[Accuracy issues when making holes and slots]

That's a good question about the layerheight. I have the feeling that with 0.1 mm, the molten filament is squeezed a little bit to the sides because of the flat nozzle. And with 0.2 mm, the filament has more space under the nozzle so it stays in it's "round" form. Putting a string of really 0.4 mm on your print instead of a squeezed string of >0.4 mm wide.

But this needs to be checked.

 

[Extrusionhead: is the gap normal?]

I also noticed this gap when building my UM and I placed 4 metal washers on each corner between the wood and the aluminium. This straightend the aluminium plate while still putting enough pressure on the PEEK and the white insert. I thought it just would be better to 'equalize' the pressure on each screw/corner.

 

[Sneak peek at the next version]

Woow, that looks promising! Nice that is also shows the actual height of the object.