Dummy filter 1.25" cho kính thiên văn

This is a dummy 1.25" filter for filter wheels, to avoid stray light from empty filter slots, especially when making flats. But can be used as a threaded 1.25" endcap as well. 

I printed mine from PETG, 100% infill and variable layer height, ~0.1mm for the threads and 0.25mm for the rest. It took 26 minutes to print one piece.

Note: Astronomy M28.5 filter thread profiles are not standardised, the thread on this dummy filter fits nicely about 80% of my accessories I tested, and a bit tight on the rest. Accuracy depends on different factors, the printer, the settings and the filament, if it won't work for you on the first try, fine tune it a bit. It's always a good idea to break in the threads with an extension tube or a nosepiece first. If it stuck, don't force, reverse a bit and make sure it's not tilted, otherwise you'll have a hard time to remove it.

I attached a Fusion360 astronomy thread profile, which I found somewhere on the net.