Three 232-180-DB's getting a little morning Mendocino sun before their long, long flight to Bangalore.

Motors & Drives Reference Library
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F.A.Q.s: [Power Supplies] [Computer Interface] [Wiring & R.F.I.] [Racks, Screws, Belts, & Gears]

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Stepping Motor Basics

Introduction to Step Motor Basics (5.5K)
Speed-Torque Curve Basics (12.7K)
Mid-Band Instability (7.7K)
Motor Power Basics (10.9K)
Motor Heating (7.3K)
Accuracy and Resolution (14.1K)
Choosing a Motor (5.8K)

Please note: Effective 01/09/02, support for legacy GeckoDrive documentation will cease. Please contact your distributor for replacement files, and thank you.

Mechanical Drawings

Nema 11 w/leads (in)
Nema 11 w/connector (in)
Nema 17 w/connector (mm)
50mm motors w/leads (mm)
Nema 23 w/leads (in)
Nema 23 w/leads (mm)
60mm motors w/connectors (mm)
Nema 34 with/leads (in)
Nema 34 with/leads (mm)
Nema 42 w/leads (in)
Nema 42 w/leads (mm)

Additional Resources

Step and Resolution charts for 10 microstep drives will give your an idea of what you can now do today with off-the-shelf components. Resolutions down to 0.5 microns are illustrated.

Size-It! is an online program in developement by the site author, and must be considered to be in the Beta testing stage. It has a long way to go ... just getting time to work on it ... well, you know how it is. I invite your comments, criticisms, and suggestions. It does not yet figure in torque for sinusoudal or trapezoidal ramp acceleration profiles. Figure five or eight times the acceleration torque it puts out for your axis inputs.

Lots of Graphs. Get an idea of the general correlations between torque and speed. With steppers and servos, aside from fine resolution you incorporate into your design, we talk alot about getting from one place to another quickly to do work. Rapid movements such as those found in pick and place machines, robotics, printed circuit board drillers, routers, N.C. punches and the like, need fast rapids.

With the DD2000, you just pick the leascrew that gives you the reslolution want and direct drive it. That's pretty straight forward. That done, getting from work position A to work position B is the next consideration. Too big a motor will slow you down and waste energy and time, and one too small will not do your ramp profiles without loosing steps. Some graphs even show a notable performance difference even between motors which are of the same frame and stack size, but with different coil amperages.

In the final analysis, use what is known to work. The micro's like the Sherline's and Max-mills scream with the 180's, like those in the photo above. The mini's in the 150 to 400 pound range will kick butt with the 297 oz/in 60's, and the larger mini's work well with the 388's. Bridgeports, and their myriad of copies should use at least a double-stack Nema 34. Now with the advent of the DD2000 drive, triple stack 34's are viable for the X and Y axis on the 2,500 to 3,500 pound machines, now getting 0.0001 resolution without belts, pulleys, chains, and so on.

On the high power end, the little DD2000 will drive the Nema 42 2,690 oz/in Brute without a hitch. It (the 426-2690-SB) runs at 6 amps. Pretty amazing ... a little 2.8 ounce drive cranking a 23 pound triple stack Nema 42.

The F.A.Q. I will be putting one up very soon. But I want to answer a couple of questions which have been asked most recently.

Q: Will the Dolphins power my uni-polar motors? Yes, if your motor can draw at least one ampere from the drive. See the Motor Connections document for connections to a 6 or 8 wire uni-polar motors.

Q: Do you have something like the DD2000 available for brushed D.C. Servos? No. Losing steps is preventable with appropriate design criteria. The display will tell you which of the seven resolution tables you are using, or other drive diagnostics when a fault condition occurs. Serial data out for external position displays, or feedback to your interpreter/indexer software, is available at pins 1 through 4 on J2.

Q: Will the Dolphins run off of solar panels? Yes. Your panels must provide the necessary power to the drive, just like you were using a conventional linear or switching supply. The Dolphins must see a minimum 12 VDC source, and provide the current necessary to power your motor(s). Photovoltaic power souces are quite unique in that they want to work at a voltage which is dependant upon the load resistance.

For example, you can charge a 2 volt battery with a 12 volt panel all day without any harm to either. However, the panel will only be putting out 15% of it's capacity to the battery. Solar panels work best at their PPP, or Peak Power Point. Every panel has a PPP, and that is what you want your panels to see as a load. Power is WATTS, and that is what you want to convert into motion, and work, with your motors.

Your motors only have a very low resistance. As a direct load, they will not even come close to making an array Work. (Low voltage panels used for remote anodic protection systems do not put out sufficient voltage) The solution is very simple. Put some rechargable batterys in parallel so the solar panel array sees a load which makes it work towards its Peak Power Point. Forget capacitors; they have a very limited ability to store energy, as that is what they are designed for.

For remote and show applications, I reccommend gelcells, similar to those used in emergency lighting systems, and the majority of better alarm systems and UPS products. They transport easily, and don't spill :-) Panels are rated in Watts, at their Peak Power Point. Three 75 watt panels will give you about 5.5 amps at 42 volts. If this interests you, either for Zambia or the County Fair, size accordingly for your machines amperage requirements. Remember, You must make the array work at a voltage which produces the most current; the Peak Power Point. That is WATTS solar panels are all about!

Your spindle or headstock motor could also be powered by a common array, as long as the array supplies adequate power to run all of your loads. Having gelcells in parallel with your array gives a marvelous boost to a systems peak power capability. They are like giant capacitors, only 30 times better. Steppers, which are basically 50 pole brushless motors, can also be used for spindle motors. No brushes to wear out, shorter thermal path (the windings are in the stator), and start-up current requirements are limited by the drive.

For off-grid indexing, an old Compaq LTE 5380 laptop would be my first choice. Cheap, available, and hardy.

A final note on PV power. If you are harnessing the suns energy to make electricity, the last thing you want to do is waste it. The Dolphins use 12 watts max when driving 6 amps.

How do you know this stuff? I designed and intalled AE systems after graduating from ARCO PV school in a previous life. This file you are reading, and the other 3,500+ like it on the MendoNet system, where created using not one single electron of grid electricity.

Note: PDF documents are in English and cannot be translated.

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