On 09/08/2015 09:30 PM, Chris Radek wrote: > On Tue, Sep 08, 2015 at 08:30:13PM -0500, Jon Elson wrote: > >> Now, you COULD figure out the right number by modulo >> division and work it that way. > You know, I hadn't thought about this. The original design for > spindle-synced motion was when we had single precision floating > point positions, which get really ... (what's the opposite of > smooth?) crunchy when you get far away from zero. Resetting after > the spindle was perhaps running at 10krpm for while before you tap > was a VERY important thing to do. > > We now have double precision floating point for hal floats, so I > think the consideration is gone or mostly gone, but a spindle could > conceivably run fast and for a LONG time in one linuxcnc session > (weeks? months?) and always in the same direction. > > I wonder how long you'd have to run before orient (which doesn't > reset, with the current design) works badly...? > > Ohhh, that sounds like trouble brewing! I can think of a high speed spindle running for 8 hours at 20K RPM with a 1000 count/rev encoder, that gives 9.6 billion counts. Then, a tool change that needs a spindle orient. Hmm, maybe a little electrical noise that causes it to pick up a few extra counts per minute, too. And then it is mispositioned for the change.
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