I made a schoolboy error - I had a fault and fiddled in two areas - powered it up again, realised I had fixed the problem but now don’t, of course, know why!
I’m sharing the problem just in case others have had it, and maybe then we can jointly chase this problem away. Here goes…
770MX running super well with Microarc4 and I have been doing some work in 3+1 successfully. Suddenly out of the blue, the fourth axis begins to “under-rotate” causing crashes. And it’s slowed down too. A G0 A180 instruction actually gave a turn of approximately 25 degrees (measured by me with a protractor). And it turns much much slower.
After powering fully down, I did two things. I know I know
On the back of the stepper driver control box there is a 8 position DIP - SWITCH. I flicked each one back and forth to “wipe” their contacts.
Then I noticed the microARC’s cable, where it plugs into the electrical cabinet, was warm. I unplugged it, squirted some electrical switch cleaner into both sides of the plug and socket and re-made the connection a few times.
Powered up the 770MX again and all was well. I don’t think the plug/socket should get warm, but maybe it does on some machines. Does it? I am finding it difficult to believe this is the problem, because why would it make the microARC run slowly and not turn enough?
If it was a bad DIP SWITCH connection, I can imagine the microARC being placed in the “wrong mode” and this counting the wrong number of pulses.
So what do others think it was that fixed it? And is this a fault anyone else has seen?
My money is on you reseating the cable on the side. If that is warm then that shows you don’t have a good connection. This can be caused by a few different things but it’s worth reaching out to our support department for more information.
Thanks Davie
That makes sense. A kind person on the MX Facebook group suggests some dielectric grease on the contacts of the through-chassis connector. I think I’ll give that a go and see if things improve. Failing this, I might invest in a military grade connector (the standard part is a bit “floppy loose” even when the locking ring is fully engaged, so it’s not startlingly high quality to say the least )
I have had an on-going problem with my micro arc. Sometimes you power up the machine and the 4th axiis performs and SOUNDS like it should. Intermittently it looses voltage and its angular accuracy. Command 90 degrees it may travel 5. The motor is quiet while turning. E stop and reset sometimes brings it back to life. Not aways. The voltage from individual wire to ground is 4 to 6volts. Any suggestion? Love the machine. Been machining and making parts since my junior year in high school. Back in 1996.
Hi John, this does indeed sound rather similar to the effects I was getting.
I had no further issues with my microARC after I carefully applied silicone dielectric grease to each contact pair within the big black connector.
I still think this is a cheap switch - it’s so ‘wobbly’ even when it’s fully engaged and locked. It just doesn’t give you a cosy feeling of quality switch.
I have not swapped this out with better, more military grade one, but that would be my next move if I get further issues.
I suggest the grease is worth trying. And it’s hardly any cost.
Let us know if this works. Can I also suggest you don’t do anything else, so that this then becomes a control experiment and we will know for sure if the problem lies here, or is something else. That’s the mistake I made when I fiddled with different things. So I can’t say for sure which of my actions fixed it.
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