Which plastic to bond to brass.

Ed,

Just for clarification; am I correct in assuming that you will only be selling replacement knobs, to fit the owner's existing potentiometer shaft. ??

... With its potential for variability [ouch, sorry]

MichaelG.

Hi Michael,

Yes, the idea is they will be replacements to match originals which have been lost. However on some guitars the pots have been replaced with newer versions and/or different resistance values for varying reasons.

Ed.

Just a thought... this here Telecaster on my lap has nickel plated brass knurled knobs with pressed in soft plastic inserts... O.K. it's a Korean Squier, but probably the tightest fitting knobs on any of my guitars and if it's good enough for that...?

Neil

P.S. by 'only a volume knob' I was meaning that some of teh stress/duty observations seemed better suited to 'heavy duty' applications (I suppose the guitar could be meant for Paul Simonon though...)

Edited By Neil Wyatt on 04/05/2016 18:27:48

Ed,

Thanks for the confirmation

I think you could probably 'make a virtue out of necessity' if you played this right.

By doing minimal 'splining' work on the inserts, they could fit any variant of splined pot-shaft equally well. ... I do think, though, that you might want the bore in the brass to be less than its current 10mm diameter.

For example: Your inserts might [with luck] be sliced from 8mm OD tubing.

MichaelG.

.

Edit: Neil posted whilst I was composing this ... I think we're on the same lines.

Edited By Michael Gilligan on 04/05/2016 18:28:31

Thanks guys,

Michael, I've pondered the plain sleeve method and willl have to have another look at it. My original concerns were that I wanted the knobs as per the exisiting, but I realise now that making allowances for updates and changes to original parts will require some compromise.

The 10mm sleeve OD is just a figure I pulled from my head, thinking that a bigger OD will have more surface area and a better bond strength. If I go for the push fit I'll not need to worry about that. Some testing will have to be done.

Neil, thanks for the photos and info. Is that a rubber/neoprene type sleeve inside a plastic sleeve, or just a counter-bore?

Ed.

It's just a counterbore, Ed. It appears to be a nylon insert. As it is probably 25+ years old*, I don't know if the insert was splined originally or has just taken a set from the pot spindle.

Neil

*wow, that's scary. Just worked out that I've had my acoustic for nearly 33 years, I thought it was old at about 10 when I got it.

Ok, thank you Neil. I ordered some nylon rod last night and will see what I can accomplish when it arrives.

Ed.

Hi Ed,

When you machine nylon, make sure your cutters are really sharp and with steep angles. More like tools for wood. Otherwise you'll find that you have to do a lot of work de-burring.

Sam

Will do, thank you Sam

I spent some time on the lathe today and I think I'm just about there using the press fit method.

I drilled 10mm holes which finish at 10.14mm and turned down some 10mm nylon rod(10.34mm as supplied) to 10.24mm, so an interference fit of 0.1mm ish.

The plastic inserts are then drilled 5.8mm and are a good push fit onto the splined pot shafts, a bit tight actually so I might try a 5.9mm drill. As a bonus if I mess up a plasic insert I can just drill it out and replace it. If I can get consistency, the jobs a good `un, then it's off to the local laser etcher to have some characters added to one knob in each set.

I think I might owe a couple of beers to few people here

Thank you all again for your expertise and encouragement.

Ed.

All you need now is a genuine CRUD sticker

Neil

Nice work Ed!

I'm also impressed with your clean knurling. That's a job I never enjoyed doing.

Sam

And a nice Guitar, can't figure out what it is...

N.

Thanks chaps.

Neil, it's a Westone Thunder 1A (A for active circuit) 1984 I think. Refinished in Nitro Cellulose Laquer, various shades.

Ed.