Serious issue with extruder on pre-assembled core one makes it useless.
[Reposting this question since I've had no time to look at it recently and need to know how to fix it]
I bought a pre-assembled core one, and have printed successfully on it about 5 times (only with PLA).
A while ago it jammed while printing while I was out of the room.
I thought it was a nozzle, so I tried purging, un-loading, loading and cleaning, but nothing helped.
After extracting the nozzle, while I found filament in it, it wasn't the issue. The filament had broken off just above the top of the nozzle entry.
Looking into the gear assembly, I see (attached photo).
It looks like a bomb has gone off it there!
What on earth could have caused this? Is it repairable?
What I want to know is:
* What parts do I need to repair this (look at the photo to see the massive damage in the extruder)?
* Can I order a pre-assembled part to fit (I'm not the sort of person to build these things from scratch and don't have a 2nd printer - I bought the Core One for reliability and got nothing of the sort)?
RE: Serious issue with extruder on pre-assembled core one makes it useless.
I wouldn't call this "massive damage". It looks like maybe the top part of the main plate filament guide got chipped.
How old is the PLA you are printing? PLA can get brittle over time and can snap easily. Have you tried a different filament?
You best recourse to contact support over chat. If they determine the main plate is damaged, they will send you a new one.
RE: Serious issue with extruder on pre-assembled core one makes it useless.
For reference the part is here: https://www.prusa3d.com/product/extruder-main-plate/
RE:
I wouldn't call this "massive damage". It looks like maybe the top part of the main plate filament guide got chipped.
How old is the PLA you are printing? PLA can get brittle over time and can snap easily. Have you tried a different filament?
You best recourse to contact support over chat. If they determine the main plate is damaged, they will send you a new one.
The metal teeth appear to be heavily chewed up. Thanks for the name and link to the part though, that's helpful.
This was about my 5th or 6th print and the PLA was opened less than a week before and kept in a zip-lock with desiccant.
David
RE: Serious issue with extruder on pre-assembled core one makes it useless.
Ah OK, in that case I think a piece of metal somehow got between the gears and idler bogie pulleys. Filament on it's own would not do this. You will need to get the planetary gear box replaced then.
Most definitely you should get on webchat with support. They can guide you to what to do next. Perhaps send you the parts for free under warranty.
RE:
I've disassembled and cleaned around the teeth and head plate. A few things to note:
1. This is factory assembled and never opened by me.
2. The 3 bolts holding the gear cover on were so loose that they started turning as soon as I put the allen key in, before I applied any torque. The cover wasn't obviously moving, but there was no tension in the bolts at all.
3. Most of the damage was cosmetic, a lot of ground up filament, but a little damage to the teeth (but I assume these are only for gripping and pulling filament and don't have to engage with anything else). I am hoping it's going to work and avoid me needing to replace the whole gear assembly.
4. There was some small amount of ground up filament in with the planetary gears. I cleaned the metal teeth carefully with a small amount of IPA and re-applied lubricant from the small tube provided by Prusa (it had about the same viscosity and colour as what was there, so I've assumed it's okay to use there, *please* correct me if I'm wrong though and I can clean it out before I use it).
5. The head plate is (technical term) "knackered" though, and I don't have a 2nd printer or know anyone local who can print it, so I guess I'll be ordering that rather than printing it. At least it's $3.50 instead of hundreds though.
One thing I'd be interested in knowing is how to best test the filament that's been sitting out for ~6 months at this point (or do I just bin it)?
I've got a drier and have put it in for 45c for 4 hours, but I'm a bit worried this whole thing happened because the filament was more brittle/hard than expected (I had put it in the drier as a test when I got the drier and don't know if that can harden it). Does the printer have way to test this or is there a test with hand tools you can do? The filament bends without breaking, but that's not strictly a measure of "hardness" or ability to melt at the expected temperature.
And next I have to unblock the nozzle (I don't have a soldering iron with controllable temperature, so I might try the oven approach and a cold pull).
RE: Serious issue with extruder on pre-assembled core one makes it useless.
PLA can become brittle and crumble due to moisture if leaving it out in the open for 6 months or so. In dry storage it can last for years. Would be good though to pop in a dryer for 6-8 hrs.
Also make sure after you reassemble the planetary gears to run the gear box calibration wizard before attempting a print.
RE: Serious issue with extruder on pre-assembled core one makes it useless.
Luckily I didn't have to disassemble the gears themselves, but thanks for the advice about the calibration. I did slide the assembly out of the inward facing ring section, clean it and re-insert (it seems only possible to insert it with exact alignment and it moves freely/smoothly). I'll still calibrate though.
When everything is working again I'll try a very small test with the old filament (after drying extensively). Any sign of issues and it's out though.
