On Wed, 20 Dec 2017 23:35:08 +0000, David Billington
wrote:

On 20/12/17 23:19, Ed Huntress wrote:
On Wed, 20 Dec 2017 13:23:34 -0700, Bob La Londe
wrote:

On 12/20/2017 1:07 PM, rangerssuck wrote:
On Wednesday, December 20, 2017 at 2:54:13 PM UTC-5, Bob La Londe wrote:
I'm not sure how this will work out, but I am going to try it. This is
strictly a fun personal project to find out.

The goal is a two sided embossing die for paper. One is a positive and
the other is a negative. I know I could just have one made cheap by the
guys who make notary stamps, but this one will have a 3D image of my mom
from a painting my grandmother did when she was dating my dad. I want
to make it myself.

Here is the process I am going to try.

1. Machine pocket with all the features raised at the bottom of the
pocket. 2hrs apx

2. Spray it with UMR.

3. Make a backing plate the size of the pocket with some screws set in
it for anchoring.

4. Fill the pocket with casting resin, and place the backing plate into
the resin.

5. Pull resin plug at listed demold time and set aside. 10-15 minutes.

6. Machine away side walls of aluminum positive plate leaving just some
holding tabs.

7. Remove positive from bar stock and clean up on bench sander.

8. Wait 24 plus hrs for full cure of resin.

9. Mate the two halves and mount them for pressure turning on the
lathe. Turn the resin plug down to match the aluminum plug.

10. With halves mated mount on spring plates.
Do you think there might be a problem with the positive and negative being the same size without clearance for the paper? I can imagine that you could end up with more of a punch than an embosser. Of course, I'm as likely to be wrong about this as not, and it won't cost much to give it a try. Interesting project.

I am concerned about that possibility, but I have a couple commercial
embossing dies I bought to study, and they seem to cut as much as
emboss. You can hear the paper tearing when you emboss the paper.
Ideally I'd need atleast .003" difference, but title and information
pages of books vary in thickness. I'd have to find a happy medium. It
might be ok since I did design everything with about 5 degrees of draft
angle to make it easier to pull the resin plug.

I'm generating code right now.
Dampen the paper slightly before embossing, and let it stand for a
while after you dampen it. You'll have to experiment with the timing.

Wax film is a traditional medium for getting separation between the
punch and the die. It used to be available commercially, but you can
make your own from 75% paraffin wax and 25% beeswax. If you have
access to microcrystalline wax, you can try that, but I haven't worked
with it.

Microcrystalline wax should be readily available from any number of
hobby suppliers. Friends of mine here in the UK use it for certain glass
forming related techniques at the glass school they run.

Anyway, you melt the wax and float the wax on hot water, and then let
it cool. Lay the resulting film across the die and heat it enough to
work it into the corners. A hair dryer works.

Yeah, microcrystalline wax is readily available here, too. I've just
never used it so I don't know how it behaves.

The method I described is the one I used 20 years ago to make
fiberglass parts in matching two-part molds. I made some molds from
high-strength plaster (Hydrocal) and others from polyester resin. Both
worked well, but you have to seal the plaster and both need multiple
sprayed coatings of polyvinyl alcohol.

I should have pointed out that the wax should go over the half of the
die set that has the detail, because it won't hold detail itself and
it's only good as a separator and facing for the backing half of the
set. Depending on how you're doing it, that could be the male half or
the female half.

Dampening the paper is something we did when I worked in a
photoprocess/print shop when I was in high school. We made embossed
covers for invitations for the Princeton Univ. eating clubs
(Princeton's equivalent of fraternities). The dies, with the logo of
each club, came from an outside supplier, so I have no idea how they
were made, but they did have clearance for the paper. We used a pretty
thick, very fancy all-rag paper, and it had to be sprayed, covered
with plastic wrap, and allowed to sit for an hour or two before
embossing. Then it had to be dried under weight to keep it flat. It
was very tedious and we charged a bundle to do it.

--
Ed Huntress