Original poster: Terry Fritz Hi All, Here's a fun subject I have been saving up for a rainy (light hail now) day! :-) I have (had) a beautiful John Freau 4x13 toroid... One dark day, I bumped it... It's edge fell an a AC supply wire and it got a little dent: :-(( http://216.160.168.190/TeslaCoils/Misc/dent.jpg I thought, at the time, I would just get another but the supplier has limited this edition of this family airloom =:O So I got to thinking of how to do the "bodywork" needed to remove such a dent. I think it is T-6061 aircraft aluminum (?). Seeing how they "fixed" a coworkers Honda that was "bumped" by a cement truck to like new condition, I figure miracles are possible. The two halves of the toroid are epoxied together and I could use the nasty chemicals at work to dissolve it, but that would be cheating. I know trumpets and other brass musical instrument often need such fixing but I think they rely on getting to the other side to push those dents out... I think this dent is far beyond the "dry ice" trick. My great idea is to use some dissolvable glue like super glue to "attach" a pulling rope or such to the dent and pull it out. light sanding with like 60 grit sand paper should smooth the rest. The dent does not affect the terminal's operation as the streamers ignore the concave area, but it is kind of an obnoxious reminder of my clumsyness and I always have to "explain" it... So, if a easy fix is available, it would be worthwhile but high risk solutions are not called for. Any ideas on this "new" subject are welcome and I know there are others out there who would also be interested ;-) With the recent big group buy of toroids there will be future (trust me) interest too ;-)) Cheers, Terry Original poster: "Travis Tabbal" Tesla list wrote: > Original poster: Terry Fritz > > > I have (had) a beautiful John Freau 4x13 toroid... One dark day, I bumped > it... It's edge fell an a AC supply wire and it got a little dent: :-(( > My great idea is to use some dissolvable glue like super glue to "attach" a > pulling rope or such to the dent and pull it out. light sanding with like > 60 grit sand paper should smooth the rest. Terry, many tools are available for auto body work that would probably work. I don't think super glue would hold your pull rope. That stuff has never held up to a beating for me. Most of the tools for cars involve drilling a small hole, something I think you would preffer to avoid. ;) On a car it's no big deal, just throw a little bondo on and sand. But bondo would not look too good on a toroid. ;) There is a device that may work, though I don't know the cost. It's basicly a spot welder that attaches a small pin to the dent. Then you use that to pull it out. Afterward just remove the pin and sand. Should be good as new. It's made for harder metals, but I think the Al you have should be able to take it. Travis Original poster: "Bert Pool" Terry, how about this? Think big capacitor bank. SCR, ignitron, or even spark gap switch. Small, heavy gauge coil. Place coil over dent. Fire switch. Bam! Multi-kilo joule magnetic pulse pops dent. I know we have shrunk quarters to a size smaller than a dime, so thet's more than enough energy to pop a mere dent. Never tried this on a toroid, but I think there is a good chance this might work. Bert ----- Original Message ----- From: "Tesla list" To: Sent: Friday, September 22, 2000 7:20 PM Subject: Toriod Dent Removal =:O > Original poster: Terry Fritz > > Hi All, > > Here's a fun subject I have been saving up for a rainy (light hail now) > day! :-) > > I have (had) a beautiful John Freau 4x13 toroid... One dark day, I bumped > it... It's edge fell an a AC supply wire and it got a little dent: :-(( > > http://216.160.168.190/TeslaCoils/Misc/dent.jpg > > I thought, at the time, I would just get another but the supplier has > limited this edition of this family airloom =:O So I got to thinking of > how to do the "bodywork" needed to remove such a dent. I think it is > T-6061 aircraft aluminum (?). Seeing how they "fixed" a coworkers Honda > that was "bumped" by a cement truck to like new condition, I figure > miracles are possible. The two halves of the toroid are epoxied together > and I could use the nasty chemicals at work to dissolve it, but that would > be cheating. I know trumpets and other brass musical instrument often need > such fixing but I think they rely on getting to the other side to push > those dents out... I think this dent is far beyond the "dry ice" trick. > My great idea is to use some dissolvable glue like super glue to "attach" a > pulling rope or such to the dent and pull it out. light sanding with like > 60 grit sand paper should smooth the rest. > > The dent does not affect the terminal's operation as the streamers ignore > the concave area, but it is kind of an obnoxious reminder of my clumsyness > and I always have to "explain" it... So, if a easy fix is available, it > would be worthwhile but high risk solutions are not called for. > > Any ideas on this "new" subject are welcome and I know there are others out > there who would also be interested ;-) With the recent big group buy of > toroids there will be future (trust me) interest too ;-)) > > Cheers, > > Terry > > > > Original poster: "Lau, Gary" I'm not sure what the "dry ice" trick is but perhaps H2O ice can be employed. Make a very small hole in the ID of the toroid and use it to fill the toroid with water with a syringe. Then place it in the freezer and let the expansion of the ice push out the dent. I'm guessing that after the dent it fixed, something else will have to give so the epoxied seam will split, but that can be easily repaired. The problem is that this technique may be a bit more difficult with a 24" x 6" toroid! Gary Lau Waltham, MA USA -----Original Message----- From: Tesla list [mailto:tesla@pupman.com] Sent: Friday, September 22, 2000 8:20 PM To: tesla@pupman.com Subject: Toriod Dent Removal =:O Original poster: Terry Fritz Hi All, Here's a fun subject I have been saving up for a rainy (light hail now) day! :-) I have (had) a beautiful John Freau 4x13 toroid... One dark day, I bumped