Pot bushing thread adapter?

JTEX

JTEX

Well-known member
Did anyone by any chance run into potentiometer bushing thread adapters? Specifically, I'm looking to convert some skinny, short bushing pots (M7x0.75 by maybe 4mm long) into guitar-style, 3/8-32, 3/8" deep bushings.

Or, do you have (access to, or pointers to) a machine shop? I need lots. I'm sure other people would, too. Really, this should be a standard part, like mic thread adapters.

Here's a prototype I made.

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JTEX said:
Did anyone by any chance run into potentiometer bushing thread adapters? Specifically, I'm looking to convert some skinny, short bushing pots (M7x0.75 by maybe 4mm long) into guitar-style, 3/8-32, 3/8" deep bushings.

Or, do you have (access to, or pointers to) a machine shop? I need lots. I'm sure other people would, too. Really, this should be a standard part, like mic thread adapters.

Here's a prototype I made.

View attachment 57372

View attachment 57373
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Hmmm I don’t think I’ve ever seen one of those in the wild. Very cool idea.
 
I don't think you'll want to pay what a machine shop would want for those.

My cousin is a professional machinist in AZ and just for the heck of it I asked him to estimate what a shop would charge for something like that. Here's his texts back to me:

"For 1-5 pcs depending on material probably 20 to 30 bucks. For 100 maybe down to like 8 to 10. Get up to 200 maybe 5 to 6 bucks a piece.

That's a piece 20 to 30 bucks a piece and so on.

I doubt a shop would even touch it unless it was for like a thousand pieces minimum.

Even then it's tough because even if he charge like three four bucks a piece a thousand pieces that's only three or four grand. And something like that will keep a machine running for 2 or 3 days just to make a thousand pieces . Then the problem becomes. You can make a lot more money than that in two or three days using a machine to do something else.

Yeah that's the problem with simple parts. It's easy money but it still takes up time on your machine. So most of the time you go for the more difficult parts because that's where the money's at. I just got done making four pieces at the company I work at. Took me about a month to finish them all four The bill was about 43,000

It's kind of an extreme example, but just kind of shows why even though a simple parts could be easy money, it's not worth it to tie up your machine. Honestly for something like that my boss would rather have a machine sit then make the parts."
 
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Passinwind said:
These are the only semi close match I’ve seen: https://www.underhillbass.com/product-page/pot-nuts

Another luthier friend of mine has mentioned possibly getting into running some sets on a CNC rig, I will ask him about that the next time I get over to his shop.
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The Underhill part is what gave me the idea for the adapter I use for my Distiller SE, which I make out of a 1/4" jack bushing. I just thread the inside to M7 and voilà. Works just like a guitar tuner nut, but screws onto a pot instead of a tuner.

However, I never found this solution elegant. It's a bit of a hack. Ideally, I'd want the pot itself to be modified, not its mounting nut, so it can be installed the same way as any standard guitar pot, using the same normal 3/8" nuts, whether on a pickguard or through wood. So, basically, the solution should be transparent to the installer. A pot is a pot is a pot.
 
JTEX said:
The Underhill part is what gave me the idea for the adapter I use for my Distiller SE, which I make out of a 1/4" jack bushing. I just thread the inside to M7 and voilà. Works just like a guitar tuner nut, but screws onto a pot instead of a tuner.

However, I never found this solution elegant. It's a bit of a hack. Ideally, I'd want the pot itself to be modified, not its mounting nut, so it can be installed the same way as any standard guitar pot, using the same normal 3/8" nuts, whether on a pickguard or through wood. So, basically, the solution should be transparent to the installer. A pot is a pot is a pot.
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I hear you. I tried supergluing some threaded 3/8” lamp rod to a couple of Alpha pot bodies as proof of concept, biggest drawback was the goofy thread format. The ID was nearly perfect though, and I never encountered any problems over the several months that filter preamp was in my test bass. I just bought some custom Omeg dual pots with long 3/8” bushings that time around, but a more frugal solution would be pretty swell.;)
 
3/8" lamp post rods are the wrong thread pitch. Been there, done that 🤣 I even looked into the plumbing section at Home Depot, they have some 3/8 threaded brass adapters. No workey. Desperate times 💩 So far, the best way I've found is to destroy brand new 1/4" Tayda jacks for their precious bushings. But I hate doing this to them 😕
 
It seems like you already found a solution and are looking for a part for implementation.

My question would be, what is the challenge you're trying to solve? If this is an assumed common problem, then maybe it has already been solved with a different solution and that's why you're struggling to find your answer?
 
JTEX said:
This is 90% what I need. Just have to cut the inside thread. Drill + tap + 30 seconds:
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I understand what your trying to achieve by increasing the length of thread but the splined shaft decreases the amount of knob that can be pushed on, I detest any pot with a spline, worst design ever!
I put a piece of cable tie in the slot to increase longevity if I happen to own something that has this cursed design or I used the Brass sleeves as well so I can change to a 1/4'' smooth shaft knob.
As szukalski stated, I think you have found a solution to your problem using the tayda jacks & threading them.
Vigilante's solution is to counterbore the enclosure for a similar issue as the threads on 9mm are shorter than other pots to begin with.
Unless you need 100's of them, DIY is your best & cheapest option.
 
szukalski said:
My question would be, what is the challenge you're trying to solve? If this is an assumed common problem, then maybe it has already been solved with a different solution and that's why you're struggling to find your answer?
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I want to be able to mount just about any 9mm square pot on a standard guitar or bass in an elegant way that's suitable for assembly on a guitar production line (not just one-off instruments, where you can do anything you want).

