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Seized/rusted screws
This may be too basic, but this project has about forty opportunities to fail and I have already failed once. These screws hold a sealing strip, twenty feet long down each side of a 1976 GMC Motor home. They need to be removed so the dried out sealer material can replaced. The screws appear to be torx head #8 machine screws, the strips are aluminum and the screws are threaded into the aluminum framework of the coach. I found a thread that said to tap the head of the screw with a hammer to loosen/break loose the rust then "carefully" turn the screw back and forth. Well, that resulted in failure # 1. If they were door hinge screws I'd heat them with a torch and bang on them a bit, but aluminum scares me, a lot. No way of getting to the back-side or getting Kroil to the threads. Thinking about copper sheet to shield the aluminum and heat the screw heads with a torch. Any suggestions on how to remove these without messing up the aluminum? Any ideas on where to find similar screws?
Thanks for any help. P1010061.jpg P1010062.JPG
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Norm Henderson Last edited by Steve Hamilton; 03-01-2020 at 12:15 AM. |
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Norson,
You might have galvanic corrosion, which in my experience is almost never reversible. Steel screw vs Aluminum base material. If you were to cut the heads off of them all, would you have enough to grab with tools like channel locks or vise grips to remove the remailing studs? After you had the trim off at least you would be able to attack the studs in a few different ways, kroil, heat, tools, drilling out, etc. https://www.google.com/search?q=galv...hrome&ie=UTF-8 This will be a tough one, keep us posted, as we all learn from each others experiences. TX Mr fixit for the family Chris |
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Hi,
For airplanes we use an "Old Man screw removal tool" on a rivet gun. https://www.google.com/url?sa=t&sour...JK-opY_ejf285h The tapping action, combined with turning of the screw backs them out. To help prevent the screw driver tip from slipping we put valve grinding compound on the screw head. When heating the aluminum you can use a "black magic marker" and mark around the screw head. You can heat and watch that you don't burn off the marker as a poor man heat temp stick. Once the marker burns off, you have reached (or close to) the anneal temp. Hope it makes sense, Bill
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Bill Tromblay "A sign of a good machinist, is one who can fix his F$@& Ups" My mentor and friend, Gil Zietz Micro Metric Machine. |
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Eastwood sells a tool that uses a rivet gun to jar them loose. The screws probably had a reaction with different metals and welded themselves together.
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Eddie |
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I have had some luck using a hammer impact and penetrating oil. Don't hit the hammer impact hard and start by trying to tighten. One hit to tighten followed by one hit to loosen. Continue until it loosens. Add more penetrating once it starts to move. The problem is galvanic corrosion.
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Joe Hartson There is more than one way to go to town and they are all correct. |
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For a penetrating oil try:
Half acetone and half ATF. Shake hell out of it each time you use it. Apply and let soak several times over an hour or so. Real bad stuff I will apply a few times a day for 2-3 days. Works better then any product I ever purchased off the shelf.
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Dave Bradbury |
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https://www.wivco.com/store/p3/Shake-N-Break™.html American made
I have the largest electric soldering iron American Beauty makes, and have used it many times to heat screw heads, sometimes in conjuction with paraffin, to loosen them. Sometimes it's several tools used in series to be effective-
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Karl Heinz |
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Wow! And I thought it was a dumb question. Some great ideas. That soldering gun idea made me think a stud welder with a heating tip might be worth a try. Lot of things to try. Any more ideas???
Thanks
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Norm Henderson |
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Quote:
I read through the bunch, and - penetrant is my first application - but smokes when I go to heat - (atf+acetone 50/50 is a great mix, after 50 years of doing resto metalwork I have tried a Lot of methods and chemistry) impact and twisting - rivet guns and self-twisters are a great combo - I always tighten a bit first - I also have a 1960's air impact 1/2in gun w/very sensitive trigger and a Bunch of screw bits ... great tool for success in this area ... Heat .... 350W elect. solder iron...O/A torch .... induction w/spotwelder -briefly - helps in the end after nuttin' else quite does it + impact gun set on tap-tap-tap .... walks them out nice .... *** bolts, nuts, studs - also ... got a bucket of safely-extracted stumps - only lost to one in decades - left it rusted into the Ford 390 exhaust manifold and sold it with the '56 effie cabover flatbed ....
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Kent http://www.tinmantech.com "All it takes is a little practical experience to blow the he!! out of a perfectly good theory." --- Lloyd Rosenquist, charter member AWS, 1919. |
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My personal preference, which hasnt failed (well not yet anyway )
I clean head of screw with flapwheel, ie bare steel. I then hold washer around head of screw, nice snug fit, but keep just off the panel behind. I then weld screw to washer, if necessary, blip by blip, if that makes sense. Once Ive got a good blob of weld, I then keep building away from the panel. The heat runs back to free, the stand out weld can be gripped with vice grips. As suggested above, I tighten first, a little bit, just enough to break the dissimilar metal seizure. It does take a few attempts sometimes, initial washer to screw sometimes lets go. Patience is required, but Ive had some life altering saves. I also use this method to remove broken off studs that have sheared below the surface, typically exhaust manifold studs within motorcycle alloy heads.
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Richard "Everything is in the system, if it aint working, the system aint right" |
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