Lapping Pistons at Home (Caution)

[J.Harris]

No offense intended- but this seems to be a repair that should be made by a qualified repair tech. I'm a professional tool and die maker and feel fairly confident in my metalworking skills but I would not attempt what you are suggesting on my own instrument. Any comments from the techs ?

[Dan Schultz]

No offense intended- but this seems to be a repair that should be made by a qualified repair tech. I'm a professional tool and die maker and feel fairly confident in my metalworking skills but I would not attempt what you are suggesting on my own instrument. Any comments from the techs ?

Depends on the horn. If it's a $200 Ebay 'beater', then there's not much to lose. A fellow's gotta learn somehow.

That being said, there aren't very many reasons to have to lap a piston. With freshly-plated pistons and honed casings, it's a matter of lapping then in to get them to fit properly. If the piston is binding because the casing is bent or the piston ports are distorted, removing metal may make the piston run free.... but it's really nothing more than simply wearing out the fit very quickly. If your valves are sticking it's probably not a case for lapping.

[ASTuba]

Just another reason I am a rotary valve man.

RC

Just because you have rotary valves doesn't mean that they don't have to get lapped.

Now, they don't need it as frequently as pistons... but still...

We'll turn you to the darskide eventually Robert.....

[sc_curtis]

Troll Information

The 7th definition is mildly amusing to me:

One of many unsung internet heroes who are almost entirely misunderstood. Contrary to popular belief, many trolls are actually quite intelligent. Their habitual attacks on forums is usually a result of their awareness of the pretentiousness and excessive self-importance of many forum enthusiasts. As much as people may hate trolls, they are highly effective - their actions bring much of the stupidity of other forum users out into the great wide open.

[The Jackson]

their actions bring much of the stupidity of other forum users out into the great wide open.

And boy is it fun[ny]!

[sungfw]

FWIW, I used toothpaste and a variable speed drill set to 60 rpm to fix a sluggish second valve on my Besson 767, after two highly competent repair techs were unable to fix the problem. A dab of Crest on the piston (sans valve guide[/i]) and ~2 min spin in 10 sec. bursts cleared up the problem. Compression on the 2nd valve is still better than valves 1 and 3, so clearly the home remedy didn't damage the piston or casing.

FWIW, Dr. Brian Bowman suggests using Lava soap—which is more abrasive than toothpaste—to lap tight valves in "Practical Hints for Playing the Euphonium/Baritone Horn, as does Dr. Dave Werden, though both recommend working the piston up and down manually rather than spinning it. Dr. Werden also mentions having heard of toothpaste being used as a lapping compound, but says he has not tried it.

[ASTuba]

Just because you have rotary valves doesn't mean that they don't have to get lapped.

Now, they don't need it as frequently as pistons... but still...

We'll turn you to the darskide eventually Robert.....

Bigger men than you have tried..... and failed.....

RC
(looking forward to seeing you soon man)

I notice you didn't say better though, so there's a chance!!

Looking forward to seeing you as well. It's been way too long.

[Steve Inman]

OR ... maybe your problem does not require lapping at all.

My Yamaha Eb had a sticky 1st valve and the local repair guy first suspected (correctly) that there was some tension in one of the tubes attached to the 1st valve casing. While I worked the valve, he gently (but firmly) tried applying pressure in various directions on the 1st valve slide(s) and we noticed improvement in one particular direction. He later desoldered a brace and the entire 1st valve tube moved about 1/4 inch. He then resoldered the brace to the tubing in its "new position", where it "wanted to be" and the problem was solved -- without any lapping at all.

All it takes is an unintentional "bump" to a valve tube (one that may not leave any evidence) for such a problem to occur. Eventual lapping might have fixed this problem, but it would not have corrected the true root cause.

For your collective awareness ....

Cheers,

[J.c. Sherman]

What you are doing with the toothpaste is basically cleaning the casing, perhaps over-thoroughly. There's a better way. Use a non-flamable (or flamamble) degreaser, like brake cleaner or de-natured alcohol and put it on a tightly wrapped rag on a cleaning rod. Swab out the valve thoroughly and voila! - should be fine. You can also use valve oil. Either way use a lint-free cloth, such a muslin.

Using a drill opens up LOTS of potential problems. Rocking the piston with the drill (inevitable) wears the piston and casing unevenly. Bad idea. Better idea to "lap" it in the direction of use, with the hand in playing position.

All of this assumes something other than some kind of "bump" occured during the sudsey bath you gave it. But if something happens, let a professional do it, for the love of god - this is the trickiest and least reversable repairs - run screaming!

J.c.S.

