11 replies to this topic

[Dave Clarke]

Hi all,

I'm getting to know my new toy, a 6 tonne c frame fly press made by John Heine.

I'd like to be able to punch holes in sheet metal.

More specifically, holes from 2mm-5mm in mild steel up to maybe 2mm thickness or so. I like the idea of punching as for jobs where I need a lot of holes, punching will probably be quicker than battling with a drill press.

I have done some investigating, and have already come up with a couple of alternatives.

The first idea was to buy a commercial hole punch and fabricate some new tooling holders to go in the fly press. I was thinking something like this:
http://cgi.ebay.com....=item588ccf23ef
although I recognise there is a big difference between 'inexpensive' and 'cheap', and have a bit of an idea which this might be.

The other idea was to follow the advice given here:
http://ronreil.abana.../flypress.shtml

This second option has its own challenges. The female die would be easy. However the male, to me, seeems the more difficult.

What are your thoughts on taking a drill bit, turning it around the other way and dressing the end for use as the male part of the punch?

Secondly, what think ye of usig a drill chuck as the punch holder, which would allow punches to be swapped quickly and replaced easily if they are damaged?

Cheers,

Dave

[ArtWerkz]

Perhaps check out stuff like Scotchman ironworkers http://www.scotchman.com
Check out their die set ups, may give you some more ideas.

[AvishaiW]

Punching a 2mm hole in 2mm mild steel is very difficult (if possible at all) and needs a professional dies. On thinner sheets or larger diameters it should be ok. A drill will not hold the punch tight enough unless if the punch reaches the end of the chuck. If you can turn the male from 10mm W1 steel rod and make a set of punches in different diameters you will need only one punch holder. Of course you will need to harden your dies and punches.

[PTsideshow]

Drill chuck as a tool holding device, probably not worth the time and hassle. Depending on the brand of chuck the build tolerances vary widely so with the forces being placed on the chuck it will loosen up and can cause other problems.

The biggest problem will be in the size of the hole/punch A 2mmis a #46.5 number drill, which is slightly larger than 5/64" then the take into the material thickness 2mm Closest standard material gauge is 12 B&S gauge. which is on the thick side for that size punch.

Then taking into account, the slight clearance needed for the punch to operate and the slug to clear in the dia, then the ideal punch length would be slightly longer than the material thickness. Less stress on the punch. You would also need some form of lubrication of the punch. Along with a stripper arm/plate/spring.

Will have to look and see if I still have any of the books on the subject, it was a long time ago and in a galaxy far,far away.( late 60's)

The same is true for the larger dia punches, but are easier to work out with the black drill rod that are available here in the US. I believe it is called silver steel in the UK, have no idea what it is in OZ

Here is a site for some info

Roper-Whitney hand punches has a nice table and gives tonnages etc. I have a knock off brand that was sold at tool store pre HF here in the states.
You can see the smallest punch that comes with the tool is 3/32"/ 2.38mm, which tells me that any thing smaller would be headaches for them with breakage complaints.

You can make a tooling holder for you larger tooling, then you can make each set of smaller tooling with a reduced dia shank for the tooling, then make a bushing/collar that fits the tooling holder on the press. The hole would be for the tooling group, and if you have more than one size of tooling needed you would need a collar/bushing for each set. You would be able to have a more positive locking hold of the tooling and eliminate problems.

Your size press will be a little large for the size holes you are describing. Generally the size holes were down on a small kick press, or a pull down punch set up, or a slow speed motorized one stroke press.
If a larger higher speed press was used, it would have all or most of the hole punches in the die face and punched at once. Not punch and move and punch and move etc.
This may not be what you wanted but it might save you some time, in creating a solution.

Off to move more snow

[Dave Clarke]

Hey, any help is good help. If it saves me time and effort in trying what I had originally thought...then yeah, I'm glad to hear it.

I've heard from a couple of people about 'silver steel'. Never heard of it before.

What if I were to have some punches machined from a more common steel and case harden the business end?

Or, it seems it may just be easier to buy a commerical set and make some holders.

I should have been more specific in my original post. The great majority of the material I would like to punch is 1.2mm or 1.5mm. 2mm+ is pretty rare, so I could grimmace and just use a drill for that work.

Thanks for the advice and help. Saves me time and $$$, which are two rare commodities and can't be mined.

