More Acorn Questions...

[RayL]

Reading through the Centroid v3.16 Mill Operator Manual is raising some questions. To start, looking through the Configuration section, there appear to be many options that are likely not applicable to the Acorn.

For instance: screw compensation on the axes. Is that actually supported on Acorn? There are parameters related to High Power Stall and Load Meters. Are those applicable to Acorn?

If, as I suspect, a good number of the settings are NOT applicable to the Acorn (bnecause the I/Os required to implement them are simply not present, or the feature is not supported in the Acorn firmware), is there a list of the functions that actually ARE supported on Acorn?

I'm sure I'll have more questions as I continue reading...

Regards,
Ray L.

[cnckeith]

The v3.16 operator manual applies to CNC11 v3.16 which is for Allin1DC and Oak CNC control boards which are fully closed loop units.
So, in general any of the closed loop features like encoder feedback, motor power/torque (Load Meters display) Stall, over heat warnings and similar items that require closed loop operation obviously (or maybe not so obvious) do not apply to an Open Loop system. However, many very nice features have been carried over to Acorn CNC12 from CNC11. Such as ball screw compensation.
see Alan's video for more info on ballscrew pitch compensation.viewtopic.php?f=60&t=1018&p=4838&hilit=alan#p4838

The list of functions supported by Acorn are on the Acorn web page found here. http://www.centroidcnc.com/centroid_diy ... oller.html

After the dust settles with Acorn CNC12 development we will also release CNC12 for use on the Allin1DC and Oak CNC control boards and at that time we will release a new V4.xx CNC12 operator manual covering all three systems.

[RayL]

OK, thanks. Next question:

One of the machines I want to put the Acorn on has a servo spindle. But, it also has a 4th axis. The servo capability is really only useful for rigid tapping. But, there is obviously a shortage of Step/Dir/En outputs to control 4 axes plus the servo spindle. So, I'm thinking I can "trick" the Acorn into doing what I want as follows:

2) Add external logic to switch the 4th set of Step/Dir/En signals between the 4th axis drive and the spindle drive. When not rigid tapping, the spindle configuration would be setup for the VFD, and external logic would monitor the VFD outputs, and generate Step/Dir signals to the spindle drive to drive it as requested. When rigid tapping, the 4th axis drive would be disabled, and its Step/Dir outputs switched over to the spindle servo drive. This switching would be handled in the PLC program by either the custom M-codes that it appears can be inserted before and after rigid tapping cycles. These M-code would re-configure the spindle on-the-fly before the first tapping operation starts, and restored after the last tapping operating completes. Alternatively, I would use custom M-codes inserted into the G-code to preform the switching.

Is that possible? Is there a better way?

Also, I'd like to confirm that the Acorn DOES support rigid tapping with a VFD, as long as there is a spindle encoder?

Regards,
Ray L.

[frijoli]

Also, I'd like to confirm that the Acorn DOES support rigid tapping with a VFD, as long as there is a spindle encoder?

Yes as long as there is the correct encoder.

One of the machines I want to put the Acorn on has a servo spindle. But, it also has a 4th axis.

Not sure what your time frame is, or if the drive will work with your servo, but, I am working with DMM technologies on a custom version of their DYN4 servo drive that will allow speed control(like VFD) and step/direction mode change via a single output from acorn. They had to make a couple changes and I am waiting to hear back on the change. You still would only be able to run 4 axis total and I'm not sure this would make it simpler than what you were describing.

Clay

[RayL]

Clay,

This would have to work on existing machines, and they don't use DMM drives. So, that doesn't sound like an option. unless I'm misundertanding...

Regards,
Ray L.

[frijoli]

Clay,

This would have to work on existing machines, and they don't use DMM drives. So, that doesn't sound like an option. unless I'm misundertanding...

Regards,
Ray L.

This wouldn't work for you. Wasn't sure if you were doing a servo retrofit.

