Post by Norbert Dupuis on Feb 21, 2012 20:07:49 GMT -5
I was not stupid, there're no ghost. ;D Here is the response of Greg Cary warp93d manufacturer of my smoothstepper, thanks Greg and Bob (Campbell design) I will try all tomorrow www.campbelldesigns.net www.warp9td.com
I think you are right Norbert. It is RF noise from the VFD affecting the SmoothStepper's USB communications. The USB SmoothStepper is susceptible to noise but there are a few things you can do about it. The best solution is to stop the noise at its source, which is probably the AC power lines of the VFD. You can use an AC line filter to stop the noise from the VFD from radiating out onto the AC line. If you are using an adapter USB cable that extends from the SmoothStepper to the case, you can try bypassing the cable and going straight from the PC to the SmoothStepper. Sometimes the USB cable is a problem, so you could try another USB cable. You can also try inserting a USB hub in between the PC and the SmoothStepper. It helps to regenerate the signals. Make sure that no wires run parallel, especially high-current wires. Make sure they cross at 90 degrees if they have to cross at all. Having the ground of the SmoothStepper connected to the PC's ground with a heavy gauge wire really helps. It makes sure both sides are referenced to the same ground potential If none of these things help, please let me know.
Post by sandmandave on Feb 6, 2013 13:37:49 GMT -5
You think that's weird. I am in the process of cutting a 6 x 2 foot camp sign using two of Norbert's models. It would have been 14 hours of machining time to do the whole thing with an eighth inch ball nose, so I used a quarter ball nose and a quarter end mill first to get rid of the background. I changed to the eighth ball nose for the final file, hit go to zeros, and the router went nuts, squealing and jerking like crazy. After hours of trying to find the problem, I found that the motor acceleration on the slave motor was changed!!! How does that happen? Anyway, I cut another 4.5 hour file to test it out, and it cut the whole project perfectly. So on to finish the big sign. Guess what? Same problem, only this time all motor tuning numbers are correct. By the way, I also hear strange crashing noises in the shop while I am at my computer. When I go in there, I cannot find anything out of place, nothing on the floor that should be hanging. I think I am haunted, and my ghost does not like my cnc.
A thing to note with the grounding is to always use "star" grounding, in other words run a ground wire from one single mains input line to all other equipment, so you don't create ground loops which will potentially cause more noise. Spindles when run emit a tremendous amount of electrical noise, a good quality mains filter before the input to the VFD/spindle is always a good idea. As well, the cables to the spindle should be shielded and earthed at one end only, never both. And ferrite clamps should also be used.
I find this fascinating to learn of the system problems that the signals, cables and noise can generate and the troubleshooting you have gone through to overcome the various problems. For a non-electrical person like me, I'd be so lost the entire machine would end up sitting in the corner under a tarp gathering dust. Bravo to all of you for tracking down the ghost noises. Once again you have made me appreciate my simple little CW system that just goes along with what I tell it to do with just the 1/16" ball nose carving bit. Slow and steady wins the race.
I do however have to admit that my CarveWright is somewhat like my dog. I know he hears me "tell him what I want him to do" but sometimes he just goes ahead and does what he wants to do.
Capt Bruce Kinney
CarveWright user and Independent Representative