exact spline shaft dimensions ?

[petemoore]

  I'm trying to get a 'fix' on the dimensions of a guitar pot shaft, spline shaft to begin with...how many splines and the exact ID or OD of the spline 'valleys' or peaks might be close enough.
   I have Mfr.s interested in designing a potshaft fitting for me but of course it is a pre-requirement that the dimensions of the shaft be known and communicated. Any help welcomed ! !

[defaced]

Depends on the pot shaft on the brand of pots you intend to use. I would do one of the following:
1 Buy a set of calipers and measure the brand of pots you want to use
2 Contact the mfg of the pot you're using and get a mechanical drawing of their spline pattern
3 Send a sample pot to your mfg and let them do the measuring

[GGBB]

I went through a process of trying to find some replacement knobs a while ago and figured out a couple of things.  Pots typically used for guitars and effects fall into two main categories - US and "metric".  US pots are typically CTS or Alpha (for the US market) and the likes and are found regularly on American guitars - not sure if they are found on effects a whole lot but I guess that would just depend on where the manufacturers get their parts.  Interestingly, my 1990 ProCo Turbo RAT has metric shafts and my 1998 ProCo Vintage RAT has US shafts.  The OD for US pots is 1/4" (6.35mm).  The OD for metric is 6mm.  The US pots have 18 splines (more coarse) vs. 24 for metric.  ID I don't know - but I have calipers and could measure some for you tonight when I get home if you think that would help you.

[R.G.]

2 Contact the mfg of the pot you're using and get a mechanical drawing of their spline pattern

Hold your calls. We have a winner.

There is a real danger in measuring a part in hand and assuming that all other parts will be just like it. Parts have variation. Each part is intended to be identical to the theoretically "perfect as designed" part, but in reality, there is some variation around the perfect, intended dimensions. The part you have may be at the minimum for some dimensions, maximum for others, and out of tolerance for yet others. The manufacturer's drawing tells you what they were trying to do, and what tolerances they will guarantee to keep. If you measure one, then apply a manufacturing tolerance, your resulting "fitting" parts may not fit some or all of the parts you get.

[markeebee]

It's complicated, man, and no-one understands it but his woman - POT SHAFT!

Pete - is this about fitting a standard knob onto a splined shaft, like in your other thread?  I did something similar on an amp a couple of years ago.....

I had some really nice old bakelite knobs that I wanted to use, but they had square holes in them.  I put some casting resin in the holes, like this stuff:

http://www.amazon.co.uk/DSM-Water-Clear-Polyester-Casting/dp/B002WNNFFK/ref=sr_1_1?ie=UTF8&qid=1322244833&sr=8-1 

And then I put the pot shaft in the resin (with some release agent on the shaft) until the resin set.  Then I put some vaseline on the shafts so it's easier to pull the knob of the shaft than it is to pull the resin out of the hole. 

No good if you want LOTS of them, but seemed to be ok for a small quantity.  The guy I repaired the amp for hasn't beat me up yet.

Just a thought......

[petemoore]

  Thanks for the responses guys, some great ideas and information here ! !
   I got the idea to sell some guitar knobs.

[.Mike]

It seems there is a standard referred to as T-18. I have seen it used in datasheets from companies like Re-an (Neutrik) and Eagle Plastic, and on merchant websites like Mouser and Newark.

18 teeth, 6mm shaft. Eagle makes them 0.238"/6.05mm OD according to random datasheet.

Since knobs from different manufacturers fit pots from different manufacturers, maybe there is a specification that they are all using.

Mike

[petemoore]

  It seems there is a standard referred to as T-18. I have seen it used in datasheets from companies like Re-an (Neutrik) and Eagle Plastic, and on merchant websites like Mouser and Newark.

18 teeth, 6mm shaft. Eagle makes them 0.238"/6.05mm OD according to random datasheet.

Since knobs from different manufacturers fit pots from different manufacturers, maybe there is a specification that they are all using.

   ^there we go, thanks Mike, this is exactly what I think I'm looking for ! !
   [my favorite saying before I try something though is: I'll know more 'after'...I try some fits in these cases]...
   Anyway I did submit inquiries to the Mfr.s of my "G", "F", "I'' and Epi guitars recieved inquiries last Sunday...Wednesday and I'm still waiting for any response.