it... It's edge fell an a AC supply wire and it got a little dent: :-(( http://216.160.168.190/TeslaCoils/Misc/dent.jpg I thought, at the time, I would just get another but the supplier has limited this edition of this family airloom =:O So I got to thinking of how to do the "bodywork" needed to remove such a dent. I think it is T-6061 aircraft aluminum (?). Seeing how they "fixed" a coworkers Honda that was "bumped" by a cement truck to like new condition, I figure miracles are possible. The two halves of the toroid are epoxied together and I could use the nasty chemicals at work to dissolve it, but that would be cheating. I know trumpets and other brass musical instrument often need such fixing but I think they rely on getting to the other side to push those dents out... I think this dent is far beyond the "dry ice" trick. My great idea is to use some dissolvable glue like super glue to "attach" a pulling rope or such to the dent and pull it out. light sanding with like 60 grit sand paper should smooth the rest. The dent does not affect the terminal's operation as the streamers ignore the concave area, but it is kind of an obnoxious reminder of my clumsyness and I always have to "explain" it... So, if a easy fix is available, it would be worthwhile but high risk solutions are not called for. Any ideas on this "new" subject are welcome and I know there are others out there who would also be interested ;-) With the recent big group buy of toroids there will be future (trust me) interest too ;-)) Cheers, Terry Original poster: Clearspring1@aol.com Hi Terry, What you have there appears to be a pretty "straight" dent (the toroid hit a corner or such?) in a compound curve. You want to return it to as original a condition as possible, meaning you need to pull the dent out differentially: more in the center than at the outer ends. One pull will not do this sort of thing, but you may be able to get close by pulling first in the very center of the dent, then pulling at a few more points between the center and the dent's ends. I have some doubts the glue trick will work -- hard to tell because I have no idea how thick the aluminum is. One technique the auto trade uses might be of help (don't flinch, now!): they drill a series of small holes (perhaps 5 to 7 very small holes here might do it) and pull the dent out with a screw captured by a slide hammer (in your case, a pair of pliers is enough). Then they grind down the "pulled-up" area where the screw went in, and fill the holes. Aluminum can, of course, be welded... but I would expect some distortion of the shape. Aluminum (T-6061 too, I assume...) can also be soldered -- any decent hardware store has the solder and flux. With some subsequent sanding I believe you would come as close to original as you can get. I would expect some minor color mismatch between the solder and the original material. Disassembling this toriod for repair may be a real bear due to the dent's location at the epoxied joint, which hs its own complex shape. I think it might be a nightmare to make those edges match... Luck! Michael Tandy Original poster: FutureT@aol.com In a message dated 9/22/00 6:38:21 PM Pacific Daylight Time, tesla@pupman.com writes: > Any ideas on this "new" subject are welcome and I know there are others out > there who would also be interested ;-) With the recent big group buy of > toroids there will be future (trust me) interest too ;-)) > > Cheers, > > Terry Terry, Sorry to hear about the accidental denting. The glue and pull method you mention sounds very good to me. If someone has a bad dent and needs to separate the toroid halves, one way to do it might be to just heat the edge with a propane torch while being careful not to melt the aluminum. I would think that the epoxy will burn up and let the halves separate, I never tried this though.. ho ho. Then the dents can be pressed out from the inside, the glue residue cleaned off, and the halves re-glued. John Freau Original poster: "Howden, Brian FOR:EX" This is not easy stuff to do but there are some amazing people out there. Try one of the egroup metal shapers groups or the rec metal work newsgroup. It takes way more skill than I have, but it can be done. There is a website out there run by "the timan" who beat a flat sheet of titanium into what looks like a shiny round christmas tree ornament with nothing but a hammer and welder. Rather than superglue, I suspect the recommendation will be for spot welding on little bits of al wire and grinding them off when done. The actual pulling is probably done with a slide hammer. If you do try, start at the edge of the bump and work in or you will stretch the metal. Stretching is much simpler than shrinking it. I would get a piece of scrap and practice a lot before trying it on the real thing. I am pretty sure T6061 is one of the ones that can take quite a temper so you might have to aneal it to get it soft enough to work. If it was spun, it might have work hardened. I suspect anybody talented to make one in the first place could give you excelent advice on what is needed to repair it. Brian Howden >>> I have (had) a beautiful John Freau 4x13 toroid... One dark day, I bumped it... It's edge fell an a AC supply wire and it got a little dent: :-(( http://216.160.168.190/TeslaCoils/Misc/dent.jpg ....... I know trumpets and other brass musical instrument often need such fixing but I think they rely on getting to the other side to push those dents out... I think this dent is far beyond the "dry ice" trick. My great idea is to use some dissolvable glue like super glue to "attach" a pulling rope or such to the dent and pull it out. light sanding with like 60 grit sand paper should smooth the rest. >>>>>> Original poster: "Thomas McGahee" To remove the dent you might want to try this method that I have used successfully on metal spheres. It should easily work on toroids, too: On the INSIDE of the toroid drill a *small* hole. Using a glue syringe (or any other suitable method), fill the toroid as full of water as you can. Place the toroid in a freezer with the dent at the BOTTOM and the hole near the top. Stand