Mesa 5i25/7i77 combo w/ Emco tool changer question

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07 Jun 2013 06:50 #35380 by Zahnrad Kopf
Peter, ( or anyone that might have an answer )

The Emco tool changer was briefly discussed here - in this thread.

Two questions -
Can this be controlled directly from the 5i25/7i77 combo or will there be something else needed, too?

And,

Will a 24VDC 1A power supply work for everything, or will I need to have a second power supply for the turret motor as well?

Thank you for any guidance...

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07 Jun 2013 10:34 #35384 by PCW
Without more information on the motor in the toolchanger, I can only guess whats needed.

I suspect the motor is driven forward at full current (direct 24V probably) till the proper set of sensor(s) are read (and perhaps using the Hbridge to brake the motion) and then driven in reverse (also at full power) until it stalls (detected by the motor current rising) and then the motor current is lowered (via PWM) to hold it locked without overheating the motor. The motor PWM _may_ be ramped up at the start of motion so there is not a current spike when starting (or perhaps this is just masked by timing). Overall maybe fairly involved...

A first step might be to try driving the motor with a lower voltage (say 5V) and get a feel for how fast the motor starts and stops and also measure the current when running vs stalled.

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07 Jun 2013 13:53 #35387 by ArcEye
Hi

Speak to cncbasher

I wrote the Orac toolchanger, upon which the Emco one is based, for him.
He uses it with a Mesa card combo and should be able to share his configs and advise

The Orac changer used 24v for forward moves and 12v for reversing AFAIR

regards

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07 Jun 2013 16:54 #35392 by Zahnrad Kopf
Replied by Zahnrad Kopf on topic Mesa 5i25/7i77 combo w/ Emco tool changer question
Gents, Thank you both! I have emailed cncbasher through the forum to see what information he might be able to render. If someone bumps into him in here could you please let him know in case he does not receive it.

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07 Jun 2013 17:14 #35395 by cncbasher
no problem in helping setting up for a 5i25
all connections are using gpio pins driving a few changover relays , the trick is in using 24v for forward movements and then switching to lower voltage on reverse which holds it on the pawl hard stop
i'll have to draw the circuit , it's that long since I did it , i simply used a small bridge rectifier so it became a full rectifier in forward and half on reverse , this works fine .

the emco toolchanger should have 3 or 4 opto's for position sense which is classed as a greyscale encoder .

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07 Jun 2013 18:23 #35397 by Zahnrad Kopf
Replied by Zahnrad Kopf on topic Mesa 5i25/7i77 combo w/ Emco tool changer question
cncbasher - Hey, that's great news. Thank you so much.

Per our emails, it looks like I will need to make or buy another 24V power supply for the turret motor. Do you know how fussy it is? Can this just be an automotive battery charger, cannibalized? Or does it require a little more finesse?

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07 Jun 2013 20:52 #35408 by cncbasher
no it's not fussy , so a cheap 2-3A supply or a tap off a similar voltage , with simple bridge and capacitor for rectifiying and smoothing will do.

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