Pro Has No Adjustment for the the HOME Position?

[matlandon]

I just got the mars pro today

Place paper in lcd
1. Loosen the bolts for the build plate leveling
2. Hit home button
3. Hold down plate and tighten bolts. 
4. set z=0
5. Re-home, press the home button again.
6. Check paper tension, my paper wouldn't move, 
     going up 0.1 achieved correct tension
7. Loosen bolts and re-home, now before tightening bolts, send the built plate down 0.1, and tighten the bolts.
8.set z=0
9. Re-home
10. Paper tension is now perfect at home position, because I compensated for it. 

I hope this made sense. It worked for me. Your mileage may vary.

[cliffyk]

OP and others, there is nothing wrong with your machines.

There are two Z-axis "zero" positions:

• a "physical zero" position determined by feedback to the firmware from from the optical limit switch  at the base of the Z-axis column;
  
• a "logical zero", an offset from the physical zero, set by relocating the trolley from the physical zero and pressing the "Z=0" button.
  

Pressing the "Home" button always moves the trolley to "physical zero", however a gcode positioning command calling for positioning the trolley to "0" will move the trolley to the logical zero position.

Moviement to the "logical zero" (as saved by thr "Z=0" function) can only be achieved via gcode commands.

More about this in my post here...

[mrjayd]

OP and others, there is nothing wrong with your machines.

There are two Z-axis "zero" positions:

• a "physical zero" position determined by feedback to the firmware from from the optical limit switch  at the base of the Z-axis column;
  
• a "logical zero", an offset from the physical zero, set by relocating the trolley from the physical zero and pressing the "Z=0" button.
  

Pressing the "Home" button always moves the trolley to "physical zero", however a gcode positioning command calling for positioning the trolley to "0" will move the trolley to the logical zero position.

Moviement to the "logical zero" (as saved by thr "Z=0" function) can only be achieved via gcode commands.

More about this in my post here...

But there IS something wrong with our machines meaning we shouldn’t have to go through this on a new machine fresh out of the box. I have had Anycubics and Phrozens and NEVER had these types of issues.

[cliffyk]

I fault Elegoo for not adequately (or for that matter--at all) documenting the largely uneccessary "Z=0" function. As much as I can determine based of email exchanges with Elegoo support, it exists only as a way to avoid--over a long term--doing the mechanical alignment. Their referencing it in a maintenance video for the "Pro" series--with no explanation of it's purpose--just added to the end-user's overall confusion.

It does nothing to alter anything under the control of 99.44% of users and is for them completely unnecessary if a proper mechanical alignment has been routinely performed. Other than investigating it's function I have never used or felt I needed it, nor can I envision ever needing it. I suppose it may add something for those 0.66% of technically advanced users, or perhaps in a production line environment (though I cannot easily envision the Mar's printers being production line tools).

[Mr Sprue]

I have the Mars 2 Pro which has a screen that can easily mark or scratch, and yes there can be annoying issues when leveling the build plate.

What I do now to set up the build plate is use two pieces of paper ! I use regular 80 gm A4 paper which measures 0.10 mm in thickness and a piece of oven proof or grease proof paper which measures 0.04 mm in thickness. The oven proof paper has a very smooth surface which prevents sharp airborne dust particles attaching to it which could otherwise scratch the screen.

To protect the screen the oven proof paper is placed under the A4 paper, then I zero and tighten the build plate. That difference of 0.04 mm is all that is needed to get the adjustment right as a piece of A4 on its own for some reason still makes the adjustment too tight between the screen and the plate, resulting with too much tension to be pulled out easily. Plus the surface of the build plate has a sandblasted surface which also grips the paper!

Once the two hex socket bolts have been tightened for the build plate there will still be some tension felt on the paper, but remember one piece is nearly half the thickness of the other.

Finally after raising the Z axis I place the vat into its position then lay a piece of trimmed oven proof paper that's the width of the FEP and overhangs the front edge of the vat so I am able to pull on it to test the tension. Press "Home" then check to see if there is too much downward force on the FEP.

This has worked every time for me and made setting zero pretty easy without any fapping about adjusting the offsets!