Remove dent from copper trumpet mute

If you want to spend money: Go to a body shop that has specialized in doing minor dent(al)-repair. :-) They have glue-on-pimps to pull out dents. They have the "L-shaped-tools" AND they can handle them without making inverse dents.

DIY: First put one open end onto some rubber and blow with compressed air into the other end. Don't try to completely seal both ends with tape or the like. You risk an explosion. It will (hopefully) blow out _most_ of the dent. Then go on with your L-shaped tools and don't ruin the mute.

Do NOT heaten up, it will soften the copper and make it more vulnerable to the next series of dents ...

Nick

Time machine.

Make a special shape stake with a rounded head. You can then tap on it from the outside and gradually work it back into shape. This is a sheet metal technique. You will be hammering a little off of the heat of the stake, using the stake as a kind of anvil inside the mute.

I work in sheet metal all the time. A good bodyman or jeweler knows how to do this.

There is a different technique that has you hammering on the stake, which flexes and taps at the dent from the inside. I have never tried that. You rap the side of the stake, which vibrates and then comes back and whacks the dent.

Richard

Rich wrote:

Thanks Richard. What material would you suggest for the stake - a hardwood maybe?

Accept that it's character, and you're just going to dent it again, when it falls out again? While you're at it, you might want to do some sanding on the cork to get a better fit of the mute to trumpet bell.

Won't make any significant difference to the way it sounds.

Ecnerwal wrote: ...

Probably should be addressing this to the trumpet makers group, but if it won't affect the sound I'm actually quite happy with a dent - gives somewhere to put your thumb. As it'll probably fall out again and again (even with cork sanding) I just wanted to have a repair technique up my sleeve...

Thanks, Rich

I'm a trumpet player too.

1) take it to the guy that takes the dents out of your trumpet.

2) fill it with water, plug the ends, freeze

3) put a steel ball bearing inside, lube the outside and slide one of those strong (nyobium?) magnets back and forth over the outside surface.

4) stick the rounded end of a broom handle in there and rub it around inside to push the dent out.

BTW, mine fell out of its case onto pavement the other night. Some idiot only closed the velcro flap and didn't zip it up. He also didn't carry the case with the lid toward his leg. I need some repair work done too. Randy

You asked the right group about it as a sheet metal question

I'ma drummer but Most musicians i know i wouldnt trust with a screwdriver. Although there are a few exceptions (Hammond organ players are one notable one in general) for the most part professional musicians dont have a great deal of mechanical sense.

rec.music.makers.builders might also be a good group to ask

Rich wrote:

You could use a wooden stake, but I would probably make a steel stake. A steel rod with a ball bearing welded to the end would do, or just take a steel rod, bend it to shape, round the end with a file and sandpaper, and clamp it in a vise. You should probably use a rubber or wooden hammer, unless you have a body man's style hammer.

The technique where you bang on the stake uses a z shaped stake with one end clamped in a vise and the other with a rounded end. When you hit the middle of the stake the rounded end goes up and down, and pushes out from the inside. Probably a more elegant solution, but I have no personal experience with this technique.

Richard

Rich wrote:

How about this approach. Think of the way a piano key and striker hits the string. It's kinda like an offset hammer. Perhaps you could build a small device like that with a ball bearing on the striking end that you slide up iside the mute and with a seperate anvil, bang on the inside precisely where the dent is. Piano mechanisms create quite alot of force. You could make the lever arms any dimension you need to get inside there.

The stake idea is good, but if you clamp the stake in a bench vise then you probably won't need a hammer to get out the dent - you can probably just rub it out with arm power. If you do need a hammer, try a rawhide mallet - if you resort to a steel hammer, the head should be polished smooth. The larger the radius of the stake the safer - a small ball end (or the ubiquitous drumstick) is likely to create new bulges

Really, best to take it to a brass instrument repair guy. Home repairs tend to turn one simple dent into one negative dent surrounded by sharper, harder to remove dents. Once you've stretched the metal that way, its hard for a professional to undo.

Of course if you don't care, then have fun.

Hi Rich,

Why don't you find a nice looking piece of short cord, epoxy/glue one end of it to the mute and then attach a piece of double sided Velcro to the other end. Insert mute into your trombone and then wrap and self affix the Velcro around the horn on the trombone. Now if it works loose it will just hang suspended from the cord and you can just grab & jamb it back in place.

Brownells sells an internal hydraulic expander for removing dents from shotgun barrels.

Here you go: