RE: MK3S part melted
Having this issue also - having trouble with PLA prints not staying on the bed and noticed the pinda was tilting slightly to the right. Seems that the holder is bowing slightly. I print a lot of HIPS, NGEN, XT and Polymaker PC but do use an e3d sock on copper block. Find that the only fix for now is to reseat the sensor as best it will go and recalibrate. I'm reprinting the extruder in Polymaker PC Max.....
I'd be curious to know your settings for the PolyMax.
RE: MK3S part melted
I'm using the stock prusa slic3r profile. No enclosure, just close windows and doors. For most parts I find I don't need a raft.
RE: MK3S part melted
There are paints that contain low E materials to limit IR absorption. I wonder if they'd be useful here. Apply a coat to the inside of the extruder parts that face the heater block ... and 80% of the radiant heat is no longer being soaked up by the parts.
RE: MK3S part melted
... or just put aluminum HVAC tape on it? Probably a lot cheaper...
RE: MK3S part melted
Aluminum sucks up IR ... as do most metals. Ceramics on the other hand, don't. And that's the active ingredient in those low-E paints.
RE: MK3S part melted
I was thinking to apply some regular silicone around that part to avoid damage. Would that be sufficient you think?
RE: MK3S part melted
errr, what?
Reflective is not the same as emmissive. And polished versus unpolished makes a huge difference in reflectivity. Typical aluminum we commoners have access to absorbs 40% of the heat that hits it.
| Material | Emissivity Values | ||
| 1.0µm | 1.6µm | 8-14µm | |
| Aluminum | |||
| Unoxidized | 0.1-0.2 | 0.02-0.2 | n.r. |
| Oxidized | 0.4 | 0.4 | 0.2-0.4 |
ps: aluminum can make a great mirror IF it is coated immediately with something that prevents oxides from forming.
RE: MK3S part melted
Emissivity is about losing heat the material already has within it; reflectivity is what you want to avoid picking it up (from other radiating sources) in the first place.
From the wikipedia page on low-emissivity materials ( https://en.wikipedia.org/wiki/Low_emissivity)
Conversely, a low-e material such as aluminum foil has a thermal emissivity/absorptance value of 0.03 and as an opaque material the thermal reflectance value must be 1.0 - 0.03 =0.97, meaning it reflects 97 percent of radiant thermal energy.
RE: MK3S part melted
Poor man's test: Stick a chunk of aluminum out in the sun for an hour then pick it up with bare hands. Emissive qualities are bi-directional when considering black body radiation. That's why gold is used for IR mirrors, not aluminum. You don't want the mirror substrate heating up and reradiating IR of it's own. We can disagree on the merits of aluminum to help plastic melt. lol.
RE: MK3S part melted
I reported the issue with a pretty grainy photo at https://github.com/prusa3d/Original-Prusa-i3/issues/136
Looks like Prusa are onto it and redesigning the extruder piece to reinforce the Pinda holder. In any case, I reprinted it in PC Max.
RE: MK3S part melted
I just bought (and printed too w/petg) a replacement part for the extruder that holds the pinda probe. The gorilla glue I used over a week ago to hold it in place is still working good and I've printed almost constantly at high temperatures too since making the repair. I think I'll wait now if I can before rebuilding my extruder until Prusa releases new reinforced parts for it as they recently addressed the screw issue on the back of the heatbed too, which has caused cable damage or can cause the cable bundle to catch on it if it gets low enough during a print, possibly causing a shift or some other issue during printing.
RE: MK3S part melted
My new unit was running for about a week perfectly, until it ran out of filament mid print and this was the result. I only have one printer - what's my best course of action here ?
I removed the fan shroud and tried to print a new one in PETG without the shroud and it didn't print particularly well - though it may be serviceable.
RE: MK3S part melted
Sooo anyone slapped a solution on this thing? If anyone used silicone please post a pic, I'd like to see how you did it.
I'm trying to avoid printing with this MK3S because of this until I find a solution.
RE: MK3S part melted
Sooo anyone slapped a solution on this thing? If anyone used silicone please post a pic, I'd like to see how you did it.
I'm trying to avoid printing with this MK3S because of this until I find a solution.
No. Regular silicone does not have the temperature resistance you need. You might be able to do something with high-temperature RTV though; it's what I use to mold my hot-end socks.
RE: MK3S part melted
Sooo anyone slapped a solution on this thing? If anyone used silicone please post a pic, I'd like to see how you did it.
I'm trying to avoid printing with this MK3S because of this until I find a solution.
No. Regular silicone does not have the temperature resistance you need. You might be able to do something with high-temperature RTV though; it's what I use to mold my hot-end socks.
So just apply some high temp RTV around the extending part and hopefully it should be protected?
RE: MK3S part melted
That's a start, it should help block the radiant heat and insulate it from the plastic. Anything else that offers a thermal barrier would likely help, too.
Be careful you don't seal the heat block to the bottom of the extruder though; otherwise you might end up trapping more heat between the heatsink and heat block, and making the problem the same or worse.
RE: MK3S part melted
That's a start, it should help block the radiant heat and insulate it from the plastic. Anything else that offers a thermal barrier would likely help, too.
Be careful you don't seal the heat block to the bottom of the extruder though; otherwise you might end up trapping more heat between the heatsink and heat block, and making the problem the same or worse.
I worry with my newbie-ness that I'll do exactly that and ruin it.
Would you mind marking a mockup of how it would be ideally applied without risking permanent damage?
RE: MK3S part melted
I just checked and it says C1 on the body rather than R4?? Is this problem only with R4 bodies?
RE: MK3S part melted
Just print a spare first so if things go haywire you can just replace the part?
Prusa uses different designations for their self printed parts,I don' know whether C1 equates to R4 or not.
On a related note, I just saw there's an R5 variant on the github as of seven minutes ago which has been reinforced. So just print that instead and call it done.
https://github.com/prusa3d/Original-Prusa-i3/tree/MK3S/Printed-Parts