[Iron-Man]

I'm starting a scratch-build. It will be a dedicated purpose tiny desktop CNC lathe. It will be probably smaller than a HF mini lathe but weigh twice as much. This will not be a hobby machine. It will be putting in serious hours. I want it to be fast, accurate, rigid, robust.

I am debating about what motors to put on it. I would like to save money where possible. AC servos would be ideal but they're expensive. There are some ridiculously cheap ones on eBay, $150 for 500W motor + drive. I assume they're crap and should be avoided, but thought I would check here and see if anyone has used them and had anything to say.

Also considering the hybrid stepper w/ encoder feedback option. Never used those, are they any good? Can they hold their own against an AC servo?

Also considering DC servos. I would have no qualms using DC servos but I can't seem to find any. Where can one buy decent DC servo motors?

BLDC? I know very little about them other than they seem to have much lower torque specs than the other motor technologies for a given size. I have that notion only after a cursory glance, I could be way off.

This will be a LinuxCNC machine, and I'm considering using one of the Mesa boards to drive the servos. Does anyone have anything to say about their motor driver boards? 8i20, 7i39, 7i32, 7i54, etc. etc.?

This will 100% absolutely have closed loop control no matter what motors are chosen.

Hello Strantor

I refitted a Denford NovaTurn with IBOB2, AMD GizmoSphere I, Yaskawa SGDA 01AS Servos, Mesa 6i25 / 7i77. Pathpilot is the control. Analog +- 10V fully closed loop.

See my work here; https://www.cnczone.com/forums/bench...754-cnc-2.html

More is posted on the Denford site; NovaTurn Servo retrofit AMD Gizmosphere iBOB2 PCIe x1 - Denford Software & Machines

As far as servos go, ebay can be an excellent resource for industrial drives (Yaskawa, Allen Bradley, Mitsubishi, Omron, etc. The only downside is that you may have to wait, to find good deals.

Hope this gives you some ideas.

Iron-Man

[strantor]

Hello Strantor

I refitted a Denford NovaTurn with IBOB2, AMD GizmoSphere I, Yaskawa SGDA 01AS Servos, Mesa 6i25 / 7i77. Pathpilot is the control. Analog +- 10V fully closed loop.

See my work here; https://www.cnczone.com/forums/bench...754-cnc-2.html

More is posted on the Denford site; NovaTurn Servo retrofit AMD Gizmosphere iBOB2 PCIe x1 - Denford Software & Machines

As far as servos go, ebay can be an excellent resource for industrial drives (Yaskawa, Allen Bradley, Mitsubishi, Omron, etc. The only downside is that you may have to wait, to find good deals.

Hope this gives you some ideas.

Iron-Man

Nice! Similar story...

I'm a Controls Engineer; I design control systems for industrial process equipment (conveyors, palletizers, extruders, etc.) and CNC is more of a hobby. But people usually assume I'm some sort of "whiz" or "hacker" and throw random stuff at me. Just so happens I had a customer with a Denford NovaTurn he got at auction. He couldn't run it because it didn't come with the license floppies. He sent me home with the PC and wanted me to "hack" it. I told him I would evaluate it and see if what could be done. I spent a couple of hours and came to the conclusion that it needed a retrofit. I offered to quote him, told him it would probably cost more than the machine was worth, and of course he declined. I think he sold it on eBay. Maybe you bought it?

[Iron-Man]

Nice! Similar story...

I'm a Controls Engineer; I design control systems for industrial process equipment (conveyors, palletizers, extruders, etc.) and CNC is more of a hobby. But people usually assume I'm some sort of "whiz" or "hacker" and throw random stuff at me. Just so happens I had a customer with a Denford NovaTurn he got at auction. He couldn't run it because it didn't come with the license floppies. He sent me home with the PC and wanted me to "hack" it. I told him I would evaluate it and see if what could be done. I spent a couple of hours and came to the conclusion that it needed a retrofit. I offered to quote him, told him it would probably cost more than the machine was worth, and of course he declined. I think he sold it on eBay. Maybe you bought it?

I purchased my machine back in 2014. It had no computer, control box, turret or disks. Just the machine.
I have been searching for the Denford Turret for years with no luck. One came up on ebay a few months ago but was purchased by someone immediately.
I finally have a back turret in which I am working on a lathe control board and a 8 position encoder using hall-effect devices, interface. It looks just like the one in the video except it has a stepper motor. The turret was made by David Decaussin, I believe: https://www.youtube.com/watch?v=UubzocrQ1ew

It is bi-directional, I may change to a brushless or AC servo.

Iron-Man