I am new to Mach3 and setting up a mill. I inherited a mill and I am in the process of putting it back together. I am a little confused; frankly I do not want to make a mistake and screw anything up.   The X and Y  Acme 3/4" x 6tpi and the Z has a 1/2" at 10tpi.    The y axis is driven by dual lead screws and has to belts running from the motor to the left and the right lead screw.  I am not sure how to do calculation.  The timing pulley has a pitch of .375, 10 grooves and a belt width of .5. Attached are some photos.

If there is anyone who can help me out it would be greatly appreciated. I really want to get this machine up and running. 

Thanks so much for your time.

Ok if the pulleys are the same on both the motor and screws then you can disregard them as it will be 1:1 gearing.
Few other pieces of info needed
Are they steppers or servos? If steppers what  stepping are the drives, if servos what is the line count of the encoder.

Hood

Hood,
Thanks for the quick response.  First off  they are stepper motors; not to sound like a complete idiot but how do i find out the step of the drives?  I will give you all the information I have:  Nema23 mounting 497 oz Dual shaft Stepper Motor and 360 is 4 full steps. The driver is a xs-3525/8s-3 purchased through www.xylotex.com. 

OK just had a look at the manual for the drives, they can be set full, half quarter or eighth step, suggest you probably go for eighth step.
So calcs would be for X and Y
200 steps per rev of motor x 8 for microsteps = 1,600 steps to turn motor 1 rev
Screw needs 6 turns to move 1 inch
Motor is connected 1:1 with the screw so 1,600 x 6 = 9,600 steps per inch

Z axis

200 steps per rev of motor x 8 for microsteps = 1,600 steps to turn motor 1 rev
screw needs 10 turns to move 1 inch
Motor is connected 1:1 with the screw so 1,600 x 10 = 16,000 steps per inch


Hood

Thanks so much Hood!

Your a lifesaver!

Just reading again where you say

360 is 4 full steps

Not sure what you are meaning by that, steppers are usually 1.8 degree (200 steps per rev) or sometimes 0.9 degree (400 steps per rev)
If your motors are 400 steps per rev then you will need to double the above Steps per inch numbers.
Hood

Ok, let me explain...

I am looking through a bunch of stapled sheets of paper that were poorly organized by the previous owner. On one of the pages it has a table which now after going over more thoroughly I believe is part of the packet of information on xs-3525/8s-3. On this table it has a header of Step Sequencing and goes through headers that read full, half, quarter, eighth, angle, note: and underneath these columns  consist of numbers. At the bottom of this table reads 360 is 4 FULL steps. I put that in the post because I thought it was relative information. I am not sure if I am taking out it of context  of if it pertains to what we are looking for.   

Ok no problems, I would try at the first number I gave as 1.8 degree steppers are the most common, if it only moves half the distance expected then looks like they are 0.9 degree stepper so you would need to double the steps per unit and it should be fine.
Hood

thanks you for your time.