There’s another thread about this on the front page called getting prints to the right size or something similar. There’s some very useful tips in there.
I have been trying similar, I’ve never needed high tolerances until now so originally set the printer up to get a reasonable print and left it be.
Now I’ve set my target to get within a tenth of a millimetre accuracy in both height and width, I don’t know if that’s a tight tolerance for a 3D printer or not, whilst I’ve had my printer the best part of a year, for what ive printed until now simple adjustments to get reasonable but consistent prints have been enough.
I’ve managed to get my esteps absolutely bang on. Ive measured, remeasured, and triple measured filaments at lots of different points. I also bought a dial gauge and got the four corners spot on, although mentioned in another thread I have a .1mm sag in the centre (that’s with the whole print head carriage removed and the dial gauge and its bracket don’t even weigh a fraction of the former, so it doesn’t account for x axis sag which I haven’t measured).
I’ve spent the last two days attempting to fine tune the z axis stop, and tiny changes in height make massive differences. I’ve managed to get to within .3mm horizontal and vertical accuracy printing a small 4.4mm W x 4mm H part at all four corners and the centre, with the z set at .11mm above the centre of the print bed. I don’t know if that would be considered high or low but a piece of paper will slide effortlessly under the nozzle at that height. It has also brought the best results print quality wise that I have managed so far. The prints are coming out slightly wider and taller than they should be. I think that points at overextrusion.
I’m sure all this has been discussed in detail many times previously, but using Google throws up thousands of results, pretty much all of which ive looked at refer to the paper method. When set to a piece of paper, my nozzle always eventually ends up rubbing into a part of the print and causes chaos.
I’m also beginning to wonder if the z axis wants to be changed to match whatever layer height you’re printing at, which is something I’m going to look at tomorrow. Is there a reason the first and top layers are set to be smaller than the rest in the lulzbot cura profiles? Or is it good practice to set every layer at the same height?