Glass getting knocked off

[nrbelk]

I'm trying to print a big print. Twice now this has happened at different levels of completeness. I come home to find the glass plate (along with my part still stuck on it) laying on the floor next to the printer. I have no idea what is causing this. I've printed taller prints than this with no issues. After both times I have check z height and re calibrated the x y z axis and made sure that the horizon angle was still good.

Anyone know what could be causing this? I dont' see any teeth missing on the belt and when I pull the arms up and down, they all feel the same.

[geneb]

You DO have the binder clips holding the glass on, don't you?

g.

[JFettig]

enable "z hop" or "z lift" or something along those lines in your slicer. 1mm is plenty.

[geneb]

I've never used more than .2mm.

g.

[JFettig]

I don't have a reason I use 1mm, I don't have a reason to change it either!

[nrbelk]

You DO have the binder clips holding the glass on, don't you?

g.

Yes, they clips are on the glass holding it to the heating pad.

I was looking at the print that failed the most recently, and found a indentation that looks like the hot end tip. Almost as if it went "I'm going to go lower here than anywhere else for no reason". I'm attaching a picture so you can kind of see where. What would cause this and would doing what was suggested, adjusting the z hop/lift fix this? Can I do this mid print (I started the same print over hoping that it was just something funky going on).

[Earthbound]

How big is this "big print" in the XY plane? What travel speed setting was used when you sliced the model?

[nrbelk]

How big is this "big print" in the XY plane? What travel speed setting was used when you sliced the model?

It is about 200mm X 140mm . The travel speed I left at default, 300mm/s. Should I change this? If so, can I change it mid print?

[Earthbound]

300mm/s is fine for prints where the model XY dimensions are low and the effector can stay near the center. The slicer's travel speed is governing the motion of the nozzle. Because of the delta geometry, the carriage speeds are not linear. This can easily lead to missed steps on larger (XY) models. Missed steps can cause the hot end to hit the model and displace it (or the glass, I guess you have no bonding troubles).

If you slow down the machine while mid-print, all movement will slow down, not just travel. To only change travel speed, you'll need to re-slice. I'd suggest 150mm/s for anything that extends outside of a circular area 160mm diameter.

[KAS]

I was having the same issue when printing towards the edge. Raising the z-hop/lift and slowing the print down fixed the issues.

[nrbelk]

I finally saw the symptoms. I came down in the morning to check on the print before leaving for work and found the printer printing over open air, then running into a tower, then smashing into the part, all while it was thinking it was printing. The print was probably 3 hours further along than when it happened the second time (which was probably eight hours further into the print than the first time).

Is this still a speed issue? Its like its loosing its calibrations and doesn't send all the towers to the correct height.

Please let me know what you think.

[nitewatchman]

I had the same problem while printing the Akemake Speakers. These actually are too large for the table. When one for the arms has to become nearly horizontal to reach the extreme edge the stepper speed seems to approach infinity and makes a horrible noise as it skips steps (lots). After that the effector can end up almost anywhere, hitting the bed on one side and an 1" in the air on the other side.

I think that this is due to the fact that as the arm nears horizontal each step of the motor essentially yields no movement of the effector, so the calculated pulse rate soars to a rate that is mechanically not possible.

I painfully slowed down everything to 30IPS printing AND traverse and after that had no problems other than time required. My normal printing defaults are 100IPS and 300IPStravel.

Worked for me.

nitewatchman

[BenTheRighteous]

Yeah, when any of the steppers misses a step, you're exactly right - your calibration is hosed. The carriages are no longer in the position the printer thinks they are, and anything can happen. Print in midair, collide with the print, collide with the tower... until next time the printer re-homes, then everything resets and it's back to normal.

Nitewatchman, what is an "IPS"? Inch per second is definitely not right, but that's my only guess...

[nrbelk]

Thanks so much! I am so relieved that it is something like this. I will try it when I can monitor it. Thanks!

Just to clarify, can you tell me exactly which speed settings I should be changing to 30? I'm still learning.

[BenTheRighteous]

Travel speed, you said you have it at 300, 150 is more reasonable for large-footprint prints.

[nitewatchman]

Nitewatchman, what is an "IPS"? Inch per second is definitely not right, but that's my only guess...

IPS is short for Brain Fart.

I meant to say MM/S. Consequence of getting old and fat.

[nitewatchman]

Thanks so much! I am so relieved that it is something like this. I will try it when I can monitor it. Thanks!

Just to clarify, can you tell me exactly which speed settings I should be changing to 30? I'm still learning.

I changed both Travel and Print speed to 30mm/s. You could also override the speeds down but the travel speed could still be high enough to cause the issue. 30% of 300mm/s is still high at 90mm/s.

[nrbelk]

Thanks so much! I am so relieved that it is something like this. I will try it when I can monitor it. Thanks!

Just to clarify, can you tell me exactly which speed settings I should be changing to 30? I'm still learning.

I changed both Travel and Print speed to 30mm/s. You could also override the speeds down but the travel speed could still be high enough to cause the issue. 30% of 300mm/s is still high at 90mm/s.

Thanks, I'll make these changes and try it again.

[3D-Print]

Very similar problems that I had on a large print which was near the edge of the print bed. Slowing as well as increasing the z-lift helped, but I still on occasion would hit the print when the hitend would change directions. My belts were a bit loose and one was even more so.

After tightening belts I have not had the problem again after 920 hours of printing.

[nrbelk]

Well, I changed the settings, started printing and had the same issue. Realized I didn't click "save"........

Clicked save, started printing, and in the first try, got the piece that I have been trying for. Thanks for all the great tips!

For those that might use this thread for themselves, the only thing I changed (after ensuring that there wasn't a problem with the belts or something like that) was to change the traveling speed from 300mm/s to 30mm/s.

[BenTheRighteous]

Awesome, glad you solved it!

[nitewatchman]

Outstanding!

[Eaglezsoar]

Great job!