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Pots, Shafts and Holes!


jackchaos

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I'm looking at the pots on Smash TV's site and I have a couple of questions.

ITEM 19b

Potentiometer

High quality Taiwan Alpha Potentiometer

10K Linear taper

1/4" x 3/8" Round Shaft

Specifications

http://avi.dezines.com/mbhp/images/potDatasheet.pdf

How big does the hole on your panel have to be for this pot? I'm guessing that the 1/4" measurement is for the shaft where the knob will be seated on, and the 3/8" measurement is how big the shaft is where the threads are. The hole would have to be at least a little bigger than 3/8"? Are the pots meant to be screwed into the panel with the panel between a flat nut and the lower part of the pot?

Also. When picking out knobs, would I have to make sure the inner part of the knob is compatible with a 1/4" D shaft?

He also has a: 10K Linear taper 6mm x 15mm "D" Shaft pot... Would this require a different kind on knob, or are all D shaft knobs interchangable?

Patrick Manderson

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They're M7 which I believe (someone please correct me if I'm wrong) is 7.9mm. W.R.T 'D'  - yes you will be much better off finding D fit knobs. You may be able to get away with splined ones but there's no guarantee you will be able to get them on the pot/encoder without damaging them in some way. N.B. You can't fit splined knobs on round shafts.

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yes you will be much better off finding D fit knobs

You mean round ones right? Round with set screw seems to be safe for most stuff here.

Eufex or anyone, Is there by chance more than one spec for the splined shafts in the 1/4" range? I got a great looking batch of aluminum knobs with holes like that, but they barely fit the splined pots I've tried here. I had to squish the two teeth together with pliers, which didn't feel too good.

-George

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If I'm following you guys correctly - all D shaft pots should fit a knob if the knob is described as having a "D" fitting?

What do I need to look for when matching knobs with pots?

P.S.  based on the POT's description, how big should the hole be drilled to accomodate it?

-Patrick Manderson

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If I'm following you guys correctly - all D shaft pots should fit a knob if the knob is described as having a "D" fitting?

Yes, as long as the shaft/knob is the correct size (1/4inch, 6 mm, 10mm, etc.)

Most knobs designed with a set screw will work with a D-shaft pot -if- the sizes match.

P.S.  based on the POT's description, how big should the hole be drilled to accomodate it?

7mm does the trick for me.  ;)

I think some splined shafts have a different number of teeth to others (maybe).

Unfortunately spline shaft design pots and knobs vary greatly from different manufacturers.  Apparently there is no standard for this.......

Best!

SmashTV

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I meant D fit knobs - you can get knobs with a D fitting for D shafts.

Yeah, I've got a bunch of new D knobs here (one of the things I have considered selling off).

I think some splined shafts have a different number of teeth to others

I was afraid of that. That's what they feel like. The ones I have will actually fit, but you have to plan on not using the pots for any other knobs afterward.  :'(

-George

PS- Smash - Why do the datasheet  and images make those look like round shafts?

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Smash

I made another attempt to place an order and I got stuck on the Pots again.

You have 2 different kinds of pots of different sizes. What's the difference? I'm forced to make an uninformed decision with the pots and I don't know the difference.

Can someone kindly explain why someone would buy one over the other?

Thanks!

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Can someone kindly explain why someone would buy one over the other?

... in europe our standard drills are in Millimeters in USA in inches. So if your drills say per example 1/2", you'll want to order the "1/4" x 3/8" Round Shaft "-potentiometer. If your drills are labeld with for example 7mm, you'll buy the "6mm x 15mm "D" Shaft "-potentiometers.

Greets, Roger

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Smash

I made another attempt to place an order and I got stuck on the Pots again.

You have 2 different kinds of pots of different sizes. What's the difference? I'm forced to make an uninformed decision with the pots and I don't know the difference.

Can someone kindly explain why someone would buy one over the other?

Thanks!

:o I don't believe you are forced to do anything. The difference is that one is 6mm, the other 3/8", simple as that. :)

Previously Smash only stocked encoders in 6mm format and pots in 3/8" format - all fine and dandy if you were buying them  separately but if you were mixing encoders and pots on the same box there was a problem with knobs - 6mm knobs will not fit on a 3/8 shaft (3/8 is slightly bigger), so Smash very kindly  :) has started to stock 6mm pots with the same D fitting as the encoders he stocks after I told him about the problem (I believe that others have had the same issue now that people are starting to make bigger/more complicated boxes with various mjxes of pots and encoders) I was having with knobs. Most of the knobs out there seem to be in metric format and to mix 3/8" and 6mm on the same box would mean having a different type of knob for each - not neccessarily very good for aesthetics.

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eufex:

Then it doesn't matter... unless you plan on buying pots and encoders from SmashTV?

::) Yes it does!!!

Dependent on what knobs you're using and what kind of holes you can drill (mm or inches)

Get your knobs and then you'll know, what kind of pots you need.

For example: When you'd use the knobs I use http://home.tiscali.ch/screamingrabbit/Pages/UCAppsBulk_Order/SIFAM/SIFAM_Main.htm, you'd buy the 6mm D-shaft potentiometer and encoder.

Got it?

Greets, Roger

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Smash

I made another attempt to place an order and I got stuck on the Pots again.

You have 2 different kinds of pots of different sizes. What's the difference?

The only difference worth noting is the diameter of the shaft. On the pots with the round shaft (19b) they measure 1/4 inch diameter, and require a knob with a round 1/4 inch hole for the shaft.

For the D-shaft pots (19a), the shaft diameter is 6mm.  A knob made to fit one won't fit the other.

All of the other measurements of the pots besides the shaft size don't really matter.

Spline shaft knobs won't fit either pot I sell correctly.

I'm forced to make an uninformed decision with the pots and I don't know the difference.

Just find some knobs you like, and if they have a 1/4" round hole with a set screw use 19b, if they are 6mm with a D-shaped hole or round hole with a set screw, use 19a.  Don't be forced into anything, the info is out there if ya dig or ask.....  ;)

The difference is that one is 6mm, the other 3/8", simple as that. :)

Actually that should read "the other 1/4 inch, simple as that"......3/8" is the shaft lenght, they are 1/4" diameter..... :) 

The constant jumping between Imperial and Metric measurements makes me a bit spin-dizzy on sizes too!    ;D

Previously Smash only stocked encoders in 6mm format and pots in 1/4" format - all fine and dandy if you were buying them separately but if you were mixing encoders and pots on the same box there was a problem with knobs - 6mm knobs will not fit on a 1/4" shaft (1/4" is slightly bigger), so Smash very kindly :) has started to stock 6mm pots with the same D fitting as the encoders he stocks after I told him about the problem (I believe that others have had the same issue now that people are starting to make bigger/more complicated boxes with various mjxes of pots and encoders) I was having with knobs. Most of the knobs out there seem to be in metric format and to mix 1/4" and 6mm on the same box would mean having a different type of knob for each - not neccessarily very good for aesthetics.

That is my story.....and I'm sticking to it...... ;) Eufex has it right, in the past people were using either pots or encoders on thier boxen, now people are starting to use both on the same box.

To avoid confusion I changed the 3/8" size to 1/4" in the quote above, edits in blue....

I'm still on the hunt for cheaper quality pots, but it seems a majority of the cheaper pots are spline shaft, so if I add any spline shaft pots to the store I will have matching knobs also.

I'll never trade quality for price though, so don't worry if I throw the "cheap" word around a bit.

Best!

Smash

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