Cheers,

Dave

[fidget]

Hi Dave

here is a link

http://www.hartleige...-bolster-outfit

they have got the correct bits made for fly presses
I was so lucky a few years ago and got a Hunton no8 fly-press with every single punch bolster and die these guys sell for fly-presses

hop this helps

[Rich Waugh]

I'd say forget trying to cheap out and make your own punches unless you can work s-7 tool steel and properly heat treat it. Nothing less will handle what you're going to be doing with it. A 5mm hole in 2mm annealed mild steel plate will take about 1 ton of force and requires exact clearances between die and punch or the hole will be terrible. If you can get proper punch/die sets that can be adapted to your fly press then it will certainly do the job just fine, but home made tooling probably isn't worth the trouble.

The drill chick concept will never work - if the chuck had sufficient force to resist the punch slipping it would gall the shank of the punch badly due to the forces exerted and the small contact area. Even a collet probably wouldn't hold it securely enough. Punches for work like this are made with a load bearing collar to take the force and the shank only indexes the punch. This is something to keep in mind on all tooling you make for the fly pre3ss - it should have a collar to take the force, not the end of the shank - otherwise, the end of the shank will become upset inside then ram of the press and be impossible to remove later. It only takes one episode of having to disassemble the ram from your press and mill out a tool that is swaged into the ram receiver to make you very, very cautious in the future!

[Stretch]

Punching a 2mm hole in 2mm mild steel is very difficult (if possible at all) and needs a professional dies. On thinner sheets or larger diameters it should be ok. A drill will not hold the punch tight enough unless if the punch reaches the end of the chuck. If you can turn the male from 10mm W1 steel rod and make a set of punches in different diameters you will need only one punch holder. Of course you will need to harden your dies and punches.

General rule of thumb with commercial dies is you can punch steel the same thickness as the size of the punch. You can punch 2 mm steel with a 2mm punch, just, with commercial made dies. unless you really know what you are doing I wouldn't try with home made dies.

[Stretch]

I have a keyless chuck on my small drillpress and to drill from tiny to 1/2 inch takes about 1 minute. To change and set up a punch and die in a flypress takes a lot longer than that. You need a good, couple hundred dollar keyless chuck and it is slick. I got a cheap one and it is still in my drawer. Not worth using. Used it a couple times and no more.

[Rich Waugh]

I've only used two keyless chucks that I felt were worth owning. One was a very expensive Albrecht (the industry standard) and the other, interestingly enough, is the one on my new Makita LiOn cordless drill. That one is damn near as good as the Albrecht at holding things securely. I'm seriously considering trying to find one to put on my little benchtop drill press, as the keyed chuck on it is a piece of crap. I need to remember one of these days to call a Makita repair center and see what I can get. If I can get one for less than about $75 (what I paid for the drill press), it will be worth it. If it turns out they're under fifty bucks I may buy four or five of them to replace chucks on other drill motors I have around the shop and truck.

Anybody got an "in" with a Makita repair center?

[AvishaiW]

I've only used two keyless chucks that I felt were worth owning. One was a very expensive Albrecht (the industry standard) and the other, interestingly enough, is the one on my new Makita LiOn cordless drill.

Few years ago I bought a used small bench drill - A very high quality German machine which was equipped with an Albrecht keyless chuck. It weights about 50 kilos compared to the Chinese ones which weights about 10 kilos.
The guy did not know what he was selling and asked $100 for that candy.

[Tom Maringer]

In case anybody needs to punch holes and followed the link above to Ron's fly-press page... what he left out is the stripper plate and standoff guides. The stripper plate lies above the work and "strips" the work off the punch as it is raised. You really cannot do without it unless you're literally only needing one hole. The standoff lies on the lower die face and is adjusted to give you the proper positioning of the punch hole. (because with the stripper plate in place you cannot see the work very well)

For my purposes of coinmaking it is the punching that is the object I'm making... so I have used fly presses to punch many many thousands of holes through sheet metal, from 1/4" in diameter up to 1.75" diameter, and from 0.020" thick to 0.250" thick.

I think that a 2mm punch through 2mm mild steel might work okay. Everything would need to be just right though as that sounds like a high risk of punch breakage to me. I'd probably choose to drill them myself.

Edited by Tom Maringer, 29 July 2012 - 01:08 PM.