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发表于 2021-9-1 00:21:04
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(not ----), with opposing poles touching each other (north touching south). let them sit for a while. it will slowly neutralize the magnetic force of each bar. my science teacher used to ream us out when we would put our magnets in the boxes in that way. you could definately tell the ones that sat like that over the summer and the ones that were stored properly.Later,Andy
Reply:Heat kills Magnetism, how much for what you have, you will have to find out.HTH
Reply:Originally Posted by smithboyHmmm. I am not sure your standard Harbor Freight mag-demag would work on something that big. You could use AC current if you have it available. That would help.
Reply:there are two main options for demag. first is with ac. coil your cable several times, then pass it down the length of the bar. this can be difficult with your length. the best option for this would be to set it up vertically allowing the coil to pass well past the length. the second option is to use dc and a gauss meter ( they are fairly cheap). you test the field strength and hook up + to one side and - to the other. At a low setting slowly increase the power until the gauss meter drops and/or reverses. this will need to be performed several times reversing the + and - every time, stepping down the field each time. clear as mud?
Reply:As already said use AC, I know some guys around here will wrap their ground around it several times.... I don't know how well that works.HH 187Miller Bluestar1EAHP AlphaTig 200X
Reply:You could heat the whole thing red hot and that will kill the magnetism. Cussing sometimes seems to help. LOL Just learn to weld it magnetised. If you have an AC machine weld it with 7018AC rod. I have used tons of sucker rods and tubing for structural work. The only rod you can depend on to hold magnetised steel is 7018. One thing that works pretty well is to turn up your heat and run your first pass downhill, then finish it out uphill like your supposed to run 7018. No one is going to x-ray a fence and it will hold. If you think sucker rod is bad try building something out of drill pipe.
Reply:I agree on the drill pipe,Oldtimer. It can be so magnetic it will pull the slag back into a torch kerf,requiring a lot of BFH work to break the pieces apart. MikeOl' Stonebreaker "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Nothing in the world like sticking drill pipe and sucker rod to each other, lmao. I used to have so much fun watching helpers try and build cattle guards. If you have AC use it. If you don't sometimes reversing polarity (EP to EN will help) and then there is always the wrap the lead around it a half dozen times or so and try that. If it doesn't work try wrapping it in the opposite direction. I've never tried welding it with 7018AC, but have burned tons of McKay and LH70 on it. I have also used 7024 when the positioning was right for it and it works well. Running hot seems to help too. I have used wire on it as well, but it seems to fall apart even quicker than 7018 does.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:Thanks for all the replies. Sounds like 7018AC and my old buzz box might just be the ticket.This will mean more clean up of welds, but the horses aren't that particular about how good the weld looks.I'm also going to try wrapping the ground around the sucker rod as well. The only trouble is lifting the old buzz box and wrapping it around the rod might be a little difficult. (Hee Hee).Cheers.Glenn.Sign on East Texas payphone: Calls to God 40 cents......it's a local call...
Reply:If you are going with the wraps one thing to make sure of is that you have an odd number of wraps over 9. Also instead of unwrapping and trying the other direction if it increases the arc blow just switch your cables
Reply:I'll throw in one or two more things that have worked for me. When welding magnetized metal the puddle is more fluid than with non-magnitized metal. I have no idea why and have never found any information in any welding book I've ever read. This means you to need to use a little less amps so you can control your deposit. But you need more amps to overcome the arc blow from the magnetism. I drop one electrode size from what I would use with non-magnatized metal. That way i can turn up the amps to counter-act the arc blow some and still control my weld. Some times just moving to the other side of what you are welding will help. The better fit you can get with what you are welding, the less arc blow you will have. Sometimes I have had to resort to putting the first pass in with 6011 which won't stick and cause that cussing like 7018. After you get the first pass in the arc blow is gone. Have fun and good luck.
Reply:oldtimer, the main reason the puddle looks wetter is due to the movement of the arc away and toward the puddle. Also the magnetism is stronger at the perimeter of the arc. another trick for multi pass is ac root dc out. Good point about moving to the other side (Fleming's LH rule).
Reply:I never could figure out how to run an AC root with an SA 200. Ha ha
Reply:Originally Posted by GreyhorseAs already said use AC, I know some guys around here will wrap their ground around it several times.... I don't know how well that works. |
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