Hi, thanks for showing me that. I tried to follow the same process and got as far as the screenshot below. Not show how to go from there to the actual error.

I have tried with and without a datum plane (sketch attached) but whatever I do, the moment that I try to extrude Sketch001, the model goes black.

I am battling to place the Datum planes. Could you please give me a screenshot of your Plane Parameter settings so that I can compare?

I tried adding a datum plane and then move it 40mm along the y-axis but nothing happens

Reynard1066 wrote: ↑Mon Jul 06, 2020 1:24 pm Set up a few Datum Planes at the correct place and angle.
Draw sketches of the apertures and pocket through the hollow hemisphere.
A polar pattern for each pocket.
Add in some guessing for hole shape and position.

Awesome, thanks

I also changed Maximum Mesh Deviation to 1umm and the blemish was reduce to an unnoticeable size. Large file but good result :) May I ask where this is configured? I can't find it in pre-0.19. For export there is a setting from Mesh Design WB Edit > Preferences > Import-Export > Mesh Formats tab > ...

What is the approach that I should follow to punch a series of shaped holes through a sphere e.g. trying to achieve the top part of this rattle.

Thanks for that. I also changed Maximum Mesh Deviation to 1umm and the blemish was reduce to an unnoticeable size. Large file but good result

Yes I used blender to check; its definitely a blemish.

I will need to do some reading on Mesh Workbench; from the comments, that looks like the best place to start.

I still find it strange that on a symmetrical rotation, one section glitches. Oh well, such is life

I tried upping the export resolution but going to the Mesh Design workbench and changing Angular Deflection to 2 degrees and Deviation to 0.01. I also changed Maximum mesh deviation to 0.01mm. The export was smooth but I now get the following blemishes in two different places. What confuses me is th...

Ok so it is doing it whenever there is an inside insert (insert marked by yellow). Red indicates blemish.