Brown Scale On Valve Cylinder

Abraxas · Posted: Mon May 14, 2018 9:47 pm Post subject: Brown Scale On Valve Cylinder

My wonderful Olds Special Cornet, that I've only had for a few short weeks has got really sluggish valves. It's not the pistons, cause I buffed them to a mirror finish (I know... that reduces the diameter, increasing the play...but it only took a couple passes on a very fine buffing compound). I've tried everything so far.... a serious soak in 1 / 5 CLR solution for about 4 hours. I just douched it with pure white vinegar and dish soap for about 5 minutes. I then ran a rag of iso Alcohol through it and those brown stains are still there. I don't think it's corrosion. It's poo-poo brown. I'm guessing it's ancient valve oil petrified. I just don't know how to get the crap off and my pistons are really dragging, with Hetmans 3 or 2. Should I get some blue juice and hope with playing it wears off ?? Thanks for your advice.

royjohn · Posted: Mon May 14, 2018 10:05 pm Post subject:

Try a nylon abrasive pad (that will not scratch brass) with a full strength degreaser or with acetone. If this doesn't work, you might try using Brasso. This is abrasive and will wear the brass a little, but if you use it judiciously, it shouldn't remove much metal. You will have to flush the cylinders to remove the abrasive particles when done. A last resort if nothing non-abrasive works.
_________________
royjohn
Trumpets: 1928 Holton Llewellyn Model, 1957 Holton 51LB, 2010 Custom C by Bill Jones, 2011 Custom D/Eb by Bill Jones
Flugels: 1975 Olds Superstar, 1970's Elkhardt, 1970's Getzen 4 valve
Cornet: 1970's Yamaha YCR-233S . . . and others . . .

Abraxas · Posted: Mon May 14, 2018 10:27 pm Post subject:

I have crocus cloth which is the finest abrasive cloth one can get, but being that I already polished the piston , I'm loath to do anything that would take anymore material off. Acetone it is I guess.

Abraxas · Posted: Mon May 14, 2018 11:03 pm Post subject:

Just checked my valve clearances and the first is really bad !! Valves 2 and 3 are OK. Now what ? I sure as hell don't want to fork out for a valve job on an Olds Special, tri-tone mind you. I really like this horn. I've probably got 5 thousands of clearance going on, on the first valve. I'm a machinist and I can actually measure it out tomorrow. Has anyone, say, just gotten a piston nickle plated ? Does anyone know what is a proper clearance on valves ? I'm guessing maybe 2 thou ??? 3 tops. And with that brown scale, I certainly can't take anymore material off. I have a nice lathe with a cylindrical grinding attachment. I can do wonders but, as we always say, once you take material off, you can't put it back on again. I'm curious about how they get monel cylinders in the valve casing to begin with. I'm guessing shrink fit , where the casing is super hot and allowed to cool and grip the inserted sleeve. Does anyone know what they actually do in a valve job ??

shofarguy · Posted: Tue May 15, 2018 1:54 am Post subject:

Abraxas,

The guys that really know about what you are asking are probably wishing they could Gibb-slap you right now. Instead, they are waiting... Just waiting. Because, they know you will call soon.

The stuff you wrote just above doesn't make sense to me. You say you are a machinist and all, but from what I know of what makes up a trumpet piston, the things you suppose aren't even close to what is going on there.

Just have someone who is good at this stuff do the work before the horn becomes unworkable.
_________________
Brian A. Douglas

Flip Oakes Wild Thing Bb Trumpet in copper
Flip Oakes Wild Thing Flugelhorn in copper

There is one reason that I practice: to be ready at the downbeat when the final trumpet sounds.

Abraxas · Posted: Tue May 15, 2018 2:09 am Post subject:

shofarguy... I'm not understanding you either , so we are even. What is it that I said that does not make any sense to you ??

The horn is probably going to need at least a single valve job. As I do not know what goes on in a valve job, I thought I'd ask. If it could be plated and it wound up oversize, I could certainly grind it down to a closer diameter and lap it in the rest.

I'm not going to hand it over to a pro valve shop because it is not worth the money it would cost.

In the meantime, I'd like to determine what the brown stain is and I'm assuming it's probably oil build up as opposed to corrosion. Maybe if I could get that stuff off, the valve action might improve and I might limp by with Hetmans 3 on the sloppy 1 st valve and perhaps blue juice on 2 and 3. If there is anything else I need to explain, just ask.

James Becker · Posted: Tue May 15, 2018 2:36 am Post subject:

As a machinist you should be speaking in ten thousands of an inch. Pro trumpets typically have clearences of .0003" per side or a total diameter difference of .0006" while it's not uncommon to see .0005" or more clearence per side for student model instruments. Yes, valve rebuilds are costly for a reason, it's tedious work and expensive to set up and maintain in-house. Hetman #3 Classic valve oil is a good stop gap until a rebuild can be done (so long as your valves are not "a flat tire").

As for the brown stains, my guess is the hard nickel plating has worn off and what you're seeing is discoloration of the base metal (nickel silver).

My 2 cents.
_________________
James Becker
Brass Repair Specialist Since 1977
Osmun Music Inc.
77 Powdermill Road Rt.62
Acton, MA 01720
www.osmun.com

Our workshop is as close as your nearest UPS store https://www.ups.com/dropoff?loc=en_US

Brad361 · Posted: Tue May 15, 2018 4:43 am Post subject:

ResilienceOils · Posted: Tue May 15, 2018 5:20 am Post subject:

Haunting. Firstly you don't want your valves to have a mirror finish. You can nickel plate but you have to copper flash first.

