Odd problem with a TR180

[bigbandbone]

Let me preface this by saying I'm a retired instrument repairman with 44 years at the bench. I've been retired for 4 years and have sold off most of my tools.

I've encountered a slide problem on a "new to me" TR180. I've never seen this before. I'm wondering if any other repair people have encountered it and how did you fix it.

From 1st to 4th position the slide is smooth as glass. Both individually and when the slide is put together. But 4 1/2 out to seven is rough. Again individually and together.
Basically when the inner slide stockings are at the end of the oversleeves it starts to get rough.

Before anyone asks, the outer slide tubes are parallel and flat and the inner slide tubs are spaced properly.

My thinking is that the oversleeves were too tight and were forced on when the slide was built at the factory and are slightly constricting the outer tubes???

Has anyone else seen this problem? How did you fix it?

Thanks in advance for any and all input.

[Crazy4Tbone86]

I have seen a couple of similar slides……….perfect through 4th and the problems start at about 5th position. I have seen MANY slides that are perfect through 5th and become tight at 6th and 7th.

All of the horns noted above have been slides with the nickel oversleeves. My theory is that during the assembly of the oversleeve area, the torch was much too hot and it contracted the principal outer tube just a little bit. For those trombones that get tight at 5th position, I am assuming that the torch super heated the tubing even farther away from the oversleeves, so it contracted a larger piece of the outer slide.

In terms of solutions, it depends on the horn. For those situations where the problem is subtle, I have been able to flex hone the oversleeve area of the horn with limited success. I am not a fan of using a flex hone to solve problems because it takes away some metal. However, I have been able to address this particular problem with this tool a few times.

For the times it was a bit more pronounced and the horn was relatively new, I have pulled the entire outer slide apart, used roller tools to get the inside surface of the outer slides AND oversleeves level and even, then reassembled. For the times that the problem was really bad (when you can actually feel a “bump” when moving the slide), I have resorted to buying new parts and rebuilding the outer slide.

Of course, the secret is to be very careful when soldering those oversleeves to the outer slides. I was fortunate to make the mistake of using too much heat on one of my first slides……it taught me to be careful because I had to buy all new parts. I’m pretty sure this particular problem has been discussed before on TromboneChat.

[brassmedic]

I have rarely encountered a slide with oversleeves that isn't constricted at that point (unless they're one piece tubes with extruded oversleeves). It's just something that happens when it's built. When the solder flows into the joint, it shrinks down the slide tube and makes it a slightly smaller diameter than the rest of the tube. Someone in another thread, I forget who, said the solder expands when it cools. I don't know if that's true, but it certainly makes sense. And I think the problem is exacerbated when it's an older slide that's tarnished and maybe pitted inside the tubes.

Is there a way to fix it? Some people recommend adjustable hand reamers to remove metal from inside the tube and restore the correct inner diameter. I never had any luck with that approach, but maybe others have.

[Crazy4Tbone86]

Is there a way to fix it? Some people recommend adjustable hand reamers to remove metal from inside the tube and restore the correct inner diameter. I never had any luck with that approach, but maybe others have.

Using a reaming tool on the inside of an outer slide?.....Yikes! That seems like dangerous territory to me. If there is a person out there that can do that consistently, I would like to shake their hand. That person would have VERY steady hands and might be a good candidate to be my dentist!

A slightly different tool that might have possibilities is a very narrow valve casing lapping tool. Allied still sells those, but I doubt they would have one narrow enough for even the largest of trombone slides. I believe that Feree's discontinued stocking that tool in favor of their valve casing mandrel sets. I cannot see myself using an adjustable lapping tool on an outer slide. I fear that it would only take a small amount of pressure to twist the outer slide tube into a mangled mess. It could also create cross section striations, which would result in a very scratchy and noisy slide.

[BGuttman]

What about using an expander CAREFULLY enlarging the tubing only a little. Perhaps set it to the diameter of the undamaged outer slide and use that like a dent ball?

[brassmedic]

Using a reaming tool on the inside of an outer slide?.....Yikes! That seems like dangerous territory to me.

I agree.

