Hall effect proximity sensors

[magicniner]

I will leave you to draw your own conclusions about the necessity for a chopper

I was only able to conclude the need for manual focus :D

[johnsattuk]

I was only able to conclude the need for manual focus :D

[cropwell]

I was only able to conclude the need for manual focus :D

I am sorry that my camcorder was too close (AND TOO CHEAP) to sharply define the image. However, I do believe that the definition was enough to allow you to observe that the stop point of the stepper was within a few degrees. In fact, I thought that it probably stopped at the same point and a stepper motor, when energised by hold current, would settle at the same point on the step. My crude test would probably indicate +/- 1.8 deg and if you regard it as valuable, you may like to repeat the experiment with more accurate indication of the angle that the stepper motor settles on.

I am interested in knowing more about hold points and microstepping, but even if the homing point is one full step either way, then on a 5mm pitch screw you have a positional error of +/-0.025mm, which is good enough for woodwork.

[Voicecoil]

The thought strikes me that if we're talking about switching machines off and coming back to them, the best accuracy you can expect repeatably is one full step (1.8deg)?? as the motor will tend to "click" to the detent position either side once the driver is switched off? or am I missing something?

[johnsattuk]

[QUOTE=Voicecoil;109314]The thought strikes me that if we're talking about switching machines off and coming back to them, the best accuracy you can expect repeatably is one full step (1.8deg)?? QUOTE]

Assuming 2 phase steppers