View Full Version : die/punch?

08-02-2003, 06:40 PM
I am short of detailed specifications for this query but will attempt to ask intelligent questions anyway. http://bbs.homeshopmachinist.net//smile.gif

My son-in-law (father of two marvelous grandsons, the latest born only two weeks ago, 9lb 12.5oz, 23 inches long -- but I digress.) wants (me) to fabricate a punch to make aluminum adapter rings for mounting new manufacture tachometers in old Ford pickup dashboards. The resulting pieces will be circular, reasonably narrow as they will fill the excess space in an overly large opening, and (I think) have to be bent at each edge for a cleaner mating to the tach and dash opening. He already has two pieces of 1 inch thick steel and expects to be able to use a 35ton arbor press to drive the die/punch. (someone please tell me which is which or are the terms interchangeable?)
I do not have dimensions but seek a source for recommended clearances for punching, bending and/or forming aluminum sheet of a given thickness. ANY generalizations you all can offer will be eagerly perused.
On the surface this seems that it may be a simple tooling job, but I am but a rank amateur and ignorant of what traps lay ahead. The pieces will be only circular - no complicated shapes . . . so far.


08-02-2003, 08:17 PM

www.bokers.com (http://www.bokers.com) can make the washers you need. They could also be laser or water jet cut. To make a narrow ring as you have noted would be difficult with the equipment you note and still have a presentable product. It will be easier with very light gauge material. To roll the edge is best done with a blanking press - this requires special dies.

Not a practical home project. You could machine the odd ring, but production of them would be difficult.

08-02-2003, 10:15 PM
Thrud is probably correct in what he says but if you want to know more get a copy of:
Die Design Handbook
My edition is from Mcgraw-Hill but I think I have seen ads for later editions from ASME. It will tell you more than you want to know but you can then decide if you want to tackle the project.

08-02-2003, 10:25 PM
I made similar items with a plasma cutter, cut a pattern out then traced it with the torch. I made stainless steel dashes for my rods. Kinda like I understood you want to do. I love stainless, engine turning (jeweling) gives it a look you can not get anywhere else. Cheaper to work with cardboard till you get it right.

You take the round offset of the torch, minus the radius, then cut your pattern to compensate. I fit guages with the small bezels with no gaps. (my torch was 5/8 diameter so I added 1/2 that to the circles I wanted to cut out and ended up with the desired hole) All the inside the pattern is scrap.

I swapped my plasma cutter for a 54 ford. Can't help you here. I have regretted that a time or two. It was a useful tool, but a buddy needed it more than me.


[This message has been edited by ibewgypsie (edited 08-02-2003).]

08-03-2003, 12:10 AM
Well, the main problem with the project is that an arbor press aint accurate.

Something has to align the die (the thing with a hole in it) and the punch (the thing that goes thru) so they don't collide as they are pressed together.

In a regular die set, there is a bottom and a moving portion, aligned on very accurately ground posts and close-fitting bearings. No shake.

The punch and die are precisely oriented on those, so that they clear evenly as they come together.

He could do it with a single center post...maybe.

That is a non-trivial tool, if you want to blank the part, punch the center hole, and turn up the edge at one stroke. It combines punching and drawing, about which whole books are written (or were, back when folks cared about such things).

Maybe he just wants to blank, punch center and "joggle" the washer a bit to fit in the larger hole?

Easier, but still not my choice of a first die set to make........

Clearance is variable with material, but 1/5 of the material thickness is not unusual, depending.

[This message has been edited by Oso (edited 08-03-2003).]

08-03-2003, 07:46 PM

If what you want to do involves forming flat sheet into a spacer ring around the gauge check at www.bonneydoonengineering.com (http://www.bonneydoonengineering.com)

They sell small presses for hydraulic forming of jewelry and other art type objects. From their site you may be able to get ideas on how to do your parts.

Their tooling allows forming processes that normally require more sophisticated presses.

08-03-2003, 07:50 PM
OOPS, in previous message that should be www.bonnydoonengineering.com (http://www.bonnydoonengineering.com)

08-04-2003, 03:03 PM
How about using something like a knockout punch and die such as electricians and sheetmetal workers use?

L Webb
08-04-2003, 08:23 PM
I don't know what kind of quantity he needs, but it is far easier to have a stamping shop run them.
The OD and ID is pretty straightforward and easy. A rolled or formed edge will require special tooling.
This is not a job to do on the arbor press. The amount of time spent messing with tooling and getting it right is hardly worth it.
There are people like me who do this day in and day out. And we don't run them on an arbor press.


08-04-2003, 08:54 PM

I expect when he says 35 ton arbor press he means an hydraulic H-frame press. I have a 50 ton H-frame with very sensitive controls which I use for deep drawing among other uses. I'm in the process of setting it up for dual action with a separate hydraulic system acting from the underside to supply blankholder pressure.

I also use this press for punching and with press brake dies occasionally.

It's quite possible to do most anything with an "arbor press", especially if the runs are relatively short.

Some of the most fun I've had with this press is forming over male forms with contained urethane as the "female" die. Amazing what you can do with urethane.

08-04-2003, 10:39 PM
Anything that pushes can use a real punch tool, one with upper and lower bolsters and the punch and die on them.

That was the whole reason for the "sub-press" type tooling in the first place. Accuracy of alinement independent of the press.

The issue is that when the poster said what he had, it was "two pieces of steel". So he had the makings of the punch and die (hopefully hardenable). But no bolsters, so nothing to aline them with.

Ain't no arbor press going to be precise enough to keep a punch and die lined up to within 0.007 or less of clearance without help. Not gonna happen.

Then you get into the blanking and forming aspect. Les oughta know, he runs a stamping and forming shop. Fergit me, you better listen to him.

08-04-2003, 11:52 PM
OSO wrote: "Ain't no arbor press going to be precise enough to keep a punch and die lined up to within 0.007 or less of clearance without help. Not gonna happen."

If you call a good quality H-frame press an arbor press, then yes, you can get that kind of alignment. The ram in my press is as ridgidly in position as the rams on my punch presses. Bolt a die holder onto the table of my press and it's as accurate as need be. Granted, not all "arbor" presses are this way, but then, not all of them cost anywhere near what mine did.

I guess we can't give a reasonable recommendation until we know exactly what kind of press Craig has.

L Webb
08-05-2003, 12:59 AM
DR, sounds like a nice setup you have there. Many years ago we did a lot of deep draw work. The old man was a master at it. We don't do any of it now.

I couldn't live without urethane now. Greatest stuff in the world. It makes some diemaking easier and allows us to skip some secondary operations. It's a real timesaver for us.

When someone says arbor press, I usually picture in my mind an arbor press. There are some high quality H-frame presses that are fine for blanking, punching and forming.
I would not run open die in the more commonly available cheaper H-frames.
In fact, I'm only comfortable running open die with close clearances in my Bliss C-60.
We are talking quite a few more strokes per minute.

If he wants to blank and punch small quantities of thin aluminum, he could use A2 tool steel and not even harden it. It would work just fine.
I would still want some type of guiding.

Thank you for the kind words OSO. I do make my living punching holes and forming metal. This type of work is a constant learning curve. Even a regular run-of-the-mill stamping job can leave you scratching your head and wondering why things aren't going like they should.


08-05-2003, 01:32 PM
OK, yours isn't what I pictured in my head.

The H-frame presses I usually see in people's shops are the loosey-goosey ones using a jack for power where you can shake the moving portion and it rattles about a tenth of an inch.

I have never seen one of those made as a gibbed press, but presumably they exist, you have one.