[Daniel C. Oberloh]

Many times, I have been called on to correct repairs on piston and rotor valves as well as hand-slides, solder repairs, dent work and a vast array of woodwind repairs that were attempted by individuals who really had no business doing so. These corrections can at times, be very aggravating because the original problem that would have been a straight forward repair has been converted into a total mess.

When it comes to any kind of "do it your self, at home" valve work, I must insist that you not attempt it. There are a great many variables that can and will bite you in the butt. When it comes to meddling with valves, if you do not know exactly what is wrong with them and how to properly correct the issue at hand, you are playing with fire and run the risk of getting badly burned. Because valves are high tolerance and fragile, once you screw them up, properly correcting the fruits of your ill attempt can be considerably more involved, time consuming and much more costly then would the original problem you blindly attempted to address. It should also be understood that after you have done the dead, most repair shops are not equipt to properly perform the needed additional repairs required and will have to sub-contract it to another facillity in hopes of putting things right. Consider this a friendly warning.


Daniel C. "still not obligated to save folks from themselves but compelled to do so"Oberloh
Oberloh Woodwind and Brass Works
http://www.oberloh.com" target="_blank"

[lgb&dtuba]

The sad truth is that for every Dan Oberloh quality repair person there are probably 50 repair persons who can't do most repairs any better than you can yourself. The difference is availability of the tools of the trade.

For most simple repairs not requiring specialized tools anyone with a little patience and common sense should be able to take care of their own instruments.

It's not rocket science to take apart and clean a set of rotor valves. Useful instructions on how to do so can easily be found on the internet. They've been pointed to any number of times on this forum.

Replacing the bumpers on rotary valve instruments is quite simple. I've done so several times over the past 30 years and never needed to remove the plate they mount in to do it.

The process that's been described here using toothpaste to lap valves may or may not work in your particular situation. If your valves came from the factory sticking then I'd pass on doing this myself. There's probably more wrong than a simple lapping/cleaning will take care of. In this case we're talking about a new horn. Take it back to where you bought it and insist that they fix it or replace the horn with one that doesn't have the problem. Don't back down or give up until they make it right.

If we're talking about an older horn, then maybe lapping with toothpaste would clean it up enough to cure the sticking. How much did you pay for this instrument? Is it worth attempting this to save a few bucks? Is the horn pretty dirty or is it damaged? Can you tell the difference?

Personally I draw the line at anything requiring soldering. Or extreme precision, like straightening out trombone slides.

If you take on any of your own repair work, then just be patient, think, go slow, think, make any changes in very small increments, and finally, think.

Jim 'Still thinking about that Dubro uniball conversion' Wagner

[TubaRay]

The sad truth is that for every Dan Oberloh quality repair person there are probably 50 repair persons who can't do most repairs any better than you can yourself. The difference is availability of the tools of the trade.

I think Dan brings a couple more things to the worktable--knowledge and expertise.

Jim 'Still thinking about that Dubro uniball conversion' Wagner

It works. I can personally vouch for this.

[J.c. Sherman]

Making or repairing brass instruments is an art, and as such requires training and experience. Hey playing the tuba doesn't look very hard. Why not just grab anyone to play? Or have the highschooler do the repair I have cheep? Because art requires practice, and loads of experience and oversight.

I know many of us have had bad repair experiences, and thusly most of us who have practiced our art get painted with the same brush as the unqualified. I doubt that it's really a 50/1 ratio of poor to trained professionals, but there is something to be gained by having experienced people in any field.

Dan was actually 100% right. I tried to be a little open, and got flamed for it, as did he for being straight-up correct. Valve repair is extremely costly, and often unnecessary, and if we both use "emotional" language, it's because it is very frustrating to undo a home repair, performed by well meaning people who thought we were just out for their money, and just have better tools. Believe it or not, we don't like to take your money unnecessarily. We'd rather help you out before there's a serious problem. I know Dan is a musician as well, and while not speaking for him, I like to make instruments work for musicians. There's really not a lot of money in this trade, so we wouldn't do it if it was to take your money. We love what we do.

If you must try to do it yourself, we won't be able to dissuade you. Just try to remember the rule I give college students preparing to be come teachers (which means all of them will try to become do-it-yourself-ers): Brass is SOFT - that's why they make brass instruments from it. It's much softer than you imagine, most likely. Before you take a tool harder than wood, rawhide or brass to it, you better know that the harder material is going to win... Even if it's the pumice in Lava or Toothpaste.

J.c.S.

[sungfw]

There's a better way. Use a non-flamable (or flamamble) degreaser, like brake cleaner or de-natured alcohol and put it on a tightly wrapped rag on a cleaning rod. Swab out the valve thoroughly and voila! - should be fine. You can also use valve oil. Either way use a lint-free cloth, such a muslin.

