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Author Topic: Kinda lost on servo setup- how can I control?  (Read 1326 times)

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Kinda lost on servo setup- how can I control?
« on: June 08, 2017, 09:32:29 PM »
I'm pretty new to CNC and need some help on getting a machine running.

I recently bought a CNC router and I use Mach3 to run my programs. Works great.

I ended up with a CNC lathe last week, it's in need of an overhaul. Being new to CNC, I assumed that since the lathe was running servos I could just order a set of what the router has and be golden. Wrong. I ordered two gecko320X drives, smoothstepper, c25 terminalboard, and a 1200w power supply. Get into the lathe today and upon further inspection the servos are AC and at .9kw each, I would probably be under powered anyway.

I'm not sure how to proceed. The servos are Fanuc b6/2000 and require:

2) 0V Reference voltage
3) IRC Note) Phase R motor current signal
4) ISC Note) Phase S motor current signal
9) 0V Reference voltage
10) 0V Reference voltage
11) 24VC +24V power
(with tolerance of ±10%)
12) 15VC +15V power
(with tolerance of ±10%)
13) -15VC -15V power
(with tolerance of ±10%)
14) 5VC +5V power
(with tolerance of ±5%)

Can I even use the smooth stepper to get these voltages and how do you get negative voltage??

I'm thinking I may be better off to sell the AC servos and swap out for DC?

Any help is appreciated.
Re: Kinda lost on servo setup- how can I control?
« Reply #1 on: June 14, 2017, 02:58:24 AM »
I don't know much about Fanuc, its way too expensive for me. Those servos look like genuine AC servos, in which case your going to
need some AC servo drives. The Gekos are DC and won't work and probably to small anyway.

Fanuc servo drives are probably the best way to go but expect to pay hundreds if not thousands. Another alternative is to replace the servos and
drives, Taiwanese Delta 750W servos and drives maybe $750-$1000 each. There are cheaper servos but increasingly 'cheap and nasty'. Or bargain
hunt Ebay.

You might get satisfactory performance from lower power servos, you might for instance get some with plenty of torque but only 1500 rpm or so.
Will mean your lathe has plenty of grunt but slower rapids, probably perfectly OK for hobby use.

Time to do some research online. If you can save the Fanuc servos do so, they're really really good. Cost may dictate that you have to swap them but
to get even comparable performance is not going to be cheap.

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