How many PPR should I get for Differential Rotary Encoder?

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How many PPR should I get for Differential Rotary Encoder?

Postby DavoH » Tue Jun 30, 2020 11:32 am

Hi All,
I need to buy a Differential Rotary Encoder to put on my mill spindle but don't know how many PPR (pulses per revolution) encoder to get.
I'll need three phases: A, B, and Z for the spindle index.

The UCCNC V1.2111 software I am using defaults(?) to 400 PPR but I have no idea what spindle speed that might be related to.

My spindle is 6,000rpm maximum so I need something that will cope with that and control the spindle speed correctly, but be fine enough resolution for rigid tapping at tapping speeds.

Can someone recommend a suitable PPR please?

Many thanks,
Davo.
DavoH
 
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Re: How many PPR should I get for Differential Rotary Encode

Postby cncdrive » Tue Jun 30, 2020 1:33 pm

You should multiply the spindle RPM maximum and the encoder resolution PPR value (x4 mode) and divide by 60 and then you will get the frequency the encoder will output on that spindle RPM.
The limit for the motion controllers is about 50 000 Hz, so you should select an encoder resolution which is below that.
Usually a 100CPR (400PPR) encoder does the job.
Or you can get an AMT102 or 103 encoder which has changeable resolutions using the DIP switches in the encoder, so then you can change resolution any time you want.
cncdrive
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Re: How many PPR should I get for Differential Rotary Encode

Postby DavoH » Wed Jul 01, 2020 12:34 am

Thanks for the super quick reply. 8-) 8-)
I have ordered one of each of the AMT encoders as I'm not sure which would fit my configuration and the changeable resolutions are a great idea.

Many thanks, :D
Davo.
DavoH
 
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