On Tue, 9 Dec 2008 18:19:27 -0800, "Michael Koblic"
wrote:

spaco wrote:
Yuh know, us blacksmiths chisel cut sheet steel up to 1/16" thick or
more, cold, with a sharp cold chisel. I have several dozen of these
that I have made. I have a set of them that are curved, so I can
produce radii from about 1/4" to about 2".
You could also turn a "dinker die" in your metal lathe. It's just
a piece of tubing (water pipe, etc.) whose ID is correct for the hole
size. Then you turn a chamfer on the outside of the tubing at about
60 degrees. all the way towards the ID until it is sharp. Just set
the sharp end on the tin, backed with wood, and hit it. You simply
punch out a slug.
I have made many of these over the years. Sometimes its the hole
that I want and sometimes its the slug.
----------------------------
These work great for punching holes in rubber, leather, canvas, etc.,
too.

This sounds useful.
How much metal distortion is there? And what is the biggest hole you ever
made this way? Did you have to heat-treat the sharp end?

Amount of distortion depends on thickness of material being punched
and what is used for a backing. I get very clean holes in thin
metal, rubber, leather, gasket mat'l etc using a hardwood backing
block.

No need to heat-treat for very small number of uses. For more holes
I've case-hardened with Kasenite. Honing the edge after hardening can
help a lot with soft resiliant materials.

This also works well in a vise or hydraulic press, sometimes easier to
get precise location if that's an issue.

Been making and using such things as one-offs for decades but I'd
never heard the term "dinker die", thanks to Spaco for that.