Leveling the print head for Onyx bed

[jesse]

I've been using these commands to adjust the leveling screws.

center: G1 Z5 X0 Y0 F1200
X: G1 Z5 X-120 Y-65 F1200
Y: G1 Z5 X120 Y-65 F1200
Z: G1 Z5 X0 Y120 F1200

I move the head down from 5 mm to 0 mm and use a .1 mm feeler gauge to calibrate it, move it back to G28, and repeat.

If the print head is too high, the screw must be unscrewed (raised). If the print head is too low, the screw must be screwed (lowered).

Does anyone have a better calibration method? Does anyone know how much a screw turn changes the screw vertical position in millimeters?

[Polygonhell]

The points really need to be equidistant from the center and along the center tower line, and yours aren't, this removes any issues cause by slight geometry variations.
Once you've set the height, you can ignore the center until you are done.
Nominate one tower as master and adjust the other two to match it, home after each adjustment.
Unfortunately how much a screw turn is depends on the positions you are testing at.
When you have the 3 points equal set the Z height again, yo'll have to make a firmware adjustment if the center is lower or higher than the outside points.

This is a good reference for setting up a deltabot
http://minow.blogspot.com/?m=0

I use the 3 positions in there, if you want positions further out, you can scale the X/Y values.

[dbarrans]

Assuming your screws are 6-32 screws as called for in the assembly manual, each full turn moves the screw 1/32", or 0.7938mm.

But polygonhell has a valid point; this doesn't directly determine the height of the print head. For that, you'll need to use trigonometry.

- dan

[Polygonhell]

Assuming your screws are 6-32 screws as called for in the assembly manual, each full turn moves the screw 1/32", or 0.7938mm.

But polygonhell has a valid point; this doesn't directly determine the height of the print head. For that, you'll need to use trigonometry.

- dan

On the plus side for the same position, one turn will always be the same amount and 1/2 turn half that much.

The other gotcha is that the adjustments aren't independent, so large adjustments to one endstop will change the apparent height at the other two.

[jesse]

Here's a chart for fine tuning the leveling screws:

0.099219 mm = 1/8 turn
0.198438 mm = 1/4 turn
0.264583 mm = 1/3 turn
0.396875 mm = 1/2 turn
0.529167 mm = 2/3 turn
0.595313 mm = 3/4 turn
0.793750 mm = 1 turn

d=vertical distance in mm;
t=turns;
d / 0.79375 = t

Putting a small dot on your thumbnail make it easier to track partial turns by lining up the dot with the screw head.

Too low (head touching bed before z=0), tighten screw. Too high, (head not reaching bed at z=0), loosen screw.

Is there any benefit from using points further out than the ones in the PDF guide (listed below)?
z tower: G1 Z5 Y110 F1200
x tower: G1 Z5 X-70 Y-30 F1200
y tower: G1 Z5 X70 Y-30 F1200

The towers seem to be: z=90 degrees, x=210 degrees, y=330 degrees. Formula in progress...