astronomerroyal
New Member
Greetings,
The goal:
I'm trying to build a motorized gimbal mount for my (fairly hefty) SLR camera. The purpose of the mount is to pan and tilt according to a programmed trajectory while taking images for a time lapse movie.
I have to build this more-or-less from scratch as it will eventually need to be highly programmable. So no off-the-shelf motorized telescope mounts. 1.8degree stepper motors are too coarse for direct-drive and so need gearing down. Microstepping might almost work (I've not tried this) but the motor must NOT be energized between shots as the 12v battery must last for hours. therefore, I'm fairly sure I need a gearhead.
So far:
Currently I have a one-axis microcontrolled prototype; one NEMA23 sized unipolar stepper-motor that directly turns a rotary table's handle. Exactly like this,
**broken link removed**
The rotary table's worm-gear provides a gear-down of 36x, so the final single-step resolution is 1.8deg (from stepper) / 36 (from table) =0.05degress. Barely adequate resolution, very heavy, only one axis, and the table gets so stiff from grease viscosity at freezing temps that everything locks up.
The solution?
Ideally I want to end up with something like this,
YouTube - 2 Axes Gimbal Mount
I understand that using bipolar steppers will provide more torque than unipolars - I wasn't entirely blown away with the torque my nema23 unipolar supplied. As for resolution, can I buy small 'worm gearheads'? I'm not familiar with gear assemblies and the terminology, but I need to gear down by about 100x, ideally more. Also needs to remain in position even when motor is off, which I believe a worm gear is especially good at. Perhaps stick these on something like this,
Bogen / Manfrotto | 393 Heavy Duty Gimbal Type Telephoto | 393
Particularly interested in hearing your thoughts about 'gearheads', how to select them and where to find them.
The goal:
I'm trying to build a motorized gimbal mount for my (fairly hefty) SLR camera. The purpose of the mount is to pan and tilt according to a programmed trajectory while taking images for a time lapse movie.
I have to build this more-or-less from scratch as it will eventually need to be highly programmable. So no off-the-shelf motorized telescope mounts. 1.8degree stepper motors are too coarse for direct-drive and so need gearing down. Microstepping might almost work (I've not tried this) but the motor must NOT be energized between shots as the 12v battery must last for hours. therefore, I'm fairly sure I need a gearhead.
So far:
Currently I have a one-axis microcontrolled prototype; one NEMA23 sized unipolar stepper-motor that directly turns a rotary table's handle. Exactly like this,
**broken link removed**
The rotary table's worm-gear provides a gear-down of 36x, so the final single-step resolution is 1.8deg (from stepper) / 36 (from table) =0.05degress. Barely adequate resolution, very heavy, only one axis, and the table gets so stiff from grease viscosity at freezing temps that everything locks up.
The solution?
Ideally I want to end up with something like this,
YouTube - 2 Axes Gimbal Mount
I understand that using bipolar steppers will provide more torque than unipolars - I wasn't entirely blown away with the torque my nema23 unipolar supplied. As for resolution, can I buy small 'worm gearheads'? I'm not familiar with gear assemblies and the terminology, but I need to gear down by about 100x, ideally more. Also needs to remain in position even when motor is off, which I believe a worm gear is especially good at. Perhaps stick these on something like this,
Bogen / Manfrotto | 393 Heavy Duty Gimbal Type Telephoto | 393
Particularly interested in hearing your thoughts about 'gearheads', how to select them and where to find them.