10x Micro-step (2,000 s/rev) ... Resolution Charts!

The vast majority of stepper motor torque charts are plotted against pulses per second (PPS) for full step driving of the motor. For bipolar steppers, you can divide the "Full-Step" PPS number by 200 to arrive at the Revolutions Per Second (RPS) for that torque curve.

The R.P.S. (Revolutions Per Second) will generally be approaching your minimum required torque for rapid traverse move profiles, well before approaching 200K pulses per second. The charts below will illustrate your resolution and speed capabilities avaiable when changing from a full or fractional step drive, to a 10 microstep drive, like the DD-2000 or G201A.

Remember, the charts below are only for the 2K resolution table. Rapids can be incredibly accellerated by moving to a coarser table on-the-fly, all the way down to full-stepping (200p/rev) on drives that offer that option.

The obvious advantage of utilizing a programer friendly resolution such as 0.0001 inches, is the implementation of direct drive to your leadscrew which eliminates pulleys and belts, chains and sprockets, gears and the like. Transmission losses, noise, design envelope, maintainence, saftey concerns, assembly time, and parts count and inventory are all reduced.

Best of all, your low speed moves will be markedly smoother and quieter. The inherent resonance of a bipolar stepper is virtually eliminated, because each full step is broken down into ten micro-steps.

The charts following below illustrate the relationship between R.P.S. and feed/rapid rates for some of the more commonly used leadscrews and ballscrews. The charts also illustrate the ability of drives like the DD-2000 and G201A to move your work at rapid speeds only limited by your motors' speed/torque specs, software, and your imagination.

but first ...

A step motor is a mechanical device that is manufactured to a certain tolerance. Typically a standard motor has a tolerance of +/- 5% non-accumulative error regarding the location of any given step. This means that any step on a typical 200 step per revolution motor will be within an 0.18o error range. Stated otherwise, the motor can accurately resolve 2,000 radial locations. Coincidentally this is the resolution of a 10 microstep drive.

So what does that mean to you in terms of choosing a drive? Any microstep resolution beyond 10, such as 125, yields NO additional accuracy, only Empty Resolution. By analogy, a voltmeter having a 6 digit display while having a 1% accuracy would have meaningful information only in the first two digits.

There are three exceptions justifying higher resolutions than 10x.
1. The step motor is being run in a closed-loop application with a high-resolution (greater than 2,000 line) encoder for feedback compensation. Normally not done by folks that don't already have legacy servos on their machine :-)
OR
2. The application requires smooth operation at very low speeds (below 5 full steps per second). That translates to less than 1.5 revolutions per minute ... even slow for a conveyor application. A couple of manufacturers tout this use of a stepper, as an "electronic gearbox" and so forth. Typically, they'll run out to about 50K steps/rev, and those guys get a princely sum for their packages. They are listed on Cnclinks .. nuff said :-)
OR
3. Thirdly, where the expected resolution is less critical than say 0.0001" per step, and/or, travel axes inaccuracies are compensated for in the metrics of the solfware, just like programming in a backlash compensation. Drives such as the DD-4350 do a thou per pulse, and metrics for the drive are much simpler, than that of the workpiece expansion itself. At the same time, the DD-4350 can reach down to table 1 and full step for rapids of 1,440 IPM and more. Meanwhile, your workpiece (8 foot dimension) may have grown by a 1/32" while you were cutting (e.g.: steel grows by 6 millionths/inch/degree F, copper 11, aluminum 13).

Now, you could reprogram a DD-4350 to become a DD-2000, but if you only need a 10x drive, then the previous three paragraphs will have no bearing on your needs for precision (one tenth) resolution. Match the stepper to your motion criteria, and your drive to your needs. Now, the DD-4350 is a rack drive anyway so to be clear, the charts below are for leadscrews. I just thought it approriate to amplify on resolutions beyond 10x, and why they are appropriate and useful, beyond the basic caveate above regarding micro-step resolution, for 'precision' motion control.



DD-2000 i.p.m. range with a 5 pitch [0.200/rev] ball or acme screw.
Pulses/Sec.ResolutionR.P.S.R.P.M.FeedsRapids
1000.0001.053.00.6F
5000.0001.25153.0F
1K0.0001.50306.0F
2.5K0.00011.257515F
5K0.00012.515030F
7.5K0.00013.752254545
10K0.00015.03006060
25K0.000112.5750R150
50K0.0001251,500R300
75K0.000137.52,250R450
100K0.0001503,000R600
150K0.0001754.500R900
200K0.00011006,000R1,200
R.P.S. = Revolutions Per Second; Feeds & Rapids are in Inches per Minute; Resolution is in Inches.
The placement of "F"s and "R"s above is just a broad generalization, and depends on your application.
5 pitch ballscrews are available in nine standard sizes from 0.500" up to 2.000" in diameter.
  • For 5mm pitch leadscrews, multiply above resolution, feed and rapid rates by 0.9843
  • For 4mm pitch leadscrews, multiply above resolution, feed and rapid rates by 0.7874




    • DD-2000 i.p.m. range with a 10 pitch [0.100/rev] ball or acme screw.
    Pulses/Sec.ResolutionR.P.S.R.P.M.FeedsRapids
    1000.00005.053.00.3F
    5000.00005.25151.5F
    1K0.00005.50303.0F
    2.5K0.000051.25757.5F
    5K0.000052.515015F
    7.5K0.000053.7522522.522.5
    10K0.000055.03003030
    25K0.0000512.5750R75
    50K0.00005251,500R150
    75K0.0000537.52,250R225
    100K0.00005503,000R300
    150K0.00005754,500R450
    200K0.000051006,000R600
    R.P.S. = Revolutions Per Second; Feeds & Rapids are in Inches per Minute; Resolution is in Inches.
    The placement of "F"s and "R"s above is just a broad generalization, and depends on your application.