A slightly different tool that might have possibilities is a very narrow valve casing lapping tool. Allied still sells those, but I doubt they would have one narrow enough for even the largest of trombone slides. I believe that Feree's discontinued stocking that tool in favor of their valve casing mandrel sets. I cannot see myself using an adjustable lapping tool on an outer slide. I fear that it would only take a small amount of pressure to twist the outer slide tube into a mangled mess. It could also create cross section striations, which would result in a very scratchy and noisy slide.

You can get any size adjustable brass laps you like from McMaster Carr. Warning, though: the edges are not rounded on those, so you should round them off with a file or grind them. Otherwise you will gouge the inside of whatever you're lapping. I never tried that. The drawback is when you adjust the diameter, they become slightly barrel shaped, so you have to run the tool evenly back and forth, and if you go too far, I imagine you're taking metal off of the part of the slide that doesn't need it.

[brassmedic]

What about using an expander CAREFULLY enlarging the tubing only a little. Perhaps set it to the diameter of the undamaged outer slide and use that like a dent ball?

I have never gotten that to work. the oversleeve makes it very resistant to expansion, and even if you did manage, you would probably turn it into a hexagonal shape due to the way the tool expands.

[Crazy4Tbone86]

What about using an expander CAREFULLY enlarging the tubing only a little. Perhaps set it to the diameter of the undamaged outer slide and use that like a dent ball?

I have never gotten that to work. the oversleeve makes it very resistant to expansion, and even if you did manage, you would probably turn it into a hexagonal shape due to the way the tool expands.

One of the first things that I was taught about the trombone slide expander tools was this……. The name “trombone slide expander tool” is almost a misnomer. If you are applying so much pressure that the tubing is expanding, you are probably creating outward grooves in the metal or making the tubing hexagonal (as Brad stated).

Slide tubes tend to have flat spots after doing dent work. The best application of the slide expansion tool is to help return the tubing to being ROUND after dent removal work is completed. The tool works best when very little expansion pressure is used.

[Crazy4Tbone86]

Using a reaming tool on the inside of an outer slide?.....Yikes! That seems like dangerous territory to me.

I agree.

A slightly different tool that might have possibilities is a very narrow valve casing lapping tool. Allied still sells those, but I doubt they would have one narrow enough for even the largest of trombone slides. I believe that Feree's discontinued stocking that tool in favor of their valve casing mandrel sets. I cannot see myself using an adjustable lapping tool on an outer slide. I fear that it would only take a small amount of pressure to twist the outer slide tube into a mangled mess. It could also create cross section striations, which would result in a very scratchy and noisy slide.

You can get any size adjustable brass laps you like from McMaster Carr. Warning, though: the edges are not rounded on those, so you should round them off with a file or grind them. Otherwise you will gouge the inside of whatever you're lapping. I never tried that. The drawback is when you adjust the diameter, they become slightly barrel shaped, so you have to run the tool evenly back and forth, and if you go too far, I imagine you're taking metal off of the part of the slide that doesn't need it.

Hey Brad……I didn’t know that McMaster Carr offered those. Don’t know if I will buy sizes applicable for trombone slides, but it is good information to have. Thanks!

[brassmedic]

I have never gotten that to work. the oversleeve makes it very resistant to expansion, and even if you did manage, you would probably turn it into a hexagonal shape due to the way the tool expands.

One of the first things that I was taught about the trombone slide expander tools was this……. The name “trombone slide expander tool” is almost a misnomer. If you are applying so much pressure that the tubing is expanding, you are probably creating outward grooves in the metal or making the tubing hexagonal (as Brad stated).

Slide tubes tend to have flat spots after doing dent work. The best application of the slide expansion tool is to help return the tubing to being ROUND after dent removal work is completed. The tool works best when very little expansion pressure is used.

Fun fact: It's actually not called that. It's called an Expandable Dent Removal Tool. Ferree's sells it as a dent removal tool, which it's actually terrible at. But I agree it is good for rounding out tubing that has become egg shaped. Even Ferree's doesn't suggest using it to try to increase the inner diameter of tubing.

Edit: Ha, I just noticed Allied calls theirs an "Outside Slide Internal Burnisher", but in the index they do say "slide expander", so that must be where that name came from.

[bigbandbone]

Original poster here. Just thought you might like to know how I fixed this problem.

