Question for Repair Techs

Rick Denney · Post by **Rick Denney** » Fri Jul 21, 2006 11:42 am

MaryAnn wrote:On the scratches from removing dents concept....I always wondered why a piece of chamois isn't put between the tool and the outside of the horn?

The softness of the chamois, no matter how thin, would allow the brass to raise too far. With a dent ball, that would create ridges.

Tools for removing dents should be highly polished. Your repair tech should not be using a stratched-up dent removal tool. Some minor scratching may be unavoidable, but at least it can be minimized.

To remove the dent by burnishing (which is what this is), both the burnisher and the anvil have to have a harder surface than the brass. Otherwise, the brass will dent the tool, and that's going the wrong direction.

Lacquer will sometimes fail through compression. My Holton bell still has the lacquer, but it is crazed a bit from when the bell was straightened. The force of burnishing crushed the lacquer, creating a network of fine cracks. That sort of failure is unavoidable, I think, because the lacquer is more brittle than the brass and also less strong.

Rick "who hates dependence on sandpaper" Denney

Chuck(G) · Post by **Chuck(G)** » Fri Jul 21, 2006 12:29 pm

If the dent's not too serious, blemishing when rolling out a bell can be reduced by interspersing a clean piece of HDPE (such as the bag inside of a box of breakfast cereal) between the tool and the instrument. For really bad dents and creases, however, the lacquer's going to suffer no matter what's done.

I know this doesn't answer the original question--just that scratching can be avoided.

Dan Schultz · Post by **Dan Schultz** » Fri Jul 21, 2006 5:20 pm

pulseczar wrote:... these magnets are so strong that they have to be stored at least 10 feet away from anything ferrous to be safe.

I get a little tickled when I hear comments like this... and the endorsements that can be found on the web pages of the guys that sell rare earth magnets. One gets images of meat cleavers flying across the room and the chrome being ripped of off automobiles outside the repair shop.

Although it is dangerous to get two of these magnets in the vicinity of each other, I've never had a personal injury from working with my magnets. These magnets are not only very powerful, but they are very hard. If allowed to bang against one another, they can shatter and cause eye injury.

One of these magnets could do a real number on a computor hard drive or other magnetic media. Got any video tapes you want to erase?

prototypedenNIS · Post by **prototypedenNIS** » Fri Jul 21, 2006 8:31 pm

ASTuba wrote:MDRS will not work on handmade tubas, I've seen several that have been damaged my magnet tools, in particular ones that haven't been cleaned properly before hand.

hmmmm.... why? I have yet to come accross a horn where it would not be compatible. I'm not a huge fan of the system but if you think that, I'd like to know why. Sure it's no Ferree's dent machine but for some quick work on the branch, our customers have been happy to chip in like 20$. Overhauls don't happen all that often around here but a difference of charge from 90$-200$ means we get more business and the customers (teachers and professionals) can afford the lower cost.

We use leather (wrapped around the magnet) and paraffin wax... little bit of endust and it there's no mess.

ASTuba · Post by **ASTuba** » Sat Jul 22, 2006 10:32 am

prototypedenNIS wrote:
ASTuba wrote:MDRS will not work on handmade tubas, I've seen several that have been damaged my magnet tools, in particular ones that haven't been cleaned properly before hand.
hmmmm.... why? I have yet to come accross a horn where it would not be compatible. I'm not a huge fan of the system but if you think that, I'd like to know why. Sure it's no Ferree's dent machine but for some quick work on the branch, our customers have been happy to chip in like 20$. Overhauls don't happen all that often around here but a difference of charge from 90$-200$ means we get more business and the customers (teachers and professionals) can afford the lower cost.

We use leather (wrapped around the magnet) and paraffin wax... little bit of endust and it there's no mess.

Dennis,

I've worked on several Nirschl 4/4's and 6/4's, along with a handmade Hirsbrunner, that have had texture and/or seams start to show up due to Magnetic Dent tools being used on them. I saw one of these seams appear first hand by a colleague that I know and respect in the repair field.

