[ChrisAttebery]

After building my G0704 CNC conversion about 18 months ago I'm ready to upgrade the controller and I want to make sure I'm not missing something.

Right now I'm using Mach3 with a parallel port connection through a CNC4PC C35 breakout board. I have a KBMM-225 DC motor controller that is currently just sitting out in the open on my workbench. There is no power relay or switch on the KBMM right now. I'm turning it on or off with a switch on the speed pot and disconnecting the plug from the outlet when it's not in use. I have a small 5V/12V power supply for the breakout board and case fan. I also have a 48V 12A power supply for the stepper drivers.


For the upgrade I have a few goals:

First, I want all of the electronics in one enclosure. I bought a 17"x20"x7" rack mount enclosure to transfer everything into. Even with this larger enclosure it's going to take a bit of work to get everything squeezed in and provide decent airflow to the spindle and stepper motor drives.

Second, I purchased an Ethernet Smooth Stepper. I've noticed that if I do ANYTHING on the PC while the machine is running I can hear the steppers click. I've also lost steps in the past with my rapids set at a conservative 90IPM. I lowered the rapids on all three axis to 60IPM and haven't lost any steps since. I'm hoping that the ESS will allow me to increase my rapids and make the machine run smoother overall.

Third, control the spindle with a CNC4PC C6 variable speed control and C3 for spindle RPM feedback. Use the 12V relay on the C6 board to enable and disable the spindle drive. I've purchased an Eaton power relay that uses 12V DC as a control signal and has a 220V DPDT output.

Forth, move the E-Stop, Cycle Start and home switches to from 5V to 12V to improve noise immunity. I'll use simple voltage dividers at the BOB to reduce the inputs to 5V.

Fifth, possibly add a C10 breakout board to the second parallel port on the ESS. I only have one free input on the C35. Along with the spindle RPM feedback I'd like to add a Feed Hold button and possibly move the home switches onto separate inputs. At some point I'd like to control the air and mist via relay too.

Sixth, possibly add a panel mounted switch to turn the spindle on at a set RPM (~1200) to use with my edge finder. I think this would be a lot easier than turning the spindle on and off and setting the RPM in Mach every time I want to set up a job. Correct me if I'm wrong here.


So my questions are:

1. Ideally the E-Stop should kill power to the spindle and steppers, correct?

2. Is there any advantage to using a separate input for each homing switch?

3. What the best option to control the 12V outputs to the mist and air systems? Relays, power FETS, Op amps? EDIT: The CNC4PC C15 dual output relay board looks like it would be perfect for the job.


Any feedback would be appreciated,



Chris

[phomann]

Hi Chris,

1. Yes the EStop needs to cut power to the spindle. A spinning spindle is arguably the most dangerous part of the machine.

2. No not really, unless it makes the wiring easier. Mach3 home one axis at a tome, so it knows which switch has been hit.

3. I like mechanical relays. They are simple and reliable. When solid state relays(FETS and other electronic switches) fail, often it is in the on-state, which is a problem and another reason why the EStop needs to remove power from the spindle.

Cheers,

Peter

[ChrisAttebery]

I just realized that I put this int he wrong forum. Oh well.

I placed an order for the C35 from CNC4PC. I've also been working on the layout of the electronics inside the controller. Next up is cutting all of the openings into the case panels. Once I have the panels finished I'll start moving the electronics over and the wiring.

[Fastest1]

Though I like Arturo and his products. My choice on a breakout board would be the PMDX126. It is the most robust board you will get at these price points. Check it out.

[ChrisAttebery]

Thanks for the input, if I was starting from scratch I would look in to it but at this point I don't want to completely redo the controller. I have a board that I know and understand. I'm *trying* to not let upgrading the machine become my new hobby. If I had the money I'd buy a Tormach or Novakon and be done with the upgrade bug.

[ChrisAttebery]

DOHH!!! This should have read "I placed an order for the C6 from CNC4PC." I already had the C35 from my original build. I'm making mistakes on this board left and right lately.

I placed an order for the C35 from CNC4PC.