Deforming printer parts in enclosure Prusa MK4
Hello
Recently I have started printing with ASA in my Ikea Lack Enclosure with Prusa MK4 and today X Axis belt suddenly got completely loose. Upon inspection I have noticed that where the belt is mounted to the X Carriage is deformed which caused belt to slip. I have contacted Prusa support and they said that they can send me a new part but it would also be made from PETG. I think that PETG cant withstand the heat (there was only 40-45 degrees Celsius in the enclosure) which led to deformation.
What should I do now?
Accept. Temporarily install. Use to print replacement part in whichever filament you decide is suitable. Fit new part.
Cheerio,
RE: Deforming printer parts in enclosure Prusa MK4
That part never should never get hot enough to soften PETG, even at 50C, which I doubt you'll reach in a Lack enclosure. If the belt slipped, maybe the part was already a bit deformed to begin with ? or you opened too much the belt slot when pushing the belt in ?.
If you don't trust PETG anymore, print the X carriage in ASA. Take into account acount that ASA shrinks more than PETG and maybe you'd have a tighter fit for the belt and the bearings too.
RE: Deforming printer parts in enclosure Prusa MK4
That part moves a few cm over a plate heated to around 100 °C (or more with certain filaments) and it does that for hours sometimes. That area surely will get hotter there than 50 °C. I have reprinted all the parts on the x-carriage of my MK4Ss with PCCF, which is what Prusa uses for their parts in the MK4S upgrade kit. I had printed a few spools of ASA and also some PCCF before I did this and when I disassembled the PETG parts I could see that all the edges on the x-carriage parts hat lost their clear definition and were not as "sharp" as the edges on the freshly printed PCCF parts.
RE: Deforming printer parts in enclosure Prusa MK4
I dont have PCCF but I have ASA, is it going to work well? I thought about replacing x-carriage and y-belt mounts.
RE: Deforming printer parts in enclosure Prusa MK4
ASA should be durable enough as well, I think. For the y-belt I can recommend the two mods below, which make adjusting the y-belt tension much more comfortable, especially if the printer is residing in an enclosure, because it is not necessary to turn the printer over to get at the belt tensioner like in the original design by Prusa. You need to apply both mods for this, one is to attach the belt to the y-carriage, the other one is for tensioning.
https://www.printables.com/model/585494-prusa-mk4-y-axis-belt-tensioner
https://www.printables.com/model/727247-y-belt-holder-one-piece-mod-for-mk4
RE: Deforming printer parts in enclosure Prusa MK4
Thank you! I will try to print it with ASA and later I will do the mods.
RE: Deforming printer parts in enclosure Prusa MK4
That part moves a few cm over a plate heated to around 100 °C (or more with certain filaments) and it does that for hours sometimes. That area surely will get hotter there than 50 °C. I have reprinted all the parts on the x-carriage of my MK4Ss with PCCF, which is what Prusa uses for their parts in the MK4S upgrade kit. I had printed a few spools of ASA and also some PCCF before I did this and when I disassembled the PETG parts I could see that all the edges on the x-carriage parts hat lost their clear definition and were not as "sharp" as the edges on the freshly printed PCCF parts.
This 100%. It's not the chamber temp, it's the proximity to the heated bed.
RE:
Possibly you’re right, but I’m not convinced that this is it. To begin with, I’ve read about this problem for the first time. I wonder why aren’t more reports from other users ?. Surely a good number of people prints on a regular basis filaments requiring high bed temperatures.
Besides, the part that deformed stays well above the bed, even during the first layers. Two inches or more, I’d say. It seems unlikely to me that the temperature there rises as high as 65-70C when PETG starts to soften.
There’re several reports of MK3 printers about the part that holds the PINDA sensor sagging a bit after printing a lot of ASA or PC, but this part stays much closer to the bed than the slot holding the X belt. If the OP has access to an IR thermometer it would be interesting to check the temperatures on different parts of the extruder.
Don’t get me wrong. I think that printing the extruder parts in ASA or PC instead of PETG is a good idea but, all considered, this issue seems very rare and maybe there’s more to it than just heat deforming the X carriage.
RE: Deforming printer parts in enclosure Prusa MK4
I've probably experienced a similar issue with my MK4 (in the Prusa Original Enclosure), but with the idler lever instead. Over the many hours of printing in a moderately hot enclosure, I think the PETG parts experienced some creep and slightly deformed, resulting in a weaker grip on the filament and some extrusion issues. I just re-printed all idler lever parts, changed them, and problem gone. I regard this as general wear-and-tear and the fix was super easy.
The Core One no longer uses PETG for many of the parts, which I think is a reaction to this heat creep issue (just speculation on my end though). Since all the replacement parts are printable and the files are publicly available, I would suggest reprinting them in a more heat-tolerant material, e.g. ASA, and replacing them. I personally chose PETG when printing the idler lever parts since I figured that the stiffness of the idler lever was taken into consideration when designing the exact shape of the part, since you wouldn't want too much stiffness -> too high force on the filament. But in your case, I don't think it would be a problem to have a more stiff component gripping the belt, so I would just go with the strongest and most heat-resistant material you've got on hand.
RE: Deforming printer parts in enclosure Prusa MK4
It is absolutely the proximity to the bed when printing higher temp filaments. Just go through old posts in the MK3 forums here if you want to see your desired 'more reports'. This has ALWAYS been an issue with the printers. Especially the PINDA probe mount on the mk3 series. Loads of posts reporting that sagging and causing live z issues. It all depends on what type of stuff you are printing. Smaller footprint parts that quickly move away from the bed then it is generally ok. Do enough large parts that take up most of the bed, at slow quality speeds and you will notice it happening a lot quicker. Its a time/heat factor equation.
I wouldn't even print petg with the original petg parts as extended use will also do the same. It just takes longer. Had it happen on my MK3 (original non s variety). It was one reason I redesigned my x carriage to beef up the pinda probe mount with extra support structures both sides and other parts and then printed it all in ASA. Not had a problem in the few years since I did that.
All it needs is for localised temps to get to close to the vicap temp of petg and it will happen, especially to areas under tension. All plastic creeps, even at normal room temps, the closer you approach vicap the faster that happens.
Prusa absolutely know about this problem, they just don't advertise that fact and it is my opinion that it is why more and more parts do not use petg in their machines.