New lathe control design from scratch. Questions:
- parkerbender
- Offline
- New Member
- Posts: 4
- Thank you received: 0
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
Please Log in or Create an account to join the conversation.
Welcome to the forum.
I'm guessing you don't have a wiring diagram... to start with the +-10v control wires will be tiny like 24 gauge most likely. You can use a 1.5 volt battery to "drive it around' if you can figure out what wires do what. On the axis drives what ever you do don't disconnect the feedback tackos from the motors to the drives if you have that type or it will run away.
I used the same Mesa hardware to convert my Hardinge CHCN lathe. Make sure you do a latency test on the motherboard for an extended time like overnight. With the 5i20 you don't need a base thread (which is good) but you want to make sure you don't have some hardware issues that would cause you a huge spike in latency.
Take some photos of the drives and post the model numbers if you can figure that out then maybe someone can chime in on what is what.
Trace the wires from the drives back to the control to reduce the number of guesses to a few.
Sounds like an interesting project for sure... looking forward to some photos.
John
Please Log in or Create an account to join the conversation.
- parkerbender
- Offline
- New Member
- Posts: 4
- Thank you received: 0
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
Please Log in or Create an account to join the conversation.
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.
Are the existing servo drives dead? I would imagine that keeping the PSU and drives and using EMC2 to control the existing drives might be the cheapest and best solution.
Please Log in or Create an account to join the conversation.
- parkerbender
- Offline
- New Member
- Posts: 4
- Thank you received: 0
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!
Please Log in or Create an account to join the conversation.
I'm really wanting to replace all of the 33 year old electronics in this machine that I can.
OK, that makes a certain amount of sense.
A good source of advice might be Skunkworks, as he is retrofitting a 1964 CNC mill.
You probably want to run the servos at their rated voltage, or they will run linearly slower than spec, so your 150V servos will top out at around half their rated speed at 80V.
I wouldn't really recommend those Leadshine drives either, as they appear to be step/direction drives which means that the position control loop is closed inside the drive (and will need tuning with the software mentioned in the advert, which probably won't run under Limux).
EMC2 works best with "dumb" drives, where only the power electronics is in the drive, and it gets a "how much" and "what direction" signal from EMC2. Then all the position calculations are done in the EMC2 PC, where you can alter them on the fly, and watch them all in Halscope.
For around the same price as those eBay drives you could buy this from Pico Systems
pico-systems.com/pwmservo.html
Or for $300 (but which will run two axes at a time) the 7i29 from Mesa
www.mesanet.com
Both Pico and Mesa systems are well supported by EMC2 and are very much tried and tested.
Please Log in or Create an account to join the conversation.
- parkerbender
- Offline
- New Member
- Posts: 4
- Thank you received: 0
Here's hoping I'm understanding you right!
-Parker
Please Log in or Create an account to join the conversation.
Well you would need some 3mm stand offs to mount the cards and some 50 pin ribbon cables (don't forget to order them) to go between your 7i29's and the 5i20 and depending on how much I/O you have a 7i37TA or two. Maybe PCW can chime in and confirm how the two 7i29's share the 50 pin cable to the 5i20.
John
Please Log in or Create an account to join the conversation.
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.
Please Log in or Create an account to join the conversation.
You need a suitable power supply, but then you probably have one.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
Please Log in or Create an account to join the conversation.