Lower profile DC Motor driven etalon tuning.

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A shorter 240mm timing belt turned up in the last post before Christmas. It had been out of stock at the Danish online dealer. I was unable to use the belt in same way as before without doing some metalwork. That would involve drilling and threading two new holes in the small motor bracket. Not major surgery, but I wanted to keep it simple if anyone wanted to copy my idea.

The heavier and larger motor bracket, supplied in the Skywatcher clone, focuser kit, had its screw holes lower down. Which meant the shorter belt would provide a lower profile motor siting. The downside was the necessity to file a curve on the ends of both the motor mounting bracket and the attached motor plate.[See arrow, image upper right.] 

Ideally, the heavier motor bracket should be chopped off at the X in the upper image. Otherwise the unwanted tail end of the bracket will foul the helical focuser. I haven't sawn the tail end off mine yet because I am still looking at different motor mounting options. If you don't have anything in the way you can save yourself the bother of sawing off the unwanted end.

To be on the safe side I removed the two tiny screws and filed the bare motor plate in the vice. I didn't want metal dust getting inside the motor/gearbox housing. Besides, it would be very difficult to hold the motor still while coarse filing.

The second image [lower right] shows the original layout with the longer 250mm belt and smaller motor bracket. The difference in motor height isn't huge but is probably worth the effort if you can obtain a 240mm belt. 

If you are willing to make a new motor support bracket, completely from scratch, you can lay the motor on its side using a shorter belt. This would require a much taller bracket, after the 90° bend, to match the needs of the motor slots.

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