the toroid on-end. Do NOT lay it down flat, as then the water will leak out of the hole. When the water freezes it will expand, and the internal pressure should pop out the dent. Like I said before, I have done this with spheres but not toroids, but I see no reason why it shouldn't work also with toroids. You might want to monitor the freezing process so you can remove the toroid once the expansion process has occured. Now, you may have to repeat the process more than once, as the amount of expansion will only move the aluminum/copper a certain distance each time. Remove as much water as you can by draining. To get the remaining water out you can use one of several methods: 1) Turn the toroid so the hole is at the bottom. Insert a syringe tip that is *long* and suck out the water. Since you may have trouble finding a *long* syringe tip, try stripping a foot of insulation off of something like a #21 piece of wire and using that as a sort of small diameter straw. 2) Turn the toroid so the hole is at the bottom. Take a two foot length of kite string or other absorbent string/rope and feed all but the last six inches of string into the hole. The string will act as a wick, and the water inside the toroid will come up the string and will then be able to evaporate. 3) For those who want instant gratification, turn the toroid so the hole is on the bottom. GENTLY heat the bottom of the toroid so that the remaining water is turned to steam. Most of the steam vapor will exit out the hole. Some will condense on the inside. You can safely ignore the small remaining amount of moisture. Do not over-heat the aluminum or you may damage the toroid. When all done, you can safely leave the hole as it is, since it will have no adverse affects on the toroids performance. You can also plug it up with any of the products used to repair car bodies. I recommended putting the hole along the inside of the toroid because it is easier to "hide" later. You could also make the hole somewhere along the *outer* rim if you want. This would make water removal MUCH easier, but at the small expense of a hole that is more visible Use any of these methods at your own risk. Fr. Tom McGahee ----- Original Message ----- From: Tesla list To: Sent: Friday, September 22, 2000 8:20 PM Subject: Toriod Dent Removal =:O > Original poster: Terry Fritz > > Hi All, > > Here's a fun subject I have been saving up for a rainy (light hail now) > day! :-) > > I have (had) a beautiful John Freau 4x13 toroid... One dark day, I bumped > it... It's edge fell an a AC supply wire and it got a little dent: :-(( > > http://216.160.168.190/TeslaCoils/Misc/dent.jpg > > I thought, at the time, I would just get another but the supplier has > limited this edition of this family airloom =:O So I got to thinking of > how to do the "bodywork" needed to remove such a dent. I think it is > T-6061 aircraft aluminum (?). Seeing how they "fixed" a coworkers Honda > that was "bumped" by a cement truck to like new condition, I figure > miracles are possible. The two halves of the toroid are epoxied together > and I could use the nasty chemicals at work to dissolve it, but that would > be cheating. I know trumpets and other brass musical instrument often need > such fixing but I think they rely on getting to the other side to push > those dents out... I think this dent is far beyond the "dry ice" trick. > My great idea is to use some dissolvable glue like super glue to "attach" a > pulling rope or such to the dent and pull it out. light sanding with like > 60 grit sand paper should smooth the rest. > > The dent does not affect the terminal's operation as the streamers ignore > the concave area, but it is kind of an obnoxious reminder of my clumsyness > and I always have to "explain" it... So, if a easy fix is available, it > would be worthwhile but high risk solutions are not called for. > > Any ideas on this "new" subject are welcome and I know there are others out > there who would also be interested ;-) With the recent big group buy of > toroids there will be future (trust me) interest too ;-)) > > Cheers, > > Terry > > > Original poster: "Metlicka Marc" terry, what you have there is one of the hardest dents there are to pull out, figures right? because the "crease" is long and straight, the relieving of the stress points is almost impossible to get. the only way i can see to relieve this stress is to either grind or file the one edge of the dent until a crack or gap is instilled into one side, then a couple holes are drilled in the bottom line of the crease and aircraft quality pop rivets put into the holes, you will have to visualize where the best distribution of force that will pull the crease up evenly will be. then use two vice grips and a helper to hold the toroid, pull evenly to bring the crease back into position. don't worry about the gap you make with the file, the metal has stretched when the crease was made. by putting pressure on the rivets individually, pulling out and side to side you should be able to position the metal into some assemblelance of a curve but, try to leave the metal a little bellow the plane of the surrounding metal. when all is back to some resemblance of the original shape, take the topload to a good fab shop, one that has experience with welding aluminum, make sure you tell them you want the gap and repaired area filled above the plane of the topload surface and what grade of aluminum it is. after they fill it, use a flat file, fine, and dunk the file in kerosene often, file into a general shape and curve. then using wet or dry sand paper soaked in kerosene, wet sand into final shape. try different grits as you get close to final shape to match the finish and try different density sanding foam blocks for backing of the grit that matches finish. as looking at your fine cabinetry work in your projects and your house (i don't only look at the coils in your pics) i think you can match the finish nicely? kerosene sounds strange for a lubricant but check a machinery handbook if you don't believe me? you could let a good fab shop do all of the work, but it will probably cost more