[jboyd79]

Hello All,

I am trying to build a Maslow CNC, so I purchased a pair of motors on ebay , note that I am quite new to this.

However I am unable to understand specification table as presented on the item page..
I can not figure out the CPR, PPR or resolution of the encoder.
Unfortunately the seller keeps referring me to the data on the page.

Hoping someone can help, see pics of data below:

http://www.cnczone.com/forums/attach...d=383884&stc=1

http://www.cnczone.com/forums/attach...d=383886&stc=1

http://www.cnczone.com/forums/attach...d=383888&stc=1

Link to motor : Motor

Best Regards,

[Jim Dawson]

If I'm translating that table correctly, it looks like a 12mm diameter motor has a 3 line encoder, and the 42 mm diameter motor has a 18 line encoder. Normally the counter will read both the rising and falling square wave edges, so the pulses per revolution is 4 x the line count, so 12 to 72 PPR depending on the motor size.

[jboyd79]

Hello Mr. Dawson,

Thanks, that makes sense, my motor is 37mm as per diagram, therefore am I using the value for 36mm in the table i.e 16 line count ?
So PPR = 16 x 4 = 64 ?

Just for some extra information, I tracked down that encoder to this site : https://www.yoycart.com/Product/42299022187/
The info simply did not help(me).

Is it usually to specify resolution according to motor diameter?

Thanks very much for taking the time to answer my question.

Best Regards.

[Jim Dawson]

You're welcome !

I have never seen an encoder spec'd by the motor diameter. But apparently they install whichever encoder that physically fits on the motor, and can only get the magnetic poles just so close together. I have never seen a digital encoder like this, normally the output of this type of system is dual analog sine wave which is then converted to a digital output. They just skipped that step.

My best guess is that you could use the 36mm table, but who knows. You should be able to measure the output pulses with a voltmeter and check the actual line count. Connect power to the encoder, connect the voltmeter to the output, and rotate the motor shaft with your fingers. Count the number of transitions in one motor rotation.

[jboyd79]

Sounds good,

I will try to measure the pulses as you described. The price of the unit blinded me to the lack of documentation

Over the weekend I will give it a try and I will tell you how it went.

Regards.