PRTMetricUnits

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Metric unit values (Steps per Millimeter):

The PRT4g upgrade and PRSstandard tools use 1/10 stepping Gecko Drives but the PRT tools used several different drivers and could be set to three different microstepping values to give extra resolution. 1/4 stepping divided each step into 4 parts, 1/8 stepping divided it into eight parts, and 1/16 stepping divided each step into sixteen parts.


Once you find the microstepping value for your tool, use that value to select the correct chart below. Then find the correct unit values for your tool in that chart using the gear ratio of your motors and the number of teeth on the pinion gears. The X and Y Axis will be the same but the Z axis will probably have a different pinion size and possibly a different motor gear ratio. Once you've found the correct Unit Values, enter them in the ShopBot Control Software using the [VU] command.



PRT4g and PRSstandard 1/10 Stepping (Gecko Drives)

Number of teeth in pinion
Motor gear ratio 18 20 25 30 36
1:1 27.84863 25.06377 20.05102 16.70918 13.92432
3.6:1 100.25508 90.22957 72.18366 60.15305 50.12754
7.2:1 200.51016 180.4591 144.3673 120.3061 100.2552
10:1 278.48634 250.6377 200.5102 167.0918 139.2432
25:1 696.21585 626.5943 501.2754 417.7295 348.1079


PRT 1/4 stepping

Number of teeth in pinion
Motor gear ratio 18 20 25 30 36
1:1 11.13945 10.02551 8.02041 6.68367 5.56973
3.6:1 40.10203 36.09183 28.87346 24.06122 20.05102
7.2:1 80.20407 72.18366 57.74693 48.12244 40.10203
10:1 111.39454 100.2551 80.20407 66.83672 55.69727
25:1 278.48634 250.6371 200.5102 167.0918 139.2432


PRT 1/8 stepping

Number of teeth in pinion
Motor gear ratio 18 20 25 30 36
1:1 22.27891 20.05102 16.04081 13.36734 11.13945
3.6:1 80.20407 72.18366 57.74693 48.12244 40.10203
7.2:1 160.40813 144.3673 115.4939 96.24488 80.20407
10:1 222.78907 200.5102 160.4081 133.6734 111.3945
25:1 556.97268 501.2754 401.0203 334.1836 278.4863


PRT 1/16 stepping

Number of teeth in pinion
Motor gear ratio 18 20 25 30 36
1:1 44.55781 40.10203 32.08163 26.73469 22.27891
3.6:1 160.40813 144.3673 115.4939 96.24488 80.20407
7.2:1 320.81626 288.7346 230.9877 192.4898 160.4081
10:1 445.57814 401.0203 320.8163 267.3469 222.7891
25:1 1113.9454 1002.551 802.0407 668.3672 556.9727
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