DIY magnetic bend brake - was "Magnabend"

Feb 12, 2011 2 Replies
B

I just made a 2-MOTE (MOT electromagnet) brake as an evaluation of the idea:


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I made it small to keep the time, effort, and materials small. But it has an 8-1/2" capacity, which would be enough for a lot of the stuff I do (e.g. electronics project boxes).



Unfortunately the results are very disappointing. I ran the MOTE's on



250v (AC into the bridge) and could not quite finish the bend on .040 (about 20 ga) steel. 18ga (.050) started, but only got to about 45 degrees before the clamping bar started sliding back. .030 bent very nicely and although too light for a lot of stuff, boxes in that guage would be useful.

So I have definitely ruled out MOTE's for the 24 inch brake that I'd like to make. I'll be thinking about what it would take to wind the coil for that. I expect that it would be painful, but the challenge would be interesting.



Bob


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B

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B

I checked the phasing of the MOTE's & they were indeed out-of-phase, meaning that there was some flux shorting through the brake's structure.

I put them in phase and tried bending some test pieces. There was a distinct improvement: it will now bend 20 ga (.040 +-), where it would only do .030 before.

That's good news and bad news. The good news is obvious, the bad news is now I'm uncertain what to do. Before, I had ruled out using MOTE's - now, I don't know. MOTE's would be easier and faster than winding my own electromagnet in the style of the Magnabend, but just barely strong enough.

The other thing I did was look into doubling up the windings by adding a winding from another MOT. The problem is that other windings either don't fit at all, or just fit. The just-fit ones are really too tight to use without damaging them. This is 30 ga wire.

Bob

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