Mesh Grid Compensation

Puppet172

I keep getting a mesh bed like this and i know it definitely does not start this high. why is this happening?

dc42

I think you may be probing too fast. When the bed is probed and the Z probe triggers, the firmware commands the Z motion to stop abruptly. If there is too much inertia in the Z motion system to do that, the Z motor will jump steps and the nozzle height will be less than the firmware thinks it is. This means that the next time you probe, the probe triggers early and the firmware thinks the bed is higher at that point. And so on.

To test this, place the nozzle over the bed and send G1 Z5 and G30 S-1 alternately. The G30 S-1 command should report about the same trigger height each time. If it reports increasing trigger heights, you are probing too fast. Reduce the F parameter in the M558 command until you get a consistent result.

Puppet172

@dc42

also shouldnt the first point, for me back left, be the "0" and then everything goes off of that point?

dc42

@puppet172 said in Mesh Grid Compensation:

@dc42

also shouldnt the first point, for me back left, be the "0" and then everything goes off of that point?

Isn't that what's happening? I can't rotate the height map as you can within DWC, so it's hard for me to tell.

Puppet172

@dc42
no the first point for me is way up in the air like it says on the z ~ 12 mm

dc42

Maybe you have the maximum Z speed set too high in M203, or the maximum Z acceleration set too high in M201?

When the Z probe is lifted and moved between probe points, the firmware commands both the lift and the XY movement at the speed given by the F parameter in the M558 command. On a Cartesian or CoreXY printer, the M203 Z speed limit would normally be much lower than the M558 F parameter, so the Z lift will be at this lower speed.

Puppet172

@dc42

i changed it and made it lower but then i still got this

dc42

Did you run the test that I suggested in my first reply?

Puppet172

@dc42
Yes I tried that too got the pretty much the same this as the last one I just posted.

dc42

@puppet172 said in Mesh Grid Compensation:

@dc42
Yes I tried that too got the pretty much the same this as the last one I just posted.

I meant this one:

To test this, place the nozzle over the bed and send G1 Z5 and G30 S-1 alternately. The G30 S-1 command should report about the same trigger height each time. If it reports increasing trigger heights, you are probing too fast. Reduce the F parameter in the M558 command until you get a consistent result.

Puppet172

@dc42
Yes it would go up a little by little like 4.303 to 4.350 and so on, sometimes it would eventually level out i then changed the F from i think 120 to 100 and then it seemed to level out right away to about .01 of a mm

dc42

What M201 and M203 Z parameters are you using, and what is your Z steps/mm?

Puppet172

@dc42
M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
M92 X80 Y80 Z2000 E100.1 ; Set steps per mm
M566 X900 Y900 Z12 E120 ; Set maximum instantaneous speed changes (mm/min)
M203 X6000 Y6000 Z100 E1200 ; Set maximum speeds (mm/min)
M201 X500 Y20 Z350 E250 ; Set accelerations (mm/s^2)
M906 X800 Y800 Z800 E800 I30 ; Set motor currents (mA) and motor idle factor in per cent
M84 S30

dc42

Your Z acceleration in M201 looks very high for 2000 steps/mm. I suggest you reduce it to around 40. OTOH your Y acceleration looks very low for 80 steps/mm.

Puppet172

@dc42 I think you got my m92 and m201 mixed up because my m92 z is 2000 but my m202 isn’t

dc42

@puppet172, I was referring to your M201 Z350.

Puppet172

@dc42

What would you recommend putting it at ?

dc42

40, as I said before.

Puppet172

@dc42
I will put it at 40 and then I will do another mesh bed and then post it

Puppet172

@dc42