Extruder scraping on Print.
Hallo,
just assembled the DIY Prusa core one last week. The issue occurs with tall prints. The nozzle starts scraping over one side of the build, more and more for each layer. I blew half a spool of ASA already, made sure the Bed is calibrated and the belts are properly adjusted. The second try is on pause right now but it already starts bending.
Is there a way to calibrate the core one mid Print to compensate for the Issue?
ASA is very likely to warp, especially if there is any draft or cold air - this can lift parts of the print into the path of the print head.
The Core One should protect the print from the air if the vents are closed but ASA may still warp. Try adding a rim or helper discs (aka mouse ears) to help hold it down.
More info here: https://help.prusa3d.com/article/asa_1809
Cheerio,
RE: Extruder scraping on Print.
The CORE One is good at printing materials that would warp without an enclosure.
A couple of things that can reduce the chances of lifting:
1) Make sure the chamber stays hot. So as Diem says, close the vents, and keep the door closed, and also don't be tempted to skip the 'absorbing heat' stage at the start of the print unless you've recently finished another print with ASA/ABS. A chamber temperature of around 50 degrees works well to prevent warping in my experience.
2) Glue stick is a big help with ASA and ABS. Don't pile it on thick and make the surface uneven though. My preference is to lightly wet the build plate with a wet paper towel, then gently slide the glue stick over the wet build plate so that you can barely see any glue transferring. Then give it another wipe over with the wet paper towel to really make sure that it's spread thinly and evenly. Elmer's glue stick is often recommended because it is purple until it dries, which makes it easy to see where you've applied it. I know others put a dab of glue stick on a wet paper towel as an alternative, or even onto a paper towel that's been moistened with IPA, since the usual rules about keeping the build plate clean still apply - so no greasy finger prints.
RE: Extruder scraping on Print.
I'll say it for the umpteen time, guys. It's absurd that you waste all that time and trouble with those messy glue sticks bars when get a smoother bottom on your print using liquid or spray adhesives. In two or three seconds you'll get a perfectly even and neat coat of adhesive on the plate.
Oh well, I expect that many people will continue to use glue stick simply because Prusa recommends it. I don't know why I bother.
Sometimes the problem with very long print jobs, isn't only because of warping but also from uneven thermal expansion of the whole frame holding the bed, One side of the bed may bend upwards a little more than the other, so that the printhead starts striking the model on that part. This happens usually when the bed temperature is quite high ( 100C and above ). There's nothing you can do about it, except babysitting constantly the job and adjust the Z offset a bit every time you see that the problem occurs. This isn't an ideal solution, but it helps to mitigate the issue.
Be careful with sprays, remove the build sheet and spray it well away from the printer to avoid overspray problems.
Cheerio,
RE: Extruder scraping on Print.
I'll say it for the umpteen time, guys. It's absurd that you waste all that time and trouble with those messy glue sticks bars when get a smoother bottom on your print using liquid or spray adhesives. In two or three seconds you'll get a perfectly even and neat coat of adhesive on the plate.
I may look at those options when my glue stick runs out - do you recommend any particular brand?
But it'll be a while - I bought a 5-pack of Elmer's glue sticks five years ago, and I still have a couple left. And I use it very frequently.
I have to say though, if you're not getting a smooth bottom on your print using glue stick, you're doing it wrong.
RE: Extruder scraping on Print.
Hallo,
thanks so much for all the replies. I think the bed adhesion is not the problem. The print is just higher on the one part closer to the door. The problem gets worse for each layer. How can I adjust the z axes mid print? Will changes in the “control” tab be respected when I continue the print?
RE: Extruder scraping on Print.
Ah - I see a lot of supports on the part closest to the door. is it possible that shrinkage/warping is pulling the print away from its supports? Is that the only orientation that will work? Obviously I can't see the whole model, but it seems as though you might be able to print it with the right-hand side face down and need fewer supports. The slope angles seem fairly gentle. Apologies if there's something unseen that would make that orientation unsuitable.