Magnet for removing dents

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Jmac
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Magnet for removing dents

Post by Jmac » Fri Oct 19, 2018 11:29 am

Has anyone out there bought a magnet for removing dents? There’s a place that sells a kit for $450 or so but I was hoping I could buy a strong magnet at Home Depot or the like for less. Any suggestions?
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BGuttman
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Re: Magnet for removing dents

Post by BGuttman » Fri Oct 19, 2018 11:42 am

The kit includes a magnet and a bunch of steel balls (for different tubing sizes).

You can't just use a magnet to remove dents: it has to move something inside the instrument, which is what actually removes the dents.

If you have access to some good quality steel balls the Home Depot magnet (do they even sell them?) would be OK. Note: place a piece of plastic (LDPE sheet, at least 0.010" thick) between the magnet and the brass to avoid scratching the brass as you move the magnet back and forth.

An alternate source of strong magnets might be Edmund Scientific. You need a VERY strong magnet.
Bruce Guttman
Merrimack Valley Philharmonic Orchestra
"Almost Professional"
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Jmac
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Re: Magnet for removing dents

Post by Jmac » Fri Oct 19, 2018 11:59 am

I realize I need a neodymium magnet and the steel balls. Sorry I didn’t type that in. The balls look to be available everywhere. A decent size neodymium is what I’m looking for.
SoVTTb
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Re: Magnet for removing dents

Post by SoVTTb » Fri Oct 19, 2018 12:52 pm

I have purchased a couple scary strong neodymium magnets for classroom speaker making projects at magnets4less.com.

Also, and this is just speculation - having never used a dent remover of any kind, let alone magnetic - but it might be a good idea to put some kind of casing around the magnet before using it on an instrument. They can be pretty brittle.
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ghmerrill
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Re: Magnet for removing dents

Post by ghmerrill » Fri Oct 19, 2018 3:26 pm

I put together my own set-up for removing dents in tubas and euphoniums. So I've got about four different sized balls (which are pretty easy to get), and magnet that (as I recall), produces a force on the ball of about 250 lbs. It's a bout an inch in diameter and an inch and a half long. I don't recall how much I paid for all of it, but it was significantly below $100. I got the magnet from some supply house that's accessible online. You just have to (a) decide what you want, (b) look for it (may take some effort), and (c) get it. Then be real careful how you use it.

I can't imagine that Lowes or HD has anything like what you need. I've never seen anything in either store that approaches it. You need the magnet to be of a certain size (and "gripable"). Then there's other technique you need to learn about. Without some kind of practice, it's very easy to absolutely ruin an instrument that wasn't in such bad shape to start with.

These magnets are surprisingly dangerous, and there are several ways in which they can hurt you that you won't expect.
Gary Merrill
Wessex EEb Bass tuba
Mack Brass Compensating Euph
Amati Oval Euph
1924 Buescher 3-valve Eb tuba
Schiller American Heritage 7B clone bass trombone (DE LB K/K9/112 Lexan, Brass Ark MV50R)
1947 Olds "Standard" trombone (Olds #3)
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Jmac
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Re: Magnet for removing dents

Post by Jmac » Fri Oct 19, 2018 4:29 pm

Yikes!
Jimkinkella
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Re: Magnet for removing dents

Post by Jimkinkella » Fri Oct 19, 2018 4:40 pm

Check out McMaster Carr (mcmaster.com), a super industrial supply website.
Doug Elliott
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Re: Magnet for removing dents

Post by Doug Elliott » Fri Oct 19, 2018 5:40 pm

Steel balls in the sizes for trombone tubing don't have enough mass to be effective at removing dents, even with the strongest magnets. The large kit for tubas works fairly well, but smaller balls don't do it.
Jgittleson
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Re: Magnet for removing dents

Post by Jgittleson » Fri Oct 19, 2018 8:46 pm

Doug Elliott wrote:
Fri Oct 19, 2018 5:40 pm
Steel balls in the sizes for trombone tubing don't have enough mass to be effective at removing dents, even with the strongest magnets. The large kit for tubas works fairly well, but smaller balls don't do it.
If i read that right, you're saying it takes big balls to work on a trombone :lol: :lol: :lol:
Doug Elliott
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Re: Magnet for removing dents

