Build tower gets kocked off bed on taller prints  

Eminent Member

Short summary: My wipe tower seems too narrow, even when adjusting the geometry in Slicer. I can't find any settings to set the brim size or force the tower to be larger (so as to occupy more build space). For tall print, this is proving to be a problem as the leverage on the tower when the nozzle runs over rough filament is enough to pop it off the bed.

Long explanation:

I've been trying to print this guy:

I'm using Atomic jet black and Gemstone Ruby Red and it's quite beautiful. I'm using nearly stock settings (I had to adjust ramming slightly to avoid hard pulls). The settings aren't perfect as I still occasionally get the MMU red blink but generally just have to go press the middle button to have it retry (then the right button). As an aside, seems like if the MMU re-attempted, optionally with a backoff timer or something, it would avoid that.

When that happens and the nozzle heats back up, I suspect it's leaving some plastic trail on the wipe tower. At least that's what seemed to happen this last time. I had some minor bumps which the nozzle had to run over.

The main problem is that caused the tower, which is tall and thin, to become unstuck off the bed. I'm using alcohol with a bit of glue stick wiped into the bed. This normally worked great for normal prints. But the stress on the wipe tower seems to be too much. thinking of trying Magigoo next but thought I would stop and see what other folks are doing. I think the big issue is, for tall prints, the wipe tower needs to be bigger yet I can't find a means to make it bigger (just to set its geometry) nor can I find any place to give it a larger brim.

The cup takes 2+ days to print, but I typically won't see issues until the last 25% of the model, so it's a lot of time, energy, and plastic to waste in trial and error.

Anyone have thoughts/suggestions?

Posted : 13/06/2019 2:55 pm
Antient Member Moderator

I printed that with the Mk3/MMU2:

3 colours, I think it took just over 27 hours.

You just need to ensure that the bed is clean and maybe lower "Live-Z" a bit.

There's part of one of the heads which is printed in air, but that should not cause any issues



This post was modified 1 year ago 2 times by PJR
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 : 13/06/2019 3:53 pm
Eminent Member

Yeah I printed it in a single color to check on the heads. They turned out awesome! Yours looks great as well!

Suppose my bed could have been dirty, though I give it a full wipe every go. Could perhaps try acetone as that's been a few prints since I've done that (I don't do that everytime to help preserve the PEI).

I think being able to set a brim or increase the surface area of the tower would get me there - it's awfully thin relative to the height and I think the nozzle drag is acting as a level. I get the drag typically if I had to intervene for the MMU (usually just telling it to reattempt a load and it works) where the nozzle has cooled down.

Posted : 13/06/2019 4:30 pm
Illustrious Member

Soap and water works best to clean the bed.

It is always wise to get more than one opinion......
Posted : 15/06/2019 6:11 pm

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