More punching on the Hydraulic press... | Power Hammers and Presses | Forum

Good stuff Larry, I like the dovetail quick change stuff.

Isn't punching with a press a joy to do.

My cylinder on my homebrewed 15T has a large threaded end which is a ball ache for changing tools over but good for holding the punch/drift when pulling it out of a hole. If I were to start from from a blank sheet of paper I would make all my punch tooling quick change as per steelworker tooling (I think you guys call them ironworkers). Two flanges opposite each other and 90 degree turn to lock.

My stripper is kinda universal in that the hole will allow a wide range of puch shapes to pass throgh it. It doesn't take much tonnage to pull the punch out if it's well lubed. Haven't felt the need to change it yet.

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If you look at the picture you'll see the bolster plate slides. I can either use it with no hole (solid bolster) or slide it to use with a suitable bolster hole hole. I prefer to have as little clearnce between the hole and the "final size section" of the punch, say 1mm. Kinda works for me

My punching sequence varies depending on the work, but here is a typical sequence.

1. Start with solid bolster and punch until tip of punch is almost all the way through around 3mm from bolster (using kiss blocks to let me know how near I am) TAKE CARE NOT TO GO TO FAR, IT'S THE EASIEST WAY TO WRECK A PUNCH

2. Flip the work over. STILL USE solid bolster and kiss block to take punch to about 3mm from bolster

3. back out punch slight so it is not in contact with heat of the work and slide the bolster so the hole is now under the punch. Go through with punch so it is about 1" through the work.

4. Flip over and go about 2" through

5. Flip over and go full way.

6. (optional) allow work to cool to red. Flip over and go through full way again. The cooler the work is, and the hotter (within reason) the drift part of the punch, the less shrinkage there is to the hole as it cools.

Sorry Larry, looked smaller in the photos. Still at the top end (IMHO) and those quick connects do restrict. But if it's working good no reason to worry. Looking good, my man.

Sorry Larry, I don't think you're even moving 10 GPM! Take a look as the speed of my 8" cylinder with a 12 GPM pump: Upsetting tongs

Larry the threaded end to my cylinder gives me more options but how about the idea below for a quick and easy, almost quick change punch holder. You don't have to unscrew the bolts all the way out, just a few turns.

Quick change bolsters should be easy

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Larry L;2443 wrote: The thing that would concern me with that system is upsetting the shank in the holder... I suppose if you where using all tool steel the chance would be smaller but still you wouldnt need to swell the shank much at all for it to become welded in there.... If the base was broad and flat (rather than skinny and deep:confused:) maybe that would be less likely to swell?

Not the best of engineering drawings!!! I should have shown a bit of clearnace between the walls of the "hole" that the top of the punch sits in (ie the punch will rattle without the collar). This stops any problems with upsetting. The 45 degree shoulder on the punch and the female 45 deg on the collar will locate the punch as the bolts are tightend and stop it moving sideways. If not punching off centre, most of the force is straight down so you don't need large 45 degree shoulders.

My Kingsland (none quick change) steelworker uses the same principle and 45 degree shoulder to locate the punch and the shoulder is only about 4mm wide. It's only a 40T machine but some of the bigger beasts use the same punches. It has a screw on collar (which takes time to unscrew) but the path of the forces involved would be more or less the same as with a bolt on collar

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