Hi all,
Got a mk3 aluminiumheatbed with borosilicate glas clamped ontop of it. Further I have an printsurface stuck on the glas. Now i heat up the printbed to 90 deg.
The heatbed seems to warp because the distance to the nozzle decreases by about 0.2mm or so.
Is it the aluminiumheatbed or is it the glas? Do you have that problem? When printing ABS at 125 deg I allways hat to wide first layer lines. But now I know it is the bed. How can I prevent this?
PCB-based heated beds can tend to bow upwards towards the middle but placing a flat piece of glass on top tends to even things out. As long as the clips are compliant enough to permit the glass to remain level. The glass needs to be 3mm or thicker to ensure it has sufficient resilience against bending.
The printing surface could be another factor. While the material may be fairly uniform in thickness it will have a bonding film underneath and fitting error (in the sense that there could be air micro-bubbles present). I believe the particularly flexible print surfaces e.g. BuildTak should be applied to the surface using a roller of some sort. Manual methods are imperfect.
Have you checked the bed evenness at the centre and all four corners?
Have you re-levelled your bed since it has been covered with the build surface?
Yes its completly level. But when I set the distance with a feeler gauge, then heat it up and use the gauge again it wont fit under the nozzle. So i believe it warps. The glas is 3mm btw. Have to test it without the glas thou
Heat the bed before setting the distance
@Mark_Fuller yeah but when i print abs the temp is higher and the problem remains.
@Nathan_Walkner well thats crap lol
Ah! Have you considered that your nozzle expands when heated?
An expansion of 0.15mm is common for a brass nozzle for temperatures upto 200C.
If you normally check with a 0.2mm feeler gauge try 0.35mm instead at temperature
@Neil_Darlow i dont think so. It was heated before and after the heatbed was heated up
Note the obvious error above. 0.35mm cold and 0.2mm heated.
If the error is consistent, you might just get away with using a modified Z offset for each material. You could set it in your starting GCode for each material.
@Neil_Darlow yes thats true. But i want it to be more stable. Need to find another way. Maybe testing with glas and silicone heatbed or so