Sigma 7 vs. Sigma 5 Drives on Acorn vs. Oak boards

[simmonds]

I have a couple of questions about choosing hardware to upgrade a 1999 Hardinge GT27 lathe.

The Yaskawa Sigma 7 does not appear to have the CN5 (analog) connector. Does this limit any functionality of the Oak board? Is Sigma 5 the preferred amplifier for this (or other) reasons.

It appears that the Oak board reads back encoder information from a Yaskawa amplifier but the Acorn does not. This would appear to be a valid reason for choosing the Oak when using AC servos. Would you agree?

[martyscncgarage]

I have a couple of questions about choosing hardware to upgrade a 1999 Hardinge GT27 lathe.

The Yaskawa Sigma 7 does not appear to have the CN5 (analog) connector. Does this limit any functionality of the Oak board? Is Sigma 5 the preferred amplifier for this (or other) reasons.

It appears that the Oak board reads back encoder information from a Yaskawa amplifier but the Acorn does not. This would appear to be a valid reason for choosing the Oak when using AC servos. Would you agree?

I am not familiar with Yaskawa drives yet. And I'm sure Marc or Keith will chime in as for it's specific control method (I'd be surprised if Oak can't control it)

BUT your statement: "It appears that the Oak board reads back encoder information from a Yaskawa amplifier but the Acorn does not. This would appear to be a valid reason for choosing the Oak when using AC servos. Would you agree?"
Is correct. Acorn is open loop, no encoder feedback, while Oak and All in One DC are closed loop, they rely on encoder feedback.

That said, when you drive the Sigma 7 with Acorn, the Sigma 7 drive will close the loop, as it will take the pulses from Acorn, and command the motor to move, and watch it's encoder to make sure it moves as commanded. If the motor doesn't it will push it harder to get on target, if the motor can't, it will fault and send that signal to Acorn. It's a Hybrid method. I am not sure if you can feed the index pulse from the Sigma 7 to Acorn to accurately home the machine. Does your lathe use mechanical limit/home switches?
With Acorn, you need an accurate and repeatable method to home the machine. Oak and Allin One DC use the index pulse from the servo motors encoder to home the machine after first seeing a switch trip signal. It backs off the switch and hunts for the index maker pulse, then sets home.

Incidentally, here is the tech bulleting to setup a Sigma 7 with Acorn:
https://www.centroidcnc.com/dealersuppo ... ds/307.pdf

Marty

[cncsnw]

Sigma 7 drives have CN5 under the flip-up plastic cover, same as on Sigma V.

Use of CN5 is optional. It provides the analog monitor signal from the drive to the Oak, and is used (only) to display the axis load meters and to inform the drag diagnostic.

[simmonds]

Thanks for your comments Marty. We should probably trust that the servo amplifiers can drive the loop errors to zero fast enough to follow a contour accurately. And warn us if they cannot.

I suppose one advantage of having position feedback from the encoder would be if you disabled servos, had hand-wheels to move the axes, and just used CNC12 as a DRO. But that would only work if the read-back position was being displayed. Probably an unusual operating mode these days.

[martyscncgarage]

Thanks for your comments Marty. We should probably trust that the servo amplifiers can drive the loop errors to zero fast enough to follow a contour accurately. And warn us if they cannot.

I suppose one advantage of having position feedback from the encoder would be if you disabled servos, had hand-wheels to move the axes, and just used CNC12 as a DRO. But that would only work if the read-back position was being displayed. Probably an unusual operating mode these days.

Marc anwered your question with respect to OAK and Sigma 7. (Thanks Marc)
If it were me, I would go with OAK....
I supposed it depends on your budget.

You are correct on the handwheels/DRO aspect.
Marty

[simmonds]

You guys provide great support! This gives me confidence to move forward using Centroid rather than a hybrid solution like HiCON + Mach4.

So CN5 is under the plastic cover? Who knew. It does not appear in any Yaskawa documentation pictures or drawings, but the Hardware Manual PDF mentions it (as I found after doing a search).

Considering that the full-featured CNC11 software is included with the Oak, it only cost about $750 more to get a much more flexible controller. I expect that will be about a 15% increase in my rebuild cost (not counting my labor): well worth it. Good advice Marty.

[tblough]

I have both a mill and a lathe that I probably run manually with handwheels about 30-40% of the time. Doing one-offs and prototypes a lot of operations are just faster manually.

[martyscncgarage]

You guys provide great support! This gives me confidence to move forward using Centroid rather than a hybrid solution like HiCON + Mach4.

So CN5 is under the plastic cover? Who knew. It does not appear in any Yaskawa documentation pictures or drawings, but the Hardware Manual PDF mentions it (as I found after doing a search).

Considering that the full-featured CNC11 software is included with the Oak, it only cost about $750 more to get a much more flexible controller. I expect that will be about a 15% increase in my rebuild cost (not counting my labor): well worth it. Good advice Marty.

CNC12 is out.
You should consider buying the ready made cables OAK to Yaskawa cables from Centroid.
Does your machine have a turret or manual tool post?
You should really post pictures of your machine including the control cabinet.

[tblough]

It could be a little more than $750 depending on the features you need. The options included with the "pro" Acorn are al-la-carte on the professional motion controllers so it can add some to the base price. Still, it's a lot more controller for a very good price.

[rl49]

by tblough » Sun Jul 07, 2019 7:46 pm

"It could be a little more than $750 depending on the features you need. The options included with the "pro" Acorn are al-la-carte on the professional motion controllers so it can add some to the base price. Still, it's a lot more controller for a very good price."

I Agree from previous memory I think gang tooling is an option and I believe his lathe is a gang tooling setup,
I have a t400 control since 2008 dos ver 8.53 and between intercon and g code has done quite well what ever we needed to do in a gunsmith application