Router losing steps. Solution needed. Will this help?

[JAZZCNC]

Hi Bob,

Woo Lad hang fire before buying anything lets find the problem first.? It won't be the motors that's 99.95 sure.

Few questions.

At what feed rates and point in G-code does it seem to lose steps most.?
What Size Nema 34 motors.?
What Voltage are the drives running on.?
Make and model of Drives and settings ie: amps, micro stepping.
Is it using ballscrews or Rack & pinion.?

Double check all the axis for binding that's a must.! . . . Check for lose motor couplings etc while at it.

Changing to closed loop won't help anything if you have a binding issues. Equally they will still stall if you haven't got enough Voltage for the speed your trying to run at. They only keep position within the tuning parameters and if your overtuning for system capabiltys then they won't do shit for you.!!

I'd tip that your trying to run too fast for the amount of volts your providing the motors with. Nema 34 motors, even small sizes, need high voltage to get any decent feed rates from them and it's common for people to under power them and then get stalling and missed steps. Throw into the mix running on a parallel port and then this sort of thing happens.
It's down to the fact larger motors have more inductance so need much more voltage, Nema 34 motors are only good to about 900Rpm before hitting the corner speed and then torque drops away quickly. What they do over smaller nema23 motors is hold higher torque up the speed curve and drop off quickly nearing the corner speed.

Give so specs of your system we can see what might be causeing the problem but DONT buy anything yet as I'd tip High voltage drives will cure your problem without new motors.