Printer is detecting collisions all the time
When I start to do a print, the printer starts homing, got the belts adjusted so that works.
The bed goes up 10-15cm, tries to probe the bed, rinse and repeat until it's at the top and 50% it has an collision detected on the way up.
And if I get past that, it will detect a collision while cleaning the nozzle. Probing works flawless somehow.
Anyone experienced anything similar?
Best Answer by Raaz:
Two things:
- do what Ratlet says and use the Control menu to manually move the Z-Axis. If you don't have enough range, do the "auto home" before. If that seems to work like it should, it's the hotend heating causing wonky loadcell signals.
- for the loadcell signals: search the forum for the custom Start G-Code: Prusa Slicer - expert mode - settings - printer - custom G-Code - Start G-Code: put "M104 S0 ; CUSTOM disable hotend heating" into the line above the G28 command (Homing without MBL) and the first G29 command. That's the "nozzle cleaning", which is just a clever way of using a mesh bed leveling command in only a small rectangle to clean the nozzle.
You could also disable the hotend heating for the real MBL, but although it'll become a lot quicker, due to only a single touch being needed for each probing point, the nozzle will drop about 50°C, making it a tiny bit shorter, causing inaccurate MBL.
RE: Printer is detecting collisions all the time
Have you tried using the controls to move the bed vertically up and down through the whole range? It could be something isn't quite straight and is casuning a bit of a restriction when moving. Not sure if the Z-axis motora have stallguard to detect this though.
RE: Printer is detecting collisions all the time
Two things:
- do what Ratlet says and use the Control menu to manually move the Z-Axis. If you don't have enough range, do the "auto home" before. If that seems to work like it should, it's the hotend heating causing wonky loadcell signals.
- for the loadcell signals: search the forum for the custom Start G-Code: Prusa Slicer - expert mode - settings - printer - custom G-Code - Start G-Code: put "M104 S0 ; CUSTOM disable hotend heating" into the line above the G28 command (Homing without MBL) and the first G29 command. That's the "nozzle cleaning", which is just a clever way of using a mesh bed leveling command in only a small rectangle to clean the nozzle.
You could also disable the hotend heating for the real MBL, but although it'll become a lot quicker, due to only a single touch being needed for each probing point, the nozzle will drop about 50°C, making it a tiny bit shorter, causing inaccurate MBL.
RE: Printer is detecting collisions all the time
No binding, the rods wobble a little the last 5cm before reaching the bottom.
I'll test disabling the nozzle cleaning.
Hope that solves the first layer issue I'm having at the moment as well.
RE: Printer is detecting collisions all the time
No binding, the rods wobble a little the last 5cm before reaching the bottom.
I'll test disabling the nozzle cleaning.Hope that solves the first layer issue I'm having at the moment as well.
Are the rods wobbling or the leadscrews? Both can be normal, since the leadscrews are fixed by the motors at the bottom and the rods are only fixed at the top. So both have the ability to move a little, when the other part can't.
About the G-Code: don't disable the nozzle cleaning! Only disable the hotend heating for the nozzle cleaning.
Btw, if you're unsure what line in the G-Code does what, I can recommend using ChatGPT to tell you what's what. Way easier, than deciphering the full line via the Marlin wiki + Prusa custom commands site.
I'll post my full start G-Code tomorrow, when I'm back at my PC.
RE: Printer is detecting collisions all the time
"About the G-Code: don't disable the nozzle cleaning! Only disable the hotend heating for the nozzle cleaning. "
Of course not, I ment disable the heating while nozzle cleaning, I found the script and implemented the hotend heading disabling in to my startup script.
And yes, I ment the leadscrews, rods a perfectly fine as far as I can see.
Thank you Raaz, the heating disabling made it a world of difference and now it actually works and prints again.
My next issue is bed adhesion, small prints work like a charm, larger prints like a spool-holder with holes in the sides fails.
Print in question: https://www.printables.com/model/270804-improved-bambu-lab-reusable-spool-holder
RE: Printer is detecting collisions all the time
This is the result if I try a larger Area.
RE: Printer is detecting collisions all the time
This is probably not the issue for you, but I happened to stumble across it yesterday: The printer was detecting a collision when moving in the z-axis since the filament was half-stuck on something which lead to it pulling the whole print head when it tried to move downwards towards the build plate (I was not using a bowden tube for that specific print).
RE:
I dont think that applies since the bed moves upward and the print head is stationary.
That being said, i have made sure the cablemesh and tubes does not collide anywhere and the nozzle is clean before a print as to not skew the Z-probe.
RE: Printer is detecting collisions all the time
This is the result if I try a larger Area.
Can be multiple things, sadly. Can you try to just print a single layer, full print bed rectangle? Just add a box shape in Prusa Slicer, unlink uniform scaling (bottom right corner) and then stretch it to cover most of the print bed and set the Z height to 0.2 mm.
You might need to delete the "sinking" or hit "F" and select the top or bottom surface to put it on the print bed.
And very important: what are your 1st Layer speeds? The default is way too fast for such thin patterns. I would suggest setting 1st Layer walls/perimeters to 10-20 mm/s and 1st Layer Infill to 15-40 mm/s.
NOT for the full area test though. That can be printed swiftly and only checks the MBL probing across the print bed.
In general though: such multiple, thin patterns can be tricky and I've found the Prusa Satin sheet to work best, if you don't want to use sandpaper on a smooth sheet. The smooth sheet works great for bigger contact surface prints and sticks extremely well then. But thin patterns are hit and miss for me..
I've personally took an old mk3 PEI smooth sheet and scrubbed it with 400 grit sandpaper in a chaotic pattern. Not a good job, but that print sheet has by far the most adhesion of any print sheet I've used. And I tested about 10 from textured, carbon look, biqu frostbite, Bambu supertack etc.
It seems that if the surface is too smooth, the filament only sticks, when it cools down from 200 to about 60 C. If there's too much movement too early, it won't stick. If the sheet is a bit rough, it works like tiny teeth, grabbing the filament and holding it in place, until it cools down to stick on the PEI.
The textured sheet grabs the filament nicely at first, but doesn't have the same adhesion when cooling down to 60 C. The Satin sheet is a hybrid, but also doesn't have the same, very strong adhesion, that "smooth" PEI has.