On 4 July 2010 09:15, Ian R Upton <[email protected]> wrote:

> In the 'Axis' GUI I select the machine axis and click on home. The axis
> commences to move, it then sits there with the motor whisltling and
> after some time the motor moves and then stops. I conclude that during
> the whistling phase the signals to the motor driver are directing the
> motor to work at a speed beyond it's capability.

Yes, it sounds like the stepper is being asked to move far more
rapidly than it can manage.

> This appears to be borne out by observing the display on the Axis GUI.
>
> When homing the 'Vel' (velocity) display indicates 6000.

Impressive, it it was true. That's 6 metres per minute.

> The maximum velocity configured for the axis is 50 mm per second,
> maximum acceleration is 20 mm per second.

Not related to the problem, but that's a very low acceleration. That
means that the axis will take 2.5 seconds to get up to full speed.You
probably want 500 for the acceleration number.

> Any suggestions on how to control the 'home search velocity'???

A quick experiment shows that in my system HOME_SEARCH_VEL does
control the axis homing speed. I got a bit confused at first by
looking at the wrong [AXIS] stanza in the INI file (forgetting that
when my machine is a lathe the big left to right axis is Z, [AXIS_2]
not X [AXIS_0] like it is when it is being a mill.)

Incidentally, the Velocity readout in Axis is the speed along the
path, it can be a lot higher than the max speed of any one axis if
several are moving at the same time.

If HOME_SEARCH_VEL in the correct [AXIS_N] stanza is spelled correctly
then it really should control the homing speed. And 50mm/sec is
3000m/min and not 6000. It is also fairly high for a stepper system.
Try 10 as an experiment?

-- 
atp

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