[sdiy] I've got one word for you: Plastics

[Richard Kirk Moore (rkmoore)]

I used vibration, kind of.

After filling the mold with plastic, I rotated the mold while shaking it by hand.  The resulting keys still had a couple of bubbles here and there, but I deemed the results acceptable.

Now that I think of it, I may have an old amalgamator from my dad's dental office that may be up for the job...

Thanks,
Richard


________________________________________
From: synth-diy-bounces at dropmix.xs4all.nl [synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Jerry Gray-Eskue [jerryge at cableone.net]
Sent: Sunday, January 31, 2010 9:10 AM
To: synth-diy at dropmix.xs4all.nl
Subject: RE: [sdiy] I've got one word for you: Plastics

Richard,

The result looks nice, did you need to use vacuum or vibration when you
pored the plastic into the mold to eliminate air bubbles?

- Jerry

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of Richard Kirk
Moore (rkmoore)
Sent: Sunday, January 31, 2010 8:49 AM
To: synth-diy at dropmix.xs4all.nl
Subject: RE: [sdiy] I've got one word for you: Plastics


The plastic that I was complaining about before has cured harder than I
thought at first.  While not perfect, I think the resulting keys will work
nicely for my organ.  I haven't messed with trying to dye the plastic to the
proper beige, but that's not a major concern for me.  For anyone curious, I
took a few pictures of the process that can be seen here:

https://umdrive.memphis.edu/rkmoore/sdiy/keymoldmosaicsmall.jpg

Thanks to everyone for the information!

-Richard


________________________________________
From: kheck73 at aol.com [kheck73 at aol.com]
Sent: Thursday, January 28, 2010 9:38 PM
To: Richard Kirk Moore (rkmoore); synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] I've got one word for you: Plastics

I've worked in materials testing labs where mounting compounds are used to
prepare samples for sectioning and analysis. One family of compounds are
cold curing plastics, epoxy, polyurethane, and acrylic. The mixture is
usually of a liquid and a powder. The two big companies that make the
supplies are Struers (struers.com) and Buehler (buehler.com). Look under
"cold mount consumables". I worked mostly with the epoxies, and they set
really hard. I believe we coated the molds with some sort of release
compound like a talcum powder, but its been a while ago and my memory is
fuzzy. It cures clear or with a yellowish hue to it. I see Struers has color
dyes you can add to some of the epoxies and acrylics, but I don't see white
or black. You might be able to cast the key, roughen the surface a bit with
fine grit paper, then give it a shot of gloss paint, but I don't know how
well it would stick.

-Karl.
-----Original Message-----
From: Richard Kirk Moore (rkmoore) <rkmoore at memphis.edu>
To: synth-diy at dropmix.xs4all.nl <synth-diy at dropmix.xs4all.nl>
Sent: Thu, Jan 28, 2010 8:27 pm
Subject: [sdiy] I've got one word for you: Plastics


Hi everyone,

It's been a long time since I've posted anything.  My current project is
getting
my Hammond H-111 organ fully operational.  It's in strikingly good
condition,
but several of the 50-year-old plastic keys have broken.  Instead of buying
someone else's 50-year-old keys pulled from a donor organ, I am trying to
cast
new ones.  Using a Smooth-On OOMOO 30 silicone rubber and Smooth-Cast 300
urethane plastic I have made a mold and cast a key.  The resulting key is
good
and mounts in place nicely, but the new plastic is not quite as rigid as the
original one.  As an EE, materials science is pretty far outside of my
working
knowledge.  Does anyone know of a better plastic that I could use at home
for
key casting?

Thanks,
Richard

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