then the toroid? you could probably weld it up yourself, but i would leave the reliability to the professionals. another option is to find or take it to the airport, talk to the guys that repair the skin on airplanes, but i bet they suggest the same procedures as i. good luck and it will be interesting to see what others suggest? marc Original poster: "Metlicka Marc" well after my post on what i thought was a good solution, i called a friend of mine that DID work on aircraft skin, on the USS forestall. i sent him the pic of the toroid and my suggestion, although he said that the suggestion was sound, there is an easier way. he suggested getting a small sheet of a close match aluminum grade, then using a piece of poster board a little larger then the dent, soak it in water, then form it to shape on a section of the toroid that is undamaged, let it dry on the toroid. then he suggested trimming the cardboard to a size that just fits into the dent, riding on the edges of the dent at about the same height or a little above, form your square of aluminum too basically the same curve as the toroid by shaping it to an undamaged section. using your cardboard pattern trim, file, grind the patch to just fit into the dent or a tad above. have it welded in place, then file the seams using kerosene as lube. he also said that submerged welding would be best, but make sure they understand that no liquid should be left in the void after done. i would have just forwarded his mail but, he has a very colorful way of talking and i don't think terry would have appreciated his comments as to how the dent got there in the first place? i don't think you have ten thumbs? it's your call but i have seen some great damage done too things that freeze, i would think the epoxy bond would fail far sooner then the dent would pop? also the metal in the dent has stretched so just pulling it will not bring it back without relieving the stress? well this man has said, his words" you aint seen a dent until you see what a 2 pound seagull can do to the leading edge of an A6" so all is not lost. he said send it to him and you won't even know a dent was there, but if you dent his toroid after that he'll fly out to Colorado and dent (something), must be a military thing? marc Original poster: "Kevin D" Terry, you could tap a 1/4-1/2" NPT hole on the inside diameter of the toroid and then add a hose barb fitting and then connect it up to a air compessor and slowly pressurize the toroid until the dent pops out,as long as the pressure needed to pop the dent does not exeed the pressure that the epoxy seen will burst is should work...I think. good luck, Kevin D. Original poster: "Bert Hickman" Bert and Terry, Unfortunately, applying a single pulse to a coil will actually tend to repel the metal away from the coil (Lenz's Law and all...). However, there is indeed a "paintless" dent removal process that's used for fixing airplanes that have been damaged by hailstones that uses a similar principle. In order to "pull" out the dent, two pulses are used. The first "slower" pulse is applied to a coil in order to establish a circulating eddy-current in the metal containing the dent underneath the coil. A second (larger/faster) pulse is then applied to the coil using opposite polarity. The effect is to attract the metal to the coil and thus "pull" the dent out of the metal. Check out the following for a high level explanation: http://popularmechanics.com/popmech/sci/tech/9508TUAVWM.html Further details on this/similar techniques can be found by checking patents 5,046,345, and 3,998,081. -- Bert -- Tesla list wrote: > > Original poster: "Bert Pool" > > Terry, how about this? Think big capacitor bank. SCR, ignitron, or even > spark gap switch. Small, heavy gauge coil. Place coil over dent. Fire > switch. Bam! Multi-kilo joule magnetic pulse pops dent. I know we have > shrunk quarters to a size smaller than a dime, so thet's more than enough > energy to pop a mere dent. Never tried this on a toroid, but I think there > is a good chance this might work. > Bert > > ----- Original Message ----- > From: "Tesla list" > To: > Sent: Friday, September 22, 2000 7:20 PM > Subject: Toriod Dent Removal =:O > > > Original poster: Terry Fritz > > > > Hi All, > > > > Here's a fun subject I have been saving up for a rainy (light hail now) > > day! :-) > > > > I have (had) a beautiful John Freau 4x13 toroid... One dark day, I bumped > > it... It's edge fell an a AC supply wire and it got a little dent: :-(( > > > > http://216.160.168.190/TeslaCoils/Misc/dent.jpg > > > > I thought, at the time, I would just get another but the supplier has > > limited this edition of this family airloom =:O So I got to thinking of > > how to do the "bodywork" needed to remove such a dent. I think it is > > T-6061 aircraft aluminum (?). Seeing how they "fixed" a coworkers Honda > > that was "bumped" by a cement truck to like new condition, I figure > > miracles are possible. The two halves of the toroid are epoxied together > > and I could use the nasty chemicals at work to dissolve it, but that would > > be cheating. I know trumpets and other brass musical instrument often > need > > such fixing but I think they rely on getting to the other side to push > > those dents out... I think this dent is far beyond the "dry ice" trick. > > My great idea is to use some dissolvable glue like super glue to "attach" > a > > pulling rope or such to the dent and pull it out. light sanding with like > > 60 grit sand paper should smooth the rest. > > > > The dent does not affect the terminal's operation as the streamers ignore > > the concave area, but it is kind of an obnoxious reminder of my clumsyness > > and I always have to "explain" it... So, if a easy fix is available, it > > would be worthwhile but high risk solutions are not called for. > > > > Any ideas on this "new" subject are welcome and I know there are others > out > > there who would also be interested ;-) With the recent big group buy of > > toroids there will be future (trust me) interest too ;-)) > > > > Cheers, > > > > Terry > > > > > > > > Original poster: BillEaver@aol.com Hi Terry I am very entertained at all the ways that you can fix-a-dent! Since I've build aircraft for 19 years (747s now) I can put in my . 