A recent customer experience, plus a story about a melted car is a good reminder that parts made with PLA can be deformed by temperatures that can occur under “normal” circumstances.
http://toybuilderlabs.com/blog/2013/9/4/beware-of-heat-warping
Dumb question (I have a printrbot kit on order), am I right in assuming ABS plastic would have been worse off, or do I have this bass ackwards?
No, it’s PLA that’s particularly vulnerable. ABS has a much higher Tg (somewhere around 110ºC) versus PLA’s 60. I wanted to mention this because I know that a lot of people have PLA parts on their printer – if you have a PLA printer that you’re transporting to an event, for example, make sure you don’t leave your printer baking in the car!
I did meet one out-of-state (Florida?) couple that drove their entire collection of PLA parts cross-country to CA – but the parts were not under any stress, so the pieces survived the trip. But heavier pieces, or pieces attached to (for example) metal can deform from the weight!
ABS melts at higher temperature than PLA, so it will not get soft in your car(unless you park on the planet mercury). But you need a heated bed to print with ABS because it tends to warp off the bed as it shrinks while cooling.
@Stephen_Glasskeys - I’ve updated my post to reflect ABS’s Tg. Thanks!
Check and mate, thank you.
If you must use PLA, design for composite fabrication (build grooves for carbon fiber tow) and then reinforce it with a few millimeters of wrapped CF tow in a fast hardening epoxy.
Then your PLA will act like impact absorbing cartilage though I wouldn’t design a part to treat PLA that way.
Thanks all for informative comments!
@Joe_Hacobian - Nice idea. I’ve had a similar idea of using PLA as a “form” and then using something stronger – one idea that I was was to fill a PLA print with JB Weld or other hard curing epoxy that can withstand heat and mechanical stress.
@Joseph_Chiu some composite construction topics worth exploring:
1.) Fiberglass tape, get the tightly woven stuff in 1" and 2" widths, not the stuff at Home Depot, try fiberglass warehouse in San Diego (online).
Good CF tow to get is 24K for strength sensitive applications otherwise use 6k in multiple windings for simple rigidity.
2.) Get a good epoxy like System Three or West System, these are far more powerful than consumer grade products like JB weld or other vastly overpriced epoxies. Learning to mix epoxy properly is a good skill to build up anyway. Go for fast hardeners (aka catalysts) at first.
3.) Experiment with glass fillers like micro bubbles, and both chopped glass strands as well as CF tow fragments in strategic areas.
Don’t be afraid to use nylon thread to sew fiberglass or carbon fabrics (including woven tape) tightly to the underlying form. The tightest fabric fits make the strongest and most elegant parts.
Composite construction is a lot of fun and if practiced responsibly, fairly safe.