ironworker punch table (mild steel)

I just picked up a Scotchman 35 ton (Model 314) ironworker. I was
fortunate in that it came with the manual. I see questions pertaining
to punching holes on this NG with some regularity, so I thought I'd
reproduce a little bit of information from the Scotchman manual. In
particular, there is one table of required tonnage for punching mild
steel (of 60,000 psi tensile strength) which is useful in case someone
doesn't feel like doing the math. It has a few rules of thumb for
punching as well. Check it out:
formatting link

Disclaimer: There may be typos, but I tried not to. Yes, it is the
dreaded PDF format. All requests for other formats will be silently
forwarded to the bit bucket.
Grant Erwin
Kirkland, Washington
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Grant Erwin
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I like the notes on the bottom. At school we have lost more ironworker punches and dies to people punching partial holes than anything else. Second worse is trying to punch holes smaller than the thickness of the material. Third is puting the die in upside down.
Reply to
Ernie Leimkuhler
Shape punches and dies (rectangle, obround, etc..) put in at different angles can be a real killer on them to.
Glenn G.
Reply to
Glenn, are you talking about crashing the tooling? Not much fun.
Grant, you can also use that table for different materials. All you have to do is know the tensile strength and come up with a modifier to multiply with. Say you want to punch type 304 SS. In the annealed condition the tensile is about 90,000. That's about 50% more than MS. Multiply your tonnage by 1.5 and that has you close. I never take a machine up to it's rated tonnage. I usually go with a higher tonnage machine. Of course shear angle on the punch or die can reduce tonnage required. It is dangerous though to use shear in an attempt to get within the rated tonnage of the machine, especially an older used machine. You just don't know how it was used in the past. Always better to play it safe as materials can vary.
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