# Pm757 Cnc Spindle Start



## thebeerbaron83 (Dec 31, 2016)

Can anyone help me figure out how to wire a mach3 controlled spindle relay. I have two outputs on my gecko g540 for spindle start and stop. Just not sure how to wire it into the electrical system of the pm757. Here is the wiring diagram from the manual.


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## jbolt (Jan 1, 2017)

Before I converted to the VFD I did something similar. 

The KM1 & KM2 coils are 110vac according to the manual. The G540 output relays can output up to 50vdc. 

You will need to add relays between the load and the contactor coils terminal A1 on KM1 & KM2. I would get a 12vdc or 24vdc power supply and a couple of solid state relays. If you want to keep the original FWD/REV switches you can use a DPDT switch to select either manual start of Mach3 start.

Solid state relays https://www.amazon.com/Uxcell-SSR-25-Solid-State-Monitor/dp/B004HZN628


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## thebeerbaron83 (Jan 1, 2017)

jbolt said:


> Before I converted to the VFD I did something similar.
> 
> The KM1 & KM2 coils are 110vac according to the manual. The G540 output relays can output up to 50vdc.
> 
> ...


I'm sorry, but most of this is above my electrical understanding. What two wires would I connect the 110vac side of the SSR to? Did you do a write up on your setup?


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## thebeerbaron83 (Jan 1, 2017)

Here is a picture of the actual machine wiring.


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## jbolt (Jan 1, 2017)

I did not do a write up on this. I will do my best to walk you through this.

The easiest way to do this is to leave the factory switching as it is and add a double pole double throw switch. With the switch in one position it would operate as is manually. With the switch in the other position it will bi-pass the manual control and allow for control by Mach3.

There are two contractors (also known as motor starters) labeled KM1 & KM2. These are basically switches and they are activated by a built in coil. When the coil is energized it closes all the NO (normally open) contacts and opens the NC (normally closed) contact.

On your machine KM1 turns on the motor in reverse (CCW) and KM2 turns on the motor in forward (CW). The way the coils are wired across the contactors prevents both contactors from being energized at the same time. Matt did a good write up on this in the manual.

The only wire we will be touching on the contactor is at terminal A1. This is the load side of the coil or 110vac in. A2 goes to neutral which we won't touch.

Here is a picture of the contactor showing the A1 terminal. You will probably have to loosen and back out the wires in terminal L1 directly above it to access the A1 terminal screw.









Here is a simple wiring schematic. Unfortunately this forum shrinks everything so if you can't read it PM me your email address and I will send it directly.










Here is a typical DPDT switch.









Also look at the simple wiring diagram in the G540 manual for wiring the DC power supply. The SSR relays work best with 12vdc or 24vdc.

It looks like the electrical box may be too small to fit the SSR's and a power supply so you might need a second box or a larger enclosure.

Look it over and let me know if you have any questions.


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## thebeerbaron83 (Jan 2, 2017)

Jbolt, this helps a lot! I sent you my email for the diagrams. Thank you for doing this!


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## jbolt (Jan 2, 2017)

It is also a good idea to get everything wired up except the last connection from the SSR's to the contactor A1 terminals and make sure the DPDT switch is wired correctly and the SSR's are out putting proper voltage when given a FWD or REV run command from Mach3. When testing sometimes the SSR's need a load to operate in which case I will wire it to an outlet and plug in a lamp.


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## thebeerbaron83 (Jan 3, 2017)

Ok, so I have been looking this over and I think I mostly understand it.  Two things I do not quite get.  If the SSR is connecting the load through the A1 wires, won't I need to press the momentary FRW or REV button to get the power from that momentary switch?  Also, if this is a latching type system with a momentary switch, will the spindle stop when the SSR is deactivated?  Sorry for all of the questions, but I just like to fully understand what I am doing before I do it.  Thanks!