Post by Doug Elliott » Fri Oct 19, 2018 11:37 pm

Jgittleson wrote:
Fri Oct 19, 2018 8:46 pm
If i read that right, you're saying it takes big balls to work on a trombone :lol: :lol: :lol:
No, tuba...
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Jmac
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Re: Magnet for removing dents

Post by Jmac » Sat Oct 20, 2018 5:47 am

He’s saying I don’t have big balls ..... Thanks for the info Doug. Looks like I’ll have to find a different way to pull the dent in my tuning slide. I’d like to be able to do some of that work.
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ghmerrill
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Re: Magnet for removing dents

Post by ghmerrill » Sat Oct 20, 2018 6:07 am

Doug's absolutely right. The magnet/ball technique is great on LARGE diameter tubing -- like tuba or euphonium bows or bell sections (at least up to near the final flare). But it's useless/damaging for smaller diameter tubing. That's where you need the hundred or so small diameter balls of different diameters together with the appropriate tools for pushing/pulling them through the tubing. The magnet/ball technique can be great for a (careful) amateur to do "acceptable" improvements to his own tubas/euphoniums. But unless you're willing to gear up like a pro technician (and spend the thousands of dollars involved in tool acquisition), then don't even go there.

I suggest that you pull the dent in your tuning slide by taking it to someone who can pull the right tools out a drawer and fix it in a few minutes. It will be cheaper and better. Keep in mind that depending on the depth of the dent, you may well have to make two or more passes on it with different diameter expanders. You really want to guess at what those diameters should be and how many of them you'll need? :?
Gary Merrill
Wessex EEb Bass tuba
Mack Brass Compensating Euph
Amati Oval Euph
1924 Buescher 3-valve Eb tuba
Schiller American Heritage 7B clone bass trombone (DE LB K/K9/112 Lexan, Brass Ark MV50R)
1947 Olds "Standard" trombone (Olds #3)
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Jmac
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Re: Magnet for removing dents

Post by Jmac » Sat Oct 20, 2018 6:43 am

Yes I agree it looks like I should take it to the shop. There’s a local guy that does decent work and is inexpensive but he gets kinda weird when I bring him one ding to fix. Not sure why.
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ghmerrill
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Re: Magnet for removing dents

Post by ghmerrill » Sat Oct 20, 2018 7:58 am

I think that most guys who run their own shops (instrument repair, gunsmiths, machine shops, small engine repair, etc.) are "kinda weird" in one way or another. I would be too. I think it's usually about having certain kinds of work you like to do and certain kinds you don't like to do, being able to be independent about that, and mixed in with heavy schedules at certain times of year when the work gets outrageously intense for a while. But the guy I take my stuff to (that I can't do myself) usually tells me when to come in and ends up doing it on the spot -- if it's just some minor thing that only takes a few minutes. This included, once, pulling a lead pipe that turned into a hands-on job for both of us!
Gary Merrill
Wessex EEb Bass tuba
Mack Brass Compensating Euph
Amati Oval Euph
1924 Buescher 3-valve Eb tuba
Schiller American Heritage 7B clone bass trombone (DE LB K/K9/112 Lexan, Brass Ark MV50R)
1947 Olds "Standard" trombone (Olds #3)
ToneBone
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Re: Magnet for removing dents

Post by ToneBone » Sun Jan 06, 2019 11:18 am

More to removing dents than just pressure and the force of magnets, etc. Without heat to soften it up, it'll crack, as explained in this brilliant video...

There's no doubt, more to the story of how this trombone was mangled in such a way having been borrowed. :eek: :( I presume it wasn't the owner's No.1 and pride & joy, as they wouldn't be loaning it in that case. If it was mine, I probably wouldn't even think of being able to get it repaired, much less to this standard. Rather than that, I'd be insistent it be kept by the borrower, on one condition... that it would be given back to them, by insertion! Sideways! 8-)

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