How do I keep the crispness of the pattern while working with the
pattern whether or not I dap it or manipulate it.
You will almost always get some degredation of the pattern when you
form the sheet metal, especially if it’s shaping in a way that
requires the surface of the sheet to seriously stretch or compress.
Dapping into a hemisphere is a good deal more difficult than simply
bending. Plus, if you’re dapping the metal with a steel dapping punch
into a steel (or even brass) dapping die, then the surface of the die
is contacting your pattern. You might as well planish your pattern
with a hammer, what with the forces that steel die puts on the
The way to preserve at least a good deal of the pattern (and some
delicate textures just won’t be preserved so well no matter what) is
to use a surface to form into, which is softer than the metal. Wood
is one that works to a degree, though it can mark softer metals, and
dapping into a lead block is another traditional method (though you
have to be very careful to clean the metal carefully, so there’s no
trace of lead sticking to it, before any heating, soldering, etc.
Some plastics can be made into gentle dapping dies as well.
Perhaps the best way to do this is by hydraulic die forming (funny
thing, that’s been a recent topic here on Orchid). With this, you put
your metal on top of a piece of urathane rubber, itself contained in
a boxlike contaner so it cannot spread out laterally. The pattern
faces the rubber. Now your press (if you have one ) can press the
dapping tool smoothly down into the metals’ back. No impact, this is
high pressure, but in it’s own way, rather gentle. Urethane rubber
is interesting stuff. Somewhat soft, but it cannot be compressed. So
when you press something down into it, the rubber must flow and
displace somewhere, and what it does is to essentially try to flow up
and around the intruding form, which it does with considerable
pressure. So as the dap presses down on the metal and into the
rubber, the rubber presses the sides of the metal up and around the
dap. This will not be as easy to get a full 180 degree hemisphere,
as the edges especially will not want to go that last little bit.
Great for lentil shaped beads, less so for full spheres, but it can
be done. You can also use the press like this using firmer dies,
again still made of something that won’t mark the metal, like delrin,
he downside to this type of forming is that it require rather high
pressures, and this usually requires some form of actual press. The
hydraulic presses like the Bonney Doon or others similar to it, use
20 ton or higher bottle jacks to generate thise pressures. That’s a
good deal more than you get with a hammer, and though you can form
into urethane somewhat by hand with a hammer, etc, it’s limited. To
get fully dapped hemispheres, you’d need a press. So then there is
another piece of equipment to add to your wish list.
Hope that helps.