Test STLs arent the same as the current parts about openastroguider

[daniel-gallagher]

I had the same experience. Test print middle threads were just about perfect. After printing the complete parts, I found that the middle section was far too large. I reprinted using the -1mm middle, but it is still a bit loose. I will try the -2mm middle next to see if that will be the right fit.

[freiform]

I had to shrink the -0.2mm middle by another 0.3mm in x and y to have the threads engaging properly.

I would recommend ditching the test STLs for now and just print the front and back and then print about 10 mm of the focusing ring's ('middle') thread. In the slicer

• move the part into the bed so it gets cut so you just get the thread
• use cut (in e.g. PrusaSlicer) at a height of 7-10mm or just abort the print at that height, e.g. with Cura (couldn't find an appropriate funcion there).
• Try on the 'rear' part and resize in Slicer if needed.

For me, it was okayish on the bottom part but way too loose on the front, but that may be my cheap printer, so YMMV. If you want to try out the fit for the front part, just rotate the middle by 180° in x or y and print a section of thread as described above.