Accuracy of first layer?  

RE: Accuracy of first layer?

Do you mean printing with different layer heights (.2 vs .3, etc.)? I'm curious, too, to learn how the auto 1st layer (Auto Z-height) compensates for that.

I am able to maintain repeatable accuracy of the first layer by 0.01 +(-) mm by measure with dial calipers.

That is pretty much automatic, with the correct filament diameter set you are extruding that much filament into the area so as long as the first layer is within a wide ballpark that is the thickness you will get as the melt finds its own level.   All you are really checking is that the filment diameter was entered correctly.

Cheerio,

RE: Accuracy of first layer?

I think there's more to it. Let's say for example the auto z-height is 0.15mm above the bed, so if you print with a 0.2 layer height, the 1st layer gets squished into the bed by 0.05mm. Then what if you want to print with a layer height of 0.1, isn't the 1st layer going to go down too loose by 0.05mm and not really get squished into the bed well?

If I'm right with the above assumptions, then maybe setting the z-offset in the slicer say to -0.07 (when you are laying down a 0.1 layer height), will get the nozzle closer to the bed by -0.07 so it will now be 0.08mm above the print surface (0.15mm - 0.07mm). This can be saved as a new profile for printing with a 0.1mm layer height.

Same goes for other layer heights.

Correct me if I'm missing something here.

RE: Accuracy of first layer?

Or, maybe the smart people developing the Prusa slicer designed it so when doing the auto mesh bed leveling, it automatically calculates and sets the appropriate auto z-height.

That would be awesome!!!

It's a bit cleverer than that.  The first layer tracks the bed map but does little to correct it, it's mostly about adhesion.  The corrections are tapered out over the next few layers.

Cheerio,