Y axis stalling

**JAZZCNC** · 03-08-2013

Originally Posted by richie00boy

Tuning settings are further back in this thread and the comments then said they were fine.

Ok I've been back to start to familiarise my self with original issue.!! . . . . . Did you change the wires.?

Originally Posted by richie00boy

I've now unplugged the motor and been turning the knob to move the Y axis up and down, it's not that stiff really. This is with the leadnut mounting loose, so it's just pushing the gantry on the lip and is free to rock about a bit.

Does it go tight when you tighten the mounting.? If so then you may need to shim the space between mounting and gantry surface. Some times just a piece of paper can make difference between binding and not.!!

Originally Posted by richie00boy

I also tried putting the Y axis drive on the X axis motor and running that and there is no stalling. I tried by hand to give some resistance to the head moving and it just powered through it.

No wouldn't expect it to stall either.!! The Y axis is tuned for half the speed of X axis and X axis is half the weight of Y axis. So in simple terms you have roughly twice the torque pushing half the weight.!!

Originally Posted by richie00boy

Could I have a dodgy motor?

Very unlikely Steppers are very robust things they either work or they don't.

Basicly if you haven't got bad mechanical binding or some things badly bent or misaligned like it seems to be turning out you haven't, then it's either incorrect motor tuning or you have electrical/electronic problems, either from wires or failing drive or possible PC.(thou don't think so here)

knowing there's no mechanical binding then my next place to turn, if you haven't already, is to change the wires and connectors.
I've seen them cause this sort of thing on these TB based drives before, strange but it's happened.

In mean time It may be worth playing with motor tuning to find the point were it doesn't stall. Can be tedious but some times the difference between stalling and not stalling can be less than 50 on either vel or Accl.
Get pen & paper and write down settings for each axis before starting and be methodical, only change 1 setting at time and write it down then try.
Start with Y axis and with Velocity first then Accel straight after, do one then the other until you find the balance.
My approach for getting into ballpark is to half the current setting then try, if Ok, then increase by half the difference. . . . IE 1000 original try 500=Ok so try 750=Not Ok try 625=Ok try 560 etc
This work for both Vel & Accl but best if only change one setting then do the other, All you have to remember is you can't have high Velocity and high Acceleration. When you are near usually raising one means lowering the other.

One thing to try is lowering the other Axis settings slightly and see if it affects the Y axis.? Don't think so because it's not happening while moving other axis.? Or is it.??

All that said your tuning for the Y axis is painfully slow to me so going lower to stop stalling would drive me crazy.!!

After changing wires and lowering tuning if it's still doing it then I suggest you dump the Electrics and buy some real drives.!!

**richie00boy** · 09-09-2013

Bit of an update. I think it's now sorted. There were a couple of issues, first was that it turned out the steps setting was 65kHz in Mach3, set that down to 25kHz. This became apparent trying a friends PC which was a little lower spec than mine.

The other issue was/is some binding on the leadscrew which I have improved by loosening the motor mount screws and running the axis up to the motor end and tightening the screws back up. I had to do this twice, the second time trying to do it on the tightest position, as the first time there was still some binding up at the top end.

Will see how it goes, maybe the binding will get worse again once I put the heavier 800W spindle on. But for now it's running the best it's ever run. I was able to speed the axis up to match the x axis.