As a general rule, I won't use the magnets on these handmade instruments, but I don't see them anymore now that I am in the middle of nowhere like I am now.

The MDRS is a great, profit making tool for student and school instrument use. It has its uses in the professional field, but I will stick to better techniques until I can make sure that I'm not going to cause damage on tubas.

Chuck(G) · Post by **Chuck(G)** » Sat Jul 22, 2006 11:42 am

What those magnets will do a number on is the shadow mask in a CRT. It takes many many passes with a degausser to remove the residual magnetization that one of these things imparts.

In my experience, it's darned hard to damage even a floppy disk with a DC magnetic field from a permanent magnet that's not directly in contact with the medium. The degaussers that are used to erase magnetic media use very strong AC electromagnets--and even these have to be fairly close to the medium to do their job--and are gradually moved away, leaving the domains scrambled.

If you need to irretrievably dispose of information on a hard drive, the best way is to do so mechanically. For instance, toss the drive in a commercial-grade chipper. Next best is an industrial trash compactor...

pulseczar · Post by **pulseczar** » Sat Jul 22, 2006 11:45 am

Henry wrote:Ultimately anyone who is making a serious argument against potential injury from the dent balls ought to be someone who wants to outlaw the saale of soldering torches- and demanding licensing for those wishing to walk and chew gum at the same time.

I guess soldering torches don't sell well at Ferree's then.

http://www.ferreestools.com/magnetic_dent_tools.htm

prototypedenNIS · Post by **prototypedenNIS** » Sun Jul 23, 2006 11:44 am

Ferrees wrote:I personally don't know anyone who has used magnets to repair that has not been injured, nipped or more severe; including myself.

I have not.

So, ASTuba,
you're saying that this is a problem due to pre existing irregularities of the surface area on the inside of a handmade tuba?

Dan Schultz · Post by **Dan Schultz** » Sun Jul 23, 2006 12:53 pm

prototypedenNIS wrote:
Ferrees wrote:I personally don't know anyone who has used magnets to repair that has not been injured, nipped or more severe; including myself.
I have not.

So, ASTuba,
you're saying that this is a problem due to pre existing irregularities of the surface area on the inside of a handmade tuba?

Heck, I can answer that one! On many older tubas and some of the new ones that are made the 'old fashioned' way... by hand-hammering the bows instead of hydroforming... there are irregularities on the INSIDE of the bows from the hammering and/or brazing the seams on the inside. Mirafone is famous for not finishing the seams on their bows. When one tries to use the magnet and ball to smooth out the brass, whatever irregularity that is on the inside of the bow is transferred to the outside. Also, the use of magnets and balls on horns that are not clean can result in seeing the imprints of dirt and grit on the inside of the horn in the outside surface.

How much of problem this is depends on just how 'picky' you plan to be. A few marks that remain after rolling out a severe bash in a back bow seems to me to be a small price to pay over spending hundreds of dollars having a horn taken apart and refinshed afterwards. The magnetic dent removal systems have a definite place in my shop. I certainly wouldn't let let my ten-year-old grandson play with the magnets. But then again, I wouldn't let him play with my torches, either! In the hands of the ignorant or stupid any tool can be dangerous.

ASTuba · Post by **ASTuba** » Sun Jul 23, 2006 4:29 pm

prototypedenNIS wrote:
Ferrees wrote:I personally don't know anyone who has used magnets to repair that has not been injured, nipped or more severe; including myself.
I have not.

So, ASTuba,
you're saying that this is a problem due to pre existing irregularities of the surface area on the inside of a handmade tuba?

That's exactly what I'm saying.

prototypedenNIS · Post by **prototypedenNIS** » Sun Jul 23, 2006 9:06 pm

Ok, that clarifies. I appreciate the warning.

Also, for other notes, we don't do dentwork on a horn unless it's cleaned first (by us, using an ultrasonic cleaner).

Rick Denney · Post by **Rick Denney** » Mon Jul 24, 2006 2:08 am

prototypedenNIS wrote:Also, for other notes, we don't do dentwork on a horn unless it's cleaned first (by us, using an ultrasonic cleaner).