First, I did start with an expandable mandrel. But only at the most constricted point which was at the leading end of the upper tube over sleeve.

Then I began lapping the first 6 inches of both tubes with Clover Lapping Compound. I started with 1A, 100 grit. I used the 100 grit until the slide felt almost perfect. Then I progressed through finer and finer grit compounds ending with 7A, 1200 grit to polish the tubes.

The process was very time intensive but turned out great. The slide is now a 9.7ish out of 10.

[Crazy4Tbone86]

Great to hear that you had success! I imagine that your slide will continue to get better with time because the scratches on the inside of the outer slide (caused by the lapping compound) will eventually polish to a smoother finish from the repetitive movement of the slide.

Can I ask you which expandable mandrel you used?

[bigbandbone]

Great to hear that you had success! I imagine that your slide will continue to get better with time because the scratches on the inside of the outer slide (caused by the lapping compound) will eventually polish to a smoother finish from the repetitive movement of the slide.

Can I ask you which expandable mandrel you used?

I bought tenor size and a bass size from Ferree's about 35 years ago.

[Crazy4Tbone86]

Ok, got it. You probably used one of these....

https://www.ferreestoolsinc.com/search? ... le+mandrel

I was thinking that you bought one of the McMaster-Carr expandable tools. Thanks!

[hornbuilder]

What did you use to do the lapping? The "expander" tool?? Or a dedicated mandrel?

[bigbandbone]

What did you use to do the lapping? The "expander" tool?? Or a dedicated mandrel?

Dedicated mandrel

[brassmedic]

Interesting. I guess you'd have to have a second one for dent work, since the lapping would eventually wear it down so it's out of spec?

[Doug Elliott]

I've always understood that proper lapping involves using a lap that's a softer material than the object (tube in this case), and the abrasive gets embedded into the surface of the softer material . That's why real laps are soft brass. If you're using a steel lap, that means the abrasive is going to embed in the inside surface of the brass tube and will later cause wear on the inner slide.

Here's one explanation
https://www.lapmaster-wolters.com/what- ... w0QAvD_BwE

Down the page a bit:
"Keeping in mind that the abrasive charges the surfaces of your lap plates, it is almost always preferable to have your plates softer than the material being lapped, while the abrasive should be as hard as, or harder than the work pieces."

[MStarke]

Just wanted to say that I really enjoy reading many of these modification & repair topcis.

I am really not planning to get into this myself (aside from very minor things), but this is very interesting and helps a lot in understanding how brass instruments are (not) functioning.

Thanks for sharing all these insights!

[Doug Elliott]

And a lap should only be used with one lapping compound grit. When you change grits, use a new lap. Just like buffing wheels.
They don't teach this stuff in instrument repair schools.

[Crazy4Tbone86]

What Doug is saying is what I was taught. For fixing trumpet pistons in my shop, I have hard steel mandrels for straightening valve casings and pistons. I only use a rawhide mallet to drive or shock the dents out with those. I never use lapping compound with the steel mandrels because I was taught that the hard steel would “force” the lapping compound permanently into the casings and it would accelerate the wear as the valves were used.

For lapping trumpet valves, I have separate mandrels made of brass. A couple of these have worn with time and I had to make new ones. Of course, it is my hope that the mandrels have the same or softer alloy when compared to the valve casings.

Another thing mentioned by the OP that caught my attention….he/she/they started with 100-grit compound. That is a very aggressive compound.

I am glad that the OP was able to improve the action of the slide. However, I think that further measures should be taken to ensure that the slide does not continue to wear too fast. If the slide were mine, I would use a degreasing agent on the swab (PJ’s Super Cleaner is very good at removing buffing compounds, so it might be a good option for removing as much of the lapping compound as possible) a few times a year and do a normal swabbing very frequently (every two hours of playing). After a year or two, cleaning the slide so frequently might hit the point of diminishing returns.

[bigbandbone]

And a lap should only be used with one lapping compound grit. When you change grits, use a new lap. Just like buffing wheels.
They don't teach this stuff in instrument repair schools.

Actually I learned this technique in a repair school from a master craftsman. Fred Kirchner at the Eastern School of Musical Instrument Repair. I graduated in 1978.

Doug, where did you learn the repair trade?