Prusa Mk2 ongoing issues

[Garret H]

The Mk2 prusa has seen better days.
We are all in agreement that switching it back to single extruder is the best way to go.

Synchro noted that the x-axis limit switch might be an optical sensor and is getting thrown off by the LEDs above?

Lately a lot of prints have had patchy layering, almost sponge like at times. This could be an issue of under extrusion, see here:
https://www.prusa3d.com/under-over-extrusion/
I should note that I have experienced this on g-code and materials that were fine a few months ago.
Descriptions of other common print problems are here: https://www.prusa3d.com/print-quality-troubleshooting/

We should try and do some real maintenance on that thing instead of just trying to put out fires as they pop up. Anyone who wants to jump om this has my blessing
If you need parts email me at garret@kamloopsmakerspace.com
I will have them ordered ASAP

[Garret H]

A large flat print was being made a few days ago. It had a thermal runaway failure. This issue seems to be getting worse, I am guessing a new hot end is needed?

Also whoever was making the print was using a special kind of tape over the bed, I hadn't seen this before. I assume this was done due to bed adhesion problems, would love to hear some more information and be able to take on refurbishment of this printer as a collaborative process instead of multiple people fumbling around in the dark on their own.....

[MIPS]

I started a fairly simple print and just sat there to see what it did.
Once printing started I noticed that the hotend remained stable (215c) but the bed would rise up to about 8 or 9 degrees above what it wanted(60c). The bed wasn't calling for heat so I'm not sure why it was warming up. Eventually the nozzle fan turned on and the bed temp came back down however the hotend temp nosedived until it aborted with a thermal runaway at 180c.
I removed the blue silicone boot to see if something was damaged and found it's completely gummed up with black filament and broke in my hand. The machine needs a complete service.

I have not run into bed adhesion problems ever since I started wiping the bed down with iso before every print. In fact I've had more issues with parts sticking to the bed.

[MIPS]

For now as a TEMPORARY fix I have disconnected the blower fan. This has so far stopped the runaway issue (I think it's more an overcooling issue at this point) and there's a piece going on the printer right now. Remember to reconnect this when the printer is serviced, or if you have a piece that will require that fan working.

[Garret H]

It looks like a new hot end or another part is on order or the Mk2. Thanks to whoever ordered that up. MIPS ?
Hopefully we will have this printer working better soon!

[Garret H]

The hot end has been replaced by someone.
At least 1 print has gone thru no problem.

I tried a print in ABS and it was patchy but that may not have been the printer's fault.

[Garret H]

I did some maintenance on the Mk2 printer this week. The hot end was loose resulting in really inconsistent performance. I tightened that up as well as adjusting the tension on the extruder gears that seemed to help a lot.

The multi material head is still problematic, seems to be about 50/50 when starting a new print if the filament will go in all the way or get hung up on something.

I also cleaned and fixed up the enclosure with a new door pivot so the doors aren't so floppy feeling anymore.

[Jason H]

I'm planning on coming down at about 3 or 4pm today to do a print on the MK2.
It sounds like it is operational.
Is there anything outstanding/intermittent I should be aware of when using it?

It will be about a 3 hour print so I'll be hanging around for a bit ;-)

Jason

[Garret H]

You should be ok. There is a tendency for filament to get stuck in the manifold transition from the 4 paths to the single hot end feed. Make sure the filament is cut at a nice 45 degree and no protrusions.
Sometimes I'll step the extruder forward a bit to feed it in manually with the manifold disassembled.

[Jason H]

Which extruder should I be using?
Last I heard, the boden tube on extruder 1 was broken and everyone had to use extruder 2. (that was awhile ago)

Jason

[Garret H]

Number 1 and 3 are your only options.
3 seems a little better but both have worked for me recently.