Independently leveled Z axis Issue

[mrenz999]

@fcwilt What is the correct procedure for getting a 4 point height map ? 410x410 Bed ? lol

[fcwilt]

@mrenz999 said in Independently leveled Z axis Issue:

@fcwilt Sure. I will do that in the next 15 - 20 mins

Great.

I have a MarkForged style printer with 3 Z steppers and even though the leveling appeared to work the 4 point height map still showed a "twist" along the X axis.

It turned out the the Y rails (left and right) were not in the same plane which gave the appearance of the bed being "twisted" - which it wasn't.

Frederick

[mrenz999]

Measuring the bed to nozzle it appears and is without question twisted. But if you tell me how to do a 4 point height map I will do one now.

[fcwilt]

@mrenz999 said in Independently leveled Z axis Issue:

@fcwilt What is the correct procedure for getting a 4 point height map ? 410x410 Bed ? lol

On my printer where X=0 and Y=0 is at the center of the 300 x 300 bed I used something like this:

M557 X-130:130 Y-130:130 P2:2 ; define 4 point mesh for G29

Your values will depend on the X and Y offsets of your probe and the min/max values of your X and Y axes. Just try to keep the probe area centered on the bed.

Frederick

[mrenz999]

@fcwilt

[3DPrintingWorld]

Thanks @fcwilt, think you finally helped me realize my issue. Only four points makes the map much easier to understand.

When I first ran the mesh the left back corner was really low. I have a glass plate on top of a sheet magnet. I am only using glass because I wanted to verify the bed was flat.

I'm clipping down the bed in the back center left and front center right. I moved both clips to center right and reran the mesh and the low corner goes away!

Upon further inspection of the magnetic sheet shows small cracks where it starts to turn blue in the first map. I think these crack are causing the issue. I'll remove the magnet an put the glass directly on the bed tomorrow and give it a try.

[mrenz999]

@3DPrintingWorld In your bed.g do you have it do multiple probes per point ? If so how do you accomplish that ?

[fcwilt]

@mrenz999 Thanks.

The is an extreme version of what my height map looked like.

Is this what the frame of your printer looks like?

[mrenz999]

Yes thats the one Except I have 3 z motors. 2 on the right side and 1 on the left

[fcwilt]

@mrenz999 said in Independently leveled Z axis Issue:

@3DPrintingWorld In your bed.g do you have it do multiple probes per point ? If so how do you accomplish that ?

Read up about the A and S parameters of M558.

If A = 10 and S=0.01 the process will probe each point up to 10 times trying to get two consecutive readings with 0.01.

If it fails to do that it will average all 10 readings.

Frederick

[mrenz999]

@fcwilt Perfect. Thank you. Does it matter where in the M558 I put that ?

[fcwilt]

@mrenz999 said in Independently leveled Z axis Issue:

Yes thats the one Except I have 3 z motors. 2 on the right side and 1 on the left

And the linear guides are on the underside of the top most frame pieces?

Frederick

[fcwilt]

@mrenz999 said in Independently leveled Z axis Issue:

@fcwilt Perfect. Thank you. Does it matter where in the M558 I put that ?

No just add them to your current M558 command.

Frederick

[mrenz999]

@fcwilt

[fcwilt]

@mrenz999

Sorry but I cannot tell where they are from that picture - I may be looking right at them and just not seeing them.

So where are the left and right linear guides mounted?

Thanks.

Frederick

[mrenz999]

@fcwilt So the left one is in the middle of the bed on the X axis. The 2 on the right are at the corners of the bed frame. The bed frame sits on the attachment to the linear guide mounts

[fcwilt]

@mrenz999 said in Independently leveled Z axis Issue:

@fcwilt So the left one is in the middle of the bed on the X axis. The 2 on the right are at the corners of the bed frame. The bed frame sits on the attachment to the linear guide mounts

Sorry I was not clear - I meant the Y axis guides - the ones running front to back on each side.

Frederick

[mrenz999]

@fcwilt gotcha. The are underneath

[3DPrintingWorld]

@mrenz999 said in Independently leveled Z axis Issue:

@3DPrintingWorld In your bed.g do you have it do multiple probes per point ? If so how do you accomplish that ?

I created a macro that heats the bed, calls out the mesh, homes, does the mesh, saves the mesh, then turns the bed off. I started at 10:10, then S= was my max travel minus 10. Plus you have to add/subtract your probe to nozzle offset.

M140 S60
M557 X10:365 Y10:290 S300:270
G28
G29 S0
G29 S3
M140 S0

[fcwilt]

@mrenz999

Great.

Did you print out those "tools" designed to help align the frame pieces?

I didn't have such tools and after seeing my 4 point height map I realized that my left and right Y axis guides were not in the same plane meaning the frame pieces were not in the same plane.

I closely examined the left and right frame pieces where they joined the four vertical pieces at the top and found that they were at slightly different heights, with the left piece being low in the rear and right piece being high in the front.

We are talking fractions of a mm but it was enough to generate a "twisted" height map - though not as bad as yours.

Perhaps you are having the same problem.

Frederick