02 cents. Not that we actually do those kind of things where I work! If this toriod was mine I would clean the dent with the abrade method and fill it with Aluminum putty, and grind away what is not even with the rest of the toriod. You could use one of those cheap shape duplicators you find at the $5 sale box at K-mart. OR get a "draw Cleco" from your friendly aircraft worker and drill out the dent, (read riddle it with holes) temporarily install the Cleco and wiggle it back and forth choosing the hole that starts in the center of the dent, working your way to the outside of the drilled holes. Yank this mess out until its close to the original shape and fill with Aluminum putty, grind smooth to a comparable finish. End of dent. Good luck. Denis Despins KC6TRW Original poster: Terry Fritz Hi Bill, I was thinking of this too. The putty will have a grayish appearance which would have been pretty noticeable on the original dent. But If I can pull it out mostly, such a filler could probably fill the rough areas without being obvious. Super glue seems to stick very well so drilling holes is not needed here. I ran out of glue and acetone tonight but I think it will all work out. This toroid gets heavy use and I know if I spend too darn much time and effort on this, the first thing that will happen is I'll dent it again (one of Murphy's laws ;-)) However, if such dents can be removed reasonably easily by anyone, coiling will have another little trick! So far I have only spent about 15 minutes actually working the dent (and many hours thinking about how to work it ;-)) and it is vastly better. I think with a little experimentation, a reasonably good method can be developed. If it is not obvious, I am really far more concerned with the "science" behind toroid dent repair than with this particular little dent. I suppose if I fix it, I will have to put a bunch more dents in it to really test out the methods ;-))) Ha, ha... Ok, I guess I am not that far gone yet!! Cheers, Terry At 08:52 PM 9/23/2000 -0400, you wrote: >Hi Terry >I am very entertained at all the ways that you can fix-a-dent! >Since I've build aircraft for 19 years (747s now) I can put in my >. 02 cents. Not that we actually do those kind of things where I >work! If this toriod was mine I would clean the dent with the abrade >method and fill it with Aluminum putty, and grind away what is not >even with the rest of the toriod. You could use one of those cheap >shape duplicators you find at the $5 sale box at K-mart. OR get a >"draw Cleco" from your friendly aircraft worker and drill out the dent, >(read riddle it with holes) temporarily install the Cleco and wiggle it >back and forth choosing the hole that starts in the center of the dent, >working your way to the outside of the drilled holes. Yank this mess >out until its close to the original shape and fill with Aluminum putty, >grind smooth to a comparable finish. End of dent. Good luck. >Denis Despins >KC6TRW > Original poster: "Jon Rosenstiel" Terry, Can you drill a hole on the inside of the toroid opposite the dent that a smallish, (1/4" to 3/8"), wood dowel can fit through and push the dent out? In your photo I can't really tell if that is feasible. Or would that hole just create another eyesore? If you could get to the inside of the dent your project would be cake! Well, maybe not cake, but at least muffin! Jon ----- Original Message ----- Subject: Toriod Dent Removal =:O > Original poster: Terry Fritz > > Hi All, > > Here's a fun subject I have been saving up for a rainy (light hail now) > day! :-) > > I have (had) a beautiful John Freau 4x13 toroid... One dark day, I bumped > it... It's edge fell an a AC supply wire and it got a little dent: :-(( > > http://216.160.168.190/TeslaCoils/Misc/dent.jpg > > I thought, at the time, I would just get another but the supplier has > limited this edition of this family airloom =:O So I got to thinking of > how to do the "bodywork" needed to remove such a dent. I think it is > T-6061 aircraft aluminum (?). Seeing how they "fixed" a coworkers Honda > that was "bumped" by a cement truck to like new condition, I figure > miracles are possible. The two halves of the toroid are epoxied together > and I could use the nasty chemicals at work to dissolve it, but that would > be cheating. I know trumpets and other brass musical instrument often need > such fixing but I think they rely on getting to the other side to push > those dents out... I think this dent is far beyond the "dry ice" trick. > My great idea is to use some dissolvable glue like super glue to "attach" a > pulling rope or such to the dent and pull it out. light sanding with like > 60 grit sand paper should smooth the rest. > > The dent does not affect the terminal's operation as the streamers ignore > the concave area, but it is kind of an obnoxious reminder of my clumsyness > and I always have to "explain" it... So, if a easy fix is available, it > would be worthwhile but high risk solutions are not called for. > > Any ideas on this "new" subject are welcome and I know there are others out > there who would also be interested ;-) With the recent big group buy of > toroids there will be future (trust me) interest too ;-)) > > Cheers, > > Terry > > > Original poster: "Herwig Roscher" Terry Fritz wrote to the list: >how to do the "bodywork" needed to remove such a dent. Terry, Probably this is not the solution you are looking for, but why don't you fill the bump with an aluminum/glue-mixture and sand it? Regards, Herwig Original poster: "Sarah Thompson" If you can get the halves of the toroid apart, something I saw recently might help. My partner's brother is a brass and woodwind instrument repairer, for whom the removal of dents from metal tubes (which have owners very attached to the invisible removal of such dents!) is something of a stock-in-trade. This would seem to be a logically similar situation to yours... :) The way instrument repairers traditionally do it is with a set of size-graded