PLA in heated chamber

I want to try building a box around my printer to improve ABS printing (hopefully relying on "passive" heating from the heatbed and extruder, with maybe a thermistor controlled extractor fan to regulate temperature), but most of the printer plastic parts (apart from the extruder) are PLA so I'm concerned I don't overheat these (I'd like to avoid having to rebuild my printer in ABS if possible).

Glass transition for PLA is typically quoted as 60-65C, but I suspect there may be some softening or deformation at temperatures below this (some of which may only show up over time), has anyone experiences (good or bad) of using PLA in heated build chambers, and what temperature limits do you think are safe?

I found an interesting report here which seems to confirm there will be some softening below Tg, at the moment I'm thinking that maybe 45C may be a realistic maximum temperature (and that should be warm enough to see a significant reduction in ABS warping).

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Tim

Printers:
Prusa i3 (plywood box frame)
RAMPS 1.4 and Arduino Mega

Mendel 90 (sturdy)
Smoothieware

My RepRap Blog

Hi. The PLA parts start to be flexible around 80°C. They can hold 75°C without any issu. But for ABS the chamber must be around 100°C. You definitely need ABS parts. Plan to get fresh air from outside of the enclosure to cool down the coldend, and for the part cooling if sometimes you still print PLA.

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Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

The recommendation I've seen is to limit PLA-based printers to 45, and I'll be using 40-45 as the target for mine when the enclosure is done, even if I eventually get a reason to disassemble it enough to put it back together with all ABS, as the electronics are, after all, in the same environment.

My experience has been heating the room to as little as around 25 dramatically reduces ABS warping.

There is a gentleman south of the equator who lost his PLA-printed Cherry Pi delta printer inside his car on a hot day. My delta printer's PLA effector plate folded like a taco shell whenever I cranked the E3D up for printing ABS. Personally, I wouldn't put *any* PLA near a heated chamber.....

Three very different opinions so far.

Anyone actually using PLA printer parts inside a heated chamber (or tried, and failed)?

45C is the highest chamber temperature I use with a printer made from ABS parts because the motors and extruder run at chamber temp plus about 20C, which is far too hot for PLA. A friend of mine pushes it to 50C. Over the long term ABS parts become brittle and start to crack but last sufficiently long to not be a big problem if you have more than one printer.

My Mendel was all ABS apart from the two top vertex brackets made from PLA. They softened a bit at 45C and the nuts would never stay tight due to the washers sinking in.

Edited 1 time(s). Last edit at 02/14/2015 04:29PM by nophead.

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[www.hydraraptor.blogspot.com]

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nophead
the motors and extruder run at chamber temp plus about 20C

I hear this all the time (that other peoples motors run hot), mine never even get warm to the touch. I suppose it is due to a combination of motor model, print speed, and stepper current (mine are listed below), maybe I'm just printing very slow.

Motors Wantai 42BYGHW609
Stepper current up to 1.6A
#define DEFAULT_MAX_FEEDRATE          {75, 75, 2.7, 20} 
#define DEFAULT_MAX_ACCELERATION      {750,750,60,2000}
#define DEFAULT_ACCELERATION          1000
print speed in Slic3r is 60mm/s infill, 30mm/s perimeters

My new printer has a different motor (slightly higher torque) so it will be interesting to see if I start to see hot motors when I complete that printer.

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They softened a bit at 45C and the nuts would never stay tight due to the washers sinking in.

Thanks, that's the type of information I was looking for.
So 45C maybe too hot, I wonder if anyone's found the safe limit, where PLA doesn't deform (from what I've seen so far even a 10 or 15 degree increase is worthwhile in combating ABS warping)... Perhaps I can commandeer the oven long enough to do some tests

Use your current heatbed, a small cardboard box, and a printed "MakerBot" logo in PLA (or some other suitable scrap PLA part). Place the part over the thermistor on your heatbed, with something metal underneath it to induce droop when it gets too hot. Put the box over the part as a heat retainer. Turn on the heatbed to 50C. Bake for 30 minutes. Repeat by increasing the temperature 5C until it fails. I suspect that it won't make it much above 50C before it folds.

Or, borrow a page from the delta printer folks and go buy some disposable turkey oven roaster bags, wrap around your hotend and the bed using blue prototyping tape, and use it as a temporary build chamber to print replacement ABS parts for use in your final printer.....

I'm not at all sure there is any point in a heated chamber for printing PLA unless your printer is in a particularly cold room. But it does help to shield the printer from draughts.

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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].

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dc42
I'm not at all sure there is any point in a heated chamber for printing PLA unless your printer is in a particularly cold room. But it does help to shield the printer from draughts.

Dave

I think the point was wether his PLA Printer parts would start to melt in a heated chamber when he prints with ABS

Doug

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I hear this all the time (that other peoples motors run hot), mine never even get warm to the touch.

Mine are only warm to the touch when not in a heated chamber. I.e. at room temp of 20C the get to about 40C, which is only just above body temperature. In a chamber at 45C they get to 65C, which is too hot to touch for more than an instant.

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[www.hydraraptor.blogspot.com]

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nophead
Mine are only warm to the touch when not in a heated chamber. I.e. at room temp of 20C the get to about 40C, which is only just above body temperature.

I measured mine yesterday at 5C over ambient of 21C, after a 2 hour print.