Here to talk about the “out of round” issue, as it has been plaguing me, ever since I bought the Moai a few months ago.
I’m on firmware 1.16 now, did some test prints, and here’s the thing, all square shapes print properly, e.g. 8x6mm rectangle, is really close to 8x6mm (give or take 0.1 - 0.15mm ) and is rectangular. If you have a square with a circular design inside , the circle is always ellipse shaped and tilted. The circle is ellipse shaped and tilted even though the square around it is flawless. The leveling pegs also come out with tilted elliptical cross-section. Added a leveling peg to the center and it also came out elliptical. Set up to print 10mm cubes with holes and the same thing happens, cubes come out right, holes are oval. Did a print for some parts I need and the cylinders had elliptical cross sections.
One would expect that if you are to get this, which is what i’m getting
you would be getting this too, because of the distortion
but instead you get this
The Moai calibration guide addresses this issue
which doesn’t help in the situation I’m describing cause it doesn’t fix the tilted major axis of the ellipse. You can adjust the galvo driver as instructed, to produce the square but inside it you will still get a tilted ellipse.
Another interesting thing on the calibration peg prints, is that the letter A prints out perfectly while the peg itself is distorted in XY, and the letters C and D don’t fare as well, they are a bit distorted. The G peg was placed on the center of the buildplate.
After some searching I came accross this galvo tunning demo. Granted, the function intended for that projector is different but the principle doesn’t change. And I recognize the fact that projecting a pattern on a wall at a range of meters can be different than projecting at 20cm, which is the case in the Moai.
At 7:16, he has set up the scanning to project near perfect rectangles but still it is off when it draws circles. Then he explains this happens cause the 2 drivers work on different scan speeds, and tunes the potentiometers for gain, low freq damping and high freq damping, to adjust the ellipse back to a circle.
Is it possible to make a guide for this on the Moai? It seems to be quite tedious back and forth procedure, fiddling with these pots, and probably could lead to complete detuning, but could it be made available for those who want to get the most out of the machine?
I printed out these little sample bolts and details at an angle at 50um and the distortion is not perceptible, but I want to have the option of orienting circular parts parallel to the plate.