Dual axis potentiometers?

[Martinn]

Hello all,

for a milling machine power feed (personal project, qty = 1) I'd like to have potentiometers that have a coarse/fine adjustment in two coaxial knobs. Like many old scopes had on the X and Y scale settings, outer one for the range and an inner one for dual timebase or fine adjust.
Now this is purely cosmetic and just for fun (I can simply place two potentiometers side by side), but I wondered if you could still buy those.
Sifting through Digkey I found this https://www.digikey.ch/en/products/detail/tt-electronics-bi/P082D-27CBR10K/2620655 one by sheer luck - there is no filter one could apply and I had to go through the images. This is perfect, they have 2000 in stock and it's not even expensive. But still, only one out of 635178 potentiometer models on Digikey? Would anyone know where to look?
Next will be finding knobs for that (same problem), although as backup I could make them on the lathe (nice knurling exercise).

Thanks! Martin

[themadhippy]

outer one for the range and an inner one for dual timebase or fine adjust

commonly known as a concentric  pot ,for knobs maybe try your local guitar store

[CatalinaWOW]

Another term that has been used for these is ganged potentiometers.  Haven't tried this on the usual distributor sites so don't know if it will help.

[CatalinaWOW]

Sorry, upon checking found that ganged is reserved for non-independent resistor elements.  But concentric does work.  Looking, it seems that the guitar industry is solely responsible for keeping this option alive. 

[PCB.Wiz]

Alps call these dual shaft models

https://tech.alpsalpine.com/e/products/category/potentiometers/sub/01/series/rk097/

[Martinn]

Alps call these dual shaft models

https://tech.alpsalpine.com/e/products/category/potentiometers/sub/01/series/rk097/

So this makes two types... but at least they are available.
It seems guitars are the driving force, lots of knobs there
https://www.thomannmusic.ch/potiknoepfe.html?feature-1757%5B%5D=Dome%2C%20Tandem&feature-1757%5B%5D=Fender%20Potiknopf%20Lower&feature-1757%5B%5D=Fender%20Potiknopf%20Upper&feature-1757%5B%5D=Tandem&feature-1757%5B%5D=Stacked&gk=GIETPK&sp=solr&category%5B%5D=GIETPK&cme=true&filter=true
also a few pots
https://www.thomannmusic.ch/potentiometer.html?feature-1761%5B%5D=Stacked&feature-1761%5B%5D=Tandem&gk=GIETPO&sp=solr&category%5B%5D=GIETPO&cme=true&filter=true
"stacked" or "concentric" is the naming here.

[darkspr1te]

didnt the old ww2 style radio's have these geared "knobs" with one output shaft that was then connected to the POT ?

[tooki]

I think it’s somewhat important to point out that the definition of “coaxial” is sharing one axis, and that a “dual axis potentiometer” would actually be the exact opposite of what OP is actually looking for!

[Martinn]

I think it’s somewhat important to point out that the definition of “coaxial” is sharing one axis, and that a “dual axis potentiometer” would actually be the exact opposite of what OP is actually looking for!

Naming is completely random. Double shaft, coaxial, stacked, dual axis... Might be any of those. Sometimes even the pictures are wrong, so you have to find/read the datasheet and compare the descriptions. Also neither Digikey nor Mouser (nor any other shop) provides a working filter for what I am looking for.

With Aliexpress, "double shaft" help:
https://www.aliexpress.com/w/wholesale-double-shaft-potentiometer.html

[tooki]

Naming is completely random. Double shaft, coaxial, stacked, dual axis... Might be any of those. Sometimes even the pictures are wrong, so you have to find/read the datasheet and compare the descriptions.

It certainly is not random. Inconsistent perhaps, but not random.

Dual-shaft, double-shaft, concentric, coaxial, etc are perfectly correct (though in some cases unusual), because the two (or more) shafts share the same axis.

But dual-axis is wrong for a potentiometer with concentric shafts. Not a little wrong, very wrong. Dual-axis means having two axes, like X and Y on a milling machine bed. They mean two different planes of movement.

And indeed, if you search for “dual axis potentiometer”, what comes up is potentiometer-based joysticks, which do indeed detect X and Y position. 

Just to be explicit: axis is not a synonym for shaft or axle. An axis is an imaginary line that something moves along or around. An axle or shaft is a physical rod or similar item that rotates.

Searching for “coaxial potentiometer” doesn’t find much at all. It’s not really a term that’s used.

“Concentric” is the key word you really want, because that is the word that unambiguously describes the shaft arrangement you want.

“Stacked” is not reliable, because a stacked potentiometer can also be non-concentric, sharing just one shaft. (Like a stereo pot, for example.)

[tooki]

Also neither Digikey nor Mouser (nor any other shop) provides a working filter for what I am looking for.

Digikey actually does, indirectly: the shaft diameter. If you look at the example you found by luck, you will see that under Actuator Diameter, it lists two diameters: “0.138" (3.50mm), 0.197" (5.00mm)”

If you look at the parametric search, you’ll see that there are a number of two-diameter entries in the list of actuator diameters.

Unfortunately, the one you already found is the only one they stock. The other 44 “active” parts you’d have to order an entire box of.