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## jbolt (Jan 4, 2017)

thebeerbaron83 said:


> Ok, so I have been looking this over and I think I mostly understand it.  Two things I do not quite get.  If the SSR is connecting the load through the A1 wires, won't I need to press the momentary FRW or REV button to get the power from that momentary switch?  Also, if this is a latching type system with a momentary switch, will the spindle stop when the SSR is deactivated?  Sorry for all of the questions, but I just like to fully understand what I am doing before I do it.  Thanks!



Good catch. My mill had a third contractor that powered everything and the FWD/REV was a rotary switch. I missed to load path though the two contractor setup. Let me look this through some more.


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## jbolt (Jan 4, 2017)

Question for you. Is it important or necessary to have manual control of the spindle?


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## thebeerbaron83 (Jan 4, 2017)

It would be nice to have, but I could do without it.


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## thebeerbaron83 (Jan 4, 2017)

Would this work?  connecting the the center terminal from the DPDT switch (INA and INB) to A1.  One side would go to load from KM1 and KM2 (power coming from momentary switches).  On the opposite side of the DPDT would connect to each relay.  The remaining terminal from the relay connect to load jumped from the stop momentary button.


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## jbolt (Jan 4, 2017)

Sorry I ran out of time yesterday. First day back at work after a two week break and I'm trying to get caught up. I'll take a look this evening.


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## thebeerbaron83 (Jan 4, 2017)

jbolt said:


> Sorry I ran out of time yesterday. First day back at work after a two week break and I'm trying to get caught up. I'll take a look this evening.


I can understand that! It's always hard to go back to work after a break. Thanks!


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## jbolt (Jan 4, 2017)

Just some food for thought. The hurdle with keeping the factory switching is the latching circuits. Once the contactor coil is activated it will stay on until the load path is interrupted (stop switch). It might be possible to use a switching scheme to break those latching circuits so the contactor coils are only energized while the SSR is active.


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## thebeerbaron83 (Jan 4, 2017)

My thought was by bringing the load path from the stop switch. Once the ssr is switched off it should break that path in the same way pressing the stop button would. It seems to make sense in my head, but I could be very wrong. Unfortunately I don't have a lot of experience with this.


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## JimDawson (Jan 4, 2017)

Setting this up for auto/manual operation is a little complicated with the existing system.  You still need to maintain the E-stop circuit, as well as the control power.  The DPDT switch will work for switching between auto and manual.

It looks like you need to pull power for the SSRs just downstream from the power switch. Then break it with the DPDT switch as shown on the drawing above.


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## thebeerbaron83 (Jan 4, 2017)

JimDawson said:


> Setting this up for auto/manual operation is a little complicated with the existing system.  You still need to maintain the E-stop circuit, as well as the control power.  The DPDT switch will work for switching between auto and manual.
> 
> It looks like you need to pull power for the SSRs just downstream from the power switch. Then break it with the DPDT switch as shown on the drawing above.


That did the trick! I'll post a schematic later tonight, but everything is working. Thank you guys for your help!


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## jbolt (Jan 4, 2017)

Awesome! I'm glad you got it working. Jim D's the man!


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## thebeerbaron83 (Jan 5, 2017)

jbolt said:


> Awesome! I'm glad you got it working. Jim D's the man!


Without your initial diagram I would not have figured this out.  

So here is what I did....

disconnected the wire labeled 3 from the NO side of the forward button.  I'm not sure if the wire is numbered the same on all PM727's but you want the wire that is coming from the power switch.  Connect this wire to the center post on the DPDT switch.  One of the remaining contacts on the DPDT is going to connect to the same place you pulled the wire from the NO spot on the forward switch.  This is how you will maintain manual control in this position.  The remaining contact on the DPDT switch will connect to one of the contacts on the AC side of the SSR.  The remaining contact on the AC side of the SSR will connect to the NC of the reverse button.  Do not remove any wires from the reverse button, you are just jumping power to it from the SSR.  Power and E-Stop both work when the system is in CNC and Manual mode.

Since I don't ever use reverse I did not bother setting up reverse operation though CNC control.


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## thebeerbaron83 (Jan 5, 2017)

Here is the video


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