3D prints in the heat

[jhitesma]

So for those who don't know I live in the desert. Where it tends to get a bit warm at times. Last year at this time our pool was hotter than I usually heat my hottub:



The first 3D print I owned was a RaspPi case that was given to me - I had it outside running a RTL-SDR with ADS-B decoding software. It was in the shade...but the case still melted down and deformed:



That was before I had a 3D printer...and made me wary of getting one!

But for most things it's not an issue...just don't leave them in my truck or car where I have literally baked cookies in the summer. (I have photos of that experiment somewhere...but can't find them right now.)

I was worried when I decided to make my MPCNC though - it would have to live out in my old office (now shop) which I usually don't keep air conditioned in the summer. I opted to print the MPCNC in PETG specifically because of my concerns...even so I've given in and now run the AC out there in the summer (though to save money I keep it set at 84f which is the warmest the AC's thermostat will let me go.)

All the same I decided to do some tests. While printing the MPCNC I had a few print failures resulting in unusable parts. Both out of PLA and PETG (I had initially printed all the parts in PLA - then decided to switch to PETG).

So...I put a bunch of 3D printed parts in my truck. They've been in there a bit over a year now and are on their second summer.

What have I learned so far?

Yes, PLA parts will deform in a vehicle. PETG holds up MUCH better - but in our heat even thin PETG parts can get soft enough to deform.

However - most of the MPCNC parts which are printed with 3 perimeters and heavy infill have actually held up fine even in PLA! They do get soft - but they're so dense they don't really deform. The surface can be dented but that's about it. The motor supports are the big exception to the rule - they're thin so they get soft fast in the heat - even the PETG versions make me a bit nervous. But the corner blocks and Z parts - do surprisingly well.

Now, this is in a no-load situation. A fully assembled machine would probably be another story with the weight of the gantry and tool head putting force on the parts.

I also found that the PLA parts seem to have been annealed from this torture. The parts that were left in there last summer were super stiff and hard this winter. Noticeably stiffer than my other PLA parts. And this year they don't deform nearly as easily even on really hot days. Those that I did deform last year have held the deformed shape and are highly resistant to being reshaped even on the hottest days we've had so far this summer.

Anyone else do any experiments like this? I need to add some ABS parts to the mix one of these days....

 

[LitterBug]

I have been debating setting up some sort of wind vane out at the flying field where it would be out in the elements 24x7x365. Maybe something like www.thingiverse.com/thing:1072696 for example.... Be interesting to test not only different materials, but different colors to see how they hold up. We don't get your heat, but you don't get our Freeze/Thaw cycles.....

One thing I built a while ago was a PVC bike rack for my Pickup Truck. Figured for $20, if it didn't hold up, I'd just build another. Going on six years now and no indication of cracking, warping, etc... That has been the best $20 solution for a $400-$500 problem. LOL

Cheers!
LitterBug

 

[PsyBorg]

Soo.. Hot days fresh prints deform.. Once deformed they tend to not change... Print new parts bake them at ~100 degrees for a time while not under load and "Harden" them like done with steel?

 

[jhitesma]

Soo.. Hot days fresh prints deform.. Once deformed they tend to not change... Print new parts bake them at ~100 degrees for a time while not under load and "Harden" them like done with steel?

Yes...kind of. Some PLA's are advertised as being designed for annealing. Most of the "Impact Modified" PLA's are. MakerGeeks suggests putting prints into boiling water for 10 minutes then letting them cool to anneal with their Raptor PLA for example. After annealing the prints are supposed to be a lot stronger (MakerGeeks claims their Raptor has a higher tensile strength than most Nylon's after annealing) and the become more heat resistant (their transition temperature goes up.)

But...some people have tested and found that most PLA's also react the same. The PLA I have in my truck is just run of the mill cheap esun, hatchbox and makergeeks. I do have a roll of Raptor I can try but since I only have the one roll and the stuff is expensive I haven't done a lot of tests with it.

That said - the parts do still get soft in the heat. It's just sections of them seem to have gotten harder than others and are less willing to be reformed when softened now. Not sure if that's due to the design of the print or them being left in my truck annealing them.

I'd do more controlled experiments...but...I'm just not quite THAT curious

 

[PsyBorg]

Kind of why I suggested a low temp longer baking process to heat them thru. The hot water bath seems more like case hardening rather then tempering.. Wonder what a microwave would do since they excite molecules from the center out. There has to be some sort of moisture in the stuff you guys use if humidity can effect it I would think. but with it being melted solid will it act like an egg in the microwave and explode because the steam created can not vent.. Maybe an email to Adam Savage to get him to test it hehe

 

[LitterBug]

maybe we need to find a cheap microwave to do some experiments with at FFE.... ;-o

 

[PsyBorg]

Reuse the one they used to pop corn in mid flight.

 

[FFoo33]

Since you have left it inside the vehicle, the material kind of melted and deformed, which made it harder and tougher to melt the second time around. The truck parts tend to accumulate heat (especially for dark colors) and made the temperature rise.