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Magnetic table


Chuck Fraser

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I have a 4 x 10 foot 1 inch thick steel table with a 24 ton rolling hydraulic press mounted on it that I built about 5 years ago. I use it every day, pressing, flattening, weld jigs to it.
Lately I have noticed that all the small tools that are laying on it are becoming magnetized and are covered with grinding dust, very annoying. Can any one tell me how to demagnetize my table?
Thanks
Chuck

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How long are your welding leads? Can your welder run AC? Can you WRAP the ENTIRE table with a couple passes with the stinger and/or ground cable? Then on a different welding bench (or the floor) run some heavy beads set on AC. The strong AC current should cause a strong alternating magnetic field and demagnetize the table.

Be careful there are some pitfalls. This process will cause an AC current in the work bench, but the bench should be acting like the core of a transformer, so the current should be completely internal and safe. This AC current will heat the bench, eventually, so after every 1 inch bead check your cables and table for heat. After running a couple beads, move your cables some, and repeat till you more or less cover the entire table, since your table is particularly large.

Setup and take down are probably the most time consuming portions of this. Having 3-5 wraps around the table is probably good. I have never tried this. I read about it regarding a magnetized I-beam that was installed.

Phil

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Ironwolf
I live in Joseph, Oregon, Monday we got 8'' of fresh snow on top of mud that has patches of ice ( it's March )I don't know how to post pictures.
Phil
I do have enough welding leads to do that, from the floor to the top of the rolling H frame press is about 9'. The hydraulic power unit sits on top and has a 5hp 3 phase motor, will this process hurt the motor?
Jacques
Thanks for the interesting link.

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By wrapping the power or ground lead around any iron post it will become an electro magnet. once you do this it will be localized to the area of the post. if the table is magnetized it should throw it out of phase with its self. secondly our old welding teacher used to make us wrap our welding tanks to change the phase of the output when we welded. it has a lot to due with the type of material you weld.

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I would expect it not to hurt the motor, since the motor operates on the same principles, however I would try to not wrap the motor. I would remove power from the machine, and try to stay away from any magnetic starters and the like too.

You do want the wrap to conform to the table/machine closely, but you do not need to try doing the entire machine in one go either. I would try making fairly spread out coils, say 4-6 inches apart. I would expect setup and take down to take longer than anything else.

As I said in my earlier post, I read about this, and have not tried it. Jacque's link seems to read the same principles in play.

It is possible that if you do primarily DC welding, extra cable coiled up near or on the table may have caused the original situation. This seems to be where Yetti is going.

Phil

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In Junior High science class we would magnetize stuff, then unmagnetize by tapping it against the table. The teacher said that rapping it against the table unaligned the molecules. Before you try anything with electricity, you might wish to try rapping a hammer against the table to see if that works.

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