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Getting sharp outside corners


#1

Thought I’d pass along this little technique.

I’m making a new style of head (from sheet stock.040") that takes
its basic form with a tapered square bezel punch. I was able to get
really clean sharp inside corners (where I really don’t care too
much) but the outside corners remained rounded no matter how hard I
hammered the punch, apparently the flats on the head prevented the
corners from seating fully. To file down the flats until a sharp
corner developed would thin out the metal too much. Hmmm, I want this
thing crisp and thick…I ran a fillet of solder down the inside
corners and repunched the head. The extra metal now inside the head
corners allowed the punch corners to ram the outside of the metal
deeply into the bezel block corners. neat clean sharp

I’m not concerned about solder on what will become the insides of
prongs because I’m having a mold made and then cast in Plat as I
need them. Anyway I thought the basic principle involved here might
have other applications for model making.


#2

Why not make a die that complements the square punch? Just wondering.

KPK


#3

Kevin,

Why not make a die that complements the square punch? Just
wondering. 

the square punch and die are those you see around, I think I got
mine at Rio or DRS. When you insert the punch into the die without
any metal it is indeed a perfect fit, corners seat completely. But
when you’ve got metal in between there is a larger distance between
the relative corners of the punch and die than there is on the flats.
Draw two concentric squares, measure the separation along the flats
and then at the corners. The corner has a wider gap.

I don’t know how one would make a better complimenting punch. If you
flared out the corners, that would probably make your finished object
significantly thinner at the corners and hammering the punch might
tend to chisel thru the metal.

I do enjoy a mechanical challenge though.