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packetfire 10-25-2013 07:41 PM

Novice with a Uni-Punch and a Habor Freight 6-ton press
I am not a metal worker, but I have a need to punch some aluminum ranging from 1/16th to 3/8ths with a small shape-punch, total punch circumference less than 1 inch. I will be punching hundreds, perhaps thousands of holes.

So, I have ordered a used Uni-Punch AJ 1 1/2-inch rig, and some off-the-shelf tooling is being provided by a vendor who knows Uni-Punches well.

This leaves something to apply some pressure. I did the usual math, and 6 tons is likely overkill, and the Harbor Freight 6-ton press was on sale for $69.00.

A few things that would be nice would include:

a) Some way to rig a pulley, foot pedal and spring return for the bottle-jack handle that applies the pressure.

b) Maybe another foot-pedal to operate the release valve on the bottle jack?

c) Some way to assemble the press so that it remains "square", for example, has any one assembled the thing, squared it up, and then drilled holes for cotter pins to keep the various joints from slipping out of "square"?

d) Or should the Harbor Freight press be returned as "useless", and something else be purchased in its place?

Can anyone point me in the right direction?

LKeithR 10-25-2013 07:49 PM

Your big thing is going to be time. If you really do end up punching thousands of holes pulling that jack handle is going to get old in a hurry. Your tonnage is low so some sort of air over hydraulic power unit would probably be a good choice...

GWIZ 10-25-2013 07:52 PM

Welcome to the site.

Cant say if it will fit in the press you have, HF should also have Air operated bottle-jacks you may want to consider.

Then you also need an air compressor.

akabull 10-25-2013 09:10 PM

I'd return the 6 ton and buy the 20 ton floor unit and a 20 ton air over hydraulic jack. If you are doing thousands of holes the ~$250 you will spend (less if you buy seperate and use 20% off coupouns :D ) will be well worth it :cool:

camdigger 10-25-2013 10:11 PM

Hmmm, hundreds and thousands of holes with a hydraulic jack? I'd be real concerned with cycle time.

If 6 t is overkill, what is needed to do the punching? If the forces are within reason, a mechanical system like a fly press would be faster.

For ease of operation, a slight modification to the bleed screw ( big knob to make releasing quicker and easier) on an air over hyd jack would make the operation easy, just time consuming. If 6 t is over kill, 20 T is way overkill, but the 20T air over units can be had for under $100.

The other factor is that a compressor purchase would inflate the cost. IIRC, a 20 t air over hyd jack needs 4 cfm for near continuous use like what you'll needs for the 100s and 1000s of holes.

RED caddy 10-26-2013 07:50 AM

+1 on the air over setup. I would use taper pins to preserve alignment, (frame and die's) they better resist shear forces that would try to push the frame out of square. (It's gonna be tough to maintain a tight setup and punch alignment with so many pieces. all in a pile.


allessence 10-26-2013 05:16 PM

I have a 3 ton punch press that would work wonders on something like that..

As for the air setup. It's going to be faster than hand work but still going to take you a really long time.

Is there a way to get a multi punch setup? Then you could utilize the 20tons of force and punch out a few at a time..

bigegg 10-26-2013 05:46 PM

You want a fly press

No idea if they made it to your side of the pond, but over here in England, you can pick up a no.6 (10T) for about $100 (equivalent).

One of them will punch your holes as fast as you can swing your arm

Roundrocktom 10-27-2013 10:44 AM

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I've never seen the fly press... those are neat.

Arbor Press is way to go.

For thinner aluminum, a Unibit is hard to beat. Lots of variations on those, but fast and a clean hole.

Time to dig out the machinery handbook to see how much pressure is needed.

Trivia... in order to toss oil filters into the trash, they require they are compressed to less than 20% original volume. After a few crush cycles, pumping a 20T jack by hand is for the birds! I need a air/hydo jack. :) EDIT: NAPA GOLD - Wix filters. Notice that one that had trapped oil needed almost the full 20T to burst open to release the oil. The Fram is much lighter construction.

Roundrocktom 10-27-2013 01:06 PM

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EDIT.... Uh on, Arbor press won't do unless you have a 20T Arbor Press! They are hydraulic "portable" presses.

Photo from Machinist Handbook. (1991 edition, from memory) noted page 1242 Punches, Dies, and Press Work.

Pressure required for punching.

PI*diameter*S(shearing strength)*thickness/2000

PI*One Inch diameter * 20,000 * .375 /2000

(I do the calculation in my head, someone care to check? Only math is just 3.14 x .375... which is a little under 1.2.. just carry zeros)

It about 12 tons to punch aluminum slug (1" x 3/8" thick)

Time to return the 6 ton press!

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