Some questions to JAZZCNC or any other closed loop stepper experts

[A_Camera]

Thank you once again. I did watch those videos and seen his work (I am one of his followers) but... There is no way I want to compete with Simpson36 or anyone else. I am too old for competitions, just want to have fun and learn something new. My goal is just that. In the end, if I like it, or see a huge need of a real lathe then I'll buy one. To be honest, I don't think my machine will ever be able to be as good as a cheap 800-1000 USD cheap Chinese micro lathe, even though, mine might well end up being more expensive in the end.

Regarding the needed torque, honestly, I don't know what I need. All I know is that the current stepper is labelled 1.8Nm, but that's always holding torque. I don't know what the real torque is at 2280 rpm, which is what the rpm is now when the chuck runs at 380 rpm, but it is enough to drill in steel. This weekend I did some turning tests, which was a disaster but not mainly because of the stepper, but because of the extremely weak cross slide I was trying to use. Anyway, I could only turn soft plastic...

I understand that your link was just an example, not a direct recommendation, but it seems like all 180W servo has about the same parameters. Had a look at JMC servos as well, and also the Stepperonline, but I don't think I want Stepperonline, due to that crazy RS232 enable solution. I don't know how they were thinking leaving out the EN signal and saving one opto coupler, I want a controllable enable/disable, and I don't regard RS232 is equal to that, since I can't use the same signal I am using for the other steppers, so Stepperonline is out of the picture.

The other thing about the torque is that I want to change the gearing from 6:1 to 3:1 or 2:1 (not decided yet which one) to get higher rpm, so if I do that I will lose torque but gain rpm. Anyway, if those servos are really that good, then I could test with 2:1 reduction, which could give me 1500 rpm on the chuck and about the same torque as I have now with the plain stepper, which should be fine to play with, so right now I am very much tempted to try that out. It's not too late yet to take a step up and use NEMA34, but I would prefer not to, because it would mean a huge change. It would also mean that it starts to become too large for my CNC, which means I might as well give up, which I don't want to do at this stage.

Anyway, it is fun to test this this out, even if in the end, I will not use it for anything serious, but of course, it would be more fun if I could use it for something as well.

[JAZZCNC]

It's not too late yet to take a step up and use NEMA34, but I would prefer not to, because it would mean a huge change. It would also mean that it starts to become too large for my CNC, which means I might as well give up, which I don't want to do at this stage.

That would be an expensive mistake, large motors like Nema 34's require lots of voltage to spin fast and by lots I mean 150V+ to get any reasonable speed with torque.

The price of AC servos has come down to such a level that they nearly match High voltage drives which are required to get speed and torque from large steppers. So I would look at those before large steppers.

I have these 600w AC servos on my plasma machine and while only 1.9Nm they massively outperform the 4.5Nm closed-loop stepper motors. Which at just over $200 is a very good price, I would fit these and pay the extra over the JMC or any of those types of DC servo every time. (They also do them with a brake)

https://www.aliexpress.com/item/3304...5be81468ni78om

Like I said before if you are going to go this far then do it right the first time because while digging deep hurts I always find it works out cheaper than experimenting and far less hassle.

[A_Camera]

That would be an expensive mistake, large motors like Nema 34's require lots of voltage to spin fast and by lots I mean 150V+ to get any reasonable speed with torque.

I don't mean stepper, but servo.

The price of AC servos has come down to such a level that they nearly match High voltage drives which are required to get speed and torque from large steppers. So I would look at those before large steppers.

I have these 600w AC servos on my plasma machine and while only 1.9Nm they massively outperform the 4.5Nm closed-loop stepper motors. Which at just over $200 is a very good price, I would fit these and pay the extra over the JMC or any of those types of DC servo every time. (They also do them with a brake)

https://www.aliexpress.com/item/3304...5be81468ni78om

Like I said before if you are going to go this far then do it right the first time because while digging deep hurts I always find it works out cheaper than experimenting and far less hassle.

Yes, but my problem is space, so I would like to avoid larger motors. All AC servos I have seen take up a lot of space, and even though the PSU is just a simple transformer, it does need a large one and that takes space, unless it is driven directly from the mains. At this stage, I'll avoid both for now. If need arise, I may change my view, or like I said before, buy a real lathe, which functionally will most probably be better than what I can build. To be honest, I think it would be more point in upgrading a real lathe with a large AC servo then doing it in my DIY "poor man's lathe" which will probably end up being pretty expensive in the end, I know that, but I want to try, learn and improve incrementally. I know that such approach costs money, but for me it is more fun this way. Starting a huge project to build a perfect and powerful lathe takes a long time and I don't think I have the patience to do that. Also, I am just an amateur "machinist", don't have any real need for this except as a hobby, so I am not at this stage interested in starting a huge project which will never be finished.

I feel that this hobby is like a black hole, it can swallow everything, including ones family life, fortune, space and time, so I must set some sort of realistic limit to my ambitions. I am well aware that this, once ready, will be far away from perfect, but that's OK for me, even if some parts will in the end not be used, or replaced shortly after a test.

Right now, I am aiming at some DC servos, but I think before that decision is made, I will build the X and Z out of real parts, which for me will be based on some HGR20 and HGR15 linear rails plus 1605 ball screws.

[Muzzer]

.....I don't know what the real torque is at 2280 rpm, which is what the rpm is now when the chuck runs at 380 rpm, but it is enough to drill in steel.

Sorry, I hadn't twigged that you were planning on using this motor for the SPINDLE drive. That's probably not the best idea if I have understood what you are planning. I'd seriously recommend you use a proper VFD rather than a stepper or servo drive, which are intended for position control, rather than speed control.

Forgive me if I've got the wrong end of the stick here. I have no desire to criticise so much as help you avoid disappointment. Perhaps Jazz or someone else will dive in here, in the interest of constructive advice.

[JAZZCNC]

Sorry, I hadn't twigged that you were planning on using this motor for the SPINDLE drive. That's probably not the best idea if I have understood what you are planning.

No Muzzer, it's for a 4th axis.

[A_Camera]

Sorry, I hadn't twigged that you were planning on using this motor for the SPINDLE drive. That's probably not the best idea if I have understood what you are planning. I'd seriously recommend you use a proper VFD rather than a stepper or servo drive, which are intended for position control, rather than speed control.

Forgive me if I've got the wrong end of the stick here. I have no desire to criticise so much as help you avoid disappointment. Perhaps Jazz or someone else will dive in here, in the interest of constructive advice.

You have misunderstood the thread. I have a very good VFD and have no intentions to replace that. This is a 4th axis which I experiment with as a lathe / 4th axis combo.