Potentiometer Bushing Material

[defaced]

I'm wondering if anyone has a source for the raw stock that is used to make split shaft to 1/4" shaft pot adapters similar to these: Guitar & Bass Control Pot Adapter Bushings (2)
By my measurements, it needs to be 0.250" diameter with a 0.007" wall. I'm not picky about material provided it's stainless or non-ferrous. So far my searches for this size in stainless, brass, copper, and aluminum haven't yielded anything.

[J M Fahey]

Iīd get a couple feet (or yards) of proper sized thin walled brass tube and have my friendly Machinist cut a lot of them (43 per foot).
After setting the Lathe up, you can make 200 in 10 minutes, for a very low per-piece cost.
For less than 10 or 20 units, pay through the nose for the ready made ones.
As with everything else, actual part cost is cheap, if you make enough, but setup fees or just "getting into it" set a "floor" below which you canīt go.

As an example, a customer ordered one of my 4 channel 100W mini Club Mixers, which I havenīt made for a few months now, and for which I have no front panels not PCBs left (Cabinet, PSU and Power Amp are "universal")
I cut, folded and painted 10 blank 2U high aluminum front panels (they can be used elsewhere), silkscreened 3 of them and 3 PCBs , the minimum justified because although actual screening takes less than 60 seconds each, the screens have to be properly washed later, which takes almost 20 minutes.
I will actually build 3 Mixer/Preamps anyway, even if only one was asked for.
(My "now that Iīm into it" Theory)
1 for immediate use, and about the 2 extra ones, I know that *if I have them*, Iīll sell them in a jiffy.
Worst case, I publish them in "Mercado Libre", our local branch of EBay.

Itīs good being able to make a lot of things "in house", without depending on external suppliers.

[tedmich]

heat shrink tubing can work for this, or maybe this ultra thin wall SS from McMaster Carr
12" 6100K221 $12.91

.250" OD
0.240" ID
0.005" wall

or you could hone down some smaller ID tubing with this tiny flexi-hone:
4424A256 Flexible Cylinder Hone 6.4mm (1/4") Cylinder ID, 240 Grit, 8" O'all Length $12.31

maybe this .01 wall tubing (0.230" ID)
89895K221 Type 304 SS Smooth-Bore Seamless Tubing 1/4" OD, .23" ID, .01" Wall, 12" Length $9.02

my experience is that splined shafts are pretty loose in their tolerances, maybe some RTV would snug things up a bit, and a bit of petroleum jelly on the shaft will be sure nothing is too permanent.

life is harder for people who like things JUST so....

[defaced]

Iīd get a couple feet (or yards) of proper sized thin walled brass tube and have my friendly Machinist cut a lot of them (43 per foot).

That's what I'm trying to do, I have access to a lathe though work, but I'm not having success finding raw stock.

---

I've considered the heat shrink tubing, but haven't seen if it'll work or not. Thanks for reminding me to try it.

life is harder for people who like things JUST so....

Thanks for the editorial. I'll keep that in mind.

[J M Fahey]

heat shrink tubing can work for this

This is good!
Why didnīt I think of it? ["slapping my forehead" smilie]
Or: the actual problem is that the split shaft is *almost* 1/4" diameter, not that bad; the main problem is that unless by sheer chance the screw head gets exactly in the middle of the slot, it will crush the shaft which will become irregularly "thinner", making the rotation wobbly.
*Maybe* if you can insert a proper thickness shim in the slot (it might even be pick-thickness plastic, cut with a scissor) you get "90% of the result with 10% the effort".
Try it, itīs so simple.

[Steve Conner]

That's what I do, I jam a piece of an old credit card or plectrum into the slot, and then wrap copper tape around the shaft to fit a 1/4" knob.

If it's a metric knob you just need the piece of plectrum. The pots on my old Westone bass were "converted" like this at the factory.

[Jazz P Bass]

The "jam a piece of plastic" in the slot is what is missing, when it comes to doing it right.
Why the vendors of the sleeves do not offer something (a tech tip?) elludes me.

[jrfrond]

It's not loose tolerances. That just doesn't happen in modern-day production manufacturing.

The issue is the difference between 6mm and .250" pot knobs and shafts and realizing that they are not interchangeable. Metric vs. SAE is the "problem".

[Jazz P Bass]

Yup.
1/4"= 6.35mm.

Edit: What the heck ever happened to the "Metric Act"/ from the '70's.
The most technologically advanced country (for now) on the planet & we still measure things by how long your foot is!

Edit Again: I am refering to the USA.

[Sweetfinger]

Edit: What the heck ever happened to the "Metric Act"/ from the '70's.
The most technologically advanced country (for now) on the planet & we still measure things by how long your foot is!

Where's my silver one piece body suit, personal jetpack and flying car? The future looked awesome in old movies and TV shows. Now that it's here, it totally bites!

The adapters in the OP are very likely the Allparts adapters which are just cut pieces of brass tubing like you get at the hardware store.

[defaced]

We'll find out, I ordered 10 of them. If they work, great, I can take measurments and keep looking for raw stock. If not, then I'm out 10 bucks, big whoops.

The adapters in the OP are very likely the Allparts adapters which are just cut pieces of brass tubing like you get at the hardware store.

All of the 1/4" OD brass tubing I've come across is 0.014" wall or greater, so if these parts are really what they say they are, it's not made from stock off the shelf tubing. It's either drawn down for thinner wall, or bored out (which I can't see as being economical, so I don't think that's the case).

[Enzo]

The general hobby store stuff appears to be .014 wall. Hobby stores and places like MicroMark sell tons of that.

I can't imagine they are putting any labor into this at all other than chopping to length.


Here are the guys who make the hobby store stuff. Perhaps contact them and ask if they make thinner walled stuff, or could refer you to who does.

Home - K & S Engineering: Full Line Metal Specialists

[J M Fahey]

Itīs drawn tubing.
You can reliably get any wall thickness.
Brass is a wonderful material.
Itīs been with us for 2500 years yet you can do with it things that are impossible with other materials.

[defaced]

Thanks for the link Enzo. I'll give those guys a call and see what they have/can do.

[Ronsonic]

Yup.
1/4"= 6.35mm.

Edit: What the heck ever happened to the "Metric Act"/ from the '70's.
The most technologically advanced country (for now) on the planet & we still measure things by how long your foot is!

Edit Again: I am refering to the USA.

All systems of measure are arbitrary. There is nothing more or less proper about any of them.

The length of some extinct monarch's member is as good as a fictional fraction of some portion of the planet.

The one thing that is truly outdated about the inch / foot / miles system is that it was designed for the convenience of people conversant with fractions.