Alan Ratcliffe wrote:
The important things are split or solid shaft and metric (6mm, Asian) or Imperial (1/4", 6.35mm, US). IME you don't have to match the splines to get the knobs to fit, even if you reuse the knobs.
After more Internet searching I've come to the conclusion that the US made pots have 17 teeth and is known as course spline.
I have some really nice Japanese pots here that I've bought off eBay and they have 24 teeth (I've counted) with the aid of a magnifying glass and all my knobs seem to fit on them. This is apparently called a fine-splined pot.
What I've done in the past with great success when a knob don't want to fit on a pot, is to warm the top of the shaft up with a soldering iron till its nice and hot and then pressing the knob onto it. It expands the pot just enough for it to fit over the spline. To make it easier just squirt a little Q20 into the hole of the knob to lubricate it before you push it down. This will prevent the pot sort of melting to the shaft if you've heated it up too much. It does no damage to the pot at all.
That's my 10 cents for Thursday morning! ?
