Building a hydraulic punch press
A few years ago I built a hydraulic tubing bender and have been using it nearly every day since. Recently I got a williams tubing notcher and converted it to hydraulic using the tubing benders power unit. The next piece of equipment I need in the shop is a hydraulic punch press. I dont have the $$ to buy one so I plan to build it.
I have not used a punch press before so I am researching and comparing pics on the internet. I came across this homemade punch press which I really like its simple design. It functions the same way as the hydraulic notcher I built, so I am confident I can make this punch press as well.
I am still unclear on the types of punch presses and their tooling. It seems like there are two?? One that uses a self contained die set like this.
And the other type being like the punch press pictured. Can someone explain the differences here?
I've never used either before.. but it appears the one in your link is "self-contained" able to be dropped into any press (with enough oomph) and used. While the one in your pic appears to hold the punch/die individually.
I think it would be easier to maintain proper alignment using the self-contained setup. I'd hate to have the punch come down out of alignment and go "bang".
I emailed the guy who made it and he said that is a converted mittler bros punch press.
I decided to go the easy and IMO safer route for a beginner and ordered a set of used unipunch tooling to go in my hydraulic press. I like how you can set up multiple punches on templates to make more than one hole at a time. The unipunch is a nice self contained unit to go in a press and will eliminate the dangers of the punch shattering against a misaligned die. The unipunch has its limitations but I think it will be a great addition to the shop.
A friend of mine writes cam/nesting software for CNC punch presses. He wrote a custom java for nesting on my plasma too. I guess the punch press must have some "critical" alignment or else....... He spends a large amount of his time dedicated to this art.
Pressing to make a hole is outside my comfort zone LOL.
<--------- Lazy.. prefers CNC Plasma-cut holes.. :rofl:
I can't see pictures on my phone right now so this may be irrelevant but...
All the sheet metal dies I design have 7-10% material thickness clearance per side between the punch and die block. 1/4" material gets 0.025" clearance.
The company we order smaller punches (for fastener sized holes) recommends 12.5% clearance. 1/4" material gets 0.031" clearance.
Our assembly tolerances are held to 0.001" or less.
Hole punches are aligned by centering the punch in the die block using shims. Then the top retainer is lowered (and aligned with the bottom) and dowel hole locations are transfered using fancy center punch dowels.
I'd want a self contained unit for holding that tolerance. But then again, our dies sometimes run at 60+ strokes per minute with .003" clearance. A small misalignment would cause a punch or die to wear out very fast at those speeds, or crash in spectacular fashion.
I personally would go with the self contain bump press. You only bolt down the bottom. Allows it to be used in a variety of presses.
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