4272Fwd: [traintools] Re: DIY Injection Molding vs 3D Printing
- Jun 10, 2013For now, forwarding some of the interesting stuff I see here and there.Maybe I can liven up the place a bit?Best to ya...
Milwaukee, Wi, USABegin forwarded message:From: "dcyale"Subject: [traintools] Re: DIY Injection Molding vs 3D PrintingDate: June 10, 2013 11:42:16 AM CDT
I have been playing with 3d printing- although the DIY injection molder
perks my interest, too. I have to agree about the difference in 3D
printing doing thing you cannot with injection molding.
The model I created that gets the most attention is an HO Scale
port-a-pot (go figure). I did one with interior detail.
Unpainted it's hard to see the detail, but it shows clearer in a
Computer render <http://www.dcyale.com/shapeways/portpot01.jpg>
Although you could make it close by molding the sides separately and
assembling them post molding, with 3D printing it comes out ready to
This is made with the cheap nylon material which is a little rough, not
the more expensive resin. With cheap acrylic paint a lot of the
roughness is smoothed out, though.
I suspect the cost of producing a custom mold would overshadow the lower
price per unit cost of injection molding, as the market for my
port-a-pot is most likely fairly limited. And my main intent is to make
them for myself, anyway. This is an item that will not often be seen on
Now I need a guy walking out with an HO Scale TP tucked into his pants
leading back to the paper dispenser inside AKA Jackie Gleason walking
out of the restaurant in Smokey and the Bandit.
--- In firstname.lastname@example.org, Tom & Judy Bank wrote:
potentials and problems.
DIY injection molding and 3D printing each have their own set of
curve on the software. The roughness goes down as the equipment price
With 3D printing the main problems are roughness and the learning
goes up – or as time goes by. And I guess the learning curve
improves as the new generations grow up with hardware/software
familiarity. I'm 75, so you can guess which side of the fence I am on,
and that's in spite of having a long career as a computer applications
systems analyst. But the real advantages with 3D printing are the
ability to one-off samples and improve the product through program
modification until you get it right. The plastic thread that is the raw
material for the process is relatively expensive ($5.00 a spool), but
that will soon change. There is a machine in the works that converts
("recycles") milk jugs and soda bottles into the required thread, that
is expected to be on the market next year.
or inaccessible spaces in the design. Not sure how that potential would
Beyond that, 3D printing also has the unique ability to include blind
be put to use by model railroaders, at least at this point, but I do
remember that John Allen had a boxcar with a large ball bearing on a
"rocking chair" track inside. If an operator got careless with his
consist the bearing would roll up and off the end of the track, short
out the block the train was in, and light a red light to call attention
so everyone knew what had happened. With 3D printing, the same thing
could be done with a hidden space in a load with a little blob of
mercury fed in through one of several holes that were then plugged with
wires that were part of the detector circuit.
produces the part. But since you are making an item scaled from a real
With DIY injection molding, the product is as smooth as the mold that
piece, making refinements is limited. If you make a mistake you likely
have to toss out the mold and start over from scratch. Also, the mold
requires machining, which involves an investment in both machinery and
the time necessary to learn to use it. Make no mistake, I bought a lathe
and mill fifteen years ago to enhance my model railroading. The projects
that I was working on for which I thought I needed that machinery are
still sitting on my model railroad work bench in the same state as the
day my lathe arrived. I've had fun, but it has been with learning to be
a machinist, not with my model railroading. And I'll add that I took
prizes for my models at regional and national NMRA meets before I got
side tracked. So figure out what your hobby priorities are carefully.
There's a limit on lifespan, and I'm finding out that some of the things
I postponed to learn skills I thought would aid my modeling will never