Trying to mount an 80mm guidescope

[willcastle]

Wow so my new scope arrived and I was running through all the different options for guiding. I thought I would share my experience and hopefully other beginners might find something useful from this. 

I purchased a skywatcher evostar 80ED Pro with a HEQ5 Pro mount and it came with two green dovetail bars. I already had an ST-80T that I wanted to mount on top but the “dovetail bar” that came with that was a small useless plastic block. 

The biggest, most annoying hurdle with this process was that on each dovetail bar, there were metric- and whitworth-threaded holes, with different diameters. What I ended up doing, was taking off the evostar dovetail and attaching that to the top of the evostar scope rings. This was important because this dovetail bar has a slot in it, that allowed me to correctly space the guidescope rings.

I only had two whitworth bolts (fortunately that were quite long and had nuts  with them), but I used each of those to attach the dovetail bar to the top of the evostar rings. The whitworth bolts were both cut down to size, and the spare part of the thread was used to attach one of the guidescope rings to the top dovetail bar.

Note that I had to drill out the thread of the ST80 rings, as they were metric threads, where as the dovetail had whitworth threading!

I screwed the length of whitworth bolt down from the top and used the nut and a small washer to tighten it down. For the second ring, I placed it in the slot of the dovetail bar and used a small length of metric thread, that I could then bolt from each side (effectively clamping everything together).  

Finally, I attached the dovetail bar that came with the HEQ5 (I think it might be the standard, medium dovetail bar that you can purchase separately), to the bottom of the evostar rings. I think I used the bolts that were originally in the bottom of the ST80 rings to bolt those down, and then added in the lateral screws to make sure the rings couldn’t rotate. 

It was considerably harder work than it needed to be but I am pleased with the results. It cost me nothing but time and a bit of effort. I know that the guide rings don’t have adjustment bolts, but at least with the current set up, there is no determinable flex, and with an 80mm scope, it shouldn’t be hard finding a guide star. I am a fan of having the matching green dovetail bars. And I have attached the guide camera and DSLR and can perfectly balance the mount. So overall, a great result.