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Extruder badly skipping for no obvious reason  

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nedge2k
(@nedge2k)
New Member
Extruder badly skipping for no obvious reason

I've tried the following to try and figure out why my extruder is skipping:

  • Multiple cold pulls (there was no clog)
  • Idler tension adjustment and inspection (more tension made it worse, less better)
  • Firmware and Software updates (latest)
  • Hot end tear down (no clogs)
  • Resistance check on thermistor and heater (both within spec)

The only thing I've done recently is calibrate my esteps with M92 and M500 as the default was 6% under...but it was printing fine after that.

However, if I heat the hotend up to 275°C and manually push some PLA through, I am feeling quite a lot of resistance.

Not sure what else to try?

MK2.5 i3

Posted : 26/03/2020 10:46 am
nedge2k
(@nedge2k)
New Member
Topic starter answered:
RE: Extruder badly skipping for no obvious reason

Think i've figured this out. Used a thermocouple connected to a Fluke temperature gun to measure the hotend. Initially the reading was 50°C out! Stripped/rebuilt again and now it's "only" 20-30°C out. Managed to to a 12hr print yesterday in PLA with 0.35 layer height, 0.6 wall thickness (0.4 nozzle), speeds up as high as they'll go with linear advance, a global 12mm3/sec limit, part cooling 50% max and temp set to 270°C (which should be about 245°C). Turned out pretty nice although I did have to manually knock the print speed down to 97% on the printer due to some extruder skipping. Still, MUCH better than it was.

TLDR; Think I need a new thermistor and some new thermal paste.

This post was modified 4 years ago by nedge2k

MK2.5 i3

Posted : 07/04/2020 12:11 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: Extruder badly skipping for no obvious reason

OR... you could simply recognise that at the moment you need to print hotter... and leave your printer as it is... 

Get a spare thermistor and heater rrady for when you eventually need it...

Don't fix something thats not broken. Especially in these times when access to spares is restricted.

Regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 07/04/2020 1:25 pm
nedge2k
(@nedge2k)
New Member
Topic starter answered:
RE: Extruder badly skipping for no obvious reason

The fact that the reading has suddenly drifted out of spec means that it IS broken and does need fixing. Just because I can fudge the numbers now doesn't mean i'll be able to tomorrow.

Also, where were you when I actually needed help? Instead I solve the issue myself and you reply with a snarky comment? If you don't have something valuable to add to a thread, don't bother.

MK2.5 i3

Posted : 07/04/2020 2:23 pm
bobstro
(@bobstro)
Illustrious Member
RE: Extruder badly skipping for no obvious reason
Posted by: @nedge2k

The fact that the reading has suddenly drifted out of spec means that it IS broken and does need fixing. Just because I can fudge the numbers now doesn't mean i'll be able to tomorrow.

Just to eliminate a possibility: Did you do a PID tune? It's usually for minor tuning but a few have reported it helped with wild readings. Thermistor replacement sounds reasonable and you want to have 1 or 2 on hand as spares.

Also, where were you when I actually needed help? Instead I solve the issue myself and you reply with a snarky comment? If you don't have something valuable to add to a thread, don't bother.

Joan is one of the most experience and helpful volunteers here. She's got the widest experience with Prusa printers outside of Prusa employees (and probably more than most of those). Sometimes posts just get missed and drop off the front page. We are not employees and do not guarantee 24 hour service. She's got a good point about availability of options.

You don't indicate whether you've used the Prusa online chat support. They are paid, and can probably sort you out quickly. You need to log into the online store and locate the chat option.

If you are in the US and need parts, PrintedSolid and Filastruder stock the Prusa versions of the E3D V6 hotend parts.

My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Posted : 07/04/2020 3:10 pm
nedge2k
(@nedge2k)
New Member
Topic starter answered:
RE: Extruder badly skipping for no obvious reason

PID and temp calibration, yes. No difference.

As for Joan, I could care less about her resume, her attitude and advise is the issue. 

I had used the Prusa chat but were also stumped, hence bringing it to the hive mind and closing the thread off with the solution rather than just leaving it open with nothing like so many other threads on the internet.

MK2.5 i3

Posted : 08/04/2020 10:46 am
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