"Dry" calibration idea


#1

As I continue my quest for highly accurate Z dimensions on my prints, I find that the first few layers are always thicker than they should be. One of the potential issues is the remaining resin under the build head immediately after the calibration routine. It is impossible to evacuate ALL resin. The first layer thickness is essentially the thickness of the resin left behind during the calibration routine. Iit would stand to reason that the effective “0” plane is then alway going to be off by this amount. This leads me to this idea:

Having the ability to choose to calibrate with no resin in the tray will ensure that the Z “0” plane is actually “0”.

The changes to the calibration routine would be:

  1. The user loads a dry tray (or one with all the resin wiped free from the PDMS)
  2. Instead of rotating the tray after calibration, the build head is just lifted straight up.
  3. A pause and prompt to fill the tray.

This could be also addressed as a single step, where it’s a calibration only routine, done before loading the print file. When the user loads the print file, they choose ‘skip calibration’.

Maybe this is an option allowed in the printsettings file - similar to UsePatternMode.

Thoughts?


#2

Interesting idea… I’ll ask around about modifying the firmware, but in the meantime you can try it out by doing the following:

  1. In your printer settings file, set "RHomingAngleMilliDegrees":0 (prevents rotating after a job finishes/cancels)
  2. Start the job with no resin and calibrate the build head
  3. Complete the calibration process, then cancel the job
  4. Set "RHomingAngleMilliDegrees":-60000 (the default)
  5. Run the job with resin and skip the calibration

It’s a little clunky but it should demonstrate whether the idea is sound or not.


#3

I finally got around to trying your method Owen and it works! Like you said, a bit cumbersome, but functional.

Now I just need to validate the initial layer thicknesses.


#4

Cool! I’m interested to hear your results.


#5

Scott,

How did your results turn out? I am also interested in trying this.


#6

I will get some comparison results this week.