Punching Square Holes

PHPaul

PHPaul

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I have a Whitney punch for punching small round holes in sheet metal. Handier than a pocket on a shirt.

I build toys and models out of brass and occasionally need a small square hole, say 1/16 or 1/8 up to perhaps 3/8.

Punching it round and making it square with a file works but is sort of tedious. Being able to punch it square to begin with would be wicked handy. I'm aware of the Greenlee style square punches/knock-outs, but they're too big and WAY too expensive.

Does anybody make a square Whitney-style punch?
 
An interesting question. I used to use a Roper Whitney style punch on a regular basis and they re handy. I have modified spare punches to create a custom diameter by turning down an oversized punch and boring out an undersized die.
Offhand, I see a problem with using the Roper Whitney punch. The punch is free to rotate so alignment with the die would be problematic. For that matter, the die can rotate as well.
If you are only looking at one or two sizes, you could make your own punch and die. A small arbor press would be a good candidate for the press. Make an adapter to hold the punch on the ram. For the die, I have made it by arranging four pieces of rectangular stock, pinwheel fashion and pinning bolting to a back plate with socket head cap screws in a counterbore. In my case, I had 6t. kick press and was punching 1/2" x 3/4" openings in 16 g. aluminum but it worked well for me until the time that I decommisioned it. If you use this approach , you will want to machine to grind a slight relief on the underside of the die surface to prevent sticking of the slugs in the die. I used O2 for the punch and die, hardened and tempered after machining. Using this approach, any sized rectangular die may be fabricated.
Fabricated Square Die.JPG
 
Interesting approach. Lot of work and skills I don't currently have for a tool I'd use 2-3 times a year, if that.

I'll file it away tho. Thanks!
 
I use a file for a two or three times a year part as well. As with any labor saving alternative, you have to consider the cost of the alternative vs. the value in time savings.
 
One method of making square holes is to first punch round,then use a square punch that has a keyed extension into the die thru the hole to keep the die aligned.
 
I have a Heinrich Deep throat bench punch #6 with a lot of odd shaped punches and dies, I think the 1/8" square punch is a standard size. http://www.heinrichco.com/metalwork.htm

I picked up a first model Roper hand punch at the flea market last summer for $3 that was missing a couple sizes and made my own punch and die sets. I think an 1/8" square punch set would be pretty simple but the die would need to me made longer to accept a nut to keep it from rotating out of alignment. If you were careful you might get by without the nut.
 
Holescreek said:
I have a Heinrich Deep throat bench punch #6 with a lot of odd shaped punches and dies, I think the 1/8" square punch is a standard size. http://www.heinrichco.com/metalwork.htm

I picked up a first model Roper hand punch at the flea market last summer for $3 that was missing a couple sizes and made my own punch and die sets. I think an 1/8" square punch set would be pretty simple but the die would need to me made longer to accept a nut to keep it from rotating out of alignment. If you were careful you might get by without the nut.
Click to expand...
The square punch could be easily made but the die would be a challenge with limited tooling. On my Roper clone, the punch is free to rotate. It always seemed to require three hands to use the punch with the round tooling. Adding angular alignment with the work and between the punch and die would seem to me to be highly frustrating.

Personally, I would use the file for two holes.
 
But then you wouldn't have the satisfaction of making another tool. You just drill a round hole in the die and file it square one time and you have a tool that will punch square holes.
 
Must have some kind of weird (planetary?) gearing inside the head, to oscillate/orbit the cutter. Wish they'd show that detail!!!!
 
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