Step, Stepper, Stepping Motors:

Ah, yet another interesting set of subjects. Voltage, current, impedence, resistance, holding torque, running torque, full step, half step, one-eighth step, etc...

Ebay is a popular source for step motors (can be a good one too) but beware!! Do the homework, do the math, and if you are over your head and unsure, then by all means go ahead and ask us!! We're here to help. Let us know what you found and what you want to run it with and we will let you know how it will perform (in our honest opinion).

We prefer Pacific Scientific motors because they are the best when it comes to step motors. They are on a level all by themselves. Must be lonely up there! But even their motors will not perform as desired when they are mis-matched to the drivers powering them. (although they are somewhat forgiving)

Motor choice is a multi-faceted decision that is governed by a quantity of variables. As you begin to convert each variable to a known, you narrow down the available motor choices until the decision becomes quite obvious to solve. It helps to have an overview of what you expect from the machine. Following are some variables to convert to begin the process:

1. Materials to be machined. On the smaller desktop equipment this needs to be a realistic look at "What will I actually be running on this machine?" "What is the spindle capable of?" "Is the machines base rigid enough for that?" There is no point coupling NEMA42 motors to a micro mill. Think of the relationship of motor size on the full size production machines.
2. Ball screws vs. lead screws. The stock leadscrews on these machines are typically 16 - 20 threads per inch. To go 30 inches per minute, you need to spin the lead screw 480 - 600 rpm. The ball screws in our kits are 5 turns per inch. To travel 30 IPM you need to turn the screw 150 RPM. Keep in mind, step motors generate the greatest amount of torque at 0 RPM.
3. How fast do you really need to move the machine? Most cutting on these machines will be with fairly small DIA mills and the spindle speed limitations will hold back the feed rate. As for rapid traversing, well 60 IPM is one inch per second. If you have 12 inches of travel ... Is this a production machine?

Following, we list some recommended motors to compliment our

driver/controller packages. We can provide them if you wish, complete with cables and connectors, hence the prices that reside with them. Or you can look around and let us know what you found elsewhere and we will make recommendation based on that. We are not a step motor manufacturer nor are we able to purchase huge lots of them so you may be able to do better than our prices but remember, matching the motor to the driver is the key.

Steppers and Prices:

All motors are brand new, (no surplus)

Pacific Scientific Motors:(all are powermaxII series)

pac sci motors have a 14-21 day lead time.

• M21A  NEMA23, 142 oz/in enhanced mag., 2.8 Amp series connection, 2.8 mH phase inductance, single stack, double shaft, step motor.  $TBD ea
• P22C NEMA 23, 203 oz/in standard mag., 3.1 amp parallel connection 3.9 mH phase inductance, double stack, double shaft, step motor.  $TBD ea
• P22D NEMA23, 203 oz/in standard mag., 2.5 amp parallel connection, 6.2 mH phase inductance, double stack, double shaft, step motor.  $TBD ea
• M22C NEMA23, 253 oz/in enhanced mag., 2.3 amp series connection, 6.8 mH phase inductance, double stack, double shaft, step motor.  $TBD ea

Inquire about other PacSci winding choices.

Link to Pacific Scientific's stepsel document.(1.67MB)(great info)

Link to Pacific Scientific's PowermaxII Install Bulletin.(655KB)

Non-Pacific Scientific Motors:

These step motors are all imported single shaft NEMA23 size.(4-7 day lead time)

• SM-023-276 276oz/in 3.2V 2.8Amp 1.13ohm 3.6mH $47.00ea (double stack)
• 
• SM-017-083  83 oz/in NEMA 17 2.0amp   $27.00 ea

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