Timing Belt Sizing

Mechanical Inclined CNCers:

Here is my second of three questions.

I'm retrofitting a Bridgeport copy for X & Y CNC. I'm using
785 oz-in steppers with 5A stepper drivers from Camtronics.
I plan to connect the steppers to the ballscrews with timing
belts of 2:1 reduction.

When I run the numbers for a timing belt I find I need a
1.0" wide L belt with pulleys of at least 28 teeth and 56
teeth. This is a driver pulley of 3.3" diam and a driven
(leadscrew) pulley of 6.6" diam. OR, a 1.0" wide H belt
of 14 or 16 teeth/28 or 32 teeth. These have diameters of
about 2.5" and 5.0". The H could be smaller but you run
into number of teeth in contact problems.

I used Machinery's Handbook for calcs. I used a service
factor for machine tools of 1.8. This is probably for a
spindle drive but I don't think excessive for a stepper
motor drive. Stepper motors aren't smooth.

But this still seems excessive. What are others using for
the timing belt reduction on Bridgeport sized machines?

Thank you in advance.

Hugh Currin
Klamath Falls, OR