Magnetic dent removal

[davewerden]

ok here's the problem posting If I hit quick reply it will tell me I don't have permission to post in a new window, if I hit ok, them down below hit advanced it will open a new window for me to log in then it will return me to the post quick reply page. This is after logging in to start with, is this normal??? red

Not sure why you have to keep logging in (assuming you click the "Remember Me?" box BEFORE you click "Log in"). But the message about a new window is not from the forum. It is a permissions thing from your browser, or from an ad blocking ad-on you may have installed.

[red423]

Ok I just hit the remember me button, I am hoping more people remember me but if not, this will have to do. hahahahaha, I am still messing with the dent balls, seems the much older brass becomes a little hardened in storage and requires a stronger magnet to remove the dents. As I said, I have a 550lbs coming today, Also to anyone doing this I wear gloves all the time, this is to stop my body oils and such from contaminating the balls or the magnet. I also use the plastic top off those plastic soup containers you get from either a restaurant or a chinese take out. The rim of the lid helps to keep the magnet from falling off the plastic and scratching the brass. I am still trying to focus on the cleaning. I have tried naval jelly, it was so-so, I tried citric gel, it did nothing, now onto a test with citric powder mixed with warm water, I will test on an older trumpet I have here and see if it does what they claim. This is a father daughter project, seems the more I get the dents out of the one the school loaned to her, which were excessive in my opinion. The more she will practice. If I can find a stripping soulution that will work I would love to strip at least the bell of the loaner and re lacquer just so it shines out. we'll see. I grab some pics of the damage on that loaner as I have gotten the worst ones half out I can't believe they were that deep and still played...........yours red

[red423]

a note to Dave, yes hitting the "remember me" seems to have fixed the issue. I want to thank you for your patience. yours red

[ghmerrill]

... seems the much older brass becomes a little hardened in storage and requires a stronger magnet to remove the dents.

In general the older brass is a harder alloy (rather than becoming hardened over time), and perhaps it is thicker as well.

[Sara Hood]

It would be interesting to see a video of this (using a magnet for dent removal) in action, if possible....
- Sara

[Clayton M.]

Sara, you can see videos on YouTube. It’s pretty neat.

[red423]

Well I was able to remove quite a few dents with the 220lb magnet. I have contacted the magnet supplier and they are sending me a 330 as well as a 500lb. After some research I found the N52 magnet used by many pro sets has a pull of 600lbs. Me being conservative in my expenditures will go the cheaper route. I have had an issue removing the old lacquer off a baritone I have been working on. I finally ordered some aviation paint remover from Amaz. as where we are living, it is not just a drive to a supply store that carries the stuff. I tried several less caustic methods but they didn't even budge the old finish. I must caution anyone reading this, always wear gloves. It isn't to protect you, It is the keep the integrity of your magnet and the dent balls from rusting from your body oils. This is very important. My next trial will be making a set of dent rods, I have access to a welder so getting a strong enough steel shaft that wont flex will be my next hunt. I had to send back one "550lb" magnet as it seems the trick to these things is singular pull vs a combined pull. Nevertheless, our daughter and her section in the band (6 other baritones) are excited at what her loaner is starting to look like without the massive dents it had. I still need to roll out several more, then try and re lacquer at the least the bell inner and outer that would really make it pop. keep you posted...........yours red

[daniel76309]

Thanks to Gary for starting this thread, and others for chiming in. I finally got the nerve to give this a try. Gary, I believe your assessment of older brass being harder is true, at least with my two horns. My 1971 Besson is made of alloy which does not seem to be substantially thicker than my Adams (.060"), but it is much harder. I think I could dent my Adams with my finger tip, but not so with the Besson. I found that I could get what I needed in terms of magnets and balls from Amazon, economically. I had a few small dings in the bottom bow of my Adams that were bothering me, so my plan was to practice on my Besson and move on to the Adams (CAREFULLY) if all went well. This technique works very well! I got all the little dings out of my Adams very easily, with NO unintended consequences. My Besson still has a dent in the 4th valve tuning slide loop that didn't want to come out. For one thing I think there is something about the physics involved with a smaller diameter tubing versus large--also the ball I was using (1/2") isn't quite large enough, and of course the alloy is very hard.

[AZRuss]

Sears (Craftsman) make polishing sticks in 6 different grits. I used these with a 4" cloth wheel on a desktop drill press to polish stainless steel parts from a 50 year old car. It takes time. A lot has to do with the amount of scratching on your horn. If the scratches are deep, like 200 grit sand paper, you will never get it polished. If the finish has been sanded with a scotchbrite pad, the scratches are too deep to remove with polish. You would need to sand up to 1000 grit or finer before you being polishing. Since brass horns are shiny due to the clear lacquer finish, I don't know what results you would get if the lacquer is gone.

[ghmerrill]

I must caution anyone reading this, always wear gloves. It isn't to protect you, It is the keep the integrity of your magnet and the dent balls from rusting from your body oils.

Well, the first time you get your ungloved hand pinched by one of those magnets, you may reconsider this view. Or maybe you're just a lot more skilled or careful than I am.

[ghmerrill]

My Besson still has a dent in the 4th valve tuning slide loop that didn't want to come out. For one thing I think there is something about the physics involved with a smaller diameter tubing versus large--also the ball I was using (1/2") isn't quite large enough, and of course the alloy is very hard.

It involves geometry as well. I was loathe to try to remove dents in the small diameter tubing, partly because I was concerned about getting a ball stuck in it or -- the other alternative -- using a small enough ball to avoid getting stuck, but then having it distort the circular cross section of the tubing. If the curvature of the ball gets to be too far away from the curvature of the tubing, you'll be noticeably flattening the tubing. This is why the approach won't work (or is very tricky) on bell sections where you'll start to get flat spots and some "edging" because your ball curvature is so much tighter than the bell section curvature.

But I'm glad that this has worked out so well for you guys -- though we may not have heard from others because they're still pinned by their magnets against vises, anvils, or other steel items, and can't reach their phones or computers.

[daniel76309]

-- though we may not have heard from others because they're still pinned by their magnets against vises, anvils, or other steel items, and can't reach their phones or computers.

HA HA!


Yes, I said physics, but you are correct-- "geometry" is more like it. I can't explain exactly why, but intuitively I know that something about popping a dent out of small diameter tubing is going to be more difficult than larger tubing with "flatter" contour.