Servo Motor for Spindle

[dneisler]

I read some where on the 'zone about someone using a servo motor for a spindle of there mill.

Is that doable?
Is it worth doing?
How big of a servo would I have to have for my X3 to get about 3k-4k rpm out of my spindle.

I would assume it would driven by a Gecko & mach 3, not sure on how any of this would hook up.

What are the pro's and con's of using suck if it is even possible?

[kreutz]

Originally Posted by dneisler I read some where on the 'zone about someone using a servo motor for a spindle of there mill. Is that doable? Is it worth doing? How big of a servo would I have to have for my X3 to get about 3k-4k rpm out of my spindle. I would assume it would driven by a Gecko & mach 3, not sure on how any of this would hook up. What are the pro's and con's of using suck if it is even possible?

It is possible and has been tested driving a lathe spindle with encoder attached. Look at the following post: Mach controlled spindle

The original thread is: DIY Servo controller , it is a really long thread.

Kreutz.

[dneisler]

Hmm, I thinking of giving this a try, after more research of course.

Would this servo motor work better than my factory X3 motor?
KL34-170-90 (NEMA 34) Dual Shaft, Front
Shaft 1/2" Rear shaft 1/4" 850 oz-in Peak 90V,
$139 Or 72V/40A Specification (Skewed Rotor
Design, Green is Ground, White is +, Black is
Common)

It says 40A so I need a controller that will support 40 amps correct, so the only one I know if is a Rutex, are there others? Gecko shows only 20A.

[kreutz]

Originally Posted by dneisler Hmm, I thinking of giving this a try, after more research of course. Would this servo motor work better than my factory X3 motor? KL34-170-90 (NEMA 34) Dual Shaft, Front Shaft 1/2" Rear shaft 1/4" 850 oz-in Peak 90V, $139 Or 72V/40A Specification (Skewed Rotor Design, Green is Ground, White is +, Black is Common) It says 40A so I need a controller that will support 40 amps correct, so the only one I know if is a Rutex, are there others? Gecko shows only 20A.

Need more information about that motor, most resellers talk about peak torque at maximum current, you can't work with those settings, otherwise you will demagnetize/burn the motor. Normally the marketing data are absolute maximum figures (intermittent rate), and the continuous rating is a lot less in current and torque (deceptive marketing).

Other point is the maximum voltage spec for the motor. If your motor specification is, let's say 4000 rpm at 90 V, it means that 4000 rpms is the no load speed at the maximum motor voltage.

When you use a drive whose maximum voltage is 90 Vdc (for example), your motor will never see those 90 Volts, so you will never get to maximum speed, not even close, it all depends on the maximum PWM limit used on the drive and output stage voltage drop.

Then, there is a safety margin on operating voltage for the drive. Power supply voltage changes with line voltage fluctuation (+/- 15%), add to that the regenerative effect (that increases the power supply voltage when decelerating your motor). So You need at least 20-25% voltage safety margin above the power supply voltage, and you need to find out what the maximum PWM duty cycle for your drive is, in order to calculate the required power supply voltage for maximum speed.

As you see, there are a few important things to think about before selecting a motor/drive combination. What is wrong with your current spindle motor/drive ?

Kreutz.

[dneisler]

I use alot of small tools, and 1950rpm just doesn't work very well. I may just flip the pulleys and give that a try, should result in 5000rpm or so. I need more rpm for 1/16" and 1/8" tools.

[kreutz]

Originally Posted by dneisler I use alot of small tools, and 1950rpm just doesn't work very well. I may just flip the pulleys and give that a try, should result in 5000rpm or so. I need more rpm for 1/16" and 1/8" tools.

I see, what you will probably need is a brushless high speed spindle (10,000 to +20,000 rpm) for small size tools.... A friend of mine uses a router as spindle, it makes a lot of noise, but gets the job done.

Kreutz.

[dneisler]

I am not wanting to go that high, just 3-4k should get me by.

[kreutz]

Originally Posted by dneisler I am not wanting to go that high, just 3-4k should get me by.

That could probably be done as you plan, by flipping pulleys...

[dneisler]

Yeah, just un sure of the power. If it works even a little for small bits, it is a quick change to give me 4 speed settings.

0-1000
0-2000
0-3000
0-6000

The whole other side of this is my work is getting bigger and bigger and more and more of it, I am starting to think about getting a tomach sometime, so one side of me is already thinking...Save Money!

[kreutz]

Originally Posted by dneisler Yeah, just un sure of the power. If it works even a little for small bits, it is a quick change to give me 4 speed settings. 0-1000 0-2000 0-3000 0-6000 The whole other side of this is my work is getting bigger and bigger and more and more of it, I am starting to think about getting a tomach sometime, so one side of me is already thinking...Save Money!

That is good news!!. You must be doing a really good work. Keep on doing it!...

Kreutz.