Hi
I've received a request for information from cncfrenchteam on HMEM. However my account from them is completely borked. Could someone point him to this post or forward it to him.
So in reply to cncfrenchteam :
>>>>>>>>>>>>>>>>>>>
Hi
I remember that the width of the high step pulse controlled the motor coil current - hence the torque. If a stream of pulses at 500hz is sent to the stepper input normally this would be a square wave, with high and low pulse times of 1 mS. Adjusting the high time whilst keeping the frequency constant would alter the ratio, say 0.5mS high and 1.5mS low. So although the frequency (motor speed) was constant the mark space ratio was altered. It was only after I had started to alter the board I realised what they had done. I think it used an SLA7051A driver chip sheet attached. Pretty certain it was set to half step - see data sheet. The setting of the motor current is quite important with all stepper motors. They really work best into fairly constant loads where the winding current can be optimised. Too much current with a light load causes the armature in the motor to over accelerate and possibly oscillate, too little may not overcome stiction and load resistance.
Hope the info works for you - its all still working well on my lathe using an old laptop power supply.
Good Luck !!
Best Regards
picclock
>>>>>>>>>>>>>>>>>>>
Many thanks
Best regards
picclock