Possible Electrical Noise?

[Bryan Cowan]

Machine: CAMaster 28x40 CNC w/Porter Cable router
Software: Mach3

Problem: Starting on 5/30 while running a profile program, the router would start cutting and then a few minutes later Mach3 would stop and blink reset (Like I physically hit stop in the software). I would clear the reset, resume, and the program would continue cutting where it left off. This happened a few more times before finishing the program and going back to home (X0 Y0). However, somewhere along the line during the profile program, it lost a step. What used to be X0 Y0, now was X-0.04 and Y-1.01. Unsure where it lost the step, but it was certainly visible on the finished part. And when it got back to home, the computer froze which required a hard reboot. All of this was happening when the Porter Cable router was on and spinning at 20,000 RPM. I thought maybe chips were getting caught in the gears, so I cleaned everything and reset my zero.

Yesterday, 5/31, the same problems were happening. Knowing that there was a clean"er" machine, I didn't know what was going on. I did, however, notice the Porter Cable router making an unusual noise when sitting at the home position and spinning at 20,000 RPM. As I let it sit there and spin, I witnessed the X-axis jump a bit which set it off-zero again. No program was running, but Mach3 was open on the computer. I can't say I've ever witnessed that before.

The last time I replaced the brushes in the Porter Cable was January of 2011. Luckily, I had another PC router available to swap in to finish what needed to be done. With the new PC installed, it ran the program well and returned to the actual X0 Y0 as it was registered. Now, I haven't done further testing to come to the conclusion the router was at fault because there just wasn't enough time in the day, but would a failing router be to blame? The last time I replaced the brushes, I only remember the router failing to work; not causing positional errors. I haven't opened the router up to check the brushes yet, but plan on doing so this weekend.

The computer has been optimized for Mach3 and it is the only program running on the computer.

Any thoughts or suggestions as to what may be to blame?

Thanks

[Dave Spitzer]

Bryan,

I'm not sure how your machine is wired, or the make and model of the break out board, CAMaster should be able to help with that part. In the mean time you should check all ground conections, also all input connections, if your inputs are wired NC (normally closed) a loose connection could trigger an e-stop event. Look at the history in Mach3 it will show what triggered the e-stop (such as a limit switch triggered). Noise and/or ground loop currents can be difficult to trace, but if the machine was running without problems for a long time I would suspect a loose or poor connection. You may also want to have your router checked just to be on the safe side. Is the power cord or supply line to the router next to any unsielded signal wires? This also may be an issue.

Dave

[Mike Heidrick]

The router would not cause any axis to loose a step directly. What may happen is your cutting with a router might uncover a slipping of one of your steppers.

Make sure you have no racking and that all your axis couplings are very tight.

The shutting down of mach could be caused by your watchdog timer. Try disabling it - Config -> General Config -> uncheck Use Watchdogs (far right, third down) Run the same job and try it again.

Also run some test cuts - circles and letters work great to unearth issues.

I do not know your machine so a few questions:

What operating system?
What type of steppers? How are they connected?
What drive mechanism?

I am sure the Camaster guys read this and already have your parts for fixing the issue in the mail

[George Carlson]

Try running a job without the router. If it runs through without error, your router may very well be the problem. But, that being said, the system should have been designed to eliminate RFI, and run with the noisiest of routers. Buy a filtered plug strip. Look for one with the most attenuation. Belkin is a good source. Make sure it is filtered, not just a surge suppressor. Plug the router into the filtered strip and see if that improves things.
The next step would be to install 0.1uF de-coupling capacitors on the control lines from the Camaster switches on the breakout board.

[George Brown]

I had this problem, it was due to static build up from the dust being drawn through the pvc piping. Had the pvc pipe connected directly to the x-axis plate. The problem went away when I insulated the pvc pipe from the machine chassis.

George

[Bryan Cowan]

I don't know, but ever since the new router went in, there hasn't been any problems (knock on wood). The brushes in the other router were beyond gone. With the new router in place, it's cutting better than ever. Let's hope it stays that way.