Re: [Emc-users] I did hit a lick today

[Jon E. <jon...@gm...>]

On 07/22/2016 03:54 PM, Gene Heskett wrote:
> Thats one of the reasons I thought the 627 was the better device.  Then I
> recalled that the index pulse resets the encoder counter, and it seems
> to me that the unit used for an index pulse would have its stuff all in
> one sock by the second time that ferrous flag came by, and that would
> then cancel the half a tooth error since the encoder, when in ABZ mode
> is counting edges.
>
> Am I wrong? In which case what device to use?
>
>
The 667 detects the passing of the gear tooth, so it is rather 
insensitive to small magnetic variations and the distance between sensor 
and gear.  A sensor that is affected by the space between gear and tooth 
would give a different pulse width depending on spacing.  The 667 gives 
a very good 50% duty cycle largely unaffected by spacing.  In the 
Bridgeport hack, I had a VERY small clearance around the bull gear to 
place the sensor, and no room to adjust the spacing.  If you have the 
room, a proximity sensor could be fine, but then you'd have TWO 
interacting adjustments to deal with - sensor distance to gear, and 
sensor quadrature spacing.  I hate having to adjust stuff where you have 
to position something to set TWO different parameters at the same time.

Jon