Friday, February 9, 2018

Leveling the Moai

One of the two complaints that I have stated in regards to the Moai concerns the leveling process.  Standing a big and heavy printer on its head does not sound like a good idea! I play with a couple of different vats and I have found that they are different enough to demand re leveling (unless you only print at 100um).  This would become a pain...beyond pain even!  As I worked with the printer, however, I was able to come to terms with a decent process.

The first part of the solution was this article being published on the Moai Wiki.  That led to a couple of refinements.

If you are starting fresh go ahead and turn the printer on its head.  Remove the four leveling bolts completely.  Print four of these knobs from Thingiverse.  Note that you need to do some test prints to ensure the knobs fit the bolts securely.  As in you should need to pound them on.  Once each bolt has a knob put the bolts back on the printer and do the leveling with the paper sheet and all.  Turn the printer back over!

The second part of the solution is to print the test file from this article (here is a direct link).  Measure each of the cylinders and record the measurements in your copy of this Google Sheet.  Each knurl of the knobs that you now have on your printer represents 1/8th of a turn.  With practice you can turn these knobs pretty precisely just by feel.  You can also do this through the opening where the vat sits and without removing a side panel from the printer!


As always, remember to take the build plate off the printer before removing the vat!

The final part of the solution is to come up with a way to roughly level things without turning the printer over.  Here is my technique.  Set the Z Reset Position to something like 985 or so.  Maybe even lower (which means the plate will be further from the PDMS).  Let it move into position.  Note whether or not the platform moved when the build plate settled.  What you are looking for is the first point at which you detect movement.  The Z Reset Position that I use is the one that is one lower than the first movement one.

IMPORTANT NOTE:  When the current version of firmware starts the Moai it does so with a raise of the build platform and then a tilting of the vat.  Why this order is inexplicable to me!  It will harm your PDMS and should be the other way around.  Lacking that you can protect your vat by starting a print and then turning the printer off after the initial tilt starts and gets PDMS separation.  When your turn your printer back on it will be gentle to the PDMS.

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