Mag Chuck

I can easily lift a strip of 1/16" steel off my Brown & Sharpe mag chuck.

jsw

Magnetic attraction of iron is usefully related to the energy required to break away a clamped item, but not to the force, because the relation of that force and energy is very critically dependent on geometry (the force on a distant lump is inverse-distance to the fourth power).

The spacing of the poles (closer is better, especially for thin stock) just matters too darned much, as does the surface finish of the mating faces.

The energy, which you CAN quantify, is the same as the stiffness times the swing of the clamping lever; the more work you do to unclamp, the better the original hold was. And, of course, the hold depends not only on the pull-down force, but on the lateral friction that that generates...

Bob,

I assume that you are asking this because you are thinking about a DIY Magna bend. One possible source would be your local locksmith or gate company. Magnetic locks are sometimes taken off due to a failure of the monitoring switch, but the mag is still good. those would be about the right size for a such a project.

Roger Shoaf

DOH!

I do access control work (among other things), and have installed more than a couple mag locks. I have a couple on the shelf in the shop. I think I have a couple 1200 pounders even. I know I have some 600 pounders.

I wonder if Securitron will sell me just mags instead of full kits.

Now, that's something I should have thought of... and a lot cheaper than magnetic chucks to play with.

Not really that much. They are designed to hold work being surface ground -- and even then, they are often dependent on toe plates which stick up at the end just enough to keep the grinding forces from sliding the workpiece off the end of the chuck.

If you are thinking of using it as a milling vise -- forget it. Not nearly enough strength.

Even the electro-magnetic chucks are not that strong, because they are made to run for the duration of a long surface grinding operation, while the magna bend is designed to run only long enough to bend a sheet of metal -- then shut off while you place the next piece.

Good Luck, DoN.

snipped-for-privacy@o21g2000prh.googlegroups.com...

I know that I have sent one back to them with a dead monitor switch. I am sure they will sell you anything you want, but they will be a lot cheaper if you can find a take-off. I suspect that you have enough on the shelf already however, I think the attraction is stronger if the plate is thicker, but I could be wrong on that point.

Good luck

Roger Shoaf