AZ3 mount saddle and counterweight mod

There are a couple of things about my AZ3 that I’ve never been happy with. The first is that it has fittings for scope rings rather than a saddle for a dovetail which is a pain if you want to swap between scopes (or put an OTA on that is awkward to fit rings to). The second is that the OTA doesn’t tend to stay where it’s put near the zenith. I decided to fix both of these issues by fitting an aftermarket saddle and a counterweight bar.

The counterweight bar came from Astroboot though I was tempted to use some 22mm stainless bar and probably would have done so had the easy option not presented itself. I bought a saddle from Sky’s the Limit and realised there was going to be a small problem fitting it in that the grub screw tensioning the alt movement was going to foul the bottom of the saddle:


I undid the nut and threaded retainer for the worm, removed it and flipped the block the worm passes through over so the grub screw was underneath. It’s still reachable should I need to use it, but now out of the way of the saddle.

I then made up a piece of 5mm aluminium plate to fit down the centre of the top of the mount, drilled so it could be bolted on where the rings would normally go and for the saddle to be attached:


After I took this photo I actually put another hole in as it later allowed me to put one bolt through the saddle, retaining plate, mount and counterweight bracket all in one go.

The counterweight bracket itself was similarly cut and drilled, bent slightly to push the counterweight bar out at an angle.

That was pretty much it, really. Then everything just needed bolting together:



The weight is a spare from my HEQ5. I could really do with something smaller, but for the photos this one was handy.

And here’s my ST120, riding at a rather jaunty angle…


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