[simpits-tech] to MARV re: RP

[Mike Williams]

Marv, what about the clear resin that comes in those home kits, the ones
where you can cast a snakes head
or cockroach :)- into clear resin, what is the name of that stuff and where
can it be had? Knobs are a bit away for me yet too, Although I had pretty
good luck using polyesther resin (fiberglass resin) and using one time
modeling clay molds from original. (eperimenting last winter). Has any of
the home CNC guys cranked up their mills yet, can molds be made from a CNC
for casting?

-----Original Message-----
From: simpits-tech-admin@simpits.org
[mailto:simpits-tech-admin@simpits.org]On Behalf Of Marv De Beque
Sent: Wednesday, October 02, 2002 7:37 PM
To: simpits-tech@simpits.org
Subject: Re: [simpits-tech] to MARV re: RP


Interesting about the lead-free pewter.

I have tried some experiments with translucent plastics for light plates and
I was very disappointed at the performance (almost nil).

Water clear plastic is the only way to go.  That is what the knob
manufactures use and I am sure that they put a lot of science and
engineering into the designs.  So I will take their lead since I don't want
to reinvent the wheel (only borrow it to make a mold).  ;-)

Marv
--


> From: Steve Wilson <mafsix@attbi.com>
> Reply-To: simpits-tech@simpits.org
> Date: Wed, 2 Oct 2002 18:24:32 -0400
> To: <simpits-tech@simpits.org>
> Subject: Re: [simpits-tech] to MARV re: RP
>
> Lead is toxic.  Lead-free pewter is not.  Different pewter alloys have
> different strengths, and the stronger variants can be used for harness
buckles
> and the like.  Strong stuff, especially for knobs and small mechanical
parts.
>
> What you want to cast with, Marv, is a translucent white epoxy resin that
can
> be painted, then lit from underneath.
>
> RP would only be good for mold masters.  Depending on the quality and the
> material used, perhaps they'd need a bit of a polish, but then they would
need
> to be cast in resin.
> --
> Steve Wilson, mafsix@attbi.com on 10/02/2002
>
>
> On Wed, 02 Oct 2002 18:02:52 -0400, Marv De Beque wrote:
> ::::
> ::::   Lead and pewter are things to avoid.  Not only are they too
> ::::   soft, they are
> ::::   very toxic materials.
> ::::
> ::::   For the home shop, two-part epoxies are probably the way to go.
> ::::
> ::::   There are a lot of good quality silicon molding rubbers that
> ::::   can be used to
> ::::   make a mold from.  That would be my bet.
> ::::
> ::::   As for making RP parts, they are simply not strong enough for
> ::::   real world
> ::::   use.
> ::::
> ::::   Where they shine is for making example parts to check theory
> ::::   or, if high
> ::::   enough quality, as masters for making rubber molds.  I think
> ::::   the latter
> ::::   holds some promise.  That is where my money is at.
> ::::   --
> ::::
> ::::
> ::::   > From: "Jim K." <JimK@sisna.com>
> ::::   > Reply-To: simpits-tech@simpits.org
> ::::   > Date: Wed, 02 Oct 2002 13:28:09 -0600
> ::::   > To: Simpits <simpits-tech@simpits.org>
> ::::   > Subject: [simpits-tech] to MARV re: RP
> ::::   >
> ::::   > Marv,
> ::::   > The quality of RP prototypes seems to rely on the machine
> ::::   being used and
> ::::   > what type of RP is being used.  There are several different
> ::::   RP methods and
> ::::   > they do produce different results.  I think you can change
> ::::   the quality
> ::::   > outcome of a part via your drawing and/or the settings in
> ::::   the RP machine
> ::::   > itself and the way you make the part is critical as well.
> ::::   I.E., you have
> ::::   > to choose the correct orientation of the part from which to
> ::::   start.  I have
> ::::   > some RP parts here and the top final surface that was
> ::::   generated is as
> ::::   > smooth as glass but the sides have that "grain" to it.  I
> ::::   don't think FDM
> ::::   > parts have this grain to it but I'd have to check.  I just
> ::::   brought this all
> ::::   > up as an option.
> ::::   >
> ::::   > hmmmmmm, thinking here:  What if you made a mold of the part
> ::::   via a CNC
> ::::   > machine and then melted lead or some type of plastic into
> ::::   the mold to make
> ::::   > your own parts???
> ::::   >
> ::::   > Jim
> ::::   >
> ::::   > _______________________________________________
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