I am thrilled that I got my Celestron Edge HD 9.25 SCT this week after a long wait.
I am trying to install the Celestron dovetail bar on the top of the scope.
Learned that the back two screws are #8-32, and the front screw on the corrector plate is #10-24.
The dovetail bar kit includes mounting screws that are longer than the screws that come in the SCT.
However, the #10-24 kit screw won't fit into the threaded hole.
visual inspection of the threaded hole shows that the threads seem to be in good shape. I don't see shavings. there is a touch of black paint near the top but not really enough to cause issues. And the OEM screw that came with the scope goes in without resistance.
I inspected the OEM screw that came with the OTA. It is black anodized and I noticed that the 'external' thread outsize edges are not currently anodized - as though they were scraped off from forcing into too narrow of a thread. I can picture if the tap was worn down from use and now not cutting the full thread depth.
I used a bit more finger force to get the kit screw about 1/4 a turn into the hole then backed it out. This removed some of the anodized surface from the outside of the first thread of the ket screw so that it looks like the OEM screw. See attached image - short = OEM, long = kit screw.
I am putting the dovetail bar on to carry other optics and can imagine using it as somewhat of a grip when mounting the OTA or getting it out of its storage container - so that screw will carry a load and failure of the threads would be BAD.
here were my thoughts on ways to proceed
Option 1A) force the screw in and strip the threads like the OEM screw [not really an option, in my opinion];
Option 1B) file the screw threads a little to make them fit better [seems like a bad idea].
I could go buy a tap and clean it up... but 1) have to buy the tap kit, 2) this needs to be a through hole, so I can't do it in place, I would need to remove the front corrector plate assembly of the SCT. taking apart the corrector plate assembly of a brand new OTA to do this and reassembling and re-aligning everything seems like a lot could go wrong - especially on a scope fresh out of the box.
I am a scientist who has designed, machined, and assembled 10 different scanning probe microscopes... so I should have the skills to do it. Just haven't done optics of this scale yet.
Option 3) get other options/ideas.
I also have this question in to HighPoint Sci. Technical support. Seems like overkill to return a scope over one tapped hole - would rather find a fix.
thanks for any ideas