Problems with the Z-axis

[yaqwsx]

I believe that the fix for the 2mm short issue is something that isn't in the documentation and that is- after leveling the build plate going back a screen to the Set Zero. This seems so obvious and I'm trying it on this morning print. This was mentioned to me in another forum. Has anyone already tried this step?

Well, I have. It is not in the documentation as it is I would say 'a design flaw' - what I describe in the post is a fix for the flaw.

[lbustelo]

Well... all this sound way to complicated and doubtful. I decided today to return the printer. I do not think reasonable to expect customers to fixed manufacturing issues. This whole thread and blog post do not make me feel any confidence about the company or product.

[PolkCountyMike]

I have finally found a solution to my problem. It is a design flaw in a component on the printer. You can read about it in more detail here: https://blog.honzamrazek.cz/2019/09/test...t-finally/

I believe that the fix for the 2mm short issue is something that isn't in the documentation and that is- after leveling the build plate going back a screen to the Set Zero. This seems so obvious and I'm trying it on this morning print. This was mentioned to me in another forum. Has anyone already tried this step?

I thought of resetting the zero, but on my machine the set zero button is not functional.  When pressed, it shows the message "z-zero is decided by trigger position".  Did you find a way to reset the zero after leveling the build plate?

[MikeRD03]

I ran into the same problem and it is clearly a design flaw of the z-axis. Just try to move your axis up and down with a little force and you will notice some mm movement.

For resolving this issue a simple machine swap will be no solution, so I designed a z-axis stabilizer for the Elegoo Mars with little parts and without opening the housing and loosing the warranty. After installing my mod the problem is down from 1-2mm deviation to 0,1-0,2 mm, which is OK for my designs and may be further improved by careful zero calibration. The z-axis is now stiff and doesn't move along axis direction without compromising any machine function. If you're interested you find my build on Thingiverse: https://www.thingiverse.com/thing:3918220

Mike

[admin]

Look in the mods section for the solution

[FrozenBubble]

This problem seems difficult to solve in a budget printer.
I have been researching it for about a week now. 
The consesus seems to be that the capillary flow resistance of the resin getting squished to the sides, holds the build plate away from the FEP. If the Z axis assembly was infinitely stiff then the LCD screen would get pushed down into the printer by this capillary action. So it would need more support and protection. All this is possible, but not at the Elegoo prices.

The main fix for solving this on the mars is to use UVTools to set  high "wait before cure" times for the initial layers.
But the issue remains how to get the build plate to land at the correct Z height after pushing the resin out of the way during the wait before cure

time.https://blog.honzamrazek.cz/2022/02/a-step-by-step-guide-for-the-perfect-bed-adhesion-and-removing-elephant-foot-on-a-resin-3d-printer/

To do this the Z axis would need to provide consistent force all the way down to the correct Z height, and then stop applying force while the curing commences. Obviously this is technically very difficult as it would require somehow closing the control loop on the Z axis with force sensors or encoders.

The Mars 3 Pro is solving this by adding some springinness into the Z axis. In the Mars 3 it was the whole Z tower that flexed. In the Mars 3 Pro it seems to be the leadscrew that is spring loaded into the stepper motor with a rubber damping plate and a spring washer. This can provide a force that drops off as the spring decompresses and the build plate approaches the target z height.

This is solved in high end printers wih a few features:

1. Heating the resin to reduce it's viscosity
   
2. Wiping the resin vat
   
3. Setting Z zero correctly
   
4. Using a closed resin ecosystem and calibrating their printers wait and cure times to match the resin and the force required to squish the resin into a certain space
   

In the Mars printers, improving this means finding a balance between Z axis flex and "wait before cure" time to end at the correct height above the FEP when curing starts. The elegoo team hasn't found this balance yet. The above mentioned spring force would drop off, before the z axis can reach the correct position. 

The Z zero point doesn't really come into play here. The first challenge of getting the build plate to push through the resin and arrive at the Z zero point, within the rest and cure time, must be solved. The Z zero just ensures that the full model z dimension ends up correct and the final layer is cured at the correct distance from the build plate.