Fanuc Alpha 3 Spindle Motor - Add Position Coder?
I'm putting together a retrofit to upgrade a tapping / light duty machining center from an old 0MC to a very well optioned 16i that I picked up (was previously in a high speed machine, so it has all the bells and whistles baked in, including RISC and data server). Everything is up and running in a test rack setup (amps, servos, IO unit, spindle motor, etc) and I'm working my way through the ladder conversion for the ATC unit. One challenge that I do have is that the Alpha 3 spindle motor I was able to get for a good price isn't equipped with a position coder like the exiting 2S motor. This is obviously going to be a problem for rigid tapping. I don't have an existing Alpha 3 with an integrated position coder for reference of what position encoding mechanism is typically used and how it is fitted in the spindle, so I'm wondering if anyone here might know if its possible to add a position coder to the existing motor? I'm guessing its probably as simple as replacing the existing pulse generator with a position coder ring and pickup? Can anyone share some insight into how one of these spindle motors with an integrated position coder is configured from a parts perspective? What encoder ring and pickup, any special alignment requirements, etc? I've looked at the descriptions manual and have some ideas, but a validation from anyone that actually has such a spindle would be very valuable. I considered an external position coder, but the head design of this machine doesn't offer any reasonable place to mount and tie one in via timing belt/pulleys.
Alternatively, is it possible to drive the existing 2S spindle using an alpha drive. The position coder signals look compatible, just need to double check voltage levels to ensure the differential peak voltages are the same as what the spindle amp is expecting.
Thanks!
Re: Fanuc Alpha 3 Spindle Motor - Add Position Coder?
If you have the drive manual (Description), look for an external 1 revolution marker interface. The newer drives allow a prox. switch wired to jya3(?) on the SPM to act as the marker pulse for orient and taping and parameters establish the scaling for the speed using the motor sensor.
Re: Fanuc Alpha 3 Spindle Motor - Add Position Coder?
It's able to do that with just the standard pulse generator (a/b 1v peak to peak sine) and an external 1 ppr index signal? I thought a motor with a bz or mz built-in coder was needed. Basically, a model ending in Bx9x instead of Bx0x.
If it only needs the index, I could just keep using the magnetic orientation sensor from the old 0mc setup, couldn't I? That type of input is shown in the description manual as usable for orientation.
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Re: Fanuc Alpha 3 Spindle Motor - Add Position Coder?
The breakdown should be in the manual. Unfortunately I don't have access atm.
Re: Fanuc Alpha 3 Spindle Motor - Add Position Coder?
I’m a little lost on what exactly you have, and what exactly you’re trying to have. What do you mean by pulse generator? When I hear pulse generator, I think of the MPG/handle.
I just recently worked on an 18i-TA that had an external spindle position sensor (BZ) and a built-in motor sensor (MZ). This was a bit of a bastard child but the BZ sensor is what’s relevant here.
The BZ sensor in my case was an external magnetic position sensor that had a 480(?) teeth position ring and an adjacent 1 rev ring. The magnetic face of the sensor was an oblong oval that went back to JYA2 (I believe) on the SPM.
From a signal perspective, if you check out section 4.3.4 “Checking the Feedback Signal Waveform” of manual B-65285EN/03, the Alpha-i servo/spindle motor/amp maintenance manual, it will give you a break down of the signal. The A, B and Z phase are what’s important here. If you have the ability to check the feedback signals once the you have the hardware configured, that section of the manual is what you’ll need.
You can call FANUCs phone support for free and they’ll give you advice and some direction. They may not be too much help in regards to a retro fit but it’s free support.
Re: Fanuc Alpha 3 Spindle Motor - Add Position Coder?
No worries, let me elaborate further and hopefully it will make the situation clear.
What I currently have for the new 16i based control setup is spindle motor a3/8000, model A06B-0853-B100 (note that I'm working in the older alpha series, rather than the newer Alpha i, which may or may not be relevant in this case). This motor has what the manual refers to as a pulse generator in it. Its a toothed gear looking generator with a single pickup head. The output of this is two sine wave signals (1v peak to peak, which is the spec) PA/RA and PB/RB. From the motor, there is no index channel PZ/RZ. This motor works fine with the spindle amp from a velocity perspective, but as you indicated, there is the matter of there being no index channel. From what I understand, rigid tapping needs one of three things, either a built-in sensor in the motor (models end in Bx9x), a BZ sensor on the spindle, or a position coder linked to the spindle via timing belt. What I was originally asking is if its possible to retrofit my existing spindle motor by installing a built-in sensor (which I believe is the MZ sensor that includes all 3 channels, A, B, and Z).
If not, I'll have a spindle motor for sale and just have to bite the bullet and buy one that already has the built-in sensor. I was hoping to not add that multi-thousand dollar expense to the retrofit, but If its the only way I can go, so be it.
Thanks!
Re: Fanuc Alpha 3 Spindle Motor - Add Position Coder?
You need another spindle motor with a MZi sensor inside as the senor need an extra ring beside the teeth ring for the index,so i doubt you can install that on the shaft.
I am guessing you have this one:
https://www.ebay.com/itm/17228382951...=&toolid=10050
but you need to have this one
https://www.ebay.com/itm/18221947258...kAAOSwaB5Xlkws
Re: Fanuc Alpha 3 Spindle Motor - Add Position Coder?
I have used one of the yellow cap servo motors and replaced the encoder with the more common, non-proprietary version.
I used a shoulder bolt in the existing hole and used a encoder with the commutation tracks to turn it in to a BLDC motor.
Re: Fanuc Alpha 3 Spindle Motor - Add Position Coder?
@zavateandu. You are correct regarding the gear ring that is currently installed. So, just to confirm, the external magnetic sensor wouldn't be sufficient to provide the single pulse per revolution (spindle is 1:1 with motor), as I need to have the Z channel coming in on JY2 from the motor itself. The existing magnetic sensor on the spindle from the original 0MC setup that is input to the orientation board can't be used as a substitute.
Swapping would be a matter of pulling the existing gear, pressing on the new one and swapping the sensor pickup for one that has all 3 channels. I'm guessing that may also require strict alignment of the gear teeth? I'm just trying to determine if its worth making an attempt at it. It looks like there would be room for a wider ring on the shaft.
You wouldn't happen to know the part number for the pickup that would be used, would you?
Re: Fanuc Alpha 3 Spindle Motor - Add Position Coder?
@bumzag Correct. The alpha spindle motor manual has the channel signals designated as PA/RA, PB/RB for this, but its purely semantics. Each channel is a differential, twisted pair, which is what matters. I only have the AB ring without the 1 pulse/rev ring / feature (kinda looks like the A/B/Z one zavateandu mentioned is a single piece with all but one tooth removed from half of it). In any case, getting the motor set up with the correct ring(s) and pickup seems really doable if I can just make sure I get the right parts. I just need the correct ring(s), pickup board, and pigtail cable from the looks of it. FWIW, I verified the signals with a scope and checked all phases as well as hit it with the megger to check for shorts before connecting it to the spindle amp. Didn't want to let any magic smoke out.
If anyone has an alpha 3 spindle motor with MZi position sensor / encoder, a snapshot or some part numbers would be greatly appreciated!!! :-)
Re: Fanuc Alpha 3 Spindle Motor - Add Position Coder?
I *THINK* this is the correct pickup, but really would want to confirm before buying one.
A860-2110-V001
Re: Fanuc Alpha 3 Spindle Motor - Add Position Coder?
That is a MZi SENSOR indeed
