Subject:
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Re: Monorail track molds? Factory visits?
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Newsgroups:
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lugnet.general
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Date:
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Sat, 19 Jan 2002 03:22:23 GMT
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Viewed:
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1842 times
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In lugnet.general, Jim Schifeling writes:
> Proof positive that I don't know everything.
> Frank, in your opinion would you say the "honeycomb" is an inherent part of
> the molding processing or a way to save on material? Retaining the strength
> of the unit while using far less ABS?
Material and weight savings while retaining strength.
> What about vacu-forming pieces?
I believe baseplates are vacuum formed. Vacuum forming is usually a one piece
mold and the item must be able to "fall" out. There is another molding process
which I guess is vaccuum based also which uses a two part (or more?) mold. I
barely remember some bits about molding from high school (I went to a
vocational high school and they had a plastics shop which I spent a couple days
in my freshmen year, we made some vacuum formed divider trays [gosh, I wish I
still had them, they'd be great for sorting - they were three or four inches
deep and had something in the range of three to five compartments, and very
well rounded for easy scooping out of parts] and some little footballs - using
a different machine with a two part mold). I think they also had an injection
molding machine.
The vacuum forming machine we used took a mold and a sheet of plastic which was
then heated and sucked down over the mold. I'm guessing the baseplates are done
on a similar mold, though perhaps with a higher vacuum and temperature.
Frank
> lugnet.general, Frank Filz writes:
> > crunch-o-matic wrote:
> > >
> > > You might be right if the molds are rigid.
> > > It could be done in 2 parts if the mold is flexible like vulcanized rubber
> > > or silicon (or low-tech like Knox gelatin and anitfreeze, or even hot • glue).
> > > They were injected from the center top, you can see where the sprue is/was
> > > on a long straight. I dont see any other seams, flashing or other sprue
> > > nubs. That leads me to believe it was done in a 2 part flexible mold, one
> > > for top and sides, one for underneath bottom. When it cooled the bottom • was
> > > pulled off and the top twisted like an ice cube tray and they plop on to • the
> > > conveyor belt or whatever takes them away. Fine tooth gearing like the top
> > > of the track and the side studs would wreak havok on a flexible mold after
> > > time and it would have to be recast after a "short" x-ammount of postitives
> > > were made. From my experience with mold casting if you are creating mass
> > > multiple positives you want the mother mold down to 1 or 2 parts, being
> > > easier to recast it than spend the extra time in the release and clean up
> > > (flashing & sprues) phase for all the rest. Seeing the pictures of the
> > > factory in the DK book, the whole process is automated and might require a
> > > special machine to deal with a 3 part mold. I put follow-up in .general in
> > > case anyone wants to add.
> > > I think my rambling has taken up enough space here in .dear-lego.
> > >
> > > Anyone ever visited a Lego factory? Are there tours or anything?
> >
> > TLC's molds are machined metal (there are pictures in some of the books
> > and examples at Legoland. The track is also "honeycombed" on the bottom.
> >
> > Frank
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Message is in Reply To:
 | | Re: Monorail track molds? Factory visits?
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| Proof positive that I don't know everything. Frank, in your opinion would you say the "honeycomb" is an inherent part of the molding processing or a way to save on material? Retaining the strength of the unit while using far less ABS? What about (...) (23 years ago, 19-Jan-02, to lugnet.general)
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