Clay

[martyscncgarage]

OK, thanks. Next question:

One of the machines I want to put the Acorn on has a servo spindle. But, it also has a 4th axis. The servo capability is really only useful for rigid tapping. But, there is obviously a shortage of Step/Dir/En outputs to control 4 axes plus the servo spindle. So, I'm thinking I can "trick" the Acorn into doing what I want as follows:

2) Add external logic to switch the 4th set of Step/Dir/En signals between the 4th axis drive and the spindle drive. When not rigid tapping, the spindle configuration would be setup for the VFD, and external logic would monitor the VFD outputs, and generate Step/Dir signals to the spindle drive to drive it as requested. When rigid tapping, the 4th axis drive would be disabled, and its Step/Dir outputs switched over to the spindle servo drive. This switching would be handled in the PLC program by either the custom M-codes that it appears can be inserted before and after rigid tapping cycles. These M-code would re-configure the spindle on-the-fly before the first tapping operation starts, and restored after the last tapping operating completes. Alternatively, I would use custom M-codes inserted into the G-code to preform the switching.

Is that possible? Is there a better way?

Also, I'd like to confirm that the Acorn DOES support rigid tapping with a VFD, as long as there is a spindle encoder?

Regards,
Ray L.

Please post the make and model of the spindle drive. A .PDF manual would be helpful as well. It takes step and direction but not analog +/- 0 to 10vdc signals?

Have to have a standard differential encoder belted at 1:1 to the spindle and Pro software option installed and Acorn can rigid tap.

Marty

[RayL]

The spindle drive is a Maxsine TL08F. The specific model installed on the machines in question do not support use of an analog control input. So, switching the drive between a "VFD Emulator" and one of the Step/Dir axis outputs seems to me the only option.

http://www.cnckaran.com/download/servomotor/220010.pdf

Regards,
Ray L.

[RayL]

I suspect I mis-remembered there being some custom macros that could be called automatically before/after canned cycles. I thought I remembered reading that somewhere, but can't' find it again.

So, my proposed approach is now:

1) Add external hardware to monitor the VFD output signals (analog out and direction outputs), and synthesize step/dir signals suitable for driving the servo spindle

2) Add external hardware to switch the spindle drive step/dir inputs between the output of the circuit in #1 above, and the 4th axis step/dir outputs

3) Insert custom M-codes into the G-code before and after tapping cycles to control the logic in #1 and #2 above, so that the spindle drive is connected to the 4th axis outputs when doing rigid tapping, and to the synthesized step/dir signals at all other times.

Other than the obvious issue of having to positively ensure the external logic is ALWAYS in the correct state, the only potential issue I can see in this would be that the 4th axis parameters (counts/rev, etc.) would have to change on-the-fly before/after doing rigid tapping operations.

Is that do-able?

Are there any "gotchas" that I'm not seeing?

Regards,
Ray L.

[martyscncgarage]

I suspect I mis-remembered there being some custom macros that could be called automatically before/after canned cycles. I thought I remembered reading that somewhere, but can't' find it again.

So, my proposed approach is now:

1) Add external hardware to monitor the VFD output signals (analog out and direction outputs), and synthesize step/dir signals suitable for driving the servo spindle

2) Add external hardware to switch the spindle drive step/dir inputs between the output of the circuit in #1 above, and the 4th axis step/dir outputs

3) Insert custom M-codes into the G-code before and after tapping cycles to control the logic in #1 and #2 above, so that the spindle drive is connected to the 4th axis outputs when doing rigid tapping, and to the synthesized step/dir signals at all other times.

Other than the obvious issue of having to positively ensure the external logic is ALWAYS in the correct state, the only potential issue I can see in this would be that the 4th axis parameters (counts/rev, etc.) would have to change on-the-fly before/after doing rigid tapping operations.

Is that do-able?

Are there any "gotchas" that I'm not seeing?

Regards,
Ray L.

I guess you could experiement with whatever you want. I have seen step dir signals converted to an analog output but no the other way around.

Its a shame that maker of the servo drive did not leave the analog signal input available. Must have been one of those cost cutting measures......

If it were me, I would buy a new AC drive that takes an anolog input.....

Frijoli is trying to basically do the same thing, but he wants to use the spindle for positioning as well as a a regular spindle motor....

Very interesting what you guys are conjuring up....keep us posted of your journey.
Marty