Info on MDRS (Magnetic Dent Removal System)

[Wes Krygsman]

Hello Tubenet!

I am interested in picking up one of these dent removal tools with dent balls, but I want to know which of the 4 dent magnet handles would be most useful to a hobbyist repairman (really just de-denter) that can only afford one.

I am also interested in hearing about the magnet alternatives from magnets4less and the pluses and minuses of each. I have read previous posts about pinched fingers and such with the magnet alone, as well as chipping the finish on the magnet, but I am sure there are more success stories out there.

So which is best if I could only get one and why?

MDRS
2 flat magnets (1.5inch or 2 inch)
2 Curved magnets (1.5 inch, or 2 inch)

Thanks!

[ghmerrill]

When I got my 1924 Buescher Tuba, it had a number of both shallow and deep dents, both large and small. I bought a magnet off the web (I think on Dan Schultz's recommendation). It's an inch in diameter and about an inch and a half long. Don't remember exactly where I got it from. I believe it imposes a force of about 250 lbs. on a ball when used for de-denting.

I tried several different size balls, but ended up using one that's 2" in diameter. I think I got it off Ebay. If I were to into this in a big way, I'd get some larger ones as well. This ball is dull grey rather than shiny. So no chrome content, I think.

I don't use a handle with it but (I think following something Bloke may have suggested at some point), place the magnet in a sturdy and soft cloth and then hold it by hand with a fairly heavy leather work glove. You do need to be careful since if you're careless you can end up pinching a finger even with a good work glove on. I keep the magnet in a plastic container in a small cardboard box with a BIG warning sign on it, and on a set of shelves where I have other brass repair materials and tools -- fully out of the way in a little work corner of a room in the house. This is of some extra importance in our house since our oldest child (now 39) has a pacemaker/defib, and getting in range of a magnet like this would likely have some dramatic consequences. There is, of course, an inverse square law operating here, but a high degree of caution is in order.

I have been very happy with the results, and it was an interesting learning experience. The results are very far from professionally admirable, but I accomplished what I wanted, have what most people regard as a nice-looking old tuba, and learned a lot. There is substantial skill to be learned in order not to screw up, so practice slowly as you go and THINK about what you're doing at each step. Don't try to do too much. Also, magnetic dent balls are only good for tubing of fairly large diameter. So have reasonable expectations.

I removed virtually all of the large dents and flat spots, and the horn looks quite good at this point. The ones that haven't been totally removed are one or two that were in/under guard plates (and even those are improved), and one irritating one that was a deep linear groove that looks as though someone might at one point have hit it with an axe (but even this has been improved and will be more improved over time -- just elbow grease, but it's a bear). If I wanted to take the guards off and do things the right way, I could remove the remaining shallow dents there as well. But It's not worth the trouble. There were also a lot of little dents like you might get from banging it with a nail punch or maybe firing bird shot at it from a distance. I left those alone. They're part of the "character".

[Bacchanalia]

First things first--Save tons of money by doing this:

http://www.justin-young.net/wiki/var/up ... g_mdrs.pdf

I personally skipped the handle altogether and used a PVC 2" to 1-1/2" reducing adapter with threads on the small end. That gave me something of a "handle". Then I added a big eye ring in the cap (for attaching a slide hammer if necessary) and I can remove the cap and add more 1" diameter magnets to the back of the big magnet in the handle area if needed. Then there's a simple larger cap to cover the magnet when it's not in use, which helps to avoid unintended "sticks". What's not too obvious from my pictures below is the short piece of 2" PVC around the magnet itself, which only needed a thin layer of good ole 'Murican duct tape to keep it in there. Here's a couple of pics:

dent-removal-magnet.jpg

Following the instructions for most of the document, I purchased an even thicker piece of PTFE (teflon) from another supplier--if you buy this stuff, make sure it's the "etched" or "bondable" variety. If it's called "virgin", you don't want it. The etched stuff is chemically treated on one side to let things (like contact cement) bond to it. That being said, I don't think teflon is the best stuff to use. It's slick, but even with the double thickness stuff I bought, it's really easy to gouge. I've looked at a much cheaper solutions like this:

http://www.farmandfleet.com/products/71 ... iders.html

which may or may not be teflon, but sure is slick--and much more durable. The extra eighth or quarter inch will give you a nice rounded lip around the magnet too. If you use the spray furniture wax (which works really well), the material (ptfe vs. slider) isn't that important anyway.

