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Author Topic: z axis - ac servo motor with brake - does it unlock automatically  (Read 2380 times)

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Offline nobby

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hello, in a panasonic minas a4 servo motor and drive combo, should I use a braked motor for the z axis, if so am I supposed? to use a braked motor on the z - axis
that said, does the driver control the unlocking of the brake automatically, or does mach need to send a signal 'enable' to unlock it.
or 'if you like' can you run braked motors on all three axis for holding? - are you supposed to do that?


thank you
« Last Edit: July 01, 2014, 06:05:14 AM by nobby »

Offline Hood

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Re: z axis - ac servo motor with brake - does it unlock automatically
« Reply #1 on: July 01, 2014, 08:50:06 AM »
Normally the servo drive will be configured to power (release)  the brake when you enable the drive but it all depends on the drive as to whether that is an option or not, I would think however the Panasonics would have such an option.
Failing that it could easily be done in Mach via the Enable output, I would however use the drive if possible.
Hood

Offline Hood

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Re: z axis - ac servo motor with brake - does it unlock automatically
« Reply #2 on: July 01, 2014, 08:51:28 AM »
Oh and regards using the brake to hold, the brake should only be applied when the drive is disabled, it is not meant for holding under power. If there is a need for that then your servos are too small for the job.

Hood

Offline nobby

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Re: z axis - ac servo motor with brake - does it unlock automatically
« Reply #3 on: July 01, 2014, 02:03:32 PM »
aha = thanks
so the brake on a z axis is only used for when the machine is switched off,
for example if you had the z at its upper most position on a large machine and then switched off the power to it, the weight of the spindle and big heavy motor would pull the axis down so it would slam into the lower end stop!!
= get it.
thank you.

by the way, I wonder if you wouldn't mind trawling through that minas A4 catalougue - as it appears that you can simply fire in 5v step and direction into the drives = surely it cannot be that simple?

oh p.s. do you happen to know at what wattage the isel fb2's run/ran at?


« Last Edit: July 01, 2014, 02:06:09 PM by nobby »

Offline Hood

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Re: z axis - ac servo motor with brake - does it unlock automatically
« Reply #4 on: July 01, 2014, 02:43:19 PM »
Servo drives can stay powered but not enabled, that means the motors can freewheel so for an axis that has gravity affecting it you require a brake. For example my Chiron would slam the head down in a matter of a second or so if there were no brake and I hit the E-Stop or switched the machine off etc.

Industrial type servo drives that can accept Step/Dir signals usually prefer differential signals, ie for every positive step signal there is an inverse one, same for Direction signal., this helps greatly with noise immunity.
You likely could just feed in single ended Step/Dir signals but most drive makers would warn against it.

Hood