3 Axis CNC router

**JoeHarris** · 25-10-2017

Originally Posted by Neale

That looks about right.

Splendid! Thanks for your help. I'm going to try and find time to draw it out once more as a complete circuit to be sure before I start...

**JoeHarris** · 25-10-2017

Originally Posted by Neale

That looks about right.

Here goes, I think this is my finalised estop and fault circuit:

**JoeHarris** · 26-10-2017

Limit switch circuit:

Home proximity switch circuit:

**driftspin** · 27-10-2017

Originally Posted by JoeHarris

Limit switch circuit:

Home proximity switch circuit:

Can i ask a question about limit switches / estop wiring here since it is kind of on topic? Dont want to hijack this topic.

When hitting estop/limit switches, can 68volts be shutoff.. or should/can the enable contact on the drives be used?

BTW Joe the hand drawn schematics look very good.

Grtz Bert.

Verstuurd vanaf mijn SM-A320FL met Tapatalk

**Neale** · 27-10-2017

Joe - that looks fine, except that you don't need to use three inputs on the CSMIO for the limit switches. They can all go into one input, and in the Mach3 configuration screen you point all the max and min limits for all axes at that pin. You are using home switches separate from the limit switches. No problem with that, and the wiring looks OK. I'm assuming that you have NPN NC switches. By using separate inputs for the home switches you give yourself the possibility to home more than one axis at a time. Typically, you might configure Mach3 to home Z (to get it high up out of the way) and then home X and Y simultaneously - saves a little bit of time during the homing sequence.

Bert - some people consider hitting a limit switch to be an "emergency" so you could wire them in series with the e-stop switches. Personally, I have the e-stop switches trip the safety relay which turns off the 68V PSU, and also disables the drivers via the "enable" inputs and sends a signal to the CSMIO e-stop connection. My limit switches (like Joe's diagram) just go the CSMIO. Part of the reason for this is that I use a single switch for limit and home at one end of each axis, and I don't want a home switch to operate as an e-stop!

**JoeHarris** · 27-10-2017

Originally Posted by Neale

Joe - that looks fine, except that you don't need to use three inputs on the CSMIO for the limit switches. They can all go into one input, and in the Mach3 configuration screen you point all the max and min limits for all axes at that pin. You are using home switches separate from the limit switches. No problem with that, and the wiring looks OK. I'm assuming that you have NPN NC switches. By using separate inputs for the home switches you give yourself the possibility to home more than one axis at a time. Typically, you might configure Mach3 to home Z (to get it high up out of the way) and then home X and Y simultaneously - saves a little bit of time during the homing sequence.

Bert - some people consider hitting a limit switch to be an "emergency" so you could wire them in series with the e-stop switches. Personally, I have the e-stop switches trip the safety relay which turns off the 68V PSU, and also disables the drivers via the "enable" inputs and sends a signal to the CSMIO e-stop connection. My limit switches (like Joe's diagram) just go the CSMIO. Part of the reason for this is that I use a single switch for limit and home at one end of each axis, and I don't want a home switch to operate as an e-stop!

Thanks, I thought that might be the case with regards to the limit inputs. The reason I have separate limits and homing is I wanted the repeatability and accuracy you can get with prox switches but the physical break you get with a traditional limit switch. Yes NPN NC.

**Web Goblin** · 27-10-2017

Is that not a dead short between 24v+ and 0v in the "on" switch?

Click image for larger version.

Name: 73e80d5aca677563e46eccbe7b9830a4.jpg
Views: 2027
Size: 70.1 KB
ID: 23111

**JoeHarris** · 30-10-2017

Thanks for all the comments and corrections. I have now redrawn the 'CSMIO Digital Inputs' diagram as one sketch incorporating all (I think) the comments.

**Neale** · 31-10-2017

Joe,

couple more comments!

Main one is that you have two LED indicator lamps wired in series off the 24V supply, switched by the safety relay. I'm assuming that these are both 24V LED lamps. Ideally, you should have them wired in parallel rather than series. That is, take the wire from the safety relay to both lamps, and a wire from ground to both lamps. They will probably work the way you have them but won't be at full brightness.

The other point is about the switch to the stepper PSU. What I have done on my machine is take a 24V feed from one of the safety relay contacts (in fact, the one that feeds the panel lamps as above) to the PSU. In your case, if you like, you could take this via the switch as well (my machine does not have a switch in this position). Your system will work OK, but the way I have it, if you hit an e-stop then not only do you signal the CSMIO via the e-stop digital input pin, you also remove power from the steppers. Actually, I also use the N/C contact to supply 5V to the enable inputs on the stepper drivers as well; with the safety relay de-energised, this effectively disables the stepper drivers. So, on e-stop, you tell the CSMIO to stop sending pulses, you remove power from the drivers, and you also disable the drivers explicitly. You might not want to bother with the last point here, but taking the 24V from the safety relay would be a trivial change on your diagram and adds a small (although probably unnecessary) additional safety factor.

**JoeHarris** · 31-10-2017

Originally Posted by Neale

Joe,

couple more comments!

Main one is that you have two LED indicator lamps wired in series off the 24V supply, switched by the safety relay. I'm assuming that these are both 24V LED lamps. Ideally, you should have them wired in parallel rather than series. That is, take the wire from the safety relay to both lamps, and a wire from ground to both lamps. They will probably work the way you have them but won't be at full brightness.

The other point is about the switch to the stepper PSU. What I have done on my machine is take a 24V feed from one of the safety relay contacts (in fact, the one that feeds the panel lamps as above) to the PSU. In your case, if you like, you could take this via the switch as well (my machine does not have a switch in this position). Your system will work OK, but the way I have it, if you hit an e-stop then not only do you signal the CSMIO via the e-stop digital input pin, you also remove power from the steppers. Actually, I also use the N/C contact to supply 5V to the enable inputs on the stepper drivers as well; with the safety relay de-energised, this effectively disables the stepper drivers. So, on e-stop, you tell the CSMIO to stop sending pulses, you remove power from the drivers, and you also disable the drivers explicitly. You might not want to bother with the last point here, but taking the 24V from the safety relay would be a trivial change on your diagram and adds a small (although probably unnecessary) additional safety factor.

Appreciate the help! I was actually away last week - hence the hand drawn diagrams and had totally messed that bit up! Just amended it which naught make a bit more sense.