Loosing steps when milling slowly

[nic6911]

Hi.
I have tuned my steppers in mach3 and they run smooth at 1000mm/min with acc. set to 200.

Now the speed is to high when cutting in wood, so in my gcode the plunge rate and feedrate are set to 400. But when i do this the steppers doesn't sound right and they loose steps.
I also tried to tune the steppers at 500mm/min, this also causes them to loose steps.

I only thought that i would loose steps when going faster??
But as it is now i can't run my mill slow, so i can't cut in the materials i wan't.

I just can't figure this out, so if you got a clue please feel free to post suggestions! :-)

regards Nic

[angel tech]

have you tried it with the acceleration at a lower setting.

[nic6911]

Yep. My acceleration is set to 200 for now. But i have tried to lower it when i lowered the speed. It's just weired that it looses steps when going slow. It just doesn't seem right. The only speed it runs without loosing steps is around 1000mm/min. Acceleration doesn't affect this.

[Hood]

Could it be resonance? Maybe your drives have pots for adjusting?
Hood

[nic6911]

I can only adjust decay and current... But yes, it could sound like resonance.. just wondered if any other have had this problem. Still hope its a adjustment problem in the software..

[Tweakie.CNC]

Just a thought but are you running your steppers 'full step' or are you using microstepping ?

Tweakie.

[nic6911]

1/8 microstep. But the funny thing is that my steppers do 200 steps on a turn which moves 5mm, hut i have to set it to 640 steps/mm when using 1/8 microstepping for it to move 1mm. That does not add up with my calculations...

[Tweakie.CNC]

Surely that would be 1/16 step then (assuming the screw is directly connected to the stepper without reduction) - very strange. Are they perhaps 400 step per rev steppers ?

Tweakie.

[nic6911]

They should be 200 steps. And the driver is set to 1/8. I bought the steppers in the uk, and the data table says 1.8 degre per step.

[Tweakie.CNC]

Really, really strange.

There is obviously something wrong with your Mach3 setup or machine somewhere because this just does not make any sense. 200 step at 1/8 with 5mm pitch screws = 320 steps / mm.

Wish I knew the answer.

Tweakie.