Pot shats and Knobs

[tomek]

Hi Guys,

Please allow me to introduce myself

Been tinkering w/ electronics since I was a wee child.

Took Comp. Sci in collage but just could never get my head around electricity theory. 

The explanations / analogies just never made sense to me.  Oh well..


15 years have passed and I got into building pedals last year.

Just following the schematics online, have given me great results as I love

the ability to shape the tone myself.  Just tweak, measure, tweak measure, etc..

I've done a few OpAmp based overdrives, and two and three transistor Fuzzes (germanium, and sili).

Going to try and tackle an LDR / LED tremolo next, with the help of a design on this Forum.

I have been lurking here for a bit, trying to learn as much as possible by reading all of your

excellent suggestions!


Here is my trivial yet time consuming dilemma:

The pots I've decided on are the solid shaft Alpha 16mm from Smallbear due to the awesome quality / price ratio.

They are only $1 each!

Seems that most knobs do not fit these shaft, as both the knob holes, and pot shaft are 1/4" ??

What are you guys doing to get around this?  Are you getting the more expensive split shaft pots?

Why are they almost double the price?


Ideally I am looking for a chrome / sliver dome knob with knurl (tele style) but which has a marker on the top,

that will fit the solid shaft pots.


Can anyone advise where to / how to find knobs which fit the solid shafts?

Do you guys just go w/ the split shaft pots for double the cost?

Do you just drill out the 1/4" holes to accommodate the bigger shaft?

If anyone could link to some good knob selections online, that would be very helpful too!

Sorry I hope my questions aren't too stupid or ambiguous.


Sincerely,

Tomek

[petemoore]

  As far as electricity, there's a water analogy for about anything it does.
  Study DC, which is like a water tank w/outlet hose. When it's valve is opened current flows, and voltage begins dropping, similar to a battery.
  Study AC, which is like waves because it's a cyclic nature of waves [up down, up down].
  Distinguishing these two is fundamental to understanding anything else about signal electronics.
  Either type of potential is 'floating' until assigned, it's like voltage doesn't even know it is voltage until it's referenced to some other voltage.
  Look at schematics and see AC signal input flows [often] from left to right [input>circuit>output.
  The caps let the AC waves pass and block DC potentials. NPN circuit shows how the + power [often] is on the top, and the negative is on the bottom, and the voltages inbetween tend to follows the 'higher up on schematic equates largely to closer voltage to V+ in the circuit. [for breif idea, not always the case].
  Toward the top of the schematics you'll tend to read higher voltages in the circuit.
  The base of a gain stage transistor lets in a teeny wiggle of voltage, AC of small potential compared to the output. Transistor uses DC potential to make the output waveshape follow the input waveshape, just a lot 'bigger' on a scope, higher in AC voltage swing, louder is technically incorrect word for gain. It takes say an AC V input swing of say .2v peak to peak, and using 9v DC potential as power, it metes out a magnified [multiplies the .2 peak to peak voltage] version of the waves.
 I bought my knobs at RS, and otherwise use free knobs/pots.
 Splitshaft takes different knob than 1/4'' shaft, then there are >20 other kinds of knobs/shafts too.
 The the drilled hole works best when the threads just fit through, a unibit is recommended tool to size potholes with, it can also remove burrs and leave a nice champhored edge on both sides, this makes the nut/pot work and fit better.

[tomek]

Thank you very much for getting back so quickly!

I'm not worried about the electrical theory at the moment, as I can do (have been doing) allot of read on that.

The water thing doesn't work for me looking at it from a physicist point of view.
Perhaps I'm over thinking it, but that's ok, that's just me! -hehe

I more concerned about the knobs for the immediate being.

If anyone knows where to find "tele style" knob w/ a marker on top (for a decent price)

I'm all eyes!

Good tip on the unibit!  I'll have to grab one of those, and a drill press.

Cheers, Tomek

Edit- sorry didn't see your "ninja edit" hehe.  Thanks again, those are VERY helpfull tips!

[MikeH]

All of the set-screw type knobs I've bought from small bear (and I used a lot of different kinds from there) have all fit on the 16mm smooth shaft alpha pots that I get there too.  More or less; occasionally some are a bit of a squeeze, but I havent had to drill any of them out.  I think you should be ok.

[Hides-His-Eyes]

You might have righteous metric knobs but filthy imperial pots (6.35mm > 6mm)

[zombiwoof]

I'm a bit confused with your post.  Do you need 1/4" knobs, or 6mm knobs?.  Pots either have metric 6mm or US-spec 1/4" (6.35mm) shafts, either knurled or plain, you just have to find the knobs that fit those shaft sizes.  It is a problem sometimes in that many sellers don't say which size shaft their knobs fit, I've often had to email them to find out.  Sometimes the seller doesn't even have a clue.  This goes for guitar pots, too, there are different shaft sizes and with the knurled pots there are different knurls (18-spline, 24-spline), so it's a PITA sometimes finding the right knobs.

