A350 gantry consistency

While I was trying to evenly open multiple holes in a 14’*13’ FDM, I noticed the gantry was not level. The hole on the right was completely drilled, and about 1mm remained on the left. I roughly measured the height difference between the two Z cycles, and there is indeed a 1mmish misalignment. I found New a350 gantry not level from the forum and this works well.
Then I was a little curious if I repeated the method suggested by Buzzplop and manually pulled the two Z axes to the highest point after each shutdown, how consistent the results would be. So I did some quick repeat test and got the following results


Excluding the height difference between the two diagonal endpoints (which may be caused by my self-made wasteboard), I feel that the error of ±0.1mm at the four points after each restart and homing is relatively acceptable. To optimize the relative level of the bed and the X-axis, I am afraid I have to surface the spoilboard and no longer switch to other working environments. I think I would prefer to increase the over drilling by 0.2~0.5 every time I need to drill through, rather than trying to surface the spoilboard.

There’s no guarantee the top of the Z axis end stop is in the same location on each tower. For improved results I’d recommend referencing off the top of the Y linear modules or the top of the build surface using parallels. For reference: Carriage Tolerances - Unusable Over Distance >75mm From Center - #34 by brent113

Thanks for your great suggestions. I didn’t expect that the end stop of each linear module might be different. I think I need to buy some 123 blocks now.

They are kinda handy to have around, but really 2 things the same size will do, for example two cans of tomatoes. Once you have the height set where the “cans” can just slide in and out while grazing you can turn the power on to lock the height in place under power and swap the side of the cans - if they fit the same after swapping that confirms both a) the cans are the same size and b) the gantry is tram.

Some 2x4s or any dimensional lumber should also work as it’s usually quite precise and would also be a good candidate as a gauge.

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