Quote Originally Posted by JAZZCNC View Post
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.

Quote Originally Posted by JAZZCNC View Post
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.