Makertober Day 27: Levelling your print bed

Yesterday I sorted out the printing temperature of my 3D printer. Today I’m going to spend some time on the other important aspect of 3d printer configuration: print height.

Una, my Ultimaker 3D printer is a “Fused Filament Fabrication” device. This is a posh way of saying that she “prints by squirting plastic onto a plate”. The distance the print nozzle from the plate is absolutely crucial. If the distance is too small you will get nothing because the plastic can’t get out of the nozzle. If the distance is too large you will get a ball of “plastic wool” because the plastic doesn’t stick to the plate and allow layers to build up. It’s also very important that the print head is the same height all over the bed, otherwise the plastic will stick in some places but not others.

On Una you adjust the print height by moving the height limit switch up and down and then twiddling three screws to set the level of each corner of the bed. This is made much, much easier by a plugin I’ve found for the OctoPrint system that I use to send print jobs to the printer. You give this a bunch of locations and it moves the print head to each one in turn and lowers it down to the printing position. You can then adjust the height there and move on to the next one. Once you’ve been around the print area a few times you have got your print bed level. For my printer the correct height is when I can slide a sheet of paper underneath the print head and it just (and I mean just) catches the print head. I need to do this when the print head is at printing temperature.

I used to check the print height at positions all over the bed using a little height gauge but I’ve given up on that. My starting assumption is now that the bed is flat so that once the three points where it is supported are the right height the print height will be correct. If the print bed is not flat there’s not a lot I can do about it other than buy a new one anyway….