On 1/26/26 17:39, Jon Elson wrote:
On 1/26/26 14:21, gene heskett wrote:
That leaves a question: When does motion tell the TP the direction
has changed??. It should be fine if it waits to start the backout
until the encoder's out direction is updated, which will happen in
the first degree of a new direction or does it start the backout
motion when it has issued the direction change?? If the latter, there
obviously is my problem.
The motion logic follows the spindle position, NOT velocity! But, if
the gears are creating backlash between the encoder and the actual
spindle, that could be an issue.
Jon
That is good Jon, gear backlash however is minimal, perhaps 1 degree in
either high or low gears. There is a port hole into that area in the
right face of the head, the docs claim those gears are plastic, but they
look like solid steel to me when shining a light thru that portal. And
they sound like metal when the engage.
That mux4 I mentioned is steered by the tally switches on the knob, and
I long ago used the positions when neither switch is closed, to inject a
tiny voltage that runs the motor at about 20 rpm at the motor when its
between gears. So I can be spinning the spindle at 3k revs, reach up
and start to turn the knob, by the time its turned 3 degrees, the
spindle is slowed to a creep so when one gear uncouples and it slides
into the other, there is no meshing ramp on either gears teeth but in a
few milliseconds it engages the other gear and as it finally reaches
fully engaged, the tally closes and the normal motor speed is restored.
No gear clashing at all as I can't turn the knob fast enough or far
enough w/o changing my grip on the knob. Your servo can bring the
motor, which might be spinning a bit over 20k revs at the instant I do
that, down to 20 rpm in about 100 milliseconds. That also charges up the
PSU filters to around 165-170 volts, so the accell back up is equally
brutal, about 100 milliseconds back to speed. In fact I sometimes think
I can hear the 18 amp current limit make an odd thump in the motors iron
for a millisecond or 2.
How's the weather at your place, snowing gently again here, 4" on front
deck, guessers are saying around 3F at 4 am tom. morning. Winter has
arrived I think.
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.
Cheers, Gene Heskett, CET.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Don't poison our oceans, interdict drugs at the src.
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