    DD-2000 i.p.m. range with a 20 pitch [0.050/rev] Leadscrew.
    Pulses/Sec.ResolutionR.P.S.R.P.M.FeedsRapids
    1000.000025.053.00.15F
    5000.000025.25150.75F
    1K0.000025.50301.5F
    2.5K0.0000251.25753.75F
    5K0.0000252.51507.5F
    7.5K0.0000253.7522511.25F
    10K0.0000255.03001515
    25K0.00002512.5750R37.5
    50K0.000025251,500R75
    75K0.00002537.52,250R112.5
    100K0.000025503,000R150
    150K0.000025754,500R225
    200K0.0000251006,000R300
    R.P.S. = Revolutions Per Second; Feeds & Rapids are in Inches per Minute; Resolution is in Inches.
    The placement of "F"s and "R"s above is just a broad generalization, and depends on your application.
    20 pitch ballscrews and acme screws are avaiable in standard sizes of 0.187 diameter and up.




    DD-2000 mm/min. range with a 2mm pitch [0.07874/rev] Leadscrew.
    Pulses/Sec.ResolutionR.P.S.R.P.M.FeedsRapids
    1001.0 microns.053.06.0F
    5001.0 microns.251530F
    1K1.0 microns.503060F
    2.5K1.0 microns1.2575150F
    5K1.0 microns2.5150300F
    7.5K1.0 microns3.75225450F
    10K1.0 microns5.0300600600
    25K1.0 microns12.5750R1,500
    50K1.0 microns251,500R3,000
    75K1.0 microns37.52,250R4,500
    100K1.0 microns503,000R6,000
    150K1.0 microns754,500R9,00
    200K1.0 microns1006,000R12,000
    R.P.S. = Revolutions Per Second; Feeds & Rapids are in millimeters per Minute; Resolution is in Microns.
    The placement of "F"s and "R"s above is just a broad generalization, and depends on your application.
    For 2.0mm pitch ballscrews and leadscrews, the inch equivalent is just under 4 millionths of an inch per pulse.
    2.0mm pitch ballscrews are available in standard sizes of 8mm, 10mm, 12mm, and 14mm diameters.




    DD-2000 mm/min. range with a 1mm pitch [0.03937/rev] Leadscrew.
    Pulses/Sec.ResolutionR.P.S.R.P.M.FeedsRapids
    1000.5 microns.053.03.0F
    5000.5 microns.251515F
    1K0.5 microns.503030F
    2.5K0.5 microns1.257575F
    5K0.5 microns2.5150150F
    7.5K0.5 microns3.75225225F
    10K0.5 microns5.0300300300
    25K0.5 microns12.5750R750
    50K0.5 microns251,500R1,500
    75K0.5 microns37.52,250R2,250
    100K0.5 microns503,000R3,000
    150K0.5 microns754,500R4,500
    200K0.5 microns1006,000R6,000
    R.P.S. = Revolutions Per Second; Feeds & Rapids are in millimeters per Minute; Resolution is in Microns.
    The placement of "F"s and "R"s above is just a broad generalization, and depends on your application.
    For 1.0mm pitch ballscrews and leadscrews, the inch equivalent is just under 2 millionths of an inch per pulse.
    1.0mm pitch ballscrews are available in standard sizes of 4mm, 6mm, and 8mm diameters.




    10x Microstepping Drives; the Marketplace.
    All drives below claim to be 10x (2Ks/r) drives.
    Mfgr.Model#ResolutionsAmpsVolts4Cu.In.Disp.Price1
    G.D.I.G201A11.0-7.024-805.3618$199.005
    MK.DM8010122-1024-8025.0?2$445.00
    I.M.S.IM100712.0-7.024-8019.7?$450.00
    A.A.MDM1000113?-10324-8022.5?3$435.00
    O.M.S.PMD8M17.024-8034.140$275.00
    I.E.I.DD-2000771.0-6.012-6063.9512$209.00

    Footnotes
    1. Unless otherwise noted, prices are for quantities of one to four units.
    2. MicroKinetics does not publish their resolutions or disapation.
    3. Anaheim Automation does not publish their resolutions or disapation or minumum current.
    4. All the drives below require a user supplied external D.C. power supply for the motor supply.
    5. Was available for $145 US from M.T.C. when last checked.
    6. These drives do not require an external 5v logic supply.
    7. JTAG. Programmable in increments of 50 steps/rev to 4,400, 11 bit.



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