Has anyone been having this weird heating element issue?
 
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Gabriel S
(@gabriel-s)
Trusted Member
Has anyone been having this weird heating element issue?

Hello,

Besides my Motor Creaking problem (on a different forum category) a few days ago and my Smooth Steel Sheet being wrecked by a terribly misfunctional Live-Z adjustment tool, I've also had a problem with my extruder heating up procedure.

When it starts to preheat for probing to 170C, my heating element heats up to exactly 169C, and then begins falling... 168C, 167C, 166C, 165C, until about 164C when it begins finally heating up again, and finally reaches 170C. After that, because I print PLA, it needs to heat up to 215C. Instead, it heats up to 214C, then immediately begins falling again. 213C, 212C, 211C, 210C, 209C, before finally kicking on and heating back up to 215C for real. Furthermore, this reoccurs once in a while randomly in a print, where it falls from 215C to 210C mid-print before heating up again. Or, if printing at 210C, it will fall down to around 205C before heating back to 210C. This mid-print doesn't happen too often but I have witnessed it happen several times.

Any ideas? Or do I need to contact Prusa about a replacement for that as well? (Prusa Research is going to get upset at some point at how many parts are failing. First a MINDA probe, then a steel sheet because of a bad Live-Z calibrator (despite using the new probe), then a stepper motor making snapping noises, then a heating element acting oddly... I've had a really unlucky printer!)

Posted : 14/02/2020 2:18 am
PJR
 PJR
(@pjr)
Moderator
RE: Has anyone been having this weird heating element issue?

Mine does similar, but not quite as bad as you describe.

I think it's down to PID values.

One day, I will get around to setting this up on my printer.

 

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 14/02/2020 8:47 am
vintagepc
(@vintagepc)
RE: Has anyone been having this weird heating element issue?

I don't know if you can on a Mini but on a Mk3S this sort of stuff is solved by a PID tune of the hot-end. 

Posted : 14/02/2020 2:11 pm
Gabriel S
(@gabriel-s)
Trusted Member
Topic starter answered:
RE: Has anyone been having this weird heating element issue?

Hello,

I have uploaded some videos of the problem.

https://share.icloud.com/photos/0Y2KnVRHv9YG3JCiO1QYRsBPg

Video #1 is the standard heat up procedure. Watch when it tries to hit 170C and 215C. This isn't a particularly bad example (sometimes it's fallen worse) but should make the point.

Videos #2 and #3 are mid-print temperature slips, where temperature falls to about 211C then overcorrects to about 217C before finally settling on 215C again.

I did see the PID tuning and it looks exactly like what I am looking for, but the firmware exposes no option for that, unfortunately. I think this is a pretty major firmware oversight, in my opinion. 

This post was modified 2 years ago by Gabriel S
Posted : 14/02/2020 2:48 pm
Crawlerin
(@crawlerin)
Prominent Member
RE: Has anyone been having this weird heating element issue?

Is it possible that it is down to individual printer? Mine seems to be OK with this regard.  Yesterday I printed maybe 4 batches of the same print in a row (~2 hour print) and temperatures were solid.

I think I am starting to get X bearing rattling though... oh well.

Posted : 14/02/2020 3:51 pm
Gabriel S
(@gabriel-s)
Trusted Member
Topic starter answered:
RE: Has anyone been having this weird heating element issue?

@crawlerin

I also have bearing rattling. I haven't filed any complaints with Prusa about that though. I just live with it. It comes and goes...

Posted : 14/02/2020 4:21 pm
Crawlerin
(@crawlerin)
Prominent Member
RE: Has anyone been having this weird heating element issue?

OK correction: maybe I was lucky and haven't caught moment yesterday when temperatures were swinging, but just about 3 minutes ago I caught 211 on display and then it went back to 215. Bummer. Didn't happen with first layer though. Maybe fan and travel moves?

This post was modified 2 years ago by Crawlerin
Posted : 14/02/2020 5:17 pm
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