Why not just use standard guitar pots with a 3/8" or 9mm bushing? IMO, the common unsealed carbon element types mostly suck for reliability/longevity (even the "good" ones). Design-wise, they're stuck in the early 1900's. They're only readily available (with the right "guitar" bushing) in limited values and tapers (25k, 100k, 250k/500k/1Meg, linear, log, MN). I need the freedom to use any value and taper available, in a standard guitar pot hole. I want my A5k volume pot (post-active buffer), I want my dual-gang C100k or C50k for filters, B10k etc -- with PCB pins, not solder lugs, and with the right bushing.

Great pots with a guitar-friendly 3/8" bushing do exist: the TT P260P series, for example, which is the equivalent of the sadly discontinued Clarostat modular square pots. Clarostats were used in large-format SSL, API etc consoles, (really) pro audio gear, and high end instruments such as Alembic, original graphite Steinbergers etc. P260P's use conductive plastic elements and are rated at 1 million turns, but they're really expensive ($10-$30 apiece) and getting harder and harder to find in the values I need - or that's what I would buy and use, despite the cost. I even tried to order a batch of 1000 factory-direct and they'll barely even talk to me. Maybe if I wanted a truckload?

I eventually had to settle on the much more available, smaller P092 series (9mm, green square). Like the P260P, they use a long live, low noise conductive plasctic element. They're "only" rated at 100000 rotations, but still beat the hell out of carbon pots in both life and noise levels, they're sealed, and are available in many values, tapers and shaft styles/lengths.

They only come with the skinny 7mm diameter, short bushings though. Hence my problem.
 
music6000 said:
I understand what your trying to achieve by increasing the length of thread but the splined shaft decreases the amount of knob that can be pushed on, I detest any pot with a spline, worst design ever!
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The pot I showed was just something I had lying around, with the wrong, short shaft. I just used it to show my adapter. The actual pot it would go to has a longer, non-split shaft. Here it is, with the threaded Tayda jack bushing on the "wrong way". It would be the right way if only the outer thread had a useable thread pitch to go with a standard metal nut. It's very coarse though, made for a plastic nut, so it has to go on the other way, from the top, like a guitar tuner nut. Sucks!


PXL_20230928_130849150.jpg
 
Could you put a washer (or a washer with an internal ridge) on the outside and use the native nut?
I see the challenge, it just looks like it's not cost effective unless you can find the manufacturer for the Tayda jack bushing.
 
szukalski said:
Could you put a washer (or a washer with an internal ridge) on the outside and use the native nut?
I see the challenge, it just looks like it's not cost effective unless you can find the manufacturer for the Tayda jack bushing.
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There's no native nut that comes with the jack. The bushing threads right into the plastic body of the jack, which is why it has such a coarse pitch. Wouldn't work with a metal nut, and there's no way I would mount it on a guitar with a plastic nut. Wouldn't last a week before it starts spinning.
 
JTEX said:
The pot I showed was just something I had lying around, with the wrong, short shaft. I just used it to show my adapter. The actual pot it would go to has a longer, non-split shaft. Here it is, with the threaded Tayda jack bushing on the "wrong way". It would be the right way if only the outer thread had a useable thread pitch to go with a standard metal nut. It's very coarse though, made for a plastic nut, so it has to go on the other way, from the top, like a guitar tuner nut. Sucks!


View attachment 57423
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Is it 10 x 1.25mm or 1.5mm pitch, there would be a metal nut available!???
 
music6000 said:
Is it 10 x 1.25mm or 1.5mm pitch, there would be a metal nut available!???
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You know what? I never actualy measured. All I did was try to fit a nut on it - any nut - from my pretty extensive collection, and nothing fit. Now that you made me measure it (why didn't I think of it?), it turns out to be 3/8"-24. Let's see if I can find skinny nuts this coarse. They'll have a lot of play, for sure...
 
JTEX said:
You know what? I never actualy measured. All I did was try to fit a nut on it - any nut - from my pretty extensive collection, and nothing fit. Now that you made me measure it (why didn't I think of it?), it turns out to be 3/8"-24. Let's see if I can find skinny nuts this coarse. They'll have a lot of play, for sure...
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It's available but for a price!!!!


Take advantage of these thin nuts when you need a high-fastening force in tight spaces. The zinc nuts are resistant to corrosion, which makes them suitable for outdoors. Purchase the 3/8-in dia nuts in a box of 50.
 
music6000 said:
It's available but for a price!!!!
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Way too expensive for what they are. Ugly, too! Not guitar-nice.

I've contacted Tayda to ask if they'll make those 1/4" jack bushings into a separate part #, with some changes (inside M7x0.75 thread, outside 3/8"-32). If they sell it, modded, for the same price as the jack they're normally for, I'd order like 1000. Crossing fingers...
 
JTEX said:
Way too expensive for what they are. Ugly, too! Not guitar-nice.

I've contacted Tayda to ask if they'll make those 1/4" jack bushings into a separate part #, with some changes (inside M7x0.75 thread, outside 3/8"-32). If they sell it, modded, for the same price as the jack they're normally for, I'd order like 1000. Crossing fingers...
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This is what they look like to scale:
63866722_L.jpg
Good Luck with your Endeavour.
 
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