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Author Topic: Z axis brake - how to get Mach to control it???  (Read 5272 times)

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Z axis brake - how to get Mach to control it???
« on: January 24, 2011, 06:10:36 PM »
So, I find myself needing to install a brake on the Z axis to stop it from dropping when motor power is off. I do not have a brake built into the motor, so I will build a spring loaded pneumatic actuator to press on the motor coupling. This will work just like a normal servo brake, holding the motor when power is released and releasing the motor when power is applied (via pneumatic cylinder)

I'm just not sure how to implement this electrically speaking? I am using a Galil Controller. Should I let the Galil controller handle the signal or let Mach handle the signal? Do I need a Brain or VB code or something to de-actuate the brake during run????

Appreciate any help...

Offline poppabear

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Re: Z axis brake - how to get Mach to control it???
« Reply #1 on: January 24, 2011, 06:49:42 PM »
Easy way........

   Assumes that when power is off that the Air piston closes on the Z (also assumes that on Air failure, your piston mabey has a sping to close it..... fail safe?).

at any rate.......

    Your drive that you use for your Z, should have an "Enable" signal for that drive that comes from Mach3, Mach3 puts out up to 6 Enables one for each axis, or you can just use ONE period. AT any rate, when ever mach is loaded up and running, your Enables in Ports and Pins will turn ON, and thus activate also your solinoid for yoru air cylinder to pull it off the coupling....  NOTE: when you push Reset, or mach Estops, the Enables are killed, and thus it would lock your Z then as well...

Make sure that what ever your pulling your enable off of, (ie one of the outputs on the galil board), that you have enough amps to drive the Axis Drive(s), and pull the solinoid, if not, you may need to go through a Relay.

scott
Commercial Mach3 & Mach 4, Design/Build/Retrofit CNC and Industrial machines.
http://www.ss-systems-llc.com/
Re: Z axis brake - how to get Mach to control it???
« Reply #2 on: January 25, 2011, 05:22:23 AM »
I have a similar setup using a kollmorgen ac servo drive and the dspmc controller.
When setup this way the brake releases before the drive is fully "engaged" and the drifting axis causes a following error  before it can "catch" the axis.

You may need to write a brain that applies a time delay to allow the drive to be fully ready when the enable turns the brake off.

On my drive it has an output that says the drive is ready so I am going to try and use that if possible to switch off the Z brake. My brake is built into the moto so YMMV.


Mike
We never have the time or money to do it right the first time, but we somehow manage to do it twice and then spend the money to get it right.
Re: Z axis brake - how to get Mach to control it???
« Reply #3 on: January 26, 2011, 05:07:28 PM »
I have a similar setup using a kollmorgen ac servo drive and the dspmc controller.
When setup this way the brake releases before the drive is fully "engaged" and the drifting axis causes a following error  before it can "catch" the axis.

You may need to write a brain that applies a time delay to allow the drive to be fully ready when the enable turns the brake off.

On my drive it has an output that says the drive is ready so I am going to try and use that if possible to switch off the Z brake. My brake is built into the moto so YMMV.


Mike

Yeh, I was wondering if I would have a problem with holding position if the axis had to cycle through a motor off / brake on situation. I guess I could just re-home the axis before continuing, although I would prefer not to have to think about that.

Offline Hood

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Re: Z axis brake - how to get Mach to control it???
« Reply #4 on: January 26, 2011, 07:04:42 PM »
You could maybe use the second or third Enable Output from Mach to control the brake and use the first for enabling the drive. Cant remember the delay between them, its not much but may be enough.
 Often with AC Drives (Industrial type) you have configurable outputs and you can set one as the brake and set a delay in the drive so it only releases after  the drive is enabled.

Hood