I just got a replacement Ubis head for my Simple cause I just had weird print problems (lack of extrusion, jamming, etc). In the end I settled on it maybe being heat creep so ordered a new 1.75mm head.
I just swapped in the new one and it’s back to printing like new. No jamming and it just cranked out the calibration cube step.
I noticed that with the new head (as I had thought I’d remembered) that I can touch the ceramic barrel 3/4 of the way up but couldn’t on the old one. Does the ceramic break down over time due to the heat cycles?
I originally thought maybe the thermister was giving me a bad reading by registering a lower temp and causing me to increase it beyond what it should be (200c for PLA), which would cause more heat creep up the print head barrel. But I also tried test prints at lower temps and that failed.
That sounds like an insulator is eroding away over time. That could explain the failures, once the thermal mass of the hot end gets outside the control envelope of the PID algorithm it can no longer adequately hold temperature. If you kept the old one you could take it apart and look for evidence of that erosion.
Thx for the info Chuck. When I had it apart before to double check that it wasn’t clogged, I didn’t see any obvious signs of anything amiss. I’ll have to connect it again to the printer to heat it up and be able to disassemble. What should I look for? I noticed a white sleeve within the ceramic cartridge but other than that it’s pretty straight forward.
I would look for a PTFE sleeve/tube which is ragged on one end. My speculation is that the end is eroded over time making it shorter and shorter which lets the heat get further into the print head.
If you do find that, then you should try re-assembling it with a replacement tube and see if its previous performance returns.
First time I’ve had this question. The ceramic should be fine for years. The thermistor could have been the issue. Filament jams are the usual culprit on hotend fails. Never heat it for long periods w/o filament- residue will toast and char. Plastic is very abrasive, so after months of printing, a new tip is a good idea since an ever-growing hole in the tip is hard to measure. Theoretically, you could adjust in slicing but no way to measure. Other than that, it should just work. I have no excuse for failed equipment, just friendly customer support it’s bound to happen occasionally. An extruder that never has issues for thousands if hours is a tough target, but most Ubis hotends get there without issue.
No worries Brook and it’s all good. You did make a good point that I forgot to mention. I did notice how much smaller the opening of the nozzle was on the replacement hotend. So much so that I thought it was a .2mm vs what I thought should’ve been a .4.
So that explains why it looks like over time my original nozzle has really opened up. If I had to guess, I’d imagine I’ve probably put the printer through about 1,000 hours of print time over the last few months.
I recently pulled the tip off, heated it with a torch and dropped it into a glass bottle with 50/50 water and isopropal alcohol. did this 2 or 3 times and it cleaned it right up. then verified the print hole was clear and re installed. this is the procedure suggested on the printrbot forums and it worked great. my ubis is again printing like new
@Steven_Hauser , yup, I’d seen that thread and did the same thing. I even hit the nozzle with the wire brush on the bench grinder and polished it all up like new again. For sure there was nothing in the nozzle or barrel.
When I reassembled everything, I just put teflon tape on the threads between the barrel and hot end.
Should I have used something else that would help reduce the thermal transfer up the ceramic cartridge?
@Tim_Sills I just heated up the hot end and tightened up the tip nothing else. I do have active cooling on my ubis by using this front end http://www.thingiverse.com/thing:372467 it has a built in 40mm fan shroud. my simple is still the original 2014 model but i had to raise my bed anyway so used this front end since l like having better access to the extruder and the added cooling to the ubis.
thanks for posting the fan link @Steven_Hauser , I was trolling the site the other day looking for something like this wondering if that was needed since the E3D heads have a fan. I know they’re metal bodies and will propagate heat up the barrel but still wondered if a fan would’ve solved this as well for the Ubis.
FWIW, the new Ubis head is working just fine. Unplugged the old one and inserted the replacement and have been printing ever since. Forgot how good the prints can be. I like this newer head as it’s not as bulky as my original one.
Big take away for me is that it should be expected to replace the nozzle after so many hours of print time. The filament coming out of the new head looks to be nearly half the diameter of the old head. It never crossed my mind that the tip could potentially enlarge over time due to wear.
it’s bound to happen occasionally. An extruder that never has issues for thousands if hours is a tough target, but most Ubis hotends get there without issue.