[simpits-tech] to MARV re: RP
Marv De Beque
simpits-tech@simpits.org
Tue, 08 Oct 2002 12:27:38 -0400
Let's put it this way. A shop will charge more than $50 an hour for mill
work.
Even with CAD drawings and CNC machines there is no way you can get a
finished mold in two hours time. I can assure you that there is all kind of
set up involved, so I would expect more than 2 hours.
My shop experience is lower than experts, and I do not have a CNC mill.
If I can buy a knob for $50 and spend another hour making a mold using that
knob, I have probably saved myself money and time and I have a more accurate
part in the end.
Yes, clear resin is a candidate, but it requires heated molds.
--
> From: Mike Williams <mikewilliams3@comcast.net>
> Reply-To: simpits-tech@simpits.org
> Date: Wed, 02 Oct 2002 21:38:50 -0500
> To: simpits-tech@simpits.org
> Subject: RE: [simpits-tech] to MARV re: RP
>
> 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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