Hello All,
I'm hoping someone with more electrical control experience than me may
be able to offer advice on why I am seeing occasional rogue index pulses
which are messing up my G76 cycles on larger threads.
The Halscope below shows an example of the occasional ghost index pulse
which can create a new 'thread start' and trash my parts as photo above.
A schematic of the encoder setup which is a quadrature 500ppr
incremental encoder can be downloaded here:
https://www.purbrookengineering.com/index.php?option=com_content&view=article&id=11
The signal goes to a Pico Systems USC board via a voltage level shifter.
We have a 0.75uF capacitor to filter the 5v supply to the voltage
shifter and 1kohm resistors in series on the input signals from the
encoder. The encoder cable is shielded, grounded only at the encoder
case end and is not close/parallel to any power cables. The 12v supply
to the encoder is from a voltage regulator and the 5v supply to the
level shifter is from the Pico control board.
Jon @ Pico provided me with excellent support to get me this far with
the setup which now cuts smaller threads quite reliably but with larger
threads on my small lathe I need many passes and I haven't been able to
get rid of these occasional ghost pulses which eventually cause a bad pass.
I think these pulses are 'noise' but I cannot find what might be causing
them.
Any suggestions please?
Pete
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