Cupped Aluminium Bed/ UBL Troubleshooting MODIX BIG60

[GMAsteelo]

Recently started working with a Modix BIG 60 printer and I am having some issues with it.
It runs MARLIN 1.1.9 and has a 600x600x600mm print area.

First of all the aluminium bed that is comes with is cupped in the middle so I can't get good prints on it. So I used the UBL tool that came with the firmware to compensate for the uneven bed.

My problems is I don't know how to get S3D to load the mesh that was created using UBL to properly compensate for uneven bed. I'm also getting dimensional errors in my z-axis.

The UBL is correct because I have verified the mesh and it prints well

I have entered a couple gcode commands at the start to try to get it to the UBL to work but with no luck.

Starting Script:
G28; home all axis
G1 X300 Y300 F8000; move to center
G28 Z; home z axis
G29 L0; load mesh slot 0
M900 K0; disabled linear advanced
G1 Z5; lift nozzle

Is there anyway to fix this

[ngoldberg]

Hello GMAsteelo:

I respectfully want to suggest that as a Modix user who assembled and calibrated my company's Modix and used it extensively for over a year, that the notion of the machined build plate being cupped might not actually be the case. It is what is referred to as a tooling plate and is spec'ed for flatness. Its also quite thick.

Here are some things to check:
Before you begin the procedure I have outlined, please insure that the setscrews for the ball screws are all lock tighted . The allen drivers that come with the kit are just a bit harder than frozen butter. Get a better set to do this. Also insure that belt tensions are good

Since the Modix in its present incarnation uses one driver for all three Z axis motors, the auto leveling needs to have the three motors ball screws calibrated.
To do this (assuming your Z axis offset in Gcode is set correctly):

Use the tools page to get to the jog controls

Insure the print head is not in contact with the build plate

Home the X and Y axes only
assuming you have S3D set up so that a negative Y value moves the print head toward the front of the machine , move the print head to 300 on the X axis and -300 on the Y axis

If you have installed the plastic film onto the build plate insure that as you carry out the next step, that the nozzle is not over an air bubble in the film.

Now at the center of the build plate using the Z jog control in S3D as appropriate to gradually bring the build plate INCREMENTALLY in the -Z direction per the spec in the assembly manual so that a piece of ordinary copy paper pulls out from under the nozzle with a bit of resistance without tearing or leaving a groove in the paper.

In S3D Zero out the Z value in the upper right part of the display.

Now using the jog controls, move the print surface in the + direction by 1mm or a bit more so it clears the print bed.

Then move the print head nozzle over a part of the print bed that is very close to each of the ball screws.

Do not move the bed closer to the nozzle in one step but rather sneak up on the negative Z value in a couple of smaller steps.

Check your clearance with the paper again after each negative Z move.
If you "sneak " up on the negative z value and the S3D display says you're back at the previously set zero point, and the paper clearance is too tight or too loose, use the S3D software to turn off the motors and manually rotate the related ball screw to get the clearance correct.

Repeat this step for each ball screw, then check at the center of the build plate. If this value does not set up correctly, (it may not if you found you had a discrepancy at any of the three test points) you may need to repeat the procedure.



I sincerely hope this helps.

Regards,

Neil