Al

[tomek]

Hi Guys!

Thank you all very much for the replies, you're very helpful!  

I think that might be a part of the problem..  I imagine the Alpha pots are metric as they come from Taiwan.?
It does seem like just a hair off..

Can anyone confirm if if the pots on Smallbear are metric?
It's a little interesting as they list metric, and imperial measures.. e.g. 16mm and 1/4" diameter.

Alpha Single-Gang 16mm, Solder Terms, Linear & Audio Taper
1/4" diameter, smooth shaft, no detents.
PRICE: $1.25     Shipping Wt. 0.23 oz

Here is a link to the pots I'm referring to:

http://www.smallbearelec.com/Detail.bok?no=555

Sorry again guys, seems like such a stupid question.
Perhaps I should be bugging small bear! hehe

Tomek

Edit - PS zombiwoof, I see you feel my pain.  I really like the Alpha pots I linked too, and am trying to stick w/ those.

You're right, some knob sellers have no idea.  I just ask them if they'll fit 1/4" shaft and they say yes.
The knobs arrive, but don't fit -haha  Perhaps those Alpha pots are 6.35mm shaft?  

That would make sense because if there are only two sizes 6.00mm and 6.35mm then
if they were metric (the smaller 6.00mm) any knob should fit.
(I'm trying to stick w/ setscrew knobs)

PPS - Thanks MikeH, I'll check those out!

[zombiwoof]

Hi Guys!

Thank you all very much for the replies, you're very helpful!  

I think that might be a part of the problem..  I imagine the Alpha pots are metric as they come from Taiwan.?
It does seem like just a hair off..

Can anyone confirm if if the pots on Smallbear are metric?
It's a little interesting as they list metric, and imperial measures.. e.g. 16mm and 1/4" diameter.

Alpha Single-Gang 16mm, Solder Terms, Linear & Audio Taper
1/4" diameter, smooth shaft, no detents.
PRICE: $1.25     Shipping Wt. 0.23 oz

Here is a link to the pots I'm referring to:

http://www.smallbearelec.com/Detail.bok?no=555

Sorry again guys, seems like such a stupid question.
Perhaps I should be bugging small bear! hehe

Tomek

Edit - PS zombiwoof, I see you feel my pain.  I really like the Alpha pots I linked too, and am trying to stick w/ those.

You're right, some knob sellers have no idea.  I just ask them if they'll fit 1/4" shaft and they say yes.
The knobs arrive, but don't fit -haha  Perhaps those Alpha pots are 6.35mm shaft?  

That would make sense because if there are only two sizes 6.00mm and 6.35mm then
if they were metric (the smaller 6.00mm) any knob should fit.
(I'm trying to stick w/ setscrew knobs)

PPS - Thanks MikeH, I'll check those out!

If you try to use a 6mm shaft pot with a 1/4" opening knob, it will go on if it is the set-screw type, but it will be off-center and wobble when you turn it.  Not good IMO.  You really should use the right knobs for the pots you have.  Small Bear lists those as 1/4" shaft pots, so unless he is wrong you need knobs that fit 1/4" shafts.  I think Alpha makes pots with both metric 6mm and 1/4" shafts, so you have to make sure which one you are getting when you order them. 

So are you saying you have pots with 1/4" shafts and knobs that fit 6mm shafts, so they won't go on?.  There are 1/4" shaft knobs around, again, just verify what they are before ordering.

This stuff seems trivial but can be frustrating!.

Al

[tomek]

Thanks Al, it would appear I have 6.35mm (1/4") shafts, therefore the knobs must be 6.00mm (they are from taiwan but the guy told me 1/4" hole).

You've cleared some thing else up for me! 
I was thinking perhaps 1/4" shaft + 1/4" knob hole = no go, as the hole should be just a tad bigger than the shaft.

SO,  in summary 1/4" shaft needs 1/4" hole.  6mm shaft needs 6mm hole.

Don't know what all this had to be that comlicated! hehe

I guess when talking to the sellers I need to clarify between 1/4" (6.35) and 6.0mm should do the trick.

Thanks a million guys!

[zombiwoof]

Thanks Al, it would appear I have 6.35mm (1/4") shafts, therefore the knobs must be 6.00mm (they are from taiwan but the guy told me 1/4" hole).

You've cleared some thing else up for me! 
I was thinking perhaps 1/4" shaft + 1/4" knob hole = no go, as the hole should be just a tad bigger than the shaft.

SO,  in summary 1/4" shaft needs 1/4" hole.  6mm shaft needs 6mm hole.

