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Still loving my recent King 2341 purchase, but at this point I’m picking nits. There are some bothersome clicking noises in the valves that I am certain comes from excess play in the metal valve guides. I have read here that some solve the problem by replacing them with nylon. Can I get some more info please? How are the metal guides attached? Are they soldered on, screwed on, or something else? How exactly are they removed? Where does one obtain the nylon guides, and how are they attached? Or is this not even a DIY job, but something I need to take to my horn fixer person? Thank you for any advice you can give me.

They are screwed in, and are an SAE thread.
I’m not where I can look up that thread size and it is not committed to memory, but once you have that thread size, you can purchase some nylon screws with that thread, and - using some single edge razor blades or X-Acto knife and some fine files, you can trim the heads of the nylon screws down to the shape of a valve guide and voilà.

Righty tighty lefty loosey like most other screws? And best method for removal without risking damage to the valves? Bloke, if I lived closer I’d just bring it to you for the work.

I believe (??) the correct thread for King might be SAE 3-48.
Here are pkgs. of 50 (PLENTY extra for a learning curve, and appears to have enough material BELOW the slot - which will be trimmed away - to cut into a thin properly-sized rectangle).

IF you were actually able to buy 3-48 King nylon guides, they would STILL be too large (and you would STILL have to cut them to fit), so this isn't very much more work.

https://www.ebay.com/itm/392792152194
...and yeah...The drawing also indicates that there are plenty-too-many thread turns as well.

DonO. wrote: ↑Thu Dec 09, 2021 9:40 am Righty tighty lefty loosey like most other screws? And best method for removal without risking damage to the valves? Bloke, if I lived closer I’d just bring it to you for the work.

IF (??) you would like a brand-new metal one - to use as a model (again - needs to be shaved DOWN from this supplied size to fit) - here is ONE for $11...
https://www.ebay.com/itm/273105487071

IF your own metal ones are still about new-looking/new-fitting, this would obviously be a waste of money.

For starters... properly fit brass guides running in smooth guide slots will not 'slap' back and forth in the guide slot. That 'slapping' is actually caused by the spring as the piston goes up and down. It's difficult to imagine but as the spring is compressed the wire in the spring stays the same length and forces the piston to revolve just a bit. The guide 'slaps' the other direction when the piston goes back up. You have to understand spring dynamics to fully get this. The looser the guide is in the slot... the more noise you get.

I've run the gamut with using off-the-shelf hardware store plastic screws to substitute for brass valve guides. The thread size is #3-48... which is pretty uncommon in the hardware 'World'. DEG used to sell a Willson 3mm Nylon guide. That is my choice to do a serious job but it involves retapping the hole for the new thread size. I say this is a 'serious' choice because once done it's difficult to go back to the original #3-48 thread size without filling the hole with hard solder and starting over.

Any roughness in the guide slot will chew up a new brass or plastic guide pretty quickly.

I did this procedure on two euphoniums in the past. A Besson New Standard and a B&H Round Stamp Sovereign. I used the part that Bloke and Dan Schultz are recommending. The old metal guides were pretty easily unscrewed counter clockwise with a needle nose pliers. The new nylon guides were then screwed in tightly and shaped to fit the guide slots as described above. I'm not an instrument tech, so this is definitely doable if you are good with your hands, patient, and enjoy this kind of thing. Best thing I ever did for each instrument. Smooth, fast and quiet action after the replacement with no problems since.

…??
I am experiencing difficulty seeing much similarities between our posts…

bloke wrote: ↑Mon Dec 13, 2021 10:12 pm …??
I am experiencing difficulty seeing much similarities between our posts…

I figured the OP might like to hear from a fellow layperson who did it himself. Is my post unwelcome?

Not at all…
You are one of the very-very good guys, and you would have to go about 4000% farther - towards causing me to scratch my head - for me to think otherwise.
————-
The other person suggested trying to find some European-made 3mm thread nylon guides, and re-tapping the threads in the piston bodies…and then went on to discuss that this might cause problems if ever converting back to brass guides.
——————-
My suggestion was to purchase some nylon screws with the matching SAE thread - and chunky enough heads that offer enough material to cut the heads down to - well… - guides (which totally avoids re-tapping the piston body threads).
I also pointed out that most all brand new guides require trimming to fit anyway…so it’s not as if buying nylon guides would avoid doing any trimming.
—————
SIDEBAR 1:
If valve guide slots in valve casings are rough, there are narrow files with fine teeth that actually fit into those slots which can smooth out the sides of those slots and eliminate this problem.
—————-
SIDEBAR 2:
Working on any sort of device for the very first time often requires a little bit of courage. Horn-fixers have - at least - passed the first time with many operations, but each of them had to pass that first time, obviously.

