Help determining Servo Motor size

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martyscncgarage
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Re: Help determining Servo Motor size

Post by martyscncgarage »

The "power quill" is likely just a DC Brush motor controller. Not a servo.
You could follow its wires back to the source in the cabinet and measure the voltage. That's what I would do.

Does the knee have a servo in it or is this machine just a 2 axis machine?
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
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Bill87068
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Re: Help determining Servo Motor size

Post by Bill87068 »

The knee is powered. I have not really messed with it yet and hard to see the entire plate on it but it’s a fairly big motor. My initial guess was too big for the AIO controller but after doing some math maybe not. Looks like from what I can see on the number plate 90V and 1.3HP so figuring some losses that should still be under 14 amps and 90v should be close enough to the XY servos (I think?) that I might be able to get away with it??? Not sure if it has an encoder on it yet or not.

The quill motor/servo does have more than two wires coming off it. Not sure yet what that means or what the other wires are for. No doubt the Dynapath was not controlling the quil. Have not yet chased wires to see if it was controlling the knee or if it was just 2 axis. (Guessing since it has a Z jog switch it will be 3 axis.., but maybe that switch was not hooked up… need to chase wires)

Attached photo of knee drive
martyscncgarage
Posts: 8992
Joined: Tue Mar 28, 2017 12:01 pm
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Re: Help determining Servo Motor size

Post by martyscncgarage »

Quill is for manual downfeed, like manual boring.
You knee probably has air springs that need air pressure to counter balance it.

For the quill, you just need to figure out the voltage to the unit. Make sure it's fully retracted when using CNC mode and measuring tool offsets.
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
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polaraligned
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Re: Help determining Servo Motor size

Post by polaraligned »

Bill87068 wrote: Sat Sep 25, 2021 7:46 am
I am kind of leaning staying closed loop and going with the ALlIn -DC. If. I nothing else just for the simplicity of it since servos are already installed.
You can get higher voltage DC drives for use with Acorn. I don't recall the manufacturer off hand, but someone posted a link somewhere here within the last 6 months. You can try the search function if interested.
Bill87068 wrote: Sat Sep 25, 2021 7:46 am One thing I need to still determine is the power quill servo feed voltage. If it happens to be close to the same as the X/Y servos I may really be in luck. I have powered it from an external 110VAC power and it does function off the front panel so just a matter of some measurements
If the quill motor ran off 110vac as you mentioned, then it would need to be replaced with a DC servo motor and encoder.


As for the knee, as long as you can replace and mechanically interface a new motor to what is there, a servo motor of moderate size will run that knee. The knee has a bladder in the pedestal that provides counterbalance. These sometimes go leaky, but new packing is still available from Bridgeport.

I use a 21 in-lb motor with a 5:1 planetary gearbox and 2:1 belt reduction to drive my Bridgeport Series II knee. It does so with little effort.
Bill87068
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Re: Help determining Servo Motor size

Post by Bill87068 »

Update: I pulled the trigger on the 1200 in-oz Steppers/drives that Gary had posted on the for sale page couple days ago and plan to couple that with the Acorn rather than using my old DC Servos with the AIO. Going this route seems like a very inexpensive way to at least get my feet wet and get started.
polaraligned wrote: Sun Sep 26, 2021 12:40 pm
If the quill motor ran off 110vac as you mentioned, then it would need to be replaced with a DC servo motor and encoder.
Sorry confused you. The controller board for the quill used 110VAC. I got a chance to measure whats coming off the controller to the drive and it was ~94 VDC. Agreed probably not best (even though maybe easiest) to use the quill for Z so I will figure out how to make Z the Knee.
polaraligned wrote: Sun Sep 26, 2021 12:40 pm
I use a 21 in-lb motor with a 5:1 planetary gearbox and 2:1 belt reduction to drive my Bridgeport Series II knee. It does so with little effort.
Are you doing so off the hand crank location or did you figure out a method to adapt your servo to the power knee drive (assuming you had one). I pulled the factory motor off the powered Knee last night and it has a fairly complicated helical gear arrangement on a shaft with a pilot bushing and bearing at the back of the transmission (The shaft is all one piece). I am thinking I could cut the shaft outside the gear box where the motor part was. Between the green bearing cap and motor windings, build a mount for the new servo to attach to the the square transmission plate and then just need to figure out how to direct couple the shafts with some sort of collar thing... seems doable and could keep the hand crank for what ever that is worth at that point. Sounds like a fun project.
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