Don't know what all this had to be that comlicated! hehe

I guess when talking to the sellers I need to clarify between 1/4" (6.35) and 6.0mm should do the trick.

Thanks a million guys!

Yes, you need to clarify that - if the seller even knows what he is selling!.

Al

[PRR]

> I was thinking perhaps 1/4" shaft + 1/4" knob hole = no go

That's a "Nominal" size.

A 1/4" nut fits a 1/4" bolt every time. The nut is a half-hair larger than 1/4", and any slop in the bolt is minus, not plus.

A US mil-spec "quarter inch" pot shaft is nominally 0.249" diameter. This allows using a standard 1/4" drill bit when making knobs.



BTW: a 1/4" drill bit is always a hair under 0.250" diameter... drills always wobble so the drill grinder aims a hair small so the average hole is pretty close.

I can not find detailed specs for 6mm shafts.

> I imagine the Alpha pots are metric as they come from Taiwan?

Alpha will make ANYthing (if you order enough of them).

I've seen Alphas with true USA-traditional 1/4" shafts, albeit in their higher-price lines.

I have noticed that mass-commodity gear has "undersize" (to my hand) shafts.... I had not grokked that they threw away the odd decimal for a nice round 6.0mm.

The diff is 0.36mm or 14 thousandths US inches. If you like 1/4" knobs but have 6mm shafts, you could look for 0.013" brass shim-stock. Or 30-gauge stuff, but that's mighty thin. Maybe beer-can metal? But that gets thinner every year. And knob-shims are tedious to make, don't grip great, and look cheezy when they fall out.

Some careful work with a 1/4" drill will open-up a 6mm hole to fit a 1/4" shaft. Don't even use a power tool. You are just taking out three hairs of brass (or plastic), 0.014". Get a good grip on the bit (a drill is handy, just don't turn it on) and rotate the knob onto the bit.

[tomek]

Hi PRR, you've hit the nail on the head!

Thank you very much for the explanation, it's exactly what I was looking for!

Sellers beware, I am now armed w/ knowledge! hehe

Tomek

[PRR]

On "6mm" pot shafts the allowance is apparently taken in the hole: 6.1mm

http://www.satopartsusa.com/filegroup1/AC12144/WSA11114/comp/comp_block/size_chart/K-66-new.jpg

[smallbearelec]

Apologies for any confusion.

I purposely spec'd all of my RV16 Alpha pots for the U.S. 1/4" diameter, smooth, full-round shaft. Unless a knob type is specifically noted as being for a knurled shaft, it will fit this.

The SKU 1010 knurled shaft with solder terms are more expensive because I only buy small quantities from Sovtek rather than going direct to Alpha.

[EATyourGuitar]

I was just gonna ask this same exact question, thankyou. I went to my local GC and tried the allparts chrome tele knobs. does not fit the 1/4 shaft alpha pots. nothing they have fits. so I guess american fenders are using metric shafts. HAHA. the tuners are made by PING in china on your american guitar. but anyway the other problem I'm having is my shafts are too high. I took apart some other pedals to find that a lot of guys use a washer or nut to lift the little spike off the case. I just drill a 1/8 hole next to the 1/4 hole so the pot wont spin in place. the tab fits perfect in the 1/8" hole. BUT now all the knobs are sitting high off the pedal with a nasty gap. I might try to sneak some knobs off the TV's at the local dump. I'm screwed cause I cant change the pots now, there is no room in the case.

[zombiwoof]

I was just gonna ask this same exact question, thankyou. I went to my local GC and tried the allparts chrome tele knobs. does not fit the 1/4 shaft alpha pots. nothing they have fits. so I guess american fenders are using metric shafts. HAHA. the tuners are made by PING in china on your american guitar. but anyway the other problem I'm having is my shafts are too high. I took apart some other pedals to find that a lot of guys use a washer or nut to lift the little spike off the case. I just drill a 1/8 hole next to the 1/4 hole so the pot wont spin in place. the tab fits perfect in the 1/8" hole. BUT now all the knobs are sitting high off the pedal with a nasty gap. I might try to sneak some knobs off the TV's at the local dump. I'm screwed cause I cant change the pots now, there is no room in the case.

Fender uses 1/4" shaft pots, not metric, on their US-made guitars.  The Allparts knob might be metric, but that doesn't mean that Fender uses metric pots (except on their import guitars, which probably have metric hardware).  The real Fender Tele knobs are meant for 1/4" shaft pots, but there are many copy knobs out there that are metric.  This is why you have to find out before you order which type it is.

Al

[Joseph]

you might try mammoth as well. I have placed 3 orders now with them and their knob selection is pretty great. i use the Alpha 1/4" pots as well and have had no trouble getting the knobs on the shafts.

http://www.mammothelectronics.com/category-s/25.htm



-JO