As for the radiused versions--with this design, you can simply add the radiused steel slug to one end of the magnet and jut pop out the magnet and turn it around when you want that feature. Votaw Tool has been out of the larger one for quite awhile though. And FYI: when you're using the contact cement to attach the slugs to the magnets, they really don't want to stay in the center. You'll need to use a piece of the PVC pipe to "wrap around" the slug and the magnet, long enough for it to cure. Take it from me, your fingers aren't strong enough to fight these 2 x 2 magnets for long ;O)

And for magnet variety dent balls, you can get most of what you need on Ebay. Best sellers I've found (as of June '15) were http://stores.ebay.com/theballbaronsrealm/ & http://stores.ebay.com/toolsupply/ which I think are the same company. I also purchased stuff from these guys: http://www.craigballsales.com/ but I don't think they sell on the Bay.

Good luck with your adventure. And take the advice of the guys in here who tell you to watch those fingers. These magnets are not messin' around. They will hurt you bad, if you let them.

[PaulMaybery]

I built my own kit about 10 years ago from a rare earth magnet, some PVC plumbing parts, a bicycle handlebar grip and various sized steel mill balls from a Colorado silver mine. I do use a mylar drum head and a Folgers coffee container lid to keep from marring the finish. I think the pull on the magnet is roughly 350 lbs. Since I only have solid balls, the pull can be somewhat extreme and not the best for more delicate work. The 2 1/2 inch steel ball is particularly strenuous to maneuver. But it does a fine job. If I would do it over, I would probably purchase the real thing. But I really only needed it for smoothing out some rather gross sousaphones and bottom bows on tubas.

[Three Valves]

How will it do on my car??

[Dan Schultz]

How will it do on my car??

Forget it. Unless your car is made of non-ferrous materials.

[Three Valves]

That's a good point.

How does the magnet work with brass??

[PaulMaybery]

The magnet pulls a steel (ferrous) ball on the inside of the tubing and rolls out the dents. It does not work particularly well on small tubing such as tuba tuning slides. In that case the ball being nominally 1/2 to 3/4 of an inch does not create enough pull to smooth out the narrower slides which are considerably more rigid than the larger branches. It also needs quite a bit of experience in maneuvering. It is very easy to mar and distort the tubing.

[MackBrass]

My suggestion when purchasing the magnets is to buy one at a time. I've made a few of these and found that the stronger the earth magnet the better, 250 to 350 pounds. This sounds like a lot but keep in mind that a very small area is being used with a dent ball between 2 and 3 inches in diameter. Dont waste your time on smaller magnets that are half inch thick or less that 2 inches in diameter as they will not have the pulling strength needed.

Once i bought 2 magnets at the same time and when they packaged them they did not separate them enough. When unpacking them, they stuck together and while trying to pull them apart i destroyed them as they shattered from their own draw, and yes, my hand was between them. With the help of my wife we got them off leaving a nice piched and bloddy mess on my hand. My next purchase was a 2 inch diamete by 1.5 thick and only needed one. If you decide to use the pvc from a pluming section, bring the magnet with you for a good fit but be very carefull while walking around with it as they can be dangerous. The pvc works great and you can make a nice handle.

[Three Valves]

The magnet pulls a steel (ferrous) ball on the inside of the tubing and rolls out the dents. It does not work particularly well on small tubing such as tuba tuning slides. In that case the ball being nominally 1/2 to 3/4 of an inch does not create enough pull to smooth out the narrower slides which are considerably more rigid than the larger branches. It also needs quite a bit of experience in maneuvering. It is very easy to mar and distort the tubing.

Thanks, I can visualize that process now.

[Lee Stofer]

I have owned the MDRS system for about 10 years now. At the time I purchased it, I had to read and sign paperwork before I could purchase it, as this is not a toy, game or diversion. Serious, if not extreme caution is necessary when using rare earth magnets. Every ferrous tool on my bench is now magnetized, whether I wanted them to be or not, and there are warnings posted to keep the magnets away from people with electromagnetic devices, hard drives (will wipe out your hard drive if not careful), and cards with magnetic stripes. I slipped once last week while working on a very deep dent, and my left pinky is still recovering from a nasty blood blister. I would consider that you need to employ all of the caution that a professional would if you are going to get such a tool, including figuring out a safe place to store the magnets.

I would suggest even more caution if you decide that you must get a do-it-yourself set. I have used stackable magnets in the past, but it is possible to assemble a dangerous level of magnetic pull with that system.

I would say please, be careful, or just see someone who already has and is using the system.

[Bacchanalia]

This guy's video is helpful for understanding how to separate these magnets and demonstrates just how powerful they are. I don't know that I'd want to build the wooden gadget he's using, but it's good to see the concept in action.

http://youtu.be/ybY_wdQ5MSc