Temps are way off and calibration says everything is perfect. How can I fix the hotend temp?
All factory Prusa parts that have been working fine for months but last week all of sudden I'm getting insane print blobs, stringing, and dripping molten plastic off the hotend block. I ran calibration a few times and it keeps coming back OK. Temps are all showing normal but it's obviously not.
Is this just a matter or replacing the hotend parts and try again or is there another way to check the temps?
I guess I should mention that I've been running a Bronze hotend fan duct I had custom printed. My other printers use the same part and no issues with those so I dont think that has anything to do with it. But just in case.
RE: Temps are way off and calibration says everything is perfect. How can I fix the hotend temp?
Can we have a photo of the hotend & nozzle plus one of a failed print top and bottom?
Cheerio,
RE: Temps are way off and calibration says everything is perfect. How can I fix the hotend temp?
Sure.
I haven't cleaned it up from the last failed print but I took a photo of some of the blobs. These are PETG the PLA ones are the ones that are literally dripping off the hotend onto other prints. I was doing some black parts and I could see drips of the silver PLA I had been printing the night before.
RE: Temps are way off and calibration says everything is perfect. How can I fix the hotend temp?
OK, there's no plastic running down from above the hot end, it's all being picked up from below.
I can't judge the duct but if you've had it running OK let's assume it's innocent for now.
If those blobs are resting on the print surface you've been using then, by the look of it, you need to clean your print bed. A poorly sticking print can warp, contact the nozzle and transfer some of the previous layer back onto the nozzle, this is the seed of many a blob.
Wash the steel sheet with diswashing soap (Dawn/Fairy) and plenty of HOT water, rinse well and dry with fresh paper towels. Don't touch the surface, handle it by the edges.
Try another PLA print; if it fails show us a picture of the failure and the bottom of the failed print.
Cheerio,
RE: Temps are way off and calibration says everything is perfect. How can I fix the hotend temp?
The print cleared up a bit but I'm still getting loose blobs all over the place. I have to watch the print and pull them off or they turn into a mess. Ill post pictures when its done printing.
RE: Temps are way off and calibration says everything is perfect. How can I fix the hotend temp?
OK.
RE: Temps are way off and calibration says everything is perfect. How can I fix the hotend temp?
Print never finished and now, I have a new problem. The X-axis is completely screwed. With the printer off it feels like the shaft on the stepper is bent. When I slide the hotend carriage left/right it lunges every rotation. I can't see an obstruction and the shaft looks ok but there is for sure a problem.
RE: Temps are way off and calibration says everything is perfect. How can I fix the hotend temp?
Remove the X belt and check both ends:
The idler bearing is as likely to break as the stepper. It can wear/break like any other bearing or if the belt is overtight or you were heavy handed during the build then the printed plastic housing can fail and you'll need to print another part - or get someone to print one for you. I don't know how long they're meant to last but I had to replace both my idler bearings after about 7,000 hours of printing.
With the belt removed try to rotate the stepper by hand. If it grates you may have a worn internal bearing - the motor will have to be replaced.
If you are lucky the grub screw on the active pulley has failed.
Cheerio,
RE: Temps are way off and calibration says everything is perfect. How can I fix the hotend temp?
Found the problem with the belt. Somehow some PLA got stuck to the drive pulley and I couldn't see it.
Hotend is the thermister. I did some comparison tests between it and my other printers and it appears to be about 40* off. It was working fine before so I'm not sure how it can swing that much but it did. Time to take it apart Again!!!
Funny the 1st MK3 I got 3 years ago just chugs along every day with very few issues. It has thousands of hours and I've gone through a few hotend rebuilds and some fan wire replacements but that's it. My 2nd MK3 has been nothing but trouble and constantly fails. And my new Mk3s only has weird issues like this one. Maybe the parts are of poorer quality now. Don't know.