Ceilidh ... Dragonfly Casting

Hydraulic Die Forming Discussion Group

Dragonfly Casting

Here's the sandcasting made from the clay model, shown before and after cleanup. Improper gating prevented complete filling of upper left wing. I decided to muck-up the upper right wing to make it look
like it was designed that way. It also shrunk enough to mess up the
fit, which ended up not being too hard to fix. I did a little accordion-like cut-and-stretch trick with the body sections and patched it up with brazing rod and silver solder. The casting is a
improvised mix of silver and bronze, so it wanted to melt a bit below the melting point of the brazing rod, which made the patch job rather
interesting .

A little sawing, sanding, filing, and a bit more sanding
and it's ready to use as the model for the Plastic Steel female mold.
The right-side picture shows it in it's eventual place, right on the cutting face of the blanking die. it ended up with more space between
it's edge and the die's edge than I had planned, but who cares?.

A blanking die with attached forming module like this is exactly like the old feather die I posted about about a year ago, and the balloon die a bit more recently. This particular design illustrates the difference of a shape that should NOT be used with just urethane pads
to do the forming. It's the space between the upper and lower wing sections that present a serious problem when blanking on top of a urethane pad. The pad does not support these areas sturdily enough
to keep them from flexing. if they flex, they are less engaged and therefore less functional as cutting edges. They simply sink into the pad while the rest of the design keeps it's flatness and does it's job cutting. If it were able to cut, it would do so at the risk of
breaking after repeated cycles. This is what happened to the first large butterfly design I did for the copper ornament customer a few years ago. Three dies failed before we modified the design. The new one cracked in a different spot, but that's another story (^:.

The ideal solution is to make a flat, solid base that the blanking die will function upon, with the addition of a cavity the exact size, shape, and position of the form that's attached to the die. This approach is exactly what I described in the "Giant Leaf" posts. Next,
I cut a dragonfly-shaped hole in a piece of 3/8" lexan and use it as a mold frame for pouring Plastic Steel over the metal dragonfly. Pull
out the 'fly, solder it to the die, and basically that's it!.

Dar

www.sheltech.net

This message contains the 62 kb attachment
[ D'FlyCasting.jpg ] Metal Dragonfly

Sun Apr 21