Geoff, G8BMI is cross-fertilising ideas across hobbies…
He has been assembling a uBITX, and found that the volume control has a 5mm shaft rather than the usual 1/4 inch. This means that none of his spare knobs fit. We’ve all been there. Most of us threw the supplied pot into the junk box and moved on with another standard potentiometer.
However, a waking inspiration suggested a very short length of 1/4 inch OD copper pipe, as used in model steam engines, could be used to ‘sleeve down’ a 1/4 inch bore knob. And it does!.
Geoff turned down the copper tube in the lathe, using a file just to ease the fit [It could be mounted in a power drill chuck to get the same result]. It only needs a skim. His tubing was 0.210 inches bore, which is just over 5 mm (5.18)