Finding a used 4th Axis (FANUC)

Fal Grunt · Oct 18, 2017

I have a Bridgeport Interact 720 that has a Fanuc O-M control. When looking for a used 4th axis, how do I figure out what will work? Seems like everyone I talk to that has a Used 4th for sale has no idea what it goes to. I assumed, obviously incorrectly, that there would be some form of standard for knowing what is compatible with my machine?

I've run 4th's before, but have never bought one for a machine... so this is more my ignorance than anything.

One seller told me that each 4th is individually paired to its machine?

WILLEO6709 · Oct 18, 2017

its most important to know the motor series you need to drive. If you can match the motors in your machines its easiest, but a good install tech can mix and match. for what its worth, swapping motors mechanically is pretty simple. economically it may not be.

Fal Grunt · Oct 18, 2017

So my machine has GE Fanuc AC Servo motors, I need to find something with the same type motor?

No install tech here. . . Just me trying to get my machine setup. Tired of using my Cincinnati dividing head. Hoping to find a 4th, even if it's just for positioning that is slimmer.

Vancbiker · Oct 18, 2017

Not that simple. During the GE/Fanuc era there were at least 3 different series of AC servos. The earliest style which I do not recall them having a series name, Alpha series, and Beta series. Then within the earliest style and Alpha one could have incremental or "absolute" encoder and possibly serial "absolute" encoders. A machine tool builder could specify which combination they wanted to use on their machine based on price, features, performance, etc. To top it off the CNC needs to have some firmware options installed/activated to handle a 4th and possibly some hardware. You'll need to do a lot of research and figuring out to do it yourself.

lumley32 · Oct 18, 2017

what about an indexer? the Haas 4th I have has a control box that you can program a list of angles and trigger with a switch that i just put at the end of travel in the X.

Mud · Oct 18, 2017

Vancbiker said:
Not that simple. During the GE/Fanuc era there were at least 3 different series of AC servos. The earliest style which I do not recall them having a series name, Alpha series, and Beta series. Then within the earliest style and Alpha one could have incremental or "absolute" encoder and possibly serial "absolute" encoders. A machine tool builder could specify which combination they wanted to use on their machine based on price, features, performance, etc. To top it off the CNC needs to have some firmware options installed/activated to handle a 4th and possibly some hardware. You'll need to do a lot of research and figuring out to do it yourself.

This. ^^^^
I don't have experience doing the job but I investigated it a bit. The 4th axis has a motor and an encoder. The motor needs a drive to make it move. The drive needs to read instructions from the control and send signals to the motor so it needs to be compatible with both. The control needs to read the feedback from the encoder to know where the motor has moved to and how fast it is moving. So picking a 4th at random you have a low change of the motor and feedback device being what you need for your machine without knowing a lot more.
Clear?

All this does not need to be the same brand but it must all play well together, that's why there are 'integration' people.
I have a machine that has Siemens spindle and axis drives, and a Fanuc drive to run the Tsudakoma 4th axis, it was built new that way. I don't know enough to hazard a guess why though.
Plus as said above, you'll likely need changes to the control to make it work,

If you can use an indexer, an air operated indexer is a good option, I can walk you through that probably, that I have done more than once.

cwtoyota · Oct 18, 2017

Fal Grunt said:
So my machine has GE Fanuc AC Servo motors, I need to find something with the same type motor?

No install tech here. . . Just me trying to get my machine setup. Tired of using my Cincinnati dividing head. Hoping to find a 4th, even if it's just for positioning that is slimmer.

Come up with the numbers on your servo drive (velocity control unit) that will run the fourth axis... That will tell you what type of servo you can run.

It should be a number that looks something like this: A06B-6050-H102
There's a Fanuc chart that shows which VCU pairs with which servos...

I have some pin-outs and other stuff for AC servos that I had to come up with during my retro-fit.

There are other issues to contend with as well including:
1) The gear ratio of the rotary table vs the encoder on the servo and the corresponding CMR/DMR parameters.
2) The "polarity" of the brake (Is the brake hot to apply or hot to release).
3) The "polarity" of the brake confirmation signal (Is the signal hot when brake is applied, or hot when brake is released).
4) The setting for the homing dog. (They're adjustable, but must be on the correct "side" of the limit switch depending on +/- rotation direction).
5) The pulse coder cable has two wires that can be flipped for reverse rotation units. (Wiring must match your +/- rotation direction).

For example, 2) and 3) are coded into the ladder... Most good tables have Lego parts that can be switched out to match your ladder.
In my case, I had the wrong brake polarity, so I had to purchase a different SMC solenoid-valve for my Nikken table.

I recommend buying the cables. I built my own and will share the pin-outs, but there are used cables all over e-bay and from other sources.

cwtoyota · Oct 18, 2017

By the way, my previous post assumed that your machine was pre-wired for a 4th axis from the factory...

