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ok this looks like a fantastic device to make sure the swarf and chips all get cut to a smaller size...
Great idea not just for drill press but for a small homemade surface grinder. Magnetic chucks are very expensive. Thank you.
I've made a mag chuck for my milling machine, and a Magnabend starting from basic principles. You will find that thinner wire for the windings and a greater number of turns will be more effective and provide a longer duty cycle. I suggest you measure the current draw because I very much doubt you'll need more than 10 amps at about 50 or 60 volts to get a very effective magnetic flux.
My Magnabend will pull about 10 tonnes. It's 750mm long and will bend a piece of steel 100mm wide and 16mm thick whilst being supported on 5mm blocks at either end. The steel springs back when the power is off of course.
Why dont you offer it to this website would be intereested in the design?Quote:
Originally Posted by Bony
I intend to, when I can find the time. Winter is on the way here, so maybe soon and when I can find all the photos.
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Thanks Marsh! We've added your Electromagnetic Vise to our Vises category,
as well as to your builder page: Marsh's Homemade Tools. Your receipt:
<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/homemade-electromagnetic-vise"> <img src="/uploads/254730/homemade-electromagnetic-vise.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/homemade-electromagnetic-vise">Electromagnetic Vise</a> <span> by <a href="https://www.homemadetools.net/builder/Marsh_2">Marsh</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/vise'>vise</a>, <a href='https://www.homemadetools.net/tag/magnet'>magnet</a> </div> </div> </div> </div>
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Geez, way too many errors in this. Welding the laminated cores was a terrible idea. The laminations need to be isolated from each other, otherwise the eddy currents will be huge. The cores should be attached to the top, not the bottom. The top should also be made of laminations so they act as magnetic poles. The amount of power required to operate it would be minimal (as an example my 6x18 surface grinder chuck draws less than 1 amp at 125 volts). If he'd done the slightest bit of research into magnetic chucks he could have done a much better job. Honestly a magnetic chuck on a drill press is a terrible idea anyway (part could come loose and hurt you, plus all the chips will stick in the hole). Clamps are much better. I especially like the vise-grip drill press clamps.
Yeah, I kind of thought he should have used the secondary windings but since I have done no experimentation with it I figured he knew something that I didn't. It seems that 5 VDC with a huge current draw is maybe not the best way to go either, but I really don't know.Quote:
Originally Posted by Bony
Actually the secondary winding on a microwave transformer wouldn't work. The voltage on that winding is very high so you'd need a lot more than 120 volts to do anything, even if you unwrapped half of it. The reason it draws (and needs) so much current is because of the eddy currents. Those are caused because the laminations are shorted together by his welds (and the saw cuts). The laminations are insulated from each other when the transformer is manufactured (either by paper or shellac). One other thing to note is that it won't release cleanly because there is no provision to demagnetize it when you turn it off. This is normally done by applying reverse polarity pulses, done by a magnetic chuck controller.Quote:
Originally Posted by Floradawg