Heating rusted / seized nuts and studs?
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  1. #1
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    Every so often I find myself thinking that a Hot Wrench needs to find its way into my toolbox, most often to help break a rusted, seized, or otherwise stuck nut loose, but sometimes for loosening a scrap bearing from a shaft or housing.

    I know an oxy-fuel torch with suitcase tanks will do what I want for a reasonable price, but taking care of tanks, regulators, and hoses is very high maintenance for the use I'll get out of it. An old-fashion Lincoln "tombstone" stick welder with a carbon-arc torch would also do the job but isn't nearly as portable as I'd like.

    I'd appreciate your comments on the suitability of the itty-bitty plug-in-the-wall "buzz box" to meet my needs, and -- if you vote yea -- do you think that there's enough difference between the different models that I should seek out one and shun the others?

    Thanks in advance for your suggestions.

    John

  2. #2
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    Are you intending to burn these parts loose, or just heat them up and then remove by other means?

    If just heating, a MAPP gas torch would probably serve your purposes.

    smt

  3. #3
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    Have you tried Wurth "Rost Off Ice"...its the opposite of Oyx Acet heat...Works great and comes in a spray can...

    Rob

  4. #4
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    In some cases you might get away with the cheap heat.... But what you have to consider is, when trying to expand something, you want to do it quick. if your heating it up slowly, it gives the other material time to heat up also. so both pieces are expaning, and your not gaining any clearance, which will just soften both parts and chances are they will guald together.

  5. #5
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    When heating in order to "break" free "frozen" parts, it really doesn't matter if both pieces are expanding so long as they don't expand/contract at the same rate. All the heat is doing is simply providing a mechanical breaking of the rusted/bonded parts. That said, a cheap and easy way to heat things fast is the MAPP gas method. It'll heat the target area quick with affecting too much of the surrounding materials. Good luck.--Grant

  6. #6
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    I have had to free a number of frozen fasteners and pipe fittings over the years. I have also had to heat assorted coupling hubs, gears, sleeves and similar to get them off shafts. My own experience has been to use oxyacetylene torches.
    The type of torch and tip size are a matter of what size the job is. I have found that using the most concentrated heat on a nut or pipe union or hub often does the trick. What I try to do is to find a spot where concentrated heat will produce the most expansion. On nuts & pipe unions, I sometimes heat just one flat with a smaller brazing tip. I use a hammer to keep banging away on the corners of the nut or pipe union to "break the bond". My thinking is that the concentrated heating expands a localized area and the rest of the circumference of the threads has to "spring' out. Heating the whole nut might also expand whatever male thread it is made up on. I have found that if I can keep things hot in a localized area on a nut or pipe union and get a wrench on, things usually come loose.

    If that method fails, I often will heat the whole nut and male thread up with the biggest tip I can use and let it cool slowly. As it cools down sufficiently to where penetrating oil will not flash and burn, I douse on the penetrating oil. I use anything handy and tend to discount claims made by penetrating oil makers. Kroil, PB Blaster, Zep, or any good penetrating oil or even diesel fuel will work. As the threads cool, I rap them with a hammer and keep squirting the penetrating oil. On bigger nuts and pipe unions, I use an air chipping gun with a blunt chisel steel to hammer at one corner if a wrench won't break things loose and move them.

    An older millwright once showed me his method for heating hubs to pull them off shafts. These were big bull gears and flywheels without taper-lock bushings. He applied the heat at the portion of the hub where the top of the keyway was. He explained this was the thinnest part of the hub, so woulod expand the quickets and cause the hub to spring out. I used that method many times and have always had good results.

    In one instance on this job, mechanics had been heating a Falk coupling hub with about a 10" bore for two days, trying to pull it off a shaft. They were using Porta-Power pullers and rosebuds to do the heating. Two days of that type of heating and pulling got the hub off the shaft in "jumps". The shaft was badly torn up as a result. We later had to have In-Place Machining come in and turn the shaft in-place & re-mill the keyway in place as well. We then had to bore the new hub undersized. It was a case of too much heat, getting the shaft and the hub both heated and expanded equally.

    The next such shaft had to have its coupling hub removed. It looked to be the same sort of situation. The mechanics, as they had on the previous job, had been trying with the rosebud and puller and getting nowhere. One of them gave me a call. I suggested the mechanics let things cool overnight and try my method the next day. We put the heat right on the area of the hub over the keyway with a large brazing tip rather than a rosebud. The puller had the hub off the shaft in one quick move.

    We have a couple of sets of small, portable oxyacetylene torches at the powerplant. I call them the "safecracker's torches". These torches have small botles of oxygen & acetylene, regulators and smaller torches including cutting heads. You can carry these oxyacetylene outfits with one hand. They are surprisingly handy. If you have something stubborn that needs to be heated or burned off, like a locknut on a piece of heavy equipment out in the field, these outfits work out well. Guys doing HVAC work use them when they have to heat the hubs of blower wheels or bearings to get them off air-handler shafts. These little oxyacetylene outfits provide enough firepower to heat up hubs on 1 1/4" diameter shafting. Guys have borrowed these outfits on weekends to get locknuts off stuff like tractor bush-hog blades. for the size of the bottles, these little torch outfits supply a surprisingly long amount of usage. Of course, with oxyacetylene, if you have a frozen nut and it is made of steel, if all else fails you "wash" the nut off using the torch.

    I have had a set of bottles and torches wherever I have lived for over 30 years. As a single buck, I kept a "B" tank with an adaptor for the regulator and a small oxygen bottle by my back kitchen door. Kept the hose for the torch rolled up on one of those wall racks you hang coats and hats upon. It was handy. It made a cutting outfit I could fit into a small car trunk. We always had a "B" tank ("Prestolite" torch) at my dad's house, so he simply gave me the B tank when I needed it. I leased a smaller oxygen bottle. Once I got oxyacetylene equipment in my home, I wondered how I lived without it. You get spoiled with oxyacetylene. It heats like nothing else and has the advantage of being able to do gas welding, brazing, silver soldering and cutting.

    Joe Michaels

  7. #7
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    You don't necessarily have to heat a nut to expansion to get a frozen nut loose.

    Here is a trick and it does work!!!!!

    I use a little propane torch that you buy at the hardware store. Same kind as plumbers use to sweat pipes.

    Heat the nut up until its pretty hot (it doesn't have to glow red) and then after you remove the flame very quickly spray the nut and bolt with WD40.

    The heat thins the oil and through capillary action the WD40 gets sucked into the threads as the nut and bolt cool.

    You would not believe what I've broken loose with this technique. I discovered it by dumb luck when I was about 14 (30 years ago)

  8. #8
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    Cant say there is much maintenance on a small ocy/acet set. Get a MC bottle of Acet and a 20cu O2 and your set. See them on craiglist all the time. Harris makes a set that includes a caddy to carry it all.

    Dont bother with the carbon arc. You will spend as much doing that as you will with a gas set. Plus woth the torch you can braze, cut, weld, solder, ect.


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