Special request, encoder input scalar

[martyscncgarage]

If you just want a tach for spindle speed. these cheap hall effect sensor tachs work ok. You would need to machine a pocket in the pulley and bed the magnet (correct pole orientation up, test before you install) in epoxy. Says its good to 9999RPM...I have used them, but not that fast,
DIGITEN 4 Digital Green LED Tachometer RPM Speed Meter+Hall Proximity Switch Sensor NPN
by DIGITEN
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[ScotY]

Yup. High RPM encoders are tough to find. You'll be limited by mechanical rpm or electronic bandwidth, or probably, both. The ones I used were limited to about 6K rpm with the 1024 ppr resolution I chose. It takes pretty expensive bearings to handle 10K rpm and a 1000 line encoder is approaching 700 kHz at top speed. Most encoders I found were limited to 3-4K rpm mechanically and 200-400 kHz.

If you are not going to rigid tap, I don't see why you can't use the motor encoder. The drive ratio is probably not exactly 2:1 so you'll need to experiment with the encoder counts per rev to get the spindle RPM correct. You'll have more than one index pulse per rev but as long as you don't try to peck tap, it should work fine for feed per rev calculations.

Hi Tom,
I have a Tormach 440 that’s running on their Pathpilot software. My intention was to convert to Acorn but the spindle encoder was the reason I’ve yet to do so. The spindle runs at 10,000rpm in high range. Due to the low power motor, I’d imagine rigid tapping would need to be done in low range. Due to the design of the power drawbar, using some sort of ring encoder with the sensor reading the outer diameter of the ring would be easiest to fit. Does such an encoder exist?

[tblough]

Yup. https://www.rls.si/eng/radial-magnetic-rings - it's what I used on my spindle encoder modification. See this thread - viewtopic.php?f=64&t=1944&hilit=bridgep ... le+encoder