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I am designing a front panel for an electronic device with PCB-mounted components on it. I need to provide precise CAD geometry for drill holes, etc. to the third party that will mill / manufacture the panel out of 2mm thick aluminum stock.

The device includes two PTV09A-2 (side mount) potentiometers. The potentiometer has a main shaft that obviously involves a drill hole in the front panel. The body also contains two small circular bumps that I think should align with holes in the panel to prevent the pot body from rotating if the shaft/knob is rotated to the stops, and prevent mechanical stress on the pins connecting the pot to the PCB.

Looking at the drawing from the datasheet below, however, I cannot find any dimensioning that tells me how I should align drill holes for these relative to the central shaft, or what hole diameter is appropriate for them... all I can tell is that they are 1.2mm tall. (Bumps circled in green below.) I do notice that in the profile (top) view of both variants, the anti-rotation bumps have a dashed line going through the middle; but I don't understand what that means or if it implies something about their alignment.

I can measure the diameter of the bumps easily enough with calipers, but trying to establish center-to-center offset from bumps to the pot shaft with a reasonably tight tolerance is harder. Am I missing something that would give me a clue to their relative location?

mechanical drawing of PTV09A-1 and PTV09A-2 potentiometers

Full datasheet at https://www.bourns.com/docs/Product-Datasheets/PTV09.pdf

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You're correct. The dimensions aren't there.

I suspect that the bumps may be used in the manufacturing assembly process and aren't intended for use in mounting. They may even be designed as spacers / stand-offs to keep a minimum distance between the face of the pot and the front panel. I notice that the "w/Metal Threaded Bushing" versions (which are designed for panel mounting) don't have the bumps.

Make the solder pads for the body lugs good and meaty - and maybe double-sided - and you should be fine!

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