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Old 10-08-2015, 09:37 PM   #2155 (permalink)
e*clipse
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Quote:
Originally Posted by thingstodo View Post
I have no access to a lathe nor skills to use it.

I DO, however, work at an industrial mill and perhaps could work out an exchange with one of our machinists. I picture a 2 inch diameter disk maybe a half inch thick - mild steel - with a few 'teeth'. An inductive proximity switch could sense the metal, but the prox would need to be within about 1/4 inch of the face 'teeth'.

I have access to the outboard (second) shaft of the DC motor. Mounting would not be a problem.

I have access, for now, to the motor shaft on the AC motor when it is coupled to the DC motor. Mounting may be a challenge for me.

There is no access to the motor shaft on the AC motor once it goes into a car besides the output shaft, which will be buried by the coupler to the transmission/clutch/etc. Mounting within the transmission housing is *WAY* beyond my skill level.



Agreed. I will start with that.

EDIT - found an off-the-shelf 'target ring' - kinda pricey but if you don't have access to a machine shop .. it could be less than an encoder that will survive mounting in a car?

Split Collar Pulser Wraps :: Electro-Sensors

I guess those sensor rings would be ok, but I'd be concerned about their speed rating. The standard ones are limited to 3000 rpm, the "high speed" ones are limited to 6000 rpm. I think the motor you're using is capable of about 10,000rpm, right?

The little test one I made was aluminum with slots for an optical on/off sensor. I think one of the limiting factors, believe it or not, was how fast the sensor could react. I though light was instantaneous... Also, I wouldn't call it "robust" by any stretch - especially my mounting system for the sensors.

The idea Piotrsko suggested should work, even at high speeds. A solid disk is important.

One of the advantages of a resolver is the robustness. The rotor is very simple; they use a barely off-round two or four lobe disk. If I remember correctly, all my CNC mills and lathes used resolvers for feedback. They performed very well in a wet/hot/electrically noisy/mechanically noisy environment. One of the mills had a 12,000 rpm spindle that could do rigid tapping. (not @ 12,000 rpm, but remember EVERYTHING needs to be perfectly synchronised or you break a tap.)

Take care,
E*clipse
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