New lathe control design from scratch. Questions:

Hi everyone!

I've been lurking for a bit, but havn't said much here. Anyway, I am starting a new retrofit project on a couple of late 70's Cadillac lathes, with an 8 position toolchanger, Fanuc 200M DC Servos, and existing (but not working) Fanuc 5T controllers. I'm planning on a new computer, controller cards, and servo drives, I'm hoping to use the Thyristor/scr drive for the spindle, and I'm hoping to keep the existing spindle motor and brushed dc servos. The budget isn't unlimited, but I also am not wanting to cheap out. I already have an asus M4A-785M motherboard, and 3.2 Ghz dual core phenom II. I'm planning on mesa 5i20, 7i33ta, and 7i37ta cards. I am not sure about the servo drives yet, I saw a slew of brushed servo drives on ebay when I looked, though. What I'm looking for is firstly, if what I have planned on already is going to work for me, secondly, if anyone has any recommendations on servo drives. Lastly, does anyone know how to control these scr drives for the spindles? I'm pretty sure they'r econtrolled with 0-10vdc, but, how in the world does a guy figure out where to apply it to?

I guess I'm a farm kid, looking for direction and advice. Any takers?

-Parker Bender

Thanks John!

I'm hoping to have the computer awake tonight, and I'll be sure to snap a few shots... Do you or anyone have any ideas about servo drives? The servos are Fanuc ON-2000M drives. I had read somewhere that theyr'e rated 151vdc @9 amps. Do you need to run them at that voltage? I found these servo drives: cgi.ebay.com/Leadshine-DCS810-Digital-DC...&hash=item3f048359b2 (if posting ebay links is a no-no, i apologize, just tell me and i'll take it down quick...) they're only 80 vdc, but they have enough amps. I'd love to get the thing dancing before dumping a slew of money on perfectly matched drives, unless it would be a nightmare to get it running this way... Does anyone have any experience with permanent magnet dc servos?

Thanks again for the warm weldome, I hope I can provide some entertainment!

-Parker

I can't get the machine to move with the existing control, even though it lights up and acts generally happy. I have the parameter lists, and that isn't the problem. I'm really wanting to replace all of the 33 year old electronics in this machine that I can. If I need to hunt down a better/ more expensive set of drives to see movement in this thing, I can do that, but I really really want to be able to rule out as many problems as I can, if I can't get this guy to move. Electronics that are older than myself would be one of those suspected problems... I agree it would be cheaper, but man, these guys just look, and are, ancient. I'd almost rather swap new servos and drives in, than keep the original drives. In synopsis, I just want new electronics. I'd love to have a new spindle drive too, but I'm assuning those cost a mint (for a 15hp motor) and Clevland Machine Controls is still in business, so I'm assuming that there might even be a tiny bit of support from their end.

Thanks for the reply, and the obvious sense it makes. It's just kindof a stipulation of the project, in trying to get the factory control to work for 6 months, I have decided with a retrofit, that all the control electronics are new.

-Parker


...an added benefit, is that if I can get this documented well enough, someone else with a different machine could use the same formula to get their machine up!

Am I reading the page right? That 7i29 will run two servos at 165 volts, 22.5 amps? Is that really all that I need between my controller card and the servo? If I can run my whole system with that H-bridge card, and those three controller cards, all from mesa, for less than a grand, you guys have made my christmas.

Here's hoping I'm understanding you right!

-Parker

The 7I29 is a 2 channel card so one 7I29 is probably all thats needed for a lathe.

For more than 2 channels, two 7I29s can share a 50 pin cable. They use the FPGA servo configurations that put 4 servo axis on one FPGA connector/cable. When two 7I29s are used on one cable, the 7I29s can then jumpered so that one connects to channels 0,1 and the other to channels 2.3 on the flat cable.