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What size volume knobs do I need?


shoulderpet
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Hi all

Hoping someone can help, I have a bass that I had some work done on and when the work was done the tech fitted some volume knobs with a set screw as that is what they had at the time, the bass has split shaft pots and whilst the knobs work fine I realise that really it should have push on volume knobs.

Anyhow I ordered some on Amazon blissfully unaware that there is more than one type of push on knobs and they dont fit:dash1: they just wont go on and I think maybe the inside diamter is too small, description on Amazon said they are 6mm inside diameter, anyhow I googled to try and find the information to try and order the right set and after reading about course spline and fine spline volume knobs I am even more confused and whilst I found out that course spline have 18 splines and fine spline have 24 splines I am longsighted so trying to count the splines on a pot is nigh on impossible, can anyone help me with what knobs I need to get , thank you

 

 

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The pictures aren't clear enough for me to accurately count the splines but I think that you should be OK - pretty sure fine splines are the less common of the two types.  If you're having difficulty fitting the new knobs, try taking a pair of pliers and /gently/ squeezing the pot shaft together so the gap is a little less.  See if that allows you to press the knob down.  If you go too far, use a small, flat bladed screwdriver to prise the split shaft apart a little.  I've had to do that a few times in the past.

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1 hour ago, neepheid said:

The pictures aren't clear enough for me to accurately count the splines but I think that you should be OK - pretty sure fine splines are the less common of the two types.  If you're having difficulty fitting the new knobs, try taking a pair of pliers and /gently/ squeezing the pot shaft together so the gap is a little less.  See if that allows you to press the knob down.  If you go too far, use a small, flat bladed screwdriver to prise the split shaft apart a little.  I've had to do that a few times in the past.

Thanks I will give that a try or failing that I might try and enlarge the hole on the knobs and see if that works

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12 minutes ago, shoulderpet said:

Thanks I will give that a try or failing that I might try and enlarge the hole on the knobs and see if that works

 

Trying to enlarge the hole in the knob will probably remove the ridges around the hole.  That will make them less likely to mate with the ridges on the pot shaft and make the knobs slip when you turn them.  I wouldn't try that.  Also if they do turn out to be the wrong knobs, you won't be able to return them if you alter them.

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Just now, neepheid said:

 

Trying to enlarge the hole in the knob will probably remove the ridges around the hole.  That will make them less likely to mate with the ridges on the pot shaft and make the knobs slip when you turn them.  I wouldn't try that.  Also if they do turn out to be the wrong knobs, you won't be able to return them if you alter them.

Ok thanks, I wont try that then 

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Just now, John Cribbin said:

Have a look inside and see what brand of pots you have. If there's not to much solder you should be able get the part number as well. Then a Google search will give you the spec of the pots.

 

Good thinking, I had a look inside and they seem to be CTS 300K pots, i found the code EP4880 that seems to be a part number on the back of the pots and then after that code  they have an A on 2 of the pots and what looks like BD on the other another , I will google the parts hopefully i will eb able to match up the pots with the type of knobs they need although I must confess that the insides of a bass are like another language to me so I may well end up more confused lol

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Yep, just what I thought you'd find. You have USA spec pots fitted, probably 95% + of splined pots over here are Asian spec, that's why the knobs won't fit.

 

About a year ago I was planning to upgrade a PJ bass with CTS pots. Of the thousands of knobs to suit a jazz bass, the only 24 spline knobs I could find were original Fender ones at several times the price of Asian spec ones. I gave up on that plan.

 

The set screw solution is actually pretty sensible IMHO.

 

 

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Just now, John Cribbin said:

Yep, just what I thought you'd find. You have USA spec pots fitted, probably 95% + of splined pots over here are Asian spec, that's why the knobs won't fit.

 

About a year ago I was planning to upgrade a PJ bass with CTS pots. Of the thousands of knobs to suit a jazz bass, the only 24 spline knobs I could find were original Fender ones at several times the price of Asian spec ones. I gave up on that plan.

 

The set screw solution is actually pretty sensible IMHO.

 

 

Yeah to be honest I dont even know why split shaft pots still exist surely solid shaft is much less hassle as you just find knobs with a set screw and you are good to go

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