metal spheres. The idea is that you use a sphere that only just slides along the tube. All the spheres have a tapped hole in them, so you screw a handle into the hole, and then use it a bit like a hammer to knock out the dent from the inside. The results are usually perfect, to the extent that you can't tell that a dent was ever there, and best of all, so long as you use the right sized sphere, the technique is pretty much idiot-proof. You'll need a pretty big sphere, but that shouldn't necessarily rule out this technique. I hope this helps, Sarah Original poster: FutureT@aol.com Terry, all, I'd added more details (below) to the dent removal method. > > Terry, > > Sorry to hear about the accidental denting. If someone has > a bad dent and needs to separate the toroid halves, one way to > do it might be to just heat the edge with a propane torch while > being careful not to melt the aluminum. I would think that the > epoxy will burn up and let the halves separate, I never tried this > though.. ho ho. Then the dents can be pressed out from the > inside, the glue residue cleaned off, and the halves re-glued. When pressing a dent out of metal, the dent must be removed in the opposite way that it occured. What I mean is that since the dent started at the center of the dent, the edges must be pushed out first. The tool that is used to push out the dent must be smooth and rounded at the end with a rather large radius. Something like the rounded end of a ball peen hammer, or maybe a piece of rounded hardwood. Sometimes slight tapping is needed rather than simple pushing, if you can't get enough force by simply pushing.... but the pushing tends to give a smoother result. To begin the dent removal after the halves are separated, place the toroid against a large smooth hardwood surface with the dent against the hardwood. But don't put the dent flat onto the wood, rather put just the edge of the dent onto the wood such that the undented part is tangent to the wood. This does two things; it supports the "edge" of the dent, and it allows a space for the dent to pressed out. Once the toroid shell is held in this position by hand, use the ball peen hammer (held by the head) to press against the dent (closest to the undented area... not at the center of dent), so that it is pressed out slightly in that spot. Then move the tool to the side a little, and press another area. Keep moving the tool 'round and 'round the dent moving towards the center gradually, while shifting the toroid so the good edge is always supported against the hardwood support backing. When you get to the center, the crease will be just about gone automatically, but a little pressing there will remove any crease that is left. I should mention, that sometimes pressing at the center first is OK, but it depends on the dent and the situation, etc. At this point, inspect it all carefully. If any part of the dent protrudes outward too much, simply coat a flat hammer with a piece of masking tape and tap those spots down carefully until perfect flatness is achieved. The masking tape on the hammer will prevent marring the toroid surface finish. If this is all done carefully, a very good result can be obtained, without any sanding or ruining of the surface. Then the toroid can be glued back together. Another method that is often helpful to complete the job, is to hold the ball peen hammer behind where the dent was, and tap the edge (outline) of the dent with the flat hammer from the outside of the dent, to remove any possible raised "ring" around the dent. This is needed only if such a ring remains of course. All tapping should be done softly, with only enough force to gradually shape the metal, hard tapping will create new dents. But before doing any of the above, the method can be practiced. To do this, find an old thin aluminum cooking collender or pot or other curved aluminum object, and whack it against something to make a dent similar to the toroid dent. Now you can practice the methods above, until skill is developed in pushing out the dent. Many dents can be made sequencially in the object, and each one practiced upon until satisfactory results are obtained. Still another approach which does not require opening the toroid, is to drill a 1/4" hole near the inner central web, so that a long thin (1/4" dia) metal rod can be inserted into the toroid so that it reaches the dent, and this rod can be used to press out the dent gradually as described above. The rod can be tapped upon to aid the process, but there's a danger that the rod will create new dents, so it has to be done delicately. The hole will need to be drilled in the correct spot so the dent can be properly aimed towards. After the dent is pressed out, the rod can be held against the back of the dent, and a flat hammer used on the outer surface to flatten any remaining high spots. Happy metalworking, John Freau > > John Freau Original poster: "Jim Lux" I ran out of glue and acetone tonight but I > think it will all work out. The solvent for most "super glue" (cyanoacrylates) is nitromethane... You can either buy it a few ounces at a time as "debonder", or a gallon at a time as a component for model airplane fuel, or in drums as racing fuel or an explosive. That way, after you clean the surface (with MEK or acetone) , attach your pin, pull it, then need to get the pin off, you can just dissolve the glue, rather than fooling with sanding/grinding,etc. Original poster: "S. Gaeta" I love this approach!!!!! Even if it doesn't work, it would be so much fun to try it, although I think what will happen is that the opposing fields would only make the dent even bigger. If you have totally given up on the torroid I would rest it on a teflon platform tilted slightly upwards while performing this experiment outdoors. Make sure you have a bright spotlight, a video camera, and plenty of witnesses that can't see what you are doing, but will see the results! and uh, prepare to duck when you throw the switch! Then prepare to rake in the thousands when you sell the book! I am sure that an intelligent and creative person like you can come up a darned