I managed to make another spindle holder on my CNC Taig and I dug out another helical coupler and installed it. When I turned everything back on and tested the axis by jogging back and forth, it worked fine. Basically I couldn't make it reproduce the error.
I decided to try and make a smaller lithophane picture (4" X 6") since I had no time left for the bigger one. I started the machine going again and I just watched for at least 20 minutes but it behaved itself so I went back in and worked on other stuff. About 7 or 8 hours later I just happened to be sitting in the den surfing the net and I could hear the router working when suddenly I heard a funny squealing noise. I ran out to the garage and sure enough, the axis was heading in the wrong direction again. I managed to hit the software estop with about 3 inches to spare.
To my surprise, when I looked at the helical coupler that I had replaced, I noticed it was broken and the machine hadn't crashed yet. That was kinda weird because I had initially thought my first helical coupler broke on impact. Then the final straw was when I manually turned the axis....in one direction, the axis didn't move but when I turned it the other way, the broken helical coupler managed to still engage and move the axis! Basically the aluminum helical coupler was too weak for the application and broke but it was able to engage and move the axis when traveling in one direction but not the other.
Lesson learned: I need to use a better motor coupler
Anyway, I'd never heard of this happening before so I thought I'd share it with everybody. Basically, to fix the problem I bought some big steel helical couplers that I think should work better.
I'll work on replacing the couplers and then beefing up the z-axis next. |