connecting a motor to a dome

[larrym1972]

i have built a observatory. im planing to put the motor in the dome not on the walls and mounting the telescope to the dome. my telescope is ten inch meade starfinder dobsonian. i also got the magellen 1 which in going to try to use. i using a roller chain #41 (bike chain). i dont know how much torque is need or rpms. the diameter is 82 inch. the roller chain is 1/2 pitch or 1 link per inch.

[1parsec]

Hi,

It was a while time ago but I made a small drive to rotate a similar dome. It required a 1/4 hp motor ( about 200 watts) and gearbox.
You'll require a similar size motor providing the dome runs on reasonably free running rollers.

Assuming -
1. The drive sprocket on the motor is say 3" diameter. 
2. The sprocket runs in the chain thats attached on the side wall of the dome
3. You want the dome to make 1 full revolution in 1 minute

The output shaft of the motor gearbox will need to run at 27 rpm or there abouts.

 

[hughgilhespie]

Hi,

I motorised a 2.2 metre dome, about 86 inch diameter, using a Nema 23 stepper motor. This had a 3 inch drive sprocket with 18 teeth and I fitted (glued) T10 timing belt to the dome. T10 has one tooth each 10 mm. I designed the drive electronics to give me a full dome rotation in 3 minutes. The motor has a 24 volt supply and is set up to take a maximum of 2.8 amps so not many watts being used, probably about 50 watts.

A lot of people use car windscreen wiper motors as these are powerful enough and already have the gearing down to the sort of speed needed. Ebay is your friend here.

 

Regards, Hugh