3 Axis CNC router

[JoeHarris]

Don't know why it's doing this never seen it before but the reason it kept going after feed hold was because it was emptying the buffer.

Have you done a check to see if your missing steps from the pulse being on the wrong side of the edge.? If not then Zero the Z-axis and mark it's position then write some G-code so it moves back n forth several 100 times, only needs to be short moves. Make the last move go back to Zero.
If it doesn't return to the mark then you need to change the active Hi/Low in motor tuning for that Axis.

Thanks Dean, no I don’t think I ever did that test on the Z axis but I did on the other two. I’ll give it a go and see, but really wanted to finish this job!

I reduced the Velocity on z from 2.5m/min to 2m/min and the acceleration from 250 to 200 and ran the roughing pass again a little slower than before and it cut to the end without any trouble (although it is hard to tell if it lost any steps as it is only a roughing toolpath). But once it was done and had gone back to zero for the tool change it kept making little erratic movements again. Could this still be to do with buffering if it is stopped for a tool change? I videoed it for a few seconds this time, if you have the sound on you can here it making little jerky moves. This was at the tool change so no g-code to tell it to move and nothing changing on the DRO. I don’t get it?

https://youtu.be/m1vlkqPeVMM


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[JAZZCNC]

No Joe that's definitely not the buffer...Lol

It looks very much like a noise issue.? But knowing your setup and the fact spindle isn't running I'd be surprised if it was.! . . . . Have you grounded the chassis.?

I'd be going over all the wire connections in the control box first looking for loose connections or stray wires. Also If you have any plug connections like DIN sockets on motor cables I'd check them out as well, in fact, chop them off and throw them in the bin as they are a pain in the arse.!!

[JoeHarris]

No Joe that's definitely not the buffer...Lol

It looks very much like a noise issue.? But knowing your setup and the fact spindle isn't running I'd be surprised if it was.! . . . . Have you grounded the chassis.?

I'd be going over all the wire connections in the control box first looking for loose connections or stray wires. Also If you have any plug connections like DIN sockets on motor cables I'd check them out as well, in fact, chop them off and throw them in the bin as they are a pain in the arse.!!

The motors are soldered to the cy cable and are wired directly to the drives - no connectors! And the cy shields are grounded at a star ground in the cabinet.

But... The frame is not grounded independently come to think of it, should I take a connection from the steel back to star ground? Is that what you mean by chassis?

I will go hunting for loose connections but pretty sure they are all good as I checked last time I had issues...

The last time (previous post) when I stopped the machine after noticing a problem, it carried on doing these movements after both feedhold and stop, it was only the estop cutting power to the motor that stopped it.


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[JAZZCNC]

But... The frame is not grounded independently come to think of it, should I take a connection from the steel back to star ground? Is that what you mean by chassis?

Yes, run a wire from the Star point to the Frame and if you want to take the belt n braces approach then run another to the gantry just in case it's not earthing thru the bearings very well.

Do this before doing anything else. That way you'll see if your problems go away just from this.