Worth wrote: ↑Tue Dec 14, 2021 11:39 am

bloke wrote: ↑Mon Dec 13, 2021 10:12 pm …??
I am experiencing difficulty seeing much similarities between our posts…

I figured the OP might like to hear from a fellow layperson who did it himself. Is my post unwelcome?

Coincidentally, I ran across my baggie of #3-48 nylon screws a couple weeks ago - there's still almost all of the original 100 remaining and the price tag says I coughed up all of $2.99 for them. One of the all time best horn upgrade accessory values that I've implemented.
I'd seen one of Bloke's posts on a different forum several years ago, after wondering how to eliminate both the whispery, silvery sliding sound of the metal guides when I idly slow-moved them (didn't affect playing at all, but it bugged me) and their louder clanking noises during playing.
I'd had the once-upon-a-time unfortunate experience of stripping a guide (different horn) right before a gig, so while I was in the crafting mode, I shaped a number of spares in addition to the 4 primary replacements.
After many years & countless hours of playing, I'm still on those four originals, and have zero intent to revert to the original metal guides.
The first time I played on the "screws", I remember practically giggling to myself, and during rests I found myself twiddling the valves just to enjoy the new-found silent smoothness of them. I managed to suppress the urge to stand up and tell the audience to, "Hey, check this out!!", but it really was that marvelous to me.
Typically great Bloke guidance regarding this easy improvement.

I understand now, points well taken. My spin was more of a non-tech to non-tech encouragement to the OP without the beef you and Dan provided that comes with experience. I realize such knowledge that is freely shared around this place is just enough to get someone in over his or her head on such a project, but with the parts present, even if something went awry, a local tech should be able to pick up the pieces and salvage things I would hope. Thanks Bloke

The tack that I suggested shows where (was it?) 50 correct-thread nylon screws can be purchased for single-served fast-food prices (plenty to mess up and learn with - for trimming their heads down to valve guides), and oem BRASS valve guides (simply) unscrew (regular r.h. threads) with some well-defined box-fronted pliers.

Some .XXX"/.XXmm Harbor Freight calipers would remove some of the guesswork.

ALTERNATELY, the pkg. of nylon screws could be taken to a repair-guy with the request, "Would you please cut the heads of these down to well-fitting and installed valve guides?"

I bought some delrin valve guides from Martin Wilk a few years ago for a tuba I no longer own. They weren't quite plug and play, but after a little cutting down they worked great.

His suggestion was to get some delrin rod and thread it, then cut it down to fit -- and remarked that there's no particular reason for rectangular valve guides anyway.

I believe that the rectangular valve guide shape assists in "steering" the valve straight down - just as the extra (seemingly unnecessary) length of the original York .750" bore pistons helped "steer" them through their casings...with many of those raw nickel silver York pistons - even today - not being horribly worn.

bort2.0 wrote: ↑Tue Dec 14, 2021 1:31 pm His suggestion was to get some delrin rod and thread it, then cut it down to fit -- and remarked that there's no particular reason for rectangular valve guides anyway.

I used to have a first generation Sterling 1065 (Pre-Virtuoso) which had rounded Delrin (or nylon not sure which) screwed in guides that looked like smooth projecting dots from the valve surface. I was told Sterling made the valves themselves for the Pre-V before going to Bauerfeind valves in the early versions of the Virtuoso. Them seemed to work fine, but as noted above there are limitations, most likely why you do not see them these days.

I dealt with some Hirsbrunner pistons which appeared to be the same as B&S, but with the guides moved around to a different part of the piston body, as well as the pistons being nickel plated. Delrin cylinders slipped horizontally into a hole…no threads…and a tiny lock screw held the cylinder in place from the top of the piston… Very strange.