dent balls

[bigbob]

......

Working with magnets is one heck of an education. You're gonna get hurt a couple of times and gonna tear up a few horns until you get it right.

What do you mean about getting hurt...How??

[PMeuph]

......

Working with magnets is one heck of an education. You're gonna get hurt a couple of times and gonna tear up a few horns until you get it right.

What do you mean about getting hurt...How??

Just replace the object with your finger. Crushed bones are a possibility...

http://www.youtube.com/watch?v=ClkP-QwIOAQ" target="_blank

[jsmn4vu]

Crushed bones are a possibility...

... and blood blisters are highly likely.

[Dan Schultz]

......

Working with magnets is one heck of an education. You're gonna get hurt a couple of times and gonna tear up a few horns until you get it right.

What do you mean about getting hurt...How??

I have TWO 1 5/8" diameter x 1 1/4" magnets stacked against a same size steel backing plug and shoved into a piece of reinforced vinyl tubing. Getting this thing in the proximity of loose tools on my workbench sort of reminds me of an old 3D Abbott and Costello movie where meat cleavers and knives were flying through the air!

And yeas... as one poster already said.... blood-blisters will eventually happen!

[bigtubby]

bigtubby,
All I can say is Wow ! Those magnets you bought are amazingly powerful.

Actually they are the economy size. I'm a bang for the buck kind of guy - N50 and N52 magnets in the same size have more pull but the price curve is pretty steep.

I'm starting out with smaller stackable magnets that hopefully won’t damage my horn by snapping together.
With my 1"x1" magnets I only get around 98 lbs pull. Stacked they add about 70% above that and I have an old
stack of coin sized magnets that probably add another <50 lbs. So far I have only stacked the little ones inside
a table spoon and used the two bigger ones to pull the spoon over the bumps. Where the bumps matched the
radius of the spoon, it was amazing how well it worked. It was like polishing out the dents. I can't wait to do more !
I suspect that if I ever get into higher strength applications, I will probably want to stack magnets rather then
chancing the destruction of my horn's appearance.

I'm pretty happy with the N45 1-1/2X1-1/2 and N42 2X2 combination with a combined price of about $120.00. Good thinking on not going overboard with power. The 2" magnet is too much with larger balls but has its place there (reinforcements, etc.). On normal body metal I use the 1-1/2" magnet with balls over one inch or so.

Also: "... my horn's appearance ...": I had some school horns for practice (my horns; but old strong, heavily dented ex-school horns). If you pick up a junker for a couple hundred bucks on ebay you can practice on it and probably increase its value enough to pay for the shipping or more ...

I also wonder how you can release a 368 lb attraction ! ?

That can be tricky. You have to be very careful when separating them that you don't cock or twist the magnet or you will end up with a new dent. And usually a new dent with a crease from the hard edge of the magnet. You can work the ball up under a reinforced area which will help insure against that. But even then, the act of pulling the ball under it can balloon the body metal near the reinforcement.

I want to say I appreciate you telling about the strength of magnets available. Quite eye opening. For right now though, I just want to get some proper sized balls to try. I figure if a spoon works, spheres should be awesome.

Yes, I put a lot more money into balls than I did into the magnets. Again, I hope to find a way to acquire seconds or overruns from one of the local bearing manufactories.

Sounds as if you are proceeding in a great direction and with caution, best luck with your experiments!

[bigtubby]

Working with magnets is one heck of an education. You're gonna get hurt a couple of times and gonna tear up a few horns until you get it right.

In my education I used that as a training device: After leaving an ugly ball track by getting too far up into the bell flare, I found a method of preventing that:

When working near the bell, keep your free hand just below the beginning of the flare and in the area in which you are working. It is sort of like those dog collars that give a shock when Fido crosses the line: after losing a couple of fingernails I got much better at knowing where the flare starts.

[bigtubby]

This is very interesting, especially since the "kit" starts at $450.

I pretty much replicated that starter "kit" for around $200.00 using bits from ebay Links earlier in this thread).

Any luck finding a convex magnet or steel half-sphere?

It reduces the pull somewhat but $15.00: http://www.votawtool.com/zcom.asp?pg=pr ... =jnenpqdoo" target="_blank

They have a 2" version too: http://www.votawtool.com/zcom.asp?pg=pr ... =jnenrogpm" target="_blank

[imperialbari]

As I understand posters here the right dosage of magnetic energy is a problem.

Why stay with solid physical magnets?

Couldn’t an electromagnet with adjustable strength be shaped into a manageable hand tool with pedal control?

Klaus

[tubarepair]

As I understand posters here the right dosage of magnetic energy is a problem.

Why stay with solid physical magnets?

Couldn’t an electromagnet with adjustable strength be shaped into a manageable hand tool with pedal control?

Klaus

Electro-magnets were used in the band repair industry as far back as the 1950's. From the reports I've received from the folks that tried them back then, they were mostly unfavorable. Perhaps some new experiments could be done, but my experience with the MDRS is it just like any other form of dent removal - you have to learn to feel (instantly) what is happening to the metal and adjust. Not sure that would work with electromagnetics.

As an aside, Votaw had a pneumatic dent removal tool for saxophone called "The Elimator" or "Terminator" or something that I had access to for years. While it had some use, control of force was always an issue, no matter who tried it. If you can't feel what is happening, it's too late when the dent now occurs from the inside of the horn to the outside.

Note to all you new magnet users: Stay away from the ferrules and guards. You'll be disappointed when the tubing on either side ends up higher than the ferrule/guard itself.

[Lee Stofer]

If one wishes to experiment, and doesn't mind if the subject instrument, or parts thereof, are ruined, then all is well.

I would suggest not trying any of this on something that you need to play tonight, or tomorrow.

I've spent many years trying to perfect the art of dent removal, and there is a lot more to it than is immediately observable.

One thing DP alluded to is being angry about a repair shop transforming the finish of his instrument to "hammerite" (whatever that is), what I would refer to as an orange-peel texture where the magnetic dent removal happened. The only fault of the technician was not knowing that this would happen with this particular instrument. Older instruments, and newer instruments that were made by branches being burnished on mandrels are generally smooth inside, and respond wonderfully to the magnetic dent removal technology. However, the majority of newer instruments are of thinner and harder metal. These were made by hydraulic blowing of branches to fit the inside of a mold, and then the exterior is media-polished to a mirror finish, while the inside remains relatively rough. So, when you introduce the ball and magnet to this finish, the rough inner texture transfers to the outside of the instrument, compromising the outer finish and making the portion of an otherwise wonderful looking instrument look terrible. And, there is really no fix to that orange-peel texture short of sanding and buffing the area, and refinishing it.

And, as to the hardness, softness, and/or thickness of metals, different branches on the same instrument can respond quite differently, so I find that I always have to be on guard for what might happen next, using the greatest of care at all times.
It is possible to do quite a lot of damage to a brass instrument, and very quickly, with magnets and dent balls. Now, you've been warned.