good abduction story too! But please remember to give a nice cut of the profit to Bert for the idea! I'm sorry, I laughed so hard that I just couldn't resist sharing it. Cheers, Sue ----- Original Message ----- From: "Tesla list" <tesla@pupman.com> To: <tesla@pupman.com> Sent: Saturday, September 23, 2000 12:54 PM Subject: Re: Toriod Dent Removal =:O > Original poster: "Bert Pool" <bertpool@ticnet.com> > > Terry, how about this? Think big capacitor bank. SCR, ignitron, or even > spark gap switch. Small, heavy gauge coil. Place coil over dent. Fire > switch. Bam! Multi-kilo joule magnetic pulse pops dent. I know we have > shrunk quarters to a size smaller than a dime, so thet's more than enough > energy to pop a mere dent. Never tried this on a toroid, but I think there > is a good chance this might work. > Bert > > ----- Original Message ----- > From: "Tesla list" <tesla@pupman.com> > To: <tesla@pupman.com> > Sent: Friday, September 22, 2000 7:20 PM > Subject: Toriod Dent Removal =:O > > > > Original poster: Terry Fritz <twftesla@uswest.net> > > > > Hi All, > > > > Here's a fun subject I have been saving up for a rainy (light hail now) > > day! :-) > > > > I have (had) a beautiful John Freau 4x13 toroid... One dark day, I bumped > > it... It's edge fell an a AC supply wire and it got a little dent: :-(( > > > > http://216.160.168.190/Tesl aCoils/Misc/dent.jpg > > > > I thought, at the time, I would just get another but the supplier has > > limited this edition of this family airloom =:O So I got to thinking of > > how to do the "bodywork" needed to remove such a dent. I think it is > > T-6061 aircraft aluminum (?). Seeing how they "fixed" a coworkers Honda > > that was "bumped" by a cement truck to like new condition, I figure > > miracles are possible. The two halves of the toroid are epoxied together > > and I could use the nasty chemicals at work to dissolve it, but that would > > be cheating. I know trumpets and other brass musical instrument often > need > > such fixing but I think they rely on getting to the other side to push > > those dents out... I think this dent is far beyond the "dry ice" trick. > > My great idea is to use some dissolvable glue like super glue to "attach" > a > > pulling rope or such to the dent and pull it out. light sanding with like > > 60 grit sand paper should smooth the rest. > > > > The dent does not affect the terminal's operation as the streamers ignore > > the concave area, but it is kind of an obnoxious reminder of my clumsyness > > and I always have to "explain" it... So, if a easy fix is available, it > > would be worthwhile but high risk solutions are not called for. > > > > Any ideas on this "new" subject are welcome and I know there are others > out > > there who would also be interested ;-) With the recent big group buy of > > toroids there will be future (trust me) interest too ;-)) > > > > Cheers, > > > > Terry > > > > > > > > > > > Original poster: "davep" My first thought was the air pressure trick. This is a standard technique in popping out motorcycle fuel tanks and i myself have done it, with some success. However, it, and the freezing technique, are. essentially, uncontrolled. That is, the forces can go anywhere. Some folks have seriously mangled m/c tanks with high pressure air. (I used a hand pump... even so some things bulged that shouldn't have...) My next thought was the 'fill it', either by plating over, or conductive filler. I see some support for that, also... The 'classic' autobody approch, last i knew, was to drill holes, put in sheet metal screws and 'pull' usually via a sliding weight hammer. When back (more or less) in shape, grind and fill with compound. An older technique was fill with lead (really) to original contour, the lead being 'soldered' in. Not Sure if this would be applicable to Al, certainly not directly. Welding in a piece to orignal contour (as proposed previously) seems most 'solid', requires grinding to contour/smooth. best dwp Original poster: Aric_C_Rothman@email.whirlpool.com On the subject of "filling it in," I've seen on the shelf of the local welding shop a product called "Lab Metal." It's a one-part paste that sets up in air to a light weight metallic mass. It's probably mostly aluminum. It can be machined once it is fully cured. Aric ______________________________ Reply Separator _________________________________ Subject: Re: Toriod Dent Removal =:O Author: "Tesla list" at INTERNET Date: 9/25/00 7:42 PM Original poster: "davep" My first thought was the air pressure trick. This is a standard technique in popping out motorcycle fuel tanks and i myself have done it, with some success. However, it, and the freezing technique, are. essentially, uncontrolled. That is, the forces can go anywhere. Some folks have seriously mangled m/c tanks with high pressure air. (I used a hand pump... even so some things bulged that shouldn't have...) My next thought was the 'fill it', either by plating over, or conductive filler. I see some support for that, also... The 'classic' autobody approch, last i knew, was to drill holes, put in sheet metal screws and 'pull' usually via a sliding weight hammer. When back (more or less) in shape, grind and fill with compound. An older technique was fill with lead (really) to original contour, the lead being 'soldered' in. Not Sure if this would be applicable to Al, certainly not directly. Welding in a piece to orignal contour (as proposed previously) seems most 'solid', requires grinding to contour/smooth. best dwp Original poster: Clearspring1@aol.com All, Indeed, as Aric mentions, the product Lab-Metal is described by the manufacturer as being an aluminum-filled, one-part repair putty. On visiting the manufacturer's website (http://www.alvinproducts.com/lab-metal.htm) I find the following Most Interesting Statement: "Lab-metal may be thinned to paint consistency with Lab-solvent and brushed or sprayed on practically any surface to provide a rustproof, water resistant, hard metal finish." Now let's ponder those foam toroids one more time... Comments? Regards, Michael Tandy > On the subject of "filling it in," I've seen on