3D Printing in Space- Help Requested

[VTRocksatX]

Hello, we are the Virginia Tech Rocksat-X 2015 Design Team. This year, our goal is to fly a 3D printer aboard a short sounding rocket mission.

The printer must:
Fit within a 9 in diameter cylinder with height under 9 in.
Consume less than 1 Amp Hour of Power to complete a print job.
Weigh less than 10 lb.
Be controllable by off the shelf electronics (Raspberry Pi, Arduino, Beaglebone Black)
Simple to use and setup.

If you have any recommendations or insight on how to accomplish this goal, it would be massively appreciated, and can help send one of the first 3D Printers into space.

Please contact us here or at VTRocksatX@gmail.com
Thank you

[Mjolinor]

"1 amp hour of power" << does not compute

Is the cylinder air filled and at what pressure?

My suggestion would be:
Delta printer to save weight.
Microlinear motor for vertical movement.

If you are in air then air activated liquid for extrusion. Like the silicon you get for gasket cement.
If you are in a vacuum then you would need to use a UV cured resin.
Use a stepper motor, threaded bar and piston to extrude.

[Marm]

I would assume it's sub orbital, and the 'zero' g period will be fairly short.

If it is in zero G, then I would guess UV cured resin (like the peachy? correct me if I'm wrong on that) may not work, as the fluids are layered by density, and require a definite "down" direction from gravity to hold the resin in place.

It will probably have to be mounted on some sort of shock absorbing system, for if it is printing while in 'turbulence', then the extruder head may get knocked around a bit. Also, if you are using a heated bed to adhere your parts to (or any non secured bed/layer), even though people encounter issues getting their prints to unstick at times, you don't want to finished print to come loose and tumble around loose inside a space craft.

That wouldn't be an issue on a stable platform, like the ISS, but for a sub-orbital flight (I'm guessing you're planning on recovering the device?), re-entry and parachutes are not known to be the most gentle of experiences.

[Feign]

If you're on a rocket, the time when you aren't in Zero G is the time when you're in a paint mixer being swung around by a giant toddler... So I would hope the printing is happening during the Zero G portion, for the sake of the print. (there's a reason things that go into orbit cost a boatload of money and engineering man-hours after all.)

Using a Delta form factor would be difficult, for the stresses involved, but it would save weight. Regular SLA would be downright impossible in Zero G, though a paste extruder pushing out a gelled (semi-cured) photoresin might be the best way to go. Without gravity, the beads of gel wouldn't flatten out, though and there wouldn't be quite as much layer adhesion. Also, you need to put more radiation shielding around the resin to keep the sun's x-rays and ambient gamma radiation from curing it prematurely, where thermoplastics aren't nearly as susceptible to radioactive damage. If the chamber is under vacuum, then you have a whole host of other problems with heat dissipation in the part and most all of the equipment, even if you use paste-deposition-SLA.

[Marm]

If it is in a vacuum, heat dissipation shouldn't be an issue, as there is no medium for the heat to transfer into. You need other molecules to be in contact with a surface for it to cool off, other than radiantly. That is why vacuum Thermos's work so well. There is no conductive material for the heat to transfer to.

Unless that is what you meant, that the part won't cool off.

[soofle616]

From a power consumption perspective I would think SLA would be the way to go. From a physics perspective, FDM would be more appropriate due to zero-g. Delta style machine would result in a larger build surface than a cartesian setup given the cylindrical space constraint but the additional vertical height of a delta design would have to be mitigated. The comments about structural strength I don't think are too critical as stiffening the machine should be that terribly difficult without resulting in a unit that weighs a ton. Another option would be creative packaging. A support structure consisting of air bladders (minimal weight) could be used to keep the machine and it's components firmly situated to prevent damage in flight. When it's time to print, the bladders deflate, clearing the area for the machine to operate.

Feign's idea of a combined FDM/SLA process is a good one, I don't think the lack of gravity to flatten the gel is as big of a problem as he seems to suggest. One possible solution would be a thin layer height combined with a relatively high extrusion pressure and a tiny nozzle opening. The result would be a pressure based flattening of the material as it is extruded. This would give you thicker traces though which is why I mention the small nozzle diameter. The laser would have to follow the nozzle with as close to zero delay as possible to cure the resin before it has a chance to move without curing it before it clears the nozzle which would create a plug and jam things up. Build speed would probably suffer because of this.

Marm, your points about heat transfer in a vacuum are exactly what Feign is talking about. Without a medium for the heat to conduct through it would end up staying right where it is creating a situation where the part, build surface (if heated) and extruder (again, if heated) would have no way to cool off.

[Mjolinor]

If it is at zero pressure then any liquid will boil the instant it is extruded so that laser better be pretty damn close.

You could spin the whole thing if you felt you needed "gravity"

[curious aardvark]

Just send a leprachaun with some epoxy putty.

Seriosly a micro delta is the best bet with a creopop pen (pressurised maybe) instead of an extruder. That way you only need to supply power to the motors, the extruder has it's own power supply. They're rechargeable right ?

[VTRocksatX]

The cylinder containing the printer will be sealed with air at ambient pressure prior to launch. The vehicle will take the payload into suborbital flight, and it will fall back into the ocean with a parachute. Printing will only take place during the approximately zero gravity portion of the flight (~2-3 min). We are aware of the flight loads and will have vibration isolators and structural reinforcement to mitigate the risks. We are aiming to get some insight on how 3D printer performance is affected by the reduced gravity environment.

[Geoff]

Hello, we are the Virginia Tech Rocksat-X 2015 Design Team. This year, our goal is to fly a 3D printer aboard a short sounding rocket mission.

The printer must:
Fit within a 9 in diameter cylinder with height under 9 in.
Consume less than 1 Amp Hour of Power to complete a print job.
Weigh less than 10 lb.
Be controllable by off the shelf electronics (Raspberry Pi, Arduino, Beaglebone Black)
Simple to use and setup.

If you have any recommendations or insight on how to accomplish this goal, it would be massively appreciated, and can help send one of the first 3D Printers into space.

Please contact us here or at VTRocksatX@gmail.com
Thank you

Are you guys trying to print while it's in the air? not easy, and in a rocket???

I am trying to lift a Delta Mini with a F550 Hexacopter and print something while it's hovering in mid air, right now with the current power options I have, I don't think I'll be able to print anything that takes more than 5 mins to print. Even running an 8amp 14.8v 4s just to get the thing in the air, then the delta requires a minimum 19v@ about 5amps and the battery to run that is over 1kg, which is a 6s 22.5v 8amp lipo, enough to get maybe 1 print job out before it dies.

After seeing guys lifting 30-40 kg's with hex and quadcopters I thought hang on... a delta mini is less than 10kg, that means I have a hell of alot of room to play with batteries, and thats where I am now.

I figure a Delta machine might just be able to print while hovering.. I have picked it up while printing and simulated hovering and it seems to be ok...

why? not sure really, I just though it would be a cool idea.