Maybe it does not refer to a measurement dimension but to case style. EN11 is cast metal body & shaft, EN12 is pressed metal body & plastic shaft.
Other than one has parts that are a bit more durable, and encoder is and encoder. They Give pulses as you rotate them. The various sizes have more to do with mounting than with function.
Quote from: kf2qd on Dec 12, 2012, 07:04 pmOther than one has parts that are a bit more durable, and encoder is and encoder. They Give pulses as you rotate them. The various sizes have more to do with mounting than with function.Boy I disagree. The first encoders I bought were mechanical ones with detents. Then I bought several optical ones that give a whole lot more resolution and no freaking detents. I love these encoders, they are the nicest thing I have as far as user interface parts. They also breadboard really well.http://www.ebay.com/itm/370592502534It is so choice. If you have the means, I highly recommend picking one up.
The mechanical ones I bought for less than a dollar a piece are fine enough for user interface. I'll make some videos hopefully today.
Mechanical encoders have their place, and opticals have their place. I have designed a welding machine that used 10 of the $2.58 mechanical encoders and the users loved them. Previously they had used optical encoders and they were almost useless. For an operator input the small mechanicals fit the bill well. for motion monitoring the optical encoders are much better.