High Temperature 3D Printer

Hello, as my master thesis I'm planning on creating a 3D printer for bone. Where I am doing my thesis, they suggested that I needed a high temperature (200-400ºC) for the extrusion.
As I'm a newbie on this matter, I have some questions regarding the material of the mechanism so it doesn't fail or break with the high temperatures. The design has core XY axis on top and a Z, using a linear guide system for Z movement.
So I have some questions regarding the material resistance or any advice on how to avoid damaging anything by heat dissipation o absorption.

Are there any material recommendations for this heat? I've looking for systems which can handle high operating temperatures, but still there is no option for 400C.
Are there any mechanical joints which can absorb heat or dissipate through the structure (the electronics will be outside the heated chamber?
Is there anyway I can protect stepper motors for this high temperature, the ext motor?
Can the screw thread C7 handle the heat without a problem?
Are there any special cables for the electric configurarion for this temperature, which kind of cables provides the best stability.


Maybe this questions are too dumb, but I`m newbie in this matter si any help will be great!

Thanks,
Alfonso

Alfonso,

I'm not an expert in 3d printer but should you explain why you need a high temperature print head? Are you printing metal? If you are printing metal you might want to consider using a Laser Sinter. Medical replacement organs has peaked my interest for a couple of years and I was thinking people might what to use peristaltic pump, so that they can match the genetics of the patient receiving the transplant.

If you are talking about extrusion temperature up to 400C, I don't think that is particularly difficult. A genuine E3DV6 hot end with a PT100 sensor instead of a thermistor may be able to handle that. However, I'm guessing that you need high chamber temperatures too, and that's when you have to worry about belts, stepper motors, wires, frame components etc.

Edited 1 time(s). Last edit at 03/16/2017 03:56PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

High temperature enclosure is possible.

1) Build a box to fully enclose the printer.
2) Move electronics outside the printer.
3) Upgrade heated bed to 120VAC, driven by relay (solid state, perhaps). Use foodgrade silicone to attach to a glass bed. Regular adhesive is terribly smelly at high bed temps whereas silicone can withstand crazy high temperature and the foodgrade stuff just smells like vinegar while curing.
4) You can use regular stepper motors, but build little enclosures that seal around each one with a hose going into and out of the little enclosures that you can pipe compressed air into and out of. This saves a lot of money vs high temperature magnetics.
5) Might need to replace all 3D printed parts inside the enclosure with at least polycarbonate versions or, ideally, Ultem. (polycarb will stress crack after a few months when operating at high temperature) But initially, you can get by with ABS for the first few prints. White ABS, preferably. Be prepared to replace them, as you just are using them so you can use the printer to print the Ultem parts.
6) Halogen lamps pointed at the part being printed. The higher power, the better. This isn't needed for parts that are short in the z-direction as they'll keep warm from the heated bed (which should be run at 200-230C). For big parts, up to 500Watts of halogen bulbs.
7) keep your filament dry! Ultem is especially prone to absorbing moisture. Might want to build a filament box with a lightbulb to keep it warm.
8) Use a metal spool to store the Ultem on so you can bake out the Ultem in your oven without melting the spool or having to respool the Ultem.
9) bare glass with Disappearing Purple glue stick actually works best.
10) Use a high temperature thermistor and update the thermistor table in Marlin.

Wires getting hot is not too much of a problem. Typical black neoprene belts seemed to work fine, although try not to point the lamps directly at them. Use all metal bearings if you can (they're cheap).

Here's a report on it, which used the Lulzbot Taz (4 or 5) as a baseline platform, but you can use any easily modified design.: [ntrs.nasa.gov]