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anon4321

BEER! How hot is too hot for PLA and what does Tg really mean?

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A friend asked me to print this peristaltic pump.

http://tim.cexx.org/?p=1282

It's a pretty ingenious design.

However, he wants to use it during brewing beer to circulate the wort.

I don't know much about brewing but I do know the wort is heated and/or boiled.

So the question is if we assume the wort is nearly 100c as it goes through the silicone tubing, will the PLA deform?

Or more specifically, what physically happens to PLA at temps above (but near) the glass temperature?

Certainly, in my experience, PLA needs to be at 170C before you can pull it out of the nozzle and like 180-190C before you can extrude it.

So is Tg when the part will become soft? And how soft are Tg plus about 30C?

If PLA isn't going to work, how about XT? Or ABS?

 

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I doubt PLA would work, it will become much too soft to stand up to the constant grinding. Drop one of your failed prints into boiling water, take it out after a few minutes and see how it behaves.

XT and ABS have a similar Tg, about 75C. I doubt those would work very well either at 100C.

But I have no practical experience so don't take my word as gospel (numbers don't lie though).

 

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XT and ABS have a similar Tg, about 75C. I doubt those would work very well either at 100C.

 

XT is indeed about 75C, but ABS is definitely more -- some are going well beyond the 100C

I am not a big fan of ABS (because of the fumes), but I use it for my model cars where temperature goes above 70c and it stays hard.

This website gives tg for plastics and they list ABS between 80 and 125C, so there is a full spectrum, not all ABS are equal ;)

 

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I did some destructive testing on an ABS object which I had heated on the heated bed to 90C.

While it still feels solid at 90C, it permanently deforms rather than flexing when you put some load on it. So I would not use Ultimaker ABS above 80C.

I would love to have ABS that keeps it's mechanical properties above 100C but I doubt that you can buy such ABS as a printable filament (?)

Polycarbonate is what I aim for when it comes to printing objects that can resist high temperatures.

 

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Nylon PA6 has worked fine for me in boiling water. I got it from here:

http://fbrc8.com

PA6 is easier to print than most of the Taulman nylons although Taulman Bridge is even easier but probably too flexible for your needs. PA6 is what I recommend. Or ABS.

Don't put PLA in boiling water - do this instead - boil some water in microwave in a mug or glass. Then remove and place on counter. The water is now already down to 80C. Take some PLA (filament or a model) and insert into the water for 10 seconds. Remove from the water and push on it. It has zero strength - it's like clay.

YOU WILL NEVER FORGET THIS EXPERIMENT. There is something about tactile learning that is better than learning by reading.

 

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Sometimes we deliver prints to customers. One day, we left a customers PLA print in the car for about 20 minutes. When we got back to the car, the print had permanently warped.

From that day on, I won't go near PLA for prints that require even the slightest amount of heat tolerance. That includes heat buildup form moving pieces.

ABS has worked well for me, but like Amedee said, not all ABS is created equal. So far I find that the cheap Chinese JET brand (from amazon or 3dsupplyworld) holds up to heat pretty good. I have to print it full blown 260, no fans. Other ABS brands I've tried I can get away with 235 to 250.

 

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I've had some trouble getting PA6 to stick with larger parts (> 100mm across) but I've gotten it good enough for what I needed so I haven't investigated further.

Nozzle temp has to be very hot - I print at 260 nozzle. Always. Any cooler and you get bad layer adhesion. For the same reason I print with fan at 30 to 50% (both seem fine).

Now the tricky part - getting it to stick. Of course you need brim.

I've gotten it to work with PVA glue and bed temp of 80C. That was my best result so far. Next time I will almost certainly try 100C.

Alternatively I've gotten it to work on blue tape at 50C. My notes say don't go hotter than 50C because then the blue tape doesn't stick very well. I recommend you try PVA on glass rather than blue painters tape. 80C on glass seemed much better than 50C but I'm not 100% certain.

I haven't tried kapton tape.

 

I'm thinking of getting some PA6 from George.

 

fbrc8 is Simon aka Illuminarti. Not me. He's also "Ultimaker USA" now.

 

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George, sorry about the name mix up. Right Simon = Illuminarti = fbrc8.com

Thanks for the printing info. I'll give it a try

Unfortunately, the part will be about 125mm across so we will see how the adhesion goes.

Have you tried hairspray on glass? That worked well for XT

My self built bed is 240W so should be able to get to 100C without probems.

I'll let you know how it works out.

 

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I have tried hairspray on glass for ABS but have not tried it for Nylon. 95% of my prints this year have been PLA.

This suggests PVA glue on glass. I used wood glue but this guy used glue stick. Also different types of nylons are easier/harder to get to stick to glass:

http://forums.reprap.org/read.php?1,233826

This guy likes glue which I strongly suspect is PVA also:

http://www.thingiverse.com/thing:114868

 

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