SkyWatcher ST80 rings - bolt threads don't match SkyWatcher dovetail

[Gomtuu]

I'm trying to attach my Skywatcher ST80 to a standard Skywatcher 30 cm dovetail (to piggyback as a guidescope), but the threads don't match.

I was wondering if anybody else has come up against this issue and if so, how did you get around it?

Seems odd that they make them with incompatible threads.

[emadmoussa]

Yep, had this issue. So basically original bolts didn't work well, but I had a bunch of screws in my tool box that I tried and some actually worked. Just do some experiments. 

[brantuk]

When you get them brand new the ST80 seems to come with one of those horrid little plastic blocks with a camera tripod thread in the underside. I took that off and replaced with an SW dovetail bar with straight through holes (ie not threaded). Then I simply got the right size self locking bolts for it. With your bar you might need to drill the threads out. Hth

[jgs001]

the medium dovetail has 4 holes... two are clear and accept the standard M6 bolts that afix to the tube rings. The other two holes are threaded for standard 1/4" tripod mount bolts, which are very close, but not quite the same as M6. If you want to use those holes with the M6 bolts, just drill them through to remove the thread, and you can use the bolts without issue. 

[Gomtuu]

Thanks all. Guess I'll probably be doing some drilling!