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Homing using Servo encoder index

PostPosted: Wed Aug 25, 2021 3:09 pm
by Blaise
Hi all.

I am modernizing an old FADAL 2040 CNC mill.
For more precision during homing I would like the machine to move the axis until it reaches an induction limit sensor. Once it has reached the limit sensor, it would slow down and keep moving until it finds the index position of the servo encoder that drives the axis.
Can this be achieved with UCCNC?

In the worst case scenario where this wouldn't be possible using software alone, I have a hack (Plan B). I would have the limit sensor trigger a relay and have the signal of the encoder's index pass through the relay and trigger the software. Homing would need to be very slow.

But I would rather use plan A than B if at all possible.

Any one has done something similar?

Thanks!

- Blaise

Re: Homing using Servo encoder index

PostPosted: Wed Aug 25, 2021 3:38 pm
by dezsoe
Here is a small circuit to connect the home/limit sensor to the index:

4013 home index.png

When it reaches the home/limit sensor then the output will be active, but it will only release the output when the home/limit sensor deactivates and an index signal comes.

Re: Homing using Servo encoder index

PostPosted: Wed Aug 25, 2021 5:22 pm
by Blaise
Very nice! I am planing on designing a mother board to keep things tidy. I'll incorporate this circuit in it! Using a flipflop is perfect! Thanks!

- Blaise