A hacked Ioptron cube mount 'GoTo' for Quantum Helios binos

[Mr H in Yorkshire]

As a lockdown project I hacked an old Ioptron Cube to make a 'goto' drive for a pair of 45 degree 100mm Helios Quantum binoculars.  I fixed 3/4" bearings into the threaded mounts, on one side sandwiched by steel 2" plates. The bearing rotates freely while the plates are fixed to the binocular body. The outer plate has a peg in its centre and another towards the periphery.

I separated the Cube into its two drives and attached a steel 'L' shaped fork with open sockets to the azimuth drive. The fork arms are offset so that the eyepieces stay clear of the azimuth drive when vertical. This also keeps the fork arms short, I tried a longer fork positioned centrally, although no counterweight was then required, the fork oscillated badly if bumped. The binos attach to the alt drive via a magnetic clutch, the pegs slot into the outer clutch plate. The magnets are strong enough to slew and track, but if bumped or obstructed, and for initial alignment, the binos can move.

Because the binoculars are supported in the fork, the altitude drive takes no load at all, it merely serves to effect rotation. I finessed the balance of the binoculars with small lead weights to further reduce the demand on the drive and avoid any unwanted clutch slip. The offset 16lbs weight of the binoculars is counterbalanced by a 20lbs lead weight. Withh this arrangement, even though the load on the azimuth drive is way beyond Ioptron's specifications, it slews and tracks without any problem.
The setup is controlled from an ancient 32-bit notebook PC running Stellarium, it's perfectly adequate for the job and being 12 volt can share the battery needed for the Cube mount and the home made elevating pier.

To maintain the eyepieces at a comfortable height as the binoculars are moved from low to high angle targets I have made a poor man's elevating pier which uses drawer slides and a linear actuator with a 20" extension capacity. I've managed to suppress rotational oscillations by adding stiff rings to the slides, movement dies out in less than 2 seconds, so not too bad.