Need schematic for motor on/off control

[EL34]

Hi all,
I'm using mach3 mill with a 3-axis router.
My work shop is downstairs from my business.
I usually start a job and then go back upstairs to work.
I can hear the CNC machine spindle downstairs, which is a 30,000 rpm Rotozip

I want to be able to shut the Rotozip off after the job is finished so I can go back down and load another job or shut the CNC down.

I searched here and googled the web but I didn't come up with anything solid.

I don't really ever change the motor speed, I just need to be able to shut off the motor via Mach3. I have a harbor freight variable speed motor control if I do need to vary the spindle speed.

Anyone have a schematic for a simple AC motor speed control that I can interface into Mach3?

I deal with Mouser electronics in my business all the time so getting the parts and building the board isn't a problem.

Thanks, appreciate any info

[Al_The_Man]

If you have a spare output, all you need is a for the output to operate a suitable double pole relay, this would be in the 110v supply to the spindle circuit, a M4 would energize it, and a M5 at the end of the program would drop the relay out.
You would need the output to be conditioned by a BOB or a 2n7000 driver, there is several past posts on using the 2n7000 to operate a relay.
Al.

[EL34]

Thanks Al,
I'll search for the 2n7000.

What exactly is a spare output so I can figure out if I have one.

Edit;
Found this schematic in one of the 2n7000 post.
Is this fine for what I want to do or is there something more optimal?

[Al_The_Man]

That is the diagram I was referring to, you will need a relay with contacts suitable for the current rating of your spindle.
I don't use Mach so I am not familiar with setting the ports up, but if you connected this system up you should have the details of what outputs you are already using.
The printer port in general has up to 12 outputs.
If your BOB has spare outputs you may not need the 2n7000.
Someone with Mach experience should be able to steer you on checking the I/O availability.
Al.

[EL34]

Thanks Al,
I know how to set Mach3 up for spindle control, just wanted to ask about the spare outputs.

I have plenty of control pins left on the P-Port.

I ordered a 12v coil relay that can handle 125vac/10amp.
The Roto zip is 5.5 amps nd with startup surge, 10amp sould be fine.

Ordered sone 2n7007's also.

I'll see how it goes next week.

Thanks again

[LeeWay]

I just use solid state relays. I have some for both DC operated equipment and AC. All activated by lower computer type DC voltages for control. It's best to hook these up to a BOB. I use the C10 BOB's from CNC4PC.

These are what I now use for the router and coolant pump.




These are easy to connect. Just use an input and a ground on the other side. Say pin 17 and 19 for example. Then just break the hot wire to your router switch as if it were another switch and connect each side to those terminals. This way you can turn it off to override the computer control. You can do this in a dedicated outlet box so you don't have to cut your cord. You could theoretically operate two tools with this like coolant or vacuum at the same time provided the relay has enough amps for both.

There are some other settings dealing with spindles that need to be set as well. Some can be seen here.

It is really all rather simple and I don't know why I waited so long to do it.

[EL34]

Thanks for the help and the simple/nifty little relay circuit.

I got the parts yersterday.
Desinged the board in CAD and then CAM/Cambam

Cut it out on the CNC about an hour ago.
Tested it on the bench, worked great.

Hooked it up to my Probotix Breakout board and tested it with a short Gcode file

The relay comes on when at the start of the Gcode with M03
The relay goes off at the end of the Gcode with M05

Cambam was already inserting M03 and M05 in all my Gcode, I didn't have to do anything special.

Gonna mount it in a small plastic AC box with a double receptacle.
I'll plug my RotoZip into the receptacle box to turn it on and off.

[Al_The_Man]

Very handy little device, the 2n7000, If more than a couple of drivers are needed, I usually use the ULN2803a IC.
Al.

[EL34]

Hey Al,
I posted this project on the Cambam forum also, because I use Cambam for my cam work and I thought it would be helpful to others there.

Anywho, a few people have replied to my post and said that this design needs a pull up resistor on the gate.

Is that needed or not?

I was under the impression that the FET gate was voltage controlled and the pull up resistor was not needed on the port/gate connection?

Here's the post I mentioned.
http://www.cambam.co.uk/forum/index....pic,393.0.html

Thanks Al

[Al_The_Man]

The original version of the 2n7000 Fet(lington), was designed as a FET version of a Darlington driver.
It was designed to interface directly to CMOS and TTL directly, if you have a TTL open collector driver, you may need a 10k from gate to 5v+.
If you wish to include one with TTL interface, it does not cost much, I have never found the need in all the years I have used it.
And you are correct, it is voltage driven not current.
Al.

[EL34]

Thanks Al, good explanation.

Mines working just fine also.