On Mon, 18 Jan 2021, John Dammeyer wrote:
Date: Mon, 18 Jan 2021 15:58:12 -0800
From: John Dammeyer <jo...@autoartisans.com>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: "'Enhanced Machine Controller (EMC)'" <emc-users@lists.sourceforge.net>
Subject: Re: [Emc-users] Spindle speed changes with threading.
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Just trying to get my head around this. The spindle position is really only
known by the index pulse. Knowing both Z axis acceleration and target speed
the Z is started N spindle encoder counts before an index pulse so it's up to
speed the instant the spindle ticks over another index. How many turns of the
spindle that takes then doesn't matter.
John
AFAIK the Z position for threading is fully "geared"to the spindle position
during the entire threading pass so index is only used for initial sync. The Z
position will alway be correct after the initial Z acceleration to reach
synchronization, regardless of the speed or change in speed of the spindle.
_But_ Changes at the beginning of the thread can occur with varying spindle
speeds because of X and Z acceleration and velocity limits. These can change the
start of thread position or even make threads with varing pitch if Z is not up
to speed when cutting begins
Peter Wallace
Mesa Electronics
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