DYN4 as spindle with Acorn......yup another one.

[SpacedmanSpiff]

Dear Acorn superusers,
Thank you for ALL the knowledge and tips you have posted. You have been instrumental in getting this setup up and working. With no drift !
HOWEVER.... I do have a hiccup that i have not yet been able to overcome. When in manual spindle control I get a "over volt" alarm on the DYN5 drive when I initiate SPIN STOP after getting to above 4500 rpm on the motor.
This is I presume caused by ACORN commanding zero speed and dropping the analog signal to 0.0v ASAP causing the motor to regen brake and over volt the dc bus.

IS there a parameter i can set to set a decel time for the SPIN STOP button to allow the motor to slow below alarm thresholds ?
I have searched but yet have not found any documentation or anyone else replicating this issue.

All the best
Sean

[cncsnw]

No, there is not such a parameter. CNC12 assumes that a spindle drive is capable of managing its own accel/decel ramps.

Is the problem with deceleration, or is the problem that the drive assumes that an immediate stop is required when the enable is taken away?

What happens if you transition from S4500 to S60, without doing an M5?

Does DMM not have an accel/decel time or rate setting in the drive?

[SpacedmanSpiff]

CNCSNW,

there is no issue with going from s4500 to s60. The drive handles that just fine.

The issue is that the drive assumes an immediate stop when the analog signal goes to zero and enable is removed. DMM does have an accel setting however it does not seem to be able to cope with going from 5000 to zero while Acorn has manual spindle control. I am doing the reading now to see if i can write a macro for the Spin Stop button on the VCP to step the spindle down. This is the only issue that I have found at the moment. everything else works just fine.

thanks for the reply
all the best
Sean

[cncsnw]

It sounds like the issue is the immediate stop that is assumed when the enable is removed.

When you are at S4500, and you enter S60 (or S0 if you wish) the analog is very nearly "going to zero" instantaneously.

If that is not a problem as long as the enable is maintained, then you just need a much simpler PLC change to maintain the enable for a couple seconds after a spindle stop is commanded and the analog is zeroed.

[SpacedmanSpiff]

Thanks CNCSNW,

now for the million buck question.
How do I do that simple PLC change ? grin.

I have been reading the macro, plc manuals and to be honest the brain is mush.
Sean

[martyscncgarage]

Have you spoken with DMM about your issue?
When you stop the spindle that abruptly the energy needs to go some where. Seems to me you may need a regenerative resistor added to the drive.

From the DYN4 Manual:
█ Regenerative Resistor
The DIPM power module unit built into the DYN4 servo drive is designed with a very efficient bus voltage
attenuation control circuit. It is much more efficient than conventional servo drives when handling servo
motor regenerative energy. Generally, external regenerative resistors are not needed. If the servo drive often
throws “Over Voltage“ alarm, contact DMM representative for custom regenerative energy sizing procedures.

[martyscncgarage]

PS. I want to see a video of a DMM Drive/motor used as a spindle drive, with spindle encoder feedback Rigid tap....and PECK rigid tap.

[SpacedmanSpiff]

Marty
That was my initial thought as well. And to be honest still is. However Stephan at DMM seems to believe that it's an acceleration issue on Acorns end.
Right now I'm thinking of writing a M05 macro to step the spindle down. Still reading on that part of the process.

Hopefully soon on the video. I do have a timing belt driving the spindle. It however is not 1:1 so I have to do the math to see if I can still get a consistent trigger.

[martyscncgarage]

Marty
That was my initial thought as well. And to be honest still is. However Stephan at DMM seems to believe that it's an acceleration issue on Acorns end.
Right now I'm thinking of writing a M05 macro to step the spindle down. Still reading on that part of the process.

Hopefully soon on the video. I do have a timing belt driving the spindle. It however is not 1:1 so I have to do the math to see if I can still get a consistent trigger.

Seems like an energy dump issue to me... but Stephen is pretty sharp.
I wouldn't hold my breath on anything working well at other than 1:1 with a timing belt.
Good luck,
Marty

[SpacedmanSpiff]

And also...Thank you for your video series. A large part of the progress I have made is in part due to you. Thanks much !