Both of the repair techs I took my horn to tried valve oil, brake cleaner, and several other substances. (I watched while they did it.) It didn't work. At which point, both recommended that I send the horn to Anderson (directly rather than through their companies) to have the valves rebuilt.

At that point, I could have bought a new replacement valve block and #2 piston from Windcraft AND had them installed by either of the techs for less than the cost of having the valves rebuilt. At that point, it became an, "Aw, what the heck ... might as well give it a shot." Bottom line: I had nothing to lose by trying it. Would have tried the toothpaste but wouldn't have used the drill otherwise; and even then, I ran the drill as slowly as possible, and no longer than absolutely necessary.

So I took a calculated risk, based on the relative cost of the options. Worked out fine in this instance and saved myself $400, minimum. YMMV.

[windshieldbug]

Troll Information

The 7th definition is mildly amusing to me:

One of many unsung internet heroes who are almost entirely misunderstood. Contrary to popular belief, many trolls are actually quite intelligent. Their habitual attacks on forums is usually a result of their awareness of the pretentiousness and excessive self-importance of many forum enthusiasts. As much as people may hate trolls, they are highly effective - their actions bring much of the stupidity of other forum users out into the great wide open.

Look who wrote it!

(A citable source in any context... or... A TROLL! )

[lgb&dtuba]

The sad truth is that for every Dan Oberloh quality repair person there are probably 50 repair persons who can't do most repairs any better than you can yourself. The difference is availability of the tools of the trade.

I think Dan brings a couple more things to the worktable--knowledge and expertise.

Of course he does. As do others in his class. The statement was really referring to the other 50, who are nowhere near as knowledgeable or talented and Dan (or his true peers). Some of whom have botched simple repairs on my own instruments and I had to go back and correct their mistakes.

If you know a really good repairman, then cultivate your relationship with him. Otherwise, run.

[sc_curtis]

Look who wrote it!

(A citable source in any context... or... A TROLL! )

Hello Windshield bug: You make a good point. My recommendations aren't backed up with any academic degrees or certificates of authenticity, just common sense and accurate information. I don't even profess to be a professional. See, I don't expect anyone to believe me because of the position I happen to hold, or the achievements I've made in life. I've noticed that on this site many people, like you and I, post anonymously. Its kinda fun to allow the information, with its logical supporting data, to stand on its on.

So, why are you so sarcastic about such a common practice?

MTuba

I think windshieldbug was referring to who wrote the particular definition within the quote. I don't believe his statement was aimed at you at all. Of course, I could be wrong.

[iiipopes]

Harry Callahan summed it up best:
"A man has got to know his limitations."

[J.c. Sherman]

You got me - yes, I have lapped some valves.

However, that is ONLY after correcting some other physical flaw. A valve just doesn't "stop working", thereby requiring lapping. It must be jarred, bumped, twisted, hit, spanked... something to physically deform the valve or the casing. If after a cleaning a valve isn't working, clean it again... and again. Whatever it takes to remove the obstruction that does not impact the metal.

When I do lap, it is to make a final fitting when a valve has been physically hurt. A perfect repair to a valve, once deformed, is not always possible, especially without harming the adjacent casings. So it is sometime necessary to do that last TINY bit of adjustment with lapping compound. 99.9% of those are not by rotation, but in playing position and in playing motion. If you have an irregularity in the valve, and spin it around and move it up and down, you are making that iregularity sand down the casinge in all sorts of areas where it doesn't belong or function.

I don't do full valve refits or plating, for two reasons. One, My shop isnt zoned to keep those kinds of chemicals on premises. Second, that too is an art, and there are those better than I at that, namely Anderson, et al.

So I will say again, I wouldn't recommend this.

J.c.S. (an emotional guy - chicks love that! )

[windshieldbug]

Look who wrote it!

(A citable source in any context... or... A TROLL! )

Hello Windshield bug: You make a good point. My recommendations aren't backed up with any academic degrees or certificates of authenticity, just common sense and accurate information. I don't even profess to be a professional. See, I don't expect anyone to believe me because of the position I happen to hold, or the achievements I've made in life. I've noticed that on this site many people, like you and I, post anonymously. Its kinda fun to allow the information, with its logical supporting data, to stand on its on.

So, why are you so sarcastic about such a common practice?

MTuba

I think windshieldbug was referring to who wrote the particular definition within the quote. I don't believe his statement was aimed at you at all. Of course, I could be wrong.

He COULD be wrong, but this time he's right on the nose ;
I wasn't speaking about "MTuba"'s posts, but to the submitter of the definition that was referenced, one "Jesus Hitler".

(and unless THAT shoe fits, don't be so quick to take offense, not that I'm often called an offensive person... )