Pot and Knob shafts, Ds and Flats


Is it a standard in D-shaft, right-angle potentiometers for one endpoint to point the flat face of the shaft to the right of noon, sweep clockwise, and have the other endpoint to the left of noon? And for the corresponding knobs to align the flat face of the shaft with the indicator line?

I'm looking for the right combination of knob and potentiometer for my application. From the user perspective I want a front-panel knob that indicates low at 7:30, mid at noon, and high at 4:30. The board is perpendicular to the front-panel so the pot needs pins perpendicular to the shaft. Before noticing the note "shaft shown in CCW position", I bought this pot (https://www.bourns.com/data/global/pdfs/PTV09.pdf) and this knob (http://www.newark.com/pdfs/datasheets/spc/TA-790.pdf). They look and feel great except for this one problem: the angles are wrong by 180degrees.

I looked around a bit more for alternatives: Either a knob with the indicator line opposite the flatted side of the shaft, or a potentiometer with opposite endpoints (and keep in mind the knob needs to point parallel to the board, not orthogonal to it). So far this seems impossible. Everyone I've looked at seems to be in agreement that this is the standard.

Some alternatives I would like to avoid:

  • mounting the pot on the other side of the board (there's no space)
  • using a round shaft with a set-screw knob (it needs to be fairly precise and not change with time)
  • panel-mount pots

The best alternative I can think of is to use a knurled knob/shaft but I really like the D shaft because it's so hard to screw up alignment.

Best Answer

It does look like some potentiometers are offered with options of where the full CCW position is. But anything other than the standard (30deg right of up, or about 1:30) is a special order part, or at least I couldn't find any in stock anywhere.

Here's an example: http://www.mouser.com/ds/2/414/p160-20748.pdf