[Rocket (Ed)]

I wanted to put a focus drive motor on my Mak 127, but the commercial options are expensive. I have a JMI motor focuser for my Meade SCT, but it doesnt easily fit the Mak focus knob. However, the hand control works with any DC motor. Here is a simple bracket, made from a bent and twisted aluminium strip, and a geared DC motor from eBay. The bracket mounts to the OTA via a lengthened bolt from the Vixen dovetail to the tube, and a bolt to one of the tapped holes on the dovetail, so no modifications are needed to the OTA or dovetail.
The motor couples to the focus knob with a GT2 belt and a toothed pulley on the motor. The toothed pulleys and belts are available cheaply from eBay, for use in 3D printers. I bought a 1 metre section of belt, cut it to length and joined it with a piece of bicycle inner tube and Selleys Power Grip adhesive. (There are a lot of discussions on the web about joining these belts). Alternatively, a belt of the right circumference is probably available on eBay.
The tension on the belt can be altered by washers under the Vixen dovetail, or if a wider aluminium strip is used, by pivoting the motor from the top hole, with a slot at the bottom. However, other than some slop in changing direction, tension doesnt seem critical and there is enough grip between the toothed belt and the rubber focuser knob.