Re:Dahlgren Engraver Z axis air actuation

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26 Feb 2011 09:53 #7466 by Rick G
Brian,

I think you could use a C37 relay board and a power supply such as a A3 both from cnc4pc.
www.cnc4pc.com/Store/osc/

If there is a spot where you can safely connect to an output pin from the parallel port on the board you can use that as the signal to the relay board.

If not as John said just add a second parallel port card and use that to control the c37 to control your 5 volt relay.

Rick G

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26 Feb 2011 13:37 #7467 by BigJohnT
The C47 relay can take loads of up to 10 amps 28vdc or 125VAC and 6 amps at 220VAC so you would not need another relay to turn your pneumatic solenoid on.

There is a lot of info on parallel ports here

www.epanorama.net/circuits/parallel_output.html

John

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26 Feb 2011 15:51 #7468 by bvandiepenbos
Rick,
Thanks for info and link to the c37 board from cnc4pc.
I wonder if the C9 board would be even better, it uses solid state switching instead of mechanical relay. My thinking is the mechanical contacts might not last long due to the rapid and frequent cycling of tool up/down. A CNC engraving of text would likely have hundreds of cycles.

I will probably order today, although I hate to wait for it to arrive. I was hoping to wire up something myself today from local Radio Shack parts.
This Saturday is a rare time I have "off" to play with this hobby.

~*Brian

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26 Feb 2011 16:00 #7470 by bvandiepenbos
Thanks John.
great info!
I will study it closer and maybe wire up something of my own today.

the relay board from cnc4pc suggested by Rick G looks good and would be easy.
While I am waiting for it to arrive I might try building my own circiut.

~*Brian

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26 Feb 2011 16:05 #7471 by BigJohnT
So long as your pneumatic solenoid is DC the C9 will work fine.

Keep us posted on your progress...

John

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26 Feb 2011 16:24 #7472 by bvandiepenbos
yes
24vdc 7watts

KIP Brand #241144
3-way N.C.

I will keep you guys posted.
~*Brian

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26 Feb 2011 16:49 #7473 by bvandiepenbos
ok guys, this is probably a dumb question...
I was just looking at the skematic for my HobbyCNC EZ Motor driver board and wondered if the 6 output wires that would go to a stepper motor could instead be used to trigger my relay?
I already have 9-pin connector on my enclosure where the Z stepper motor would (will) plug into.
sure would nice if I could just wire up a custom 9-pin cable to plug relay into there.
Then when I eventually get z axis motorized I could just plug stepper back in there.

I don't have any idea what comes out those wires to power the stepper, so this might be a really stupid question.
Don't steppers have coils that are energized like a relay coil?

I can easily adjust the amps output to motor... I am guessing relay coil would required less than stepper.

~*Brian

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26 Feb 2011 17:20 - 26 Feb 2011 17:32 #7474 by BigJohnT
My guess is it won't work as the stepper driver turns on and off the coils to make the stepper move...

From the IRC

can a stepper output be used to turn on a pneumatic solenoid?
[11:24] <skunkworks> I think you just would not know what sequence the stepper coils would be in.
[11:24] <skunkworks> at any given time
[11:24] <pcw_home> I guess I could but you need to know which winding is energized, easy for quadrature not for step+dir
[11:24] <pcw_home> ha SW beat me to it
[11:27] <pcw_home> quadrature = "wave mode" = stepgen mode 2


John
Last edit: 26 Feb 2011 17:32 by BigJohnT. Reason: more info from IRC

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27 Feb 2011 16:53 #7492 by Rick G
Good point John.

John of course is right you do not need the extra relay.
I suggested it as I thought from the post it was already part of the machine.
Lets us know how it all works out.

Rick G

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27 Feb 2011 16:56 #7493 by andypugh
You might be able to use the Z -stepper output.

If you have a suitable Z-scale and no microstepping you could potentially use a 2-pole relay controlled from a stepper phase with one relay pole controlling pneumatics and the other acting as a limit-switch. Then by careful choice of the home-switch location in the iNI it might be possible to have the axis home to Z=0 (relay open) in such a way that Z=1 is a position with the relay closed. Then the G-code would simply need to contain Z0 and Z1 commands to open and close the relay.

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