nylon valve guides life expectancy

[Dan Schultz]

How long plastic guides will last depends mainly on the finish of the guide slot. I've had them in the King I use for Dixieland for several years.

Side note: well-fitting metal guides are not noisy.

[PaulMaybery]

Dan's comment on the valve guide slots is dead on. I had my horn in Dan's shop back in November for some other issues and we noticed how much turning play was in the valve.
The horn was only about 2 years old. The slots were never properly finished after they were cut, and were simply chewing up the guide. When I got home after my visit, I had the shop at Red Wing go in with a burnishing tool and smooth out the slots and install new guides. It always seems that when it comes to the fine points of finish on instruments, there always seems to be something that is less than perfect. My other horn from the same manufacturer is just fine.
If they are not lasting, get a tech to address the valve slots and burnish down those little burrs.

[arpthark]

- don't trial-and-error them against the tops of the casings when putting the pistons back into the casings

No sure anyone will see this under bloke's big pic of his big valves, but this point along with having rough keyways is a big valve guide destroyer. It's something that everyone can easily avoid doing to extend valve guide longevity.

i'm pretty sure that's what's caused mine.

i live 70 miles from the nearest repair shop and they're busy as one-armed wall papers hangers right now trying to get marching band gear ready for the fall, so the turn
around on this is going to be a week, anyway... it can't be a very difficult thing to do...

where can i get the guides? it looks to me like they may just pop in? my guides are clear and i can see what looks like a hole in the valve side. i'm assuming that there is
something on back of the guide that pops into the hole? is there any adhesive used? probably not.

i may go back to brass, i play a lot, and while i have backup horns, i really like this one the best and hate having it in the shop... so i either need to go back to brass or
learn to repair them myself.

Just curious - where do you go for repairs? You're in southern KY near Lake Cumberland so - Bowling Green? Cookeville?

[arpthark]

^ Miles Ahead does great work. I'm near the Louisville location, great guys and much better service/experience than the music stores in Lexington IMHO.

[mbeastep]

I have had a lot of trouble with the nylon valve guides on my 16 year old PT-6P. Some burnishing of the slots has helped stabilize the situation, but the guides do continue to wear, and I have learned to deal with them. The hardest part is that once the guide has sheared off, it is impossible to unscrew the guide from where it screws directly into the side of the piston. After I tried some dangerous maneuvers involving razors and drills, my tech showed me how to heat a screwdriver in a butane flame and use it to create a slot in the nylon that allows you to unscrew the piece. Although replacement guides were formerly available from Allied, apparently they are no longer. I get mine directly from Bob Tucci, who has been very nice about it, even while not really believing that my horn needs so many.

In screwing in the new guide, it needs to be turned more tightly than I can do by hand, so I use blunt-nosed pliers. Once it is screwed in as far as possible to a vertical position, it must be reduced considerably on both the flat surface and the sides. I do this with a cardboard fingernail file. It's a very tedious process that requires frequent testing to see when to stop sanding. It's not really difficult, though, just time consuming.

mbeastep