holey cow

Beware, however, of the markings. Knockout punches (for conduit and the like) have size markings based on the ID of the conduit, not the OD of the fitting which goes through the punched hole. So one marked

5-1/2" would likely produce holes somewhat closer to 6" diameter. :-) Chassis punches, from the same maker (Greenlee) are sized to the diameter of the hole produced, but I've not seen them in that large a size. So come equipped to measure the punch diameter before you spend your money -- and those are *not* cheap. :-)

Good Luck DoN.

Reply to
DoN. Nichols
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No, the metal is much too thick for those - And I already have one, used it a few times where you don't want to lug a Plasma Cutter (or deal with the fire hazards...) like attics - a cordless drill is enough. Popping new take-off holes in ducts and plenums is about their max.

And I have a Plasma Cutter too - just have to make a template or get a circle cutting rig for it.

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Reply to
Bruce L. Bergman (munged human

And I'll Gaa-Ron-DAMN-tee you didn't buy that 5" new for any job of less than 100 holes, or you got someone else to buy it. ;-)

Them puppies (742BB) List at $700... Ouch. That's well past 'arts and crafts and hobbies' status.

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Reply to
Bruce L. Bergman (munged human

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:-)

Pretty good, yes. :-)

Out of curiosity -- could you measure the punch diameter in the

5" size -- to see what it really is in terms of hole diameter?

:-)

Enjoy, DoN.

Reply to
DoN. Nichols

The "real" sizes are the radio chassis punches. The other ones are for conduit knockouts and such.

Good grease on the threads, and a ball bearing screw head will work wonders up to some thickiness which is a function of hole diameter and drawscrew diameter.

Even nicer (if you have it) is the hydraulic powered drawscrew.

Enjoy, DoN.

Reply to
DoN. Nichols

If it's a standard 5" Conduit punch it's a 5-1/2" ID hole for the threads. Same as NPT for plumbing, but they punch for clearance.

If you want a real 5" hole you have to ask for it as a Chassis Punch - made the same, but... They don't sell those in volume, so hold onto your wallet with both hands when you see the price.

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Reply to
Bruce L. Bergman (munged human

Well ... *I* don't want either, but IIRC the original poster wanted to make a 5-1/2" hole.

Thanks, DoN.

Reply to
DoN. Nichols

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