Re: [Emc-users] threading Z oscillation depends on encoder PPR

[Dave <EMC@DC9.TZO.com>]

 >>16 feet maybe...  No, just over 3 feet.     I think it may have been 
originally setup to machine titanium alloys. 

Dave

Gene Heskett wrote:
> On Friday 23 October 2009, Dave wrote:
>   
>> Yet another situation where more is less..  ;-)
>>
>> In a more perfect world I guess it might be best if everyone was running
>> 1024 ppr encoders on their spindles and threading at 1000+ rpm and using
>> a hardware interface.
>>
>> Ironically if you want to thread on a really large lathe and need to run
>> at 60 RPM to do so, the position interpolated functionality would really
>> be required.
>>
>> Don't laugh at the 60 rpm, I am helping a guy on a big lathe CNC lathe
>> that can run much slower, I think 9 rpm is the lower limit on the spindle.
>>
>> Crazy slow.  :-)
>>
>> Dave
>>     
>
> And the max swing was 16 feet maybe? :)
>   
>> Andy Pugh wrote:
>>     
>>> 2009/10/23 Jon Elson <el...@pi...>:
>>>       
>>>>> Which is an interesting point. It seems that a hardware quadrature
>>>>> counter is likely to be counterproductive if you have a low-count
>>>>> encoder.
>>>>>           
>>>> I'm not sure it is COUNTER-productive, but if the spindle encoder
>>>> resolution times
>>>> the maximum spindle speed doesn't exceed the ability of the software
>>>> encoder counter,
>>>> than it doesn't GAIN anything.
>>>>         
>>> Perhaps I should have elaborated further. What I was saying is that if
>>> the hardware encoder and driver does not offer an interpolated
>>> position every servo cycle and the encoder pulse rate is low enough to
>>> have multiple servo threads per encoder count, then EMC will see a
>>> stationary spindle with the hardware encoder. This might cause the
>>> problems we are seeing.
>>>
>>> In that situation the software encoder, which does offer
>>> position-interpolated, is paradoxically superior.
>>>       
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>
>
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