Newbie- I have some big Fanuc servos motors

[KraZe_EyE]

Hi 1st post!

So we had an old Fanuc robot arm that we disassembled at my college/work. It was a welding robot that we used to train students in G code or something but it was too out dated to use in class these days. The name plate on the motors says they were manufactured in 1982.

I got some nice servo motors with built in encoders, they're rated for 1Nm of torque @ 4 amps. Is this more than enough for my future project of converting a Bridgeport (or similar large Mill) to CNC?

Also I was wondering if anyone had an idea of where I can get a pinout/datasheet for these motors and the encoder? The encoder has 17 pins is that alot? lol

Fanuc DC Servo Motor Model OOM (they're 2000 rpm)
Type A06B-O632-B011 (2000M)

Fanuc Pulse Encoder Unit
Type A860-0303-T001 2000P

I've tried google and if you guys aren't sure where to get this information then I will be getting into contact with Fanuc to see if I can request the datasheet.

Am I off to a good start with these motors, are they overkill, anyone want to buy them off me/trade?

[Al_The_Man]

Well you could be in luck, usually Fanuc robot motors have absolute encoders, but the T001 2000p indicates quadrature differential, 2000p/rev.
If you intend using them with Mach then Granite drives may be the solution for them.
Al.

[KraZe_EyE]

Originally Posted by Al_The_Man Well you could be in luck, usually Fanuc robot motors have absolute encoders, but the T001 2000p indicates quadrature differential, 2000p/rev. If you intend using them with Mach then Granite drives may be the solution for them. Al.

I am still in the planning stages of this build. So you have data on these motors or you just know alot about servo motors?

Granite drives eh?I was looking at Gecko drives but will cross that bridge when it comes.

What is quadrature differential?

[Al_The_Man]

I have worked on many Fanuc motors, but there are many many variations, the info I showed is from the Fanuc motor/encoder chart.
I think you will find that Gecko do not go high enough in voltage if you were thinking of using them with the Fanuc motors.
Quadrature encoder outputs two pulses 90deg apart and the differential is a form of transmission of the pulses called RS422 and produces a complementary pulse for every quadrature pulse input.
A search on the web should show lots of explanations.
Al.

[KraZe_EyE]

Okay thanks for the encoder lesson Al; are there any drives out there that support that right off the bat or do I have to dust off my PIC and make an 'encoder decoder'?

The gecko drive I was looking at says it goes to 80V @ 20A. G320X Digital Servo Drive
The motor name plate says the motors are 59V, which is a very random voltage IMO.

[Al_The_Man]

See this thread for some more info on Fanuc.
http://www.cnczone.com/forums/granit...fanuc_red.html

Originally Posted by KraZe_EyE The motor name plate says the motors are 59V, which is a very random voltage IMO.

Your power supply voltage should typically be at least +10% higher than the motor voltage.
Al.

[KraZe_EyE]

Okay I read thru that and left me with a few questions. I believe the motor drives require feedback from the encoder in order for the PID to work, or is that controlled from the PC/MACH? I need to contact Fanuc and get some data on these babies so I can make an executive decision on whether or not to use these motors.

Because according to another thread they only have 141 oz/in of torque. I see alot of machines with 200 to 400 oz/in of torque.

Originally Posted by arvidb N/m (Newtons per meter) would not be a measure of torque. As TAB said, it would be a very unusual unit to measure anyhing in (nothing comes to mind...). Nm (Newtons times meters) is the metric unit for torque. I have the number 1 Nm = 141.612 oz-in, almost the same as TAB wrote. Be sure to get your units right! Arvid

So are my motors too small to fit to a bridgeport mill? They seem like really beefy motors and I'd hate to have to buy other motors, that may derail my project. Aside from making a gear system to beef up the torque, but that may make it so slow as to be unusable...

10% above? Well I checked out Antek - Your reliable source of transformers, power supplies, and more. from that thread you posted and he seems to have very reasonable prices for what hes making.

[KraZe_EyE]

Well its 1 Nm at stall @ 4A if that helps any....

[Al_The_Man]

The Excello mills I have (same as B.P.) has 40lb/in at 2:1 reduction, probably a bit beefier than needed.
In the case of Mach, the PID loop is closed back to the drive, if in fact these motors have quadrature differential then you should be able to use them with Granite devices.
Al.

[KraZe_EyE]

Okay if a bit beefy is say 25% more than needed than you could comfortably run you setup with 30 lb/in?
My motors are only 8.85 lb/in. I'd have to run a 7:1 to even get close to your comfort zone. (2:1 * 30 = 60 lb/in)
So again are my motors totally underpowered for a BP conversion?

Should I go for a harbor freight mill? I was trying to avoid this route cause you can only go bigger not smaller with this kind of project!

My final plan was to make a CNC mill with 3D printing capability. I know I could achieve this with a Harbor freight mill but I wanted to go big right off the bat to save money.

Thanks for responding all day Al

[Al_The_Man]

The motors are small for a BP, I would first confirm that the encoders can be used, otherwise either route will be fruitless.
If you don't really need the size of a BP for what you want to do, and the motors can be used on a smaller mill, then this is the way I would go.
Al.

[KraZe_EyE]

Okay I guess if I need to start small than I will. Little cheaper in the beginning but I also figure I can use whatever electronics I buy for an upgrade in the future. Anyways I guess my next step still is to contact Fanuc about these motors and encoders. They are selling on ebay for around $500 - $600, so maybe I'll sell them if I get the run around from Fanuc.

Cheers! I have to grade papers now.