All the soaking and scratching and lapping and buffing...who knows what is wrong with the valve, it could be a plethora of things at this point.

Valve work on horns is a craft in itself as you have to have the right sleeves, burnishers, measuring devices and knowledge to do the work correctly.

Send it off or buy another horn.

yourbrass · Posted: Tue May 15, 2018 6:49 am Post subject: Re: Brown Scale On Valve Cylinder

[quote="Abraxas"]My wonderful Olds Special Cornet, that I've only had for a few short weeks has got really sluggish valves. It's not the pistons, cause I buffed them to a mirror finish (I know... that reduces the diameter, increasing the play...but it only took a couple passes on a very fine buffing compound). I've tried everything so far.... a serious soak in 1 / 5 CLR solution for about 4 hours. I just douched it with pure white vinegar and dish soap for about 5 minutes. I then ran a rag of iso Alcohol through it and those brown stains are still there. I don't think it's corrosion."

Try swabbing the casings with denatured alcohol soaked on a rag. It will take more off than isopropyl alcohol. And forget about the stains - brass can discolor in a multitude of colors - it's more important that everything be clean. Anything abrasive will be useless at this point, in buffing the pistons it may have changed something else for the worse as well. Follow Jim's advice about Hetman #3 or try my favorite - BerpBioOil #3.

Good luck, it sounds like triage at this point.
-Lionel
_________________
"Strive for tone." -John Coppola
Edwards X-13
ACB MV3C /ACB A1/26 backbore
https://yourbrass.com/

shofarguy · Posted: Tue May 15, 2018 9:47 am Post subject:

Tpt_Guy · Posted: Tue May 15, 2018 10:17 am Post subject:

LittleRusty · Posted: Tue May 15, 2018 11:49 am Post subject:

Here are a few links that discuss valve manufacturing. Enjoy.

Bach Trumpet: Valves and Tuning Slides
How a trumpet is made.
Manufacturing the valve casings.
A tour of Yamaha factory with Jens Lindemann.

Abraxas · Posted: Tue May 15, 2018 3:27 pm Post subject:

Abraxas · Posted: Tue May 15, 2018 3:40 pm Post subject:

Abraxas · Posted: Tue May 15, 2018 3:50 pm Post subject:

James Becker · Posted: Tue May 15, 2018 4:22 pm Post subject:

Funny, but true story. When I asked the good folks at Marcinkiewicz what clearance they start with before lapping their pistons in casings, their response was "we don't measure, we go by feel". So there you go, no engineering references needed for old school craftsmanship.

In all seriousness, the Getzen company starts with .0007" total diameter difference or .00035" per side before hand lapping. Resulting in reliable action, great feel and seal.

Yamaha in recent years relaxed their fit by .0002" total diameter or .0001" per side on pro trumpet pistons

Our valve pressure tester detects loss of pressure under a load of 1 psi. Pro trumpets typically score between 90% and 95% air tight. Student trumpets on the other hand will average between 80% and 85%. When a pro trumpet piston score drops below 80%, it's time for a valve rebuild.

Our test is provided free of charge to all customers in order to determine whether to rebuild valves or not.

We're one of only a few shops in the country that provide both piston rebuilds for trumpet and rotor valve rebuilds for trumpet, Horn, trombone and tuba on site.

I hope this is helpful.
_________________
James Becker
Brass Repair Specialist Since 1977
Osmun Music Inc.
77 Powdermill Road Rt.62
Acton, MA 01720
www.osmun.com

Our workshop is as close as your nearest UPS store https://www.ups.com/dropoff?loc=en_US

Abraxas · Posted: Tue May 15, 2018 5:56 pm Post subject:

Lapping compound is the 6th wonder of the world. I measured the pistons, with a very high end Mitutoyo micrometer to hundredths of a thou and not surprisingly, the bottoms are about 0.0003 smaller than the tops. I could not measure the cylinders as my telescoping gauges are from China. What could possibly go Wong with them ? I'll keep your shop in mind when I have a horn worthy of it.

Perhaps you would also concur that a rough and ready test, out in the field, of the condition of the valves is to try them not just with the horn in the normal horizontal position, but again with it pointed at, or tilted towards, the ground ?

The moral of the story is DON"T BUY ANY HORNS FROM GOODWILL online. I've bought about 6 in the last few months and only one is playable and the rest are beyond repair.

Cheers and sorry for my confusion and ignorance.

shofarguy · Posted: Wed May 16, 2018 11:00 am Post subject:

The valve casing IS the brass tube we hold. The piston is what goes up and down. It is an assembly of the finger button, stem, pads, spring barrel w/spring, Monel sleeve w/ports and a vented bottom plug. The parts of the piston are soldered together except the stem and finger button, which screw together and to the spring barrel. The dissimilar metals of the bearing surfaces (Monel/brass) prevent galling when sliding and will not wear quickly, provided there is sufficient oil film to lubricate them.
_________________
Brian A. Douglas

Flip Oakes Wild Thing Bb Trumpet in copper
Flip Oakes Wild Thing Flugelhorn in copper

There is one reason that I practice: to be ready at the downbeat when the final trumpet sounds.

Abraxas · Posted: Sat May 19, 2018 8:52 am Post subject:

Thanks for clearing that up. I wish they'd stick with the nomenclature of other piston assemblies and just call it the cylinder, but I digress. The quote for a valve job is $600 USD well beyond the value of the horn. It is slowly coming back with use. I may practice on some old scrap horns to see if I can home plate them and relap cylinders. Pity I just gave 3 away that were junkers.