Jon Elson wrote:
> Chris Radek wrote:
>> On Mon, Apr 23, 2007 at 11:06:07AM -0500, Jon Elson wrote:
>>
>>> I saw the 1/3rd scale Ferrari by Pierre Scerri of France, and he
>>> ran it, producing a huge cloud of blue smoke.  Lots of other 
>>> incredible artistry, too.
>>
>> Sounds like a neat show - I would have liked to see his model.
> My photo, and hundreds of others will be on the web shortly.
>>
>>
>>
>> Sadly I haven't tried it lately as my lathe is apart.  However as it
>> seems you are WELL aware :-) it heavily relies on correct index
>> behavior.  If you can collect some more data with halscope, we can dig
>> deeper.
>>
>> In case you did not know, the sim/lathe sample config has a simulated
>> spindle with index - you can run the threading program in it.
>> Reproducing any bad behavior there will ensure that it's not your
>> stuff.
> Hmmm, interesting thought - I could watch it in Axis and see if 
> it jumps during the threading pass.

You can do the same that we had Stuart do.  Scope the index-enable and 
position HAL pins of the encoder driver.  Trigger on falling edge of
index-enable.  On that falling edge, position had better be within a 
couple counts of zero, or the index isn't working.

I think the spindle index enable is immediately turned back on by motion 
each time it falls unless you are actually in a threading pass.  The 
result is that spindle position is a sawtooth that counts up to one rev 
and then resets.  During a threading pass, motion does _not_ set 
index-enable, so the spindle position ramps up over multiple 
revolutions, and the tool tracks that ramp.  At the end of the pass, 
motion sets index enable, and position goes back to the sawtooth until 
the start of the next pass.  This should be easily observed with 
halscope.  (Note that I haven't checked this, its late... but I'm about 
95% sure thats how it works.)

Regards,

John Kasunich

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