Geared encoder

Hi I'm converting my old lathe to CNC, now I've attached an encoder where some of the change gears used to be, but it is geared 1:2 from the spindle, so the index will pulse twice per revolution, will this cause issues or is it ok?

That will not work because threading will start at either 0 degrees or 180 degrees (randomly)

You either need to mask the encoder index with a once per turn signal
or use a different index source (say a proximity detector)

Is there a reason that this cannot be done in software, using a component that takes the number of counts per turn as a parameter and outputs an index signal every time that number of counts has been reached?

Say a 4000 count encoder and a 2x gearing, the component would output an index pulse every 8000 counts, ignoring the index from the encoder. With 1.25x gearing every 5000 counts, etcetera.

Absolute spindle position would be lost at power off, but... is that a problem? Am I missing something?

(If it is a problem, I think absolute spindle position could theoretically be synced e.g. during homing, but now it's getting complicated...)

What about using every second index pulse?

I don't think just removing every other index pulse is enough; HAL encoders have pins like encoder.N.position for example, that would have to be modified as well. At least that's what I get from a quick look at the motion and encoder man pages. Perhaps this feature would be best implemented in the encoder component itself.

Mostly I was curious if this is something that could be done at all, or if there's some mechanical aspect that I'm overlooking.

Standard incremental encoder?

Just double the scale?

I'm using an OMRON E6B2-CWZ6C 1000P/R, I suppose I can print a new gear to get 1:1 with the spindle, if it can't be done in software.