Calculations needed for spur gear drive


Tom Gideon
 

Hi,
I'd like to configure a system for (ok...) a Criterion 4000. It's been refurbished and the optics are actually good. The main gear is a 217 tooth 48P gear being driven by a 13 tooth gear attached to a .75 RPH motor. I had to replace the motor with a 220VAC unit and I'd just as soon do away it.
I've been trying to figure out what stepper motor configuration would work and I'm stuck. Any help would be appreciated!
Thanks,
Tom


Khalid Baheyeldin
 

Gear pitch is not important as long as both gears are the same.

The spreadsheet has two RATIOS since most mounts have two stages of reductions.
If your mount only has one gear reduction stage, then just enter 1 in the other.

If your mount has 13 teeth to 217 teeth, and nothing else, then use GR1 = 1,
and GR2 = 217/13 = 16.692.

This reduction is not enough even with a 400 step motor (0.9 deg), and 1/32 microsteps.
So you'd better use a geared motor, and enter that ratio in GR1.

For example with a 50:1 gearbox:

200, 32, 50, 16.692 = 14,837.333

If your goal is visual observing only, then less reduction may work.


Tom Gideon
 

Great!!

Thanks,
Tom

On Jul 22, 2021, at 9:24 AM, Khalid Baheyeldin <kbahey@...> wrote:

´╗┐Gear pitch is not important as long as both gears are the same.

The spreadsheet has two RATIOS since most mounts have two stages of reductions.
If your mount only has one gear reduction stage, then just enter 1 in the other.

If your mount has 13 teeth to 217 teeth, and nothing else, then use GR1 = 1,
and GR2 = 217/13 = 16.692.

This reduction is not enough even with a 400 step motor (0.9 deg), and 1/32 microsteps.
So you'd better use a geared motor, and enter that ratio in GR1.

For example with a 50:1 gearbox:

200, 32, 50, 16.692 = 14,837.333

If your goal is visual observing only, then less reduction may work.