper03/01/2020 06:25:10
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4535 forum posts
94 photos

Coins can be thick and hard to punch. Might be easier to drill and bore the hole in the lathe. Or drill it with a small holesaw in the lathe. Or with a fine trepanning tool in the lathe. And concentricity is assured.

You could machine a lot of coins in the time it would take to make a set of punch dies.

Robert Atkinson 203/01/2020 07:14:41
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647 forum posts
16 photos

If your existing punch works OK other than centering would it not be easier to make a set of slides that fit in the slot and have coin sized holes to center them under the punch? to might have to block one side of the slot in the block to give a register to push the slide against. I guess it depends how many different size coins you deal with.

Robert G8RPI.

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