Gearbox reduction ratio calculation for EQ3-2 motor drive

[JamesF]

Work has been tedious this afternoon, so during a break I split the gearbox from my spare DEC drive and photographed all the gears so I could count the teeth in gimp by putting a blob on each tooth as I counted. Here are the results:

Motor out: 12

Gear 1 in: 30, out: 14

Gear 2 in: 42, out: 14

Gear 3 in: 28, out: 14

Gear 4 in: 28, out 10

Final drive in: 40

I make that to be reduction ratios of 30/12, 42/14, 28/14, 28/14 and 40/10, or 5/2, 3, 2, 2 and 4, giving a total reduction ratio of 120:1.

Does that look right?

James

[AstroTux]

Work has been tedious this afternoon, so during a break I split the gearbox from my spare DEC drive and photographed all the gears so I could count the teeth in gimp by putting a blob on each tooth as I counted. Here are the results:

Motor out: 12

Gear 1 in: 30, out: 14

Gear 2 in: 42, out: 14

Gear 3 in: 28, out: 14

Gear 4 in: 28, out 10

Final drive in: 40

I make that to be reduction ratios of 30/12, 42/14, 28/14, 28/14 and 40/10, or 5/2, 3, 2, 2 and 4, giving a total reduction ratio of 120:1.

Does that look right?

James

Not to me. You quote 30, out 14: for the first gear but use 30/12 in your calculation. Maybe you should check again - I know it's difficult 'cos I've been doing a lot of gear calculations recently and it's very easy to get numbers muddled up .

[AstroTux]

Sorry, didn't realise that you were using the motor out as the first link . I think you are right as my calculations also make this 120:1.

[JamesF]

Jolly good. In that case I just need to work out my own system to replace it with a roughly similar reduction ratio then. Hardly any wonder there's so much backlash when there are six spindles involved.

James