You guys have an ultrasonic cleaner a tuba will fit into? That's a big cleaner! I'll bet you need thee-phase power to run that puppy.

Rick "whose ultrasonic cleaner will hold a set of four valve pistons or maybe a mouthpiece" Denney

ASTuba · Post by **ASTuba** » Mon Jul 24, 2006 8:59 am

Rick Denney wrote:
prototypedenNIS wrote:Also, for other notes, we don't do dentwork on a horn unless it's cleaned first (by us, using an ultrasonic cleaner).
You guys have an ultrasonic cleaner a tuba will fit into? That's a big cleaner! I'll bet you need thee-phase power to run that puppy.

Rick "whose ultrasonic cleaner will hold a set of four valve pistons or maybe a mouthpiece" Denney

Rick,

The biggest one is 100 gallons that I have seen, and will fit most tubas. Your Holton, however, may not fit it exactly.

prototypedenNIS · Post by **prototypedenNIS** » Sun Jul 30, 2006 3:56 pm

Rick Denney wrote:
prototypedenNIS wrote:Also, for other notes, we don't do dentwork on a horn unless it's cleaned first (by us, using an ultrasonic cleaner).
You guys have an ultrasonic cleaner a tuba will fit into? That's a big cleaner! I'll bet you need thee-phase power to run that puppy.

Rick "whose ultrasonic cleaner will hold a set of four valve pistons or maybe a mouthpiece" Denney

I have heard that we have 90 gallons... pleanty of room for a YBB321, we've fit a Cerveny piggy in there. No dissassembly required

iiipopes · Post by **iiipopes** » Sun Jul 30, 2006 5:35 pm

My tech got one a few months ago as well. But for the $$ he wants for a dip, I think I'm going to defer that one awhile.

Kenton · Post by **Kenton** » Sun Jul 30, 2006 10:56 pm

Doesn't always work, but if I had your tuba, I'd try putting a dent barrel on a cable, and put a chaser barrel on behind it and see if I couldn't pop the dent out from the inside by letting the chaser barrel pound a bit on the first barrel.

prototypedenNIS · Post by **prototypedenNIS** » Mon Jul 31, 2006 11:30 am

that just might anger people more than using MDRS...

iiipopes · Post by **iiipopes** » Mon Jul 31, 2006 12:57 pm

Guys, this is turning into a really interesting intellectual/theoretical exercise -- but it's the size of a quarter! Let it go!

Lee Stofer · Post by **Lee Stofer** » Tue Aug 01, 2006 9:08 am

Wow, what a discussion! The Dent Eraser is not a toy, but it is a tool. When it first appeared on the market, I saw the potential for this tool, when the MDRS was not yet developed. Mr. Fedderly at Baltimore Brass and I have discussed this issue, and while it is a useful tool, it is not a replacement for any of our more traditional tools. There is a learning curve to this tool, like everything else in the shop. It is certainly more primitive than the MDRS System, which will most likely grace my new shop in Iowa within the next two months. Due to the fact that the same area on two identical-looking instruments can vary greatly in hardness, the force needed for magnetically removing a dent from one instrument may not be enough for another, or might be too much. Because of that element of risk, I will try to err on the conservative side The Dent Eraser system is available with a set-up that allows one, two, or three magnets to be used on the handle. With a moderate amount of practice, one is not likely to hurt any brass instrument with just one magnet. For some of the really bad school sousaphones where they simply could not afford the overhaul needed, I would use three magnets on the large body portions, with appropriate protection for the finish. With sufficient care, scratching can be held to an absolute minimum or avoided altogether. As just one of the many tools in the brass instrument repair shop, there are only certain situations where I use magnetic dent removal, but it is quite appropriate for certain situations.

Concerning the Quarter-sized indentation - if it bothers you sufficiently, it is worth having it removed. If the dent didn't bother you, you wouldn't have mentioned it on TubeNet. There is an almost-invisible, tiny little ding on my Rudi CC, and it will be gone before next rehearsal. Does it affect the playing at all? Of course not, but it bothers me.