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#### Konstantin

• 5
« on: February 26, 2006, 03:04:10 PM »
First of all, what is a 'unit' ? That word just messes me up because I cant even imagine what it could be. I mean the way that Mach2 uses the word unit.

Anyway.

My Y axis:
I have a leadscrew that travels 19mm per one turn. I use a XL timing belt (wich is 5.08 mm pitch) and two gears, on the motor  11 tooth and on the screw  21 tooth.
What is the 'Mach2 steps per unit' for this axis? I am using 1.8deg steppers in half step mode so there are 400 steps per revolution.

shaft revs per unit = 1/(5.08*21)
motor revs per unit = (1/(5.08*21) )*(21/11) = 1/5.08*11 = 1/55.88
Mach2 steps per unit = 400 * (1/55.88) = 7.158
Is this correct?

My X axis:
The lead screw travels 3mm per turn. The stepper is directly connected. Half step = 400 steps per revolution.

Shaft revs per unit = 1/3
Motor revs per unit = 1/3
Mach2 steps per unit = 400/3 = 133.33(3)
I am right with this calculations?

Konstantin.

#### Art

« Reply #1 on: February 26, 2006, 04:45:33 PM »
Hi K:

A unit is a mm, or an inch. Depending on what you use and what is set in config/units.

The X for example, is 3mm per turn, 400 steps per turn, so 1200 is 3mm, so  1200/3 is 400 steps/unit..

Thanks
Art

#### Konstantin

• 5
« Reply #2 on: February 27, 2006, 01:59:21 AM »
Art are you sure?
I mean the lead screw advance with 360 deg is 3mm. Not 3 turns to advance 1 mm.

I am getting more confused.

EDIT:
I am using Mach3 also and it looks a bit simpler to input steps per millimeter or inch in motor tuning.

#### Hood

« Reply #3 on: February 27, 2006, 03:24:47 AM »
Motor Revs per unit(mm) = 1/pitch = 1/19 = 0.05263157....
Motor steps per Rev = 200steps x half step x gearing = 200 x 2 x(21/11) = 763.6363.....
Mach steps per unit(mm) = motor rev per unit x motor step per rev = 0.05263157..... x  763.6363..... = 40.191387......

Keep all decimal places on your calculator while doing the calcs so that you dont round up.

Hood

EDIT I forgot to say that you dont need to figure the pitch of your belts teeth into your calcs at all, as it would make no difference to the gearing if it was a 10mm or 5mm pitch on the belt, the pulley sizes are what matter and gives you the reduction.
« Last Edit: February 27, 2006, 03:33:44 AM by Hood »

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