the library Rotary_Encoder has PEC12R and other encoders that have a 0.0 thats not on the axis of the weel. i think thats wrong. but may be there is a reason for this?
You’re probably talking about pad A, where the reference point is? That’s normal and true for all parts, whether ICs or discretes.
You cannot operate with an imaginary “centre”. If it annoys you, set the 0,0 point to where you like.
I have seen some strong feelings about where the 0,0 point should be. (Component body center, or pin1, or ???) But I make most of my own footprints, and I have been consistently inconsistent in that regard. It has not yet caused me a lot of pain although I have not been designing boards for mass production.
Through hole parts, that is. (EDIT: sorry, not just tht parts.) The most important function of the zero point of a footprint is to be the zero point for automated pick and place. Traditionally THT components have been placed manually and the zero point doesn’t matter. My personal opinion is that the zero point for KiCad PCB editing should always be in the center if possible.
Yes, that happens, but DIP IC’s have been placed by machines for over 40 years, and those are not an exception.
A screenshot of the offensive footprint:
According to the KLC
For through hole components the footprint anchor should be placed at the location of pin 1.
There is no pin “1” on this footprint, but pin A is the closest, so the footprint is conforming to the KLC.
this part has an axis where You can put an knob on it. If You make a layout, then You likely want to place the knob at a point on a front-panel or in a case.
the actual reference isnt on a pad, its near the center of the knob, but not exactly.
i You simply place the parts where You want Your knobs, it looks ok from far, but will not be correct.
i write not about the 90°, but there i think its the same. the axis of the knob will be the thing that for the PCB designer will matter.
do You dont agree?
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I use handfuls of Encoders of various types, including PEC12. I mostly use Optical encoders these days (for Telescope projects) - they also do Not have Zero physical position… It’s all about Coding…
Most Encoders do Not have an orientation for Zero. Zero is accomplished in Code (Why? Because that’s a part of the Beauty of using Encoders as Volume, Tone…etc controls wherein missing Pulses does Not matter). The turn a Wheel with cutouts… Knobs for this purpose seldom have Numbers and, though there is a Flat on the shaft, it’s only so the knob doesn’t slip on the shaft.
Notice the Shaft’s Flat but, it’s not meaningful in a physical/usage sense.
now You are writing about the missing zero-puls of a quadratur-encoder?
i was writing about the mechanical center of the rotatable axis of the encoder. when You place Your encoders on Your nice PCB, what do You prefer: placing the mechanical center of the axis, or placing some other point of the encoder (as example 0.45inc left and 333um above the axis-center)?
Yes. I guess I missed the part re physical center of shaft… sorry…
I design the PCB and estimate physical position. When the PCB is designed, then I worry about Panel and/or 3D-Printed panel/enclosure holes and getting them where needed.