spindle with encoder

For rigid tapping i need only index signal from spindle shaft
A-B signals can come from elsewhere the encoder is mounted that is not 1:1 ratio correct ?

I have also some backlash to geartrain..
This will be problem for rigid tapping when tap goes backwards ?
If yes then must mount also encoder on spindle shaft..

Spindle RPM is so high, backlash will be totally negligible.

Your motor and/or geartrain might not be designed for, or capable of, instant-reversing.

The motor could break, the gears could shatter.

(Steel can shatter; I've seen old worn-down scrap rails, stored beside the edge of the track, shatter like potterewy in placed where stresses, presumably due to thermal exansion, snapped them)

motor is 7.5kw so it has enough power machine is heavy 3tons knee mill
and gears are strong enough..
If something breaks will be the tap.

How many degrees of backlash at the spindle?
 With this and the thread pitch, you could determine
the Z axis error caused by the backlash to see how serious it is.

I guess you could even make a hal backlash component for the
encoder position if need be. (create a deadzone on reversals)

I still would not recommend instant-reversing.
Let the motor stop, then reverse it.

Who cares about backlash anyway?

Just wait a second after the motor starts before reading RPM from encoder.

The backlash makes a miniscule difference only when reversing and sometimes starting (if direction is always the same, there is no backlash at all).

If the direction changes, there is backlash only during the directional change.

The backlash won't cause an error of 1 revolution!

It's negligible!


Stronger gears shatter more.
Stronger steel generally shatters more easily than weaker steel (so long as quality is same).

Just wait a second after the motor starts before reading RPM from encoder.

This would not work with rigid tapping (the OP's question)