Improving the Celestron CG2 tracking mount

When you take something apart and put it back together a few times you start to question just why the designer did some of the things they did. There are probably good reasons (some of which would be out of the designer’s control, like price, production formats, assembly costs, etc). However when you’re not so limited by these things…some of the results really stand out. No hate on the designer, they did make a tracking mount that wasn't all bad for wonderfully cheap.

So allow me to present the problem:

If you have a looksie at this diagram you’ll see that because the main barrel of the tracking mount is cast the tolerances on certain sections are not very good. Even if they were it would still be difficult to get exactly what is needed using soft aluminum.

Rotation in direction A there is the enemy of tracking (well there are other things too, of course, but this is the one I’m poking at). The way the original mount is designed this play is controlled either by tension in direction B, or the tolerances between the axle shaft and the walls of the cast tube it resides in. Since there are no bearings B cannot be very good, and because this is cast A cannot be very good.

What really strikes me about this is that they cast this long tube, which if they had made use of could have helped this issue a great deal. My solution will add a little more weight back in to the fixture but I think it’s worth the sacrifice:

Longer shaft means play has less effect, and tighter tolerances are made by using pre-made bronze sleeve bearings on either end. As much as I’d love to put in precision tapered needle bearings? This is not the place for that. In total it will cost me $7 to change these parts out, and I will need to do a small amount of machine work. Parts are on order…