the shelf of the > local welding shop a product called "Lab Metal." It's a one-part > paste that sets up in air to a light weight metallic mass. It's > probably mostly aluminum. It can be machined once it is fully cured. > > Aric > Original poster: Terry Fritz Neat! I glued straps to the dent and pulled "really hard"! But pulling is no longer effective (or I have to eat more Wheaties...) I got some aluminum glue stuff (Victor aluminum repair) at the auto store but it's epoxy content was really high and it looks more like a gray insulator. The label saying "seals, fills, and bonds worn and 'rusted' aluminum..." did not impress me ;-)) I have worked with all kings of aluminum and silver filled epoxies but this lab-metal stuff sounds neat. If anyone has any let me know or I can look for it locally. A toroid body filler would be great! To answer Alan... I think 300kV will remove most "insulative" properties of such stuff but it may tend to burn due to the power dissipated in the resistance there is in these insulators filled with aluminum. Much to study here... Perhaps a "custom" filler would work too... Mixing aluminum powder with glue is not rocket science, but getting it to be "just right" is... Cheers, Terry At 11:33 AM 9/26/2000 -0400, you wrote: >All, > >Indeed, as Aric mentions, the product Lab-Metal is described by the >manufacturer as being an aluminum-filled, one-part repair putty. > >On visiting the manufacturer's website >(http://www.alvinproducts.com/lab-metal.htm) I find the following Most >Interesting Statement: > >"Lab-metal may be thinned to paint consistency with Lab-solvent and brushed >or sprayed on practically any surface to provide a rustproof, water >resistant, hard metal finish." > >Now let's ponder those foam toroids one more time... > >Comments? > > >Regards, > >Michael Tandy > >> On the subject of "filling it in," I've seen on the shelf of the >> local welding shop a product called "Lab Metal." It's a one-part >> paste that sets up in air to a light weight metallic mass. It's >> probably mostly aluminum. It can be machined once it is fully cured. >> >> Aric >> > Original poster: "Jim Lux" Interesting idea here... why not get aluminum powder (as a pigment from most big paint stores, as well as craft stores) and mix it with cyanoacrylate as a binder. Get a real runny CA. You'll probably need to do a bunch of passes to build it up. Another approach would be to get aluminum powder and mix it with powdered plastic and then gently heat it with a heat gun until the powdered plastic melts.. Sort of the "sintering" idea... it works for those Stereolithography machines. ---------- > From: Tesla list > To: tesla@pupman.com > Subject: Re: Re[2]: Toriod Dent Removal =:O > Date: Tuesday, September 26, 2000 6:27 PM > > Original poster: Terry Fritz > > Neat! > > I glued straps to the dent and pulled "really hard"! But pulling is no > longer effective (or I have to eat more Wheaties...) > > I got some aluminum glue stuff (Victor aluminum repair) at the auto store > but it's epoxy content was really high and it looks more like a gray > insulator. The label saying "seals, fills, and bonds worn and 'rusted' > aluminum..." did not impress me ;-)) > > I have worked with all kings of aluminum and silver filled epoxies but > this lab-metal stuff sounds neat. If anyone has any let me know or I can > look for it locally. A toroid body filler would be great! > > To answer Alan... I think 300kV will remove most "insulative" properties > of such stuff but it may tend to burn due to the power dissipated in the > resistance there is in these insulators filled with aluminum. Much to > study here... Perhaps a "custom" filler would work too... Mixing aluminum > powder with glue is not rocket science, but getting it to be "just right" is... > > Cheers, > > Terry > > > > At 11:33 AM 9/26/2000 -0400, you wrote: > >All, > > > >Indeed, as Aric mentions, the product Lab-Metal is described by the > >manufacturer as being an aluminum-filled, one-part repair putty. > > > >On visiting the manufacturer's website > >(http://www.alvinproducts.com/lab-metal.htm) I find the following Most > >Interesting Statement: > > > >"Lab-metal may be thinned to paint consistency with Lab-solvent and brushed > >or sprayed on practically any surface to provide a rustproof, water > >resistant, hard metal finish." > > > >Now let's ponder those foam toroids one more time... > > > >Comments? > > > > > >Regards, > > > >Michael Tandy > > > >> On the subject of "filling it in," I've seen on the shelf of the > >> local welding shop a product called "Lab Metal." It's a one-part > >> paste that sets up in air to a light weight metallic mass. It's > >> probably mostly aluminum. It can be machined once it is fully cured. > >> > >> Aric > >> > > > > Original poster: "Kelly & Phillipa Williams" Hello all, This is certainly a little late, I hope not too late? (I've been on holiday for two weeks, came back to 600 something Tesla List emails ;) > > Original poster: Terry Fritz > > > > > > I have (had) a beautiful John Freau 4x13 toroid... One dark day, I bumped > > it... It's edge fell an a AC supply wire and it got a little dent: :-(( > > > My great idea is to use some dissolvable glue like super glue to "attach" a > > pulling rope or such to the dent and pull it out. light sanding with like > > 60 grit sand paper should smooth the rest. > There is a device that may work, though I don't know the cost. It's basicly a > spot welder that attaches a small pin to the dent. Then you use that to pull it > out. Afterward just remove the pin and sand. Should be good as new. It's made > for harder metals, but I think the Al you have should be able to take it. > > Travis I think that is a good way to fix it. I a brass instrument, and all brass instruments have very thin tubes and bells made of high-copper brass. This is fairly soft and easy to dent. If this happens you sent it away to the repair man and he solders a wire to the metal and pulls out the dent, then desolders the wire. It comes out like new. (and you can really tell) I don't think the process is overly expensive. My 2 cents, Alan Williams