Expert: Kenton Scott - 6/20/2005

Question
Hi, Kenton

I received some helpful information from you last month about trumpet valves (I'm teaching myself to repair band instruments).  This is about trombone slides: I bought a used Yamaha tenor trombone and find a lot of binding in the action.  The outer slide doesn't drop down on its own when I hold the slide vertical, and the friction gets worse when the outer slide is pushed almost all the way in.  When I pull the slides apart I see the inner slide stocking ends are about 1/8 inch wider than the openings in the outer slide.  Also the outer slide doesn't lie totally flat when I put it on a flat surface; there's a little bit of rocking between diagonally opposite corners.  I've cleaned all the insides with the long flexible brush and with the chemical stuff I got from Ferree's.  That's all so far.  The questions are: What else can I do to find any other causes for the slides not working smoothly? How can I tell which of the inner slides needs to be bent in to make them parallel so they'll fit the openings of the outer slide (assuming the tubes themselves are perfectly straight, which I haven't checked yet)? How do I make the outer slide lie flat?
All ideas and suggestions on this topic are welcome, and thanks in advance.

Answer
Hi Joe,

You don't need to contact me through this Ask an Expert.  You can contact me through my regular email address.  It is Kenton@PunxyPa.com

I'll happily try to answer your repair questions.  I'm not that long into it either, so I know how hard it is sometimes to find answers.  I was befriended by a tuba repair specialist that helped me immeasurably.

Trombone slides are tough, and I'm not completely satisfied with my skills in that regard either, and as a trombone player, I really want to be good at them.  

The slides have to be straight with no bowing, they have to be parallel to each other, they have to be free of dents, the tubes have to be round, and the surfaces have to be smooth.  Oh, yes they also have to be clean.

After that, it is duck soup!

You can use the slide to help diagnose what is going on.  Pu t one inner tube in the outer tube to see how smooth it is.  Then reverse it and put the inner tube in the opposite outer tube.  Unless you have one of the trombones that have different size tubing on each side, that is a good way to determine which tube is the culprit.  

Do you have an Allied catalog? I can't remember.  Most of my trombone tools I got from Allied.  One is basically a piece of angle iron that is tooled flat.  It is used to check to see if the slide tubing is straight.  You can roll the slide around on the iron to see if it lays flat from all angles.

From Ferrees I got the expandable dent removable tools (p 134), and they are the workhorses.  They do most of the fixing.

I also have a couple of honing rods from Allied, but I'm not convinced that they are worth the cost.  I don't see that they do a lot.

Then my other tool is my caliper.  I use it to make sure that the outer slides are parallel.

My biggest caution on trombone slides is not to be too sure you have the problem diagnosed correctly.  Be cautious and be alert for the problem resulting from something other than what you expected it to be.  

Another scary part of trombone slides, is when you decide you have to unsolder them and take them apart.  It really isn't as bad as you imagine, if you are careful.  And, know what to expect.  

I sounds like your slide has a lot of problems that need to be adjusted, and you really need to do them all, if the slide is going to come back to life.  

You might also want to look up the cost of replacement tubing.  It probably isn't as expensive as you might think, and it does give you an idea of what you are risking if you make a serious mistake.

Mistakes are far less serious on a relatively new Yamaha than they would be on an antique Holton, for example, where exact replacements aren't available.

Outer slides often will go out of parallel if the bottom bow has been dented up.  That will often cause them to spread, then they aren't parallel.  

Lots of possibilities.  

I'm going to sign off here, but feel free to contact me whenever you want.  

But, I'm going on vacation tomorrow.  I'll be back on Monday.


Good luck

Kenton