Re: Modelling HO Scale Trains with RP

Date: Tue Jan 04 2000 - 19:31:29 EET


We use a process we use for making intricate toy molds called 3D Keltool
Process. It is a replication process. The cost of the cavities comes out to
about $30usd a cubic inch. So in other words a set of cavities for an HO
caboose might cost around $2000 - $2500 dollars. If you have any tool making
equipment available to you like milling machines and grinders you could
finish the molds up yourself. If not Im sure you could find a local
neighborhood toolshop to fit the cavities into a moldbase for you for a
reasonable cost. We don't really care how the master pattern is produced. One
suggestion would be to go buy one you like then we can duplicate it into
Keltool. There are thousands of styles produced in places like China. The
downside to this is there is a shrinkage involved in the process of .006 per
inch plus whatever the plastic shrink is (usually .006 per inch also). So the
final product would be about .03-.05" shorter than the original. Which
probably wouldn't hurt anything. The mold would actually be capable of
running hundreds of thousands of parts. The final parts can then be hand
painted and silk screened fairly easily to make them really unique. This
might be a way to start a cottage business producing toy trains. Another
method if you are only looking for dozens might be to get the trains from
China then cast them in silicone rubber and make urethane castings. Their is
less shrinkage involved than what I outlined above with the Keltool. Of
course you still have to hand paint them and shadowmask. A suggestion on that
if you want to go high tech would be to design the artwork on your PC then
print it with a color printer onto an iron-on appliqué (iron on stensil for T
shirts) I have seen some beautiful work done this way onto things like mouse
pads, dishes, etc. You could easily take a digital photo of a real train then
replicate it onto your HO train just using a home PC.
good luck
Bob Morton
Fusion Engineering

In a message dated 1/3/00 9:56:59 PM Central Standard Time, writes:

<< Hi!
 May be this question is too silly to this forum but... here it goes.
 As everybody knows, the cost of injection moulds is high. A plastic
 injection molded piece is feasible only if thousands or thousands
 of parts are to be produced.
 This is a real problem whre only some dozens or even hundreds of
 parts are to be made. This is the case, for example, of HO scale
 model trains, cars and locomotives.
 The variety of model cars and locomotives in the HO scale here in Brazil
 is very scarce. The main cause, of course, is the high price of the
 injection molds...
 A group of rail fans approached me and asked if RP could be used for
 the production of small series of specific model locomotives and
 cars in the HO scale. As this technology is very new to me, I do
 not know if this is feasible, so I am forwarding the question to the
 Nevertheless, I think that some toys eventually used RP during its
 Thanking you very much in advance!
 All the best,
 Antonio A. Gorni

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