3D printing questions

To all youse folks doin' tree dee printing-
I have been thinking about this technology recently and was wondering
about different materials printed on the same part. More specifically,
printing the plastics over metals and woods. The differential
expansion and shrinking, and bonding. So, for example, suppose the
plastic was printed surrounding a metal or wood part. Would the
plastic crack as it cooled? And will it bond to the metal or wood? I
suppose the wood could be heated before the plastic is applied but how
long would it stay warm? I have seen machines with heated platens so
maybe the wood or metal object could be heated by the platen. But most
of the metal objects I have been thinking about surrounding with the
printed plastic are fasteners or stiffeners. They wouldn't be sitting
on the platen. So nuts held captive by the plastic are a good example.
And does the plastic need to bond to the metal for my application? I
don't know, but lets say it does. Is there some type of glue that
could be used that would make the hot plastic bond to the metal? For
lightness wood can be a very good material to combine with plastic to
make a strong part. I can envision a part that is plastic on the
outside to achieve a particular shape, like a handle, but with a wood
core for strength. And what about using a variety of plastics to make
an even better part? Say a luggage handle that is wood core surrounded
by a hard plastic contoured to fit the fingers with soft plastic in
the finger grooves. Can this be done with the materials available to
the average experimenter with a limited budget?
I know there are a lot of questions above and I appreciate any answers
from folks who know about this stuff. I want to experiment with 3D
printing and have some ideas but I have not been able to find much
info about the above questions from people who actually have
experience trying to do what I want to do.
Thanks,
Eric
Reply to
etpm
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Interesting idea, Eric. I'm sure it's possible but have no idea how to go about it with a 3DP.
Have you tried asking on some of the 3D printing blogs or forums? You'd find extremely active experimenters there with all sorts of printers and software types.
Reply to
Larry Jaques
On Fri, 21 Feb 2014 18:26:31 -0800 in rec.crafts.metalworking, snipped-for-privacy@whidbey.com wrote,
The hot plastic certainly does shrink as it cools. If it didn't, it might be permanently bonded to the print bed. One of the tricks to master is getting it to stick enough to stay there until the print is complete, in spite of shrinkage, but still be able to remove it without damage.
Cracking, not so likely. Warping, more likely.
Captive nuts are easy. They don't even have to stick, just be trapped in a matching cavity so they can't rotate. Put a Pause in your G-code at the top of the cavity so you can place the nut before it's filled over.
Typical construction is plastic deposited solidly at the surface of the part, with the inside filled with a network of threads to achieve a specified percentage of infill to give the needed combination of lightness and strength. But you could certainly use a wood insert in some cases if you designed for it.
Soft plastic is not common yet, but I saw some from adafruit. You would probably have to make the parts separately and assemble them.
Reply to
David Harmon
The local electronics parts store has one of the open frame Velleman units on display, and it's always making one thing or another. From looking at the thing, it's basically got a nozzle like a hot glue gun, except it's fed with monofilament that is unwound from a spool as it is needed. The nozzle apparatus is moved about with stepper motors in an x-y fashion, bumping up a notch in z when one layer is done.
The deposition is too fine to see it being built, except for the head moving about, but given enough time it certainly does make something. They've also got a 3-D scanner that can scan an object to be printed, but I don't know how well it could see into cavities.
Jon
Reply to
Jon Danniken
Your metal part has to be the same temperature as the plastic. You need to have some experience cleaning injection molding nozzles!
All molded plastic shrinks as it cools. This is how you are able to remove plastic objects from a mold. Where plastic must be molded to produce a hole, the hole must be tapered so the mold can be removed in spite of the shrinking.
Wood would probably smoke at the temperature of molten plastic.
Paul
Reply to
Paul Drahn
Your metal part has to be the same temperature as the plastic. You need to have some experience cleaning injection molding nozzles!
All molded plastic shrinks as it cools. This is how you are able to remove plastic objects from a mold. Where plastic must be molded to produce a hole, the hole must be tapered so the mold can be removed in spite of the shrinking.
Wood would probably smoke at the temperature of molten plastic.
Paul
Reply to
David Billington
Your metal part has to be the same temperature as the plastic. You need to have some experience cleaning injection molding nozzles!
All molded plastic shrinks as it cools. This is how you are able to remove plastic objects from a mold. Where plastic must be molded to produce a hole, the hole must be tapered so the mold can be removed in spite of the shrinking.
Wood would probably smoke at the temperature of molten plastic.
Paul
Reply to
David Billington

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