hybrid steppers

[Muzzer]

You can now buy clones of the Leadshine closed loop stepper ("Integrated Easy Servo") - the ones with the stepper drive and encoder all integrated together on the motor. I've only used the genuine Leadshine parts but if these clones are any good, they would be a pretty good option for the money.

[Boyan Silyavski]

This Hybrid stepper is driven at 36VDc and we all know it must be driven at 70VDC and 4.5A , so-I dont think so.

I dont see a benefit in a hybrid stepper anyway. Prefer servo motor or a plain stepper.

is there any gearing intended in the CNc kit? if it was me I would prefer my mini CNC mill geared, so be able to do really precise stuff. So no direct drive.


This seems a very good machine, dont be too savy, do it properly and it will serve you right for life.

[komatias]

Hi Rob,

didn't take you long :D

You are aware of my kits are in development right? They are made to accept Nema 23 motors with a 2:1 gearing ratio for the exact reason Boyan says.

4Nm would be more than sufficient and to keep the costs down, I would also recommend going with plain steppers. Did use leadshine steppers on my KRV converstion and the cost/benefit was questionable really.

Best spend money on good ballscrews in my opinion.

R's

[Muzzer]

About gearing down steppers - the torque falls off very rapidly with increasing speed, so gearing the motors down 2:1 probably doesn't actually improve the torque to speak of, yet you will half the maximum speed. Hmm, that's actually made things worse. If you plot the power against speed, you will see that steppers are generally close to constant power, so gearing them doesn't help a lot. It's different for servos which have lower torque but a much better constant torque range, so benefit from gearing down.

If you are looking for good resolution, go for a driver that can achieve proper microsteps (but not too many of them). Or possibly a motor / driver that has an encoder so that it does what you are asking. Oh, wait a minute....

With a 2.5mm leadscrew and 200 steps (no microsteps), you'd get about 12um per step. With only a few microsteps you will be well past what a machine of this build can achieve. You'll be doing extremely well to get under 5um surely?

[magicniner]

About gearing down steppers -

Acceleration and deceleration 'n' stuff ;-)

[komatias]

About gearing down steppers - the torque falls off very rapidly with increasing speed, so gearing the motors down 2:1 probably doesn't actually improve the torque to speak of, yet you will half the maximum speed. Hmm, that's actually made things worse. If you plot the power against speed, you will see that steppers are generally close to constant power, so gearing them doesn't help a lot. It's different for servos which have lower torque but a much better constant torque range, so benefit from gearing down.

If you are looking for good resolution, go for a driver that can achieve proper microsteps (but not too many of them). Or possibly a motor / driver that has an encoder so that it does what you are asking. Oh, wait a minute....

With a 2.5mm leadscrew and 200 steps (no microsteps), you'd get about 12um per step. With only a few microsteps you will be well past what a machine of this build can achieve. You'll be doing extremely well to get under 5um surely?

All very true. more speed less torque. The torque however is more important at the low speeds for acceleration and deacceleration purposes. When you are steady state, you should be ok if you do not want to be running at high rapid speeds.

2.5mm leadscrews would be a waste of time imo. A CNC conversion would need to be run on ballscrews and those are easy to find in 5mm pitch.

You can of course still gear it 1:1 through a belt to retain the handles. I know I used them shitloads on my kneemill conversion.

It all comes down to personal preference.

The voltage you run your motors on will largely depend on your drivers too. I think my original set of drivers from cnc4you disliked being run at 70V so had to get a 48V supply.

[Muzzer]

This Hybrid stepper is driven at 36VDc and we all know it must be driven at 70VDC and 4.5A , so-I dont think so.

I dont see a benefit in a hybrid stepper anyway. Prefer servo motor or a plain stepper.

Sorry I bothered to offer an opinion. Seems you have an expert here who knows all the answers!

It didn't know that "it must be driven at 70VDC and 4.5A" - that must be a universal truth I wasn't aware of. Sounds as if it will be a hell of a beast. Motors as big as the machine itself.

[Boyan Silyavski]

Sorry I bothered to offer an opinion. Seems you have an expert here who knows all the answers!

It didn't know that "it must be driven at 70VDC and 4.5A" - that must be a universal truth I wasn't aware of. Sounds as if it will be a hell of a beast. Motors as big as the machine itself.

Now you know.

[Robsuffolk]

Thanks all for the advice it's helped a lot in my research.
Hi George, it was always the intention to convert as the first project been fun machining the mounts for the CNC conversion on it. Yes i was aware of you plans for the kit but quite enjoying the process of the conversion.

Think i've come to the thinking of nema23 3Nm steppers on the x-y and Nema 34 4Nm on the Z, C5 1605 ballscrews on all axis with double ballnut i'll direct drive to start of with to to see how it goes may change to being belt driven in future from Zapp. Leadshine 808 or 828 stepper drivers. Intention is to run LinuxCNC.
Does that sound like a sensible approach?
Thanks in advance
Rob

[Snapper]

I have steppers with encoders fitted to the shaft on my lathe. The real benefit is when you reference off the switches at power up they repeat to 0.00mm every time, so no need to touch off at the beginning of the day to account for the error in the switch. And as the spindle is encoded too, threading.