surftom wrote:
Hi Gang -

In the process of finishing the hydraulic punch and have a question on
tooling.
I have to build a railing (steel) and want to use 1/2" SQUARE bar for
the stiles (vertical) that pass through a rail (horizontal) 2" wide x
1/4" thick flat stock
Should I punch with a 1/2" square punch or go up to the 9/16" punch.
The intent is to weld around the bar when in position. Does a 1/2"
punch actually make a 1/2" hole or is it a little bigger? Also, what
are the tolerences on typical steel bars (when they say 1/2" is it
really 1/2")?

HRS (hot rolled steel) is often supplied with a
10% over to 5% under tolerance by weight.
As a rule of thumb for punching holes use a die
clearance for the bottom die of 10% of the material
thickness. In that case the resulting hole will be
very close to the punch size for the top 1/3 of the
material thickness. From there the bottom 2/3 part
of the hole is torn out and tapers to the die size.
If you want to punch holes for 1/2 square HRS bars
a 9/16 square or larger punch should work. HTH.
--
SATOR AREPO TENET OPERA ROTAS
Have 5 nice days! John
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