Anyone ever reamed out a 6mm aluminium knob for a 6.35mm shaft? Good idea or not??

Drilling out the hold in an aluminium knob isn't difficult if you have a drill press. The key is simply to go really slowly. I've used locking pliers with cloth around the pot before and it works ok. The other thing to do is have the base of the drill press wound up nice and close to the drill so you can keep the knob flat on it. Then it's not so hard to keep it all square.
 
Is 16mm 6.35 shaft the usual size everyone uses for pots?

Yep. Those 2 metrics are what you want: 16mm pot, 6.35mm shaft (aka 1/4" shaft.)

Although you can get away with 6mm shaft if 6.35 is out of stock on a value. But the knob can become ever so slightly off-center if you do, assuming you're using knobs for 1/4" shafts.
 
Yep. Those 2 metrics are what you want: 16mm pot, 6.35mm shaft (aka 1/4" shaft.)

Although you can get away with 6mm shaft if 6.35 is out of stock on a value. But the knob can become ever so slightly off-center if you do, assuming you're using knobs for 1/4" shafts.
That's what brass pot sleeves are for!
I always keep a handful if I can't find a pot value in 6.35mm
 
... The only time it was really bad was when the set screw was perfectly parallel to the split middle seam. I tightened it too much and crushed the two halves together. But if I'm careful, I can avoid that.
...




You know the little tab that you break off to sit the pot flush in the enclosure?


D9366497-BA4C-4857-ACE6-79F867500075.jpeg
That’s the one…

74EF5B2B-182F-4B5C-AF2A-60659A7B3AC4.jpeg
It’s a snap…

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Where’d it go?

BFAE407E-2B22-4755-89DC-16AB1B5FC5AE.jpeg
Bam! Right up the snout of the ol' Spice Weasel!


It just so happens that, in most cases, the little breakaway tab is the perfect size to jam into the split, thus preventing a knob’s set screw from pushing the split together and wrecking the pot right away or through long-term fatigue.

I've jammed it in and it's usually solid without any additional fuss, BUT...

If you're unsure that the little tab won't stay put or you find a pot with a tab that most definitely shifts around in the split (like the one in the above photos), then just add a dab of solder to keep it in place. This one will require a dab of solder, on either/both side(s), not on top, so the severed tab sits flush with the top of the split, allowing the knob to sit all the way down.



Of course, only do this tab-trick for set-screw knobs, the knobs meant for splined split-shafts don't work so well once you solder the tab in.

I rarely use split-shaft pots, and prefer set screw knobs...
 
I wanna order these groovy ass knobs for my next envelope filter, but I can't find a 6mm shaft pot in reverse log 100k (not even from Tayda.)

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I have a harbor freight drill press and below-average skills with it. Can I ream these out? Is it worth trying? Or am I gonna end up with a case of regret and an emergency room bill?
You'll definitely need the ER unless you use a vise. Reaming out with a drill going the proper direction will bite the edge and yank that sucker right out of your hands. However,,,,, if the drill is going the opposite direction there will be no yanking. It'll take longer but you won't need any bandages. I'd still use a vise tho, large holes in fingers never quite heal all the way. I have some that are 20 years old and still kinda sensitive.
 
Thanks, Meower. This is the best thing I've learned in a long time. The best tricks are hiding in plain sight.
As well as the phrase "Spice Weasel." Thank you.
I just recently purchased this set for my dremel, They are Great & you can't beat the price!
When working with Aluminium with burrs, Be careful & use wax to stop burr from clogging up & clean regularly with wire brush!
 
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