The Servo Motor Hype

[tauscnc]

Hey guys,

My stepper motor died after falling off the table..no joke..its locked and death.

So I was thinking of going to a servo setup with Geckos. My question is are servo motors REALLy better then steppers? I have read that they are not anymore accurate then steppers and require more wires/tuning to work.

Do servo motors keep there torque thoughtout their rpm? I know my steppers lose torque as the rpms go up.

So what to do??? Buy a new stepper or just get new servos with Geckos?

There has to be some reason that servo motors are "higher end."

thanks
taus

[DerekZahn]

> My question is are servo motors REALLy better then steppers?

As with most things, people have different opinions on what "better" means.

> I have read that they are not anymore accurate then steppers and require more wires/tuning to work.

I think this is "basically" true if you have a good reliable microstepping stepper system, but it depends on the resolution of the encoder on the servo, which could be of arbitrarily high precision. The advantage of a servo system regarding accuracy that it is "closed loop" -- because the actual motor position is read back by the electronics there are no "missed steps" like you can have with a stepper system.

It's possible to make a stepper system closed loop also, though that adds significantly to the expense.

If your stepper system is a decet one that has enough power it should give you plenty of accuracy (to the point where you'd have to have an amazingly accurate machine mechanically to have the stepper resolution be a limiting factor).

> Do servo motors keep there torque thoughtout their rpm? I know my steppers lose torque as the rpms go up.

This is one of the biggest benefits of a servo system. Most servos are capable of producing their "rated torque" throughout their "rated speed" range. Sometimes there will be a falloff at the very highest rated speeds. Between the feedback and the nice high speed torque, servo systems are capable of maintaining their accuracy to quite high speeds.

> So what to do??? Buy a new stepper or just get new servos with Geckos?

Sorry, can't really answer that. If you were happy with your stepper system, just replacing one stepper motor is likely a lot cheaper and easier than switching to servos.