If it's not pre-wired and set up for a 4th axis, you may be looking at ladder modifications, I/O unit wiring to "expose" the correct signals to interface the items I mentioned above...

Then, you would have to install the additional axis card (if the 0M control doesn't have that on-board).

I've done the whole retrofit, but my ladder was already setup for the 4th and 5th axis.

If your ladder and wiring aren't there, I would pretty much throw in the towel and go with an indexer as suggested by Mud.

If the ladder and wiring are there, prepare to spend a lot of evenings working on this project and go for it.
I'm very happy with my Nikken table and the additional functionality:

Fal Grunt · Oct 18, 2017

Ok, I will start digging into this.

In theory the machine is 4th axis "ready". That is one of the reasons I bought it. This is of course according to the previous owner. He had a 4th sitting under the machine that I tried talking him into selling, but he said he used it for his other machine as well.

I don't think I have the air to run a air operated indexer, though maybe as I get further into this it will become an option. I have never used an air operated indexer, so there would be a bit of a learning curve.

Bobw · Oct 18, 2017

I've got a 4th sitting here that came off an Acroloc, '84 vintage with a 6MB...

A member here bought it from me about 8 years ago and its been sitting here ever
since.. I have no idea what happened to him.

Anyways... Maybe we can get him some of his money back... I've never seen it run, the
machine it was in was fine, I don't even remember what the problem was.

Fal Grunt · Oct 18, 2017

Ok, looked at a few things quick before dinner.

Found this in my box of "stuff" that was included by the seller. Have not tracked the serial number down yet, but presume it is for this machine?

YET...

I feel like I should have something there... that AXIS DRIVE or B AXIS?

I have 3 of these

and 2 of these

Looking at my electrical drawing I see XYZ encoders, XYZ Axis drive, and a B Axis Brake?

Vancbiker · Oct 18, 2017

Your first picture shows the wiring to connect an SMW indexer to your machine and use M51 in the program be the index start command.

Second picture is the machine builder's cable interface board. Machine builder specific. Not Fanuc so it's tough to say what all is being done there.

Third and 4th pictures are mostly just showing a proprietary Fanuc electronic component. Pic three is part of a 3 axis drive and likely your X, Y, and Z axes but can not say for sure without more info.

Take a picture of the entire cabinet.

Fal Grunt · Oct 18, 2017

As you wish...

Let me know if there is anything else I can get to help.

Vancbiker · Oct 18, 2017

The upper Fanuc drive in your cabinet is the spindle drive. The lower Fanuc drive is a 3 axis drive. Almost assuredly your X, Y, and Z are from this drive. There is no other drive in that picture. Either that means you are not pre-equipped to run a 4th axis or there is another cabinet for the additional drive.

cwtoyota · Oct 18, 2017

Vancbiker said:
The upper Fanuc drive in your cabinet is the spindle drive. The lower Fanuc drive is a 3 axis drive. Almost assuredly your X, Y, and Z are from this drive. There is no other drive in that picture. Either that means you are not pre-equipped to run a 4th axis or there is another cabinet for the additional drive.

That's what I'm seeing too.

More than likely you'd have to install another drive for the addition of a 4th axis.
In that case, it's likely that you don't have the transformer to support the additional drive.

That's not always the case... My VMC had a space for the 4th drive with mounting screws and everything.
Also, it already had the correct input transformers.

Fal Grunt · Oct 23, 2017

Wellll S#*&

Guess I will be looking at indexers....

Is the SMW indexer mentioned above, that I found in my notes an air operated unit? It is still tied to the control, and I can program using the control?

doug925 · Oct 23, 2017

I've got a spare (not used) SMW, 8" table, with controller & tailstock.
I would make you a sweet deal, if you're interested.
FWIW, I bought it of Ebay about 6 years ago, & it's still bolted to the shipping pallet. :nutter:

I ended up buying 2 ea, Haas and 1 ea Hurco 4th's for my mills, (they are plug and play) so I never needed the SMW.

Doug.

Vancbiker · Oct 23, 2017

Fal Grunt said:
Wellll S#*&

Guess I will be looking at indexers....

Is the SMW indexer mentioned above, that I found in my notes an air operated unit? It is still tied to the control, and I can program using the control?

The SMW indexer is a motor driven unit. IIRC it only uses air for the brake. It is tied to the control but only in that an M code starts the index and stops further program execution until a finish signal is sent from the SMW control box to the CNC. You program the indexes at its own control box, not in the CNC.

Fal Grunt · Oct 23, 2017

Well, I guess that may be a good thing considering the control only has 49k of memory and I have not been able to get it to drip feed as of yet...

Finding a used 4th Axis (FANUC)

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