RE: Serious issue with extruder on pre-assembled core one makes it useless.
If you need a "head plate" I'd start with Prusa Support via chat. They should send you one for free. (Shipping costs alone make this worth your time.)
Also, if you say where you're located perhaps someone can print and send you a replacement. I assume the "head plate" means the bit surrounding the planetary gears?
RE:
2. The 3 bolts holding the gear cover on were so loose that they started turning as soon as I put the allen key in, before I applied any torque. The cover wasn't obviously moving, but there was no tension in the bolts at all.
Be aware that tension (or maybe more accurately: "non-tension") of those screws is critical. They are being set as part of the calibration program, see here:
https://help.prusa3d.com/guide/9-calibration-first-run_835546?product=core-one#836517
And, regarding brittle filament, I've never had issues with that. When I take it out of the drier it's bone-dry and sometimes snaps during insertion through the PTFE tubes (I've been advised to leave it out for a short time so it may re-aquire some moisture and that seems like a good idea). But once loaded, it works reliably.
RE: Serious issue with extruder on pre-assembled core one makes it useless.
And next I have to unblock the nozzle (I don't have a soldering iron with controllable temperature, so I might try the oven approach and a cold pull).
Why not use the built-in hotend? On the front panel controls ("Controls" page) you can set a temperature. Then either push in filament through the idler door or use "E"-Axis controls in the motors menu to feed filament. If using the latter, once it stops the extruder will "click". It's the "on-board toolkit", always with the printer 🙂
RE: Serious issue with extruder on pre-assembled core one makes it useless.
Sadly the amount of filament sticking out of the nozzle is about 3 mm. I can (just about) grab it with pliers but have no hope of doing that while it's in the printer.
If I can heat the nozzle enough to start stretching the filament, I can grab more, but I think once I can do that I'm pretty much "doing a cold pull" anyway.
However if you think there's a better way given the amount (or lack of amount) of filament to grip, please let me know.
RE: Serious issue with extruder on pre-assembled core one makes it useless.
Oh that's interesting. I wonder if I used it too soon after drying?
I've opened a new PLA roll now, and if, after drying, the old roll is basically the same in terms of how it bends and when it snaps, I might reuse it, otherwise I'll bin it.
Thanks for the info though, it's very helpful.
RE:
Given the material is PLA you might reach sufficient temperature to pull out the filament end just by holding the nozzle into boiling water with pliers (never tried it this way but 95..100°C is a temperature range that should work quite well for "cold pull". And don't worry about the 3 mm... it'll get longer 🙂 )
My own approach would be
- as above - try to pull out as much as possible. As long as it doesn't tear but refuses to move further, increase the temperature
- with the nozzle in the printer, try to push through as much material as possible (e.g. 20 cm of filament, "purge" via E-axis controls), then cold pull, repeat as needed
- if a 2 mm drill meets resistance in the cold zone (~ 50 mm), try to drill it out by clamping the drill in a vice and carefully rotating the nozzle on top of it. I wouldn't advertise this as any kind of "recommended procedure" and try to avoid it, but haven't ever broken a nozzle yet. I didn't run into issues with filament residue in the cold zone anymore after starting to use thermal paste.
RE: Serious issue with extruder on pre-assembled core one makes it useless.
...otherwise I'll bin it.
I wouldn't throw it away. Come back to it once the problem is sorted out to understand better what actually happened.
I've fallen into the trap myself - blaming it on the material is lazy. But AFAIK you can't permanently damage standard filaments by over-drying, they may get harder to handle but that's a temporary condition.
RE: Serious issue with extruder on pre-assembled core one makes it useless.
Have the same EXACT experience. The filament is stuck, sheared off at the top of the tube after maybe 6 prints, max. WTF.
The gears appear intact. Everything, including the filaments are brand new.
[Reposting this question since I've had no time to look at it recently and need to know how to fix it]
I bought a pre-assembled core one, and have printed successfully on it about 5 times (only with PLA).
A while ago it jammed while printing while I was out of the room.
I thought it was a nozzle, so I tried purging, un-loading, loading and cleaning, but nothing helped.
After extracting the nozzle, while I found filament in it, it wasn't the issue. The filament had broken off just above the top of the nozzle entry.
Looking into the gear assembly, I see (attached photo).
It looks like a bomb has gone off it there!
What on earth could have caused this? Is it repairable?
What I want to know is:
* What parts do I need to repair this (look at the photo to see the massive damage in the extruder)?
* Can I order a pre-assembled part to fit (I'm not the sort of person to build these things from scratch and don't have a 2nd printer - I bought the Core One for reliability and got nothing of the sort)?