Here’s a story that belongs right up there with UFO sightings.
I just finished upgrading my original OneFinity BB CNC to the Redline controller. It took about three days with a few interruptions here and there. On the second day, I opened up the garage door and completed most of the wiring. Excitement was mounting as it was now time to light it up and run it through its paces. Excitement quickly turned into bewilderment as I attempted to “Home All” and was immediately presented with failure. Messages displayed were “Closed Loop Motor Error Detected” and various “Failed To Detect X, Y or Z home switch” errors. I tried multiple times, resetting the machine before each attempt and received the same responses on one or more axis’s. Finally, the problem mysteriously disappeared and didn’t return for the remainder of the day.
On the next day, I again opened up the garage door and immediately the same problems occurred. I checked the assembly and the wiring and couldn’t identify any obvious issues. Finally, as storms were starting to move in, I wrapped everything up and closed the garage door, however I just couldn’t leave this alone as I was determined to find out what the problem was. A couple hours later, I returned to the garage and fired up the CNC and pressed “Home All” and boom, boom, boom, all three axis homed without any errors. I couldn’t believe what I was seeing.
So, I had a theory. On the next day, while the garage door was closed, I again started up the CNC and successfully homed all axis on the first try and repeated the same two more times all successfully. Then I opened the door which lets in indirect sunlight. I tried the homing process three more times, failing each time.
Hmmm…there’s something about the light that’s interfering with the homing sensors. With that in mind, I tried shining one of my blinding light flashlights directly into the ‘Z’ homing sensor as I was homing the ‘Z’ axis and it had no effect. So my conclusion is that there is some spectral component of natural daylight that is impeding the operation of the homing sensors. This is not a fluke…it’s absolutely 100% A++ repeatable.
So, my message is this:
If you may be experiencing weirdness homing your CNC, be aware of your lighting situation. It may be causing a problem. You can scratch your head for a long time trying to get a handle on this.
For OneFinity:
I’m not so sure that using optical homing sensors is a good idea. Obviously, they can be subject to light interference and additionally they can be subject to contamination from dust and debris. Something like Hall Effect sensors, which are sealed, work on proximity and are impervious to light interference and dust contamination might be worth consideration.
Here’s a link with a short clip demonstrating this problem
First homing sequence is with door closed, second is with door open.
