Losmandy G11 OnStep Belt Drive Tucked Motor Bracket

Made these brackets / motor mounts for my Losmandy G11 equatorial mount to use with the OnStep control system. These allow for tucked stepper motors up to 50mm in depth. The belt drive system it outboard (off to the side). The pulley shaft on the worm side is supported by dual ball bearings and does not require the worm to support any load.

They fit NEMA 17 stepper motors. They should allow for between 60t/12t and 60t/20t pulley ratios with a 200mm belt. Other ratios are possible with custom belt lengths. The covers just barely clear my 60t pulleys, but some 60t pulleys may have too large an OD, and will need to have the sidewalls turned down just a bit. Mine were 44mm OD and fit without rubbing. These will also clear the bellows style couplings found on aliexpress. The bearing bores will need to be sized to 16mm. I used a stepper drill bit for this.

Materials:
Nema 17 Stepper Motor
16T GT2 5mm Pulley
60T GT2 5mm Pulley
200mm GT2 Belt
5mm x 50mm shaft
5mm x 6.35mm flexible coupling (or bellows style) 16mm OD max
(4) M3x16mm Screws
(4) M3 Washers
(2) 625-ZZ Bearings
(2) 6-32x1.5 Inch Socket Head Screws
6-32x1 Inch Socket Head Screw