Got a new welding table a while ago (actually its a cast iron surface plate, 6 feet by 3 feet by 7 inches thick)...

I originally planned to drill and tap a bunch of holes in it for fixturing, but recently I've been thinking it would be cool to have some heavy duty magnetic clamps--like a mag base for a dial indicator, but with much more pull...

The closet i've been able to find are 90 degree magnets with a switch on each side.

http://www.stronghandtools.com/img/pdt/magnets/ms280.jpg

The above certainly useful, but only half the equation. 100lb pull on the magnet would work for this, but not on a clamp that would clamp down on the workpiece. Think a c-clamp cut in half and welded to the table, except having a mag base instead of a weld.

Why do I think that if I do find this, it is going to be expensive.

Here is a pic of the table just for the hell of it (click the thumbnail)...
http://asmc.net/pics/d/7849-2/IMG_2147.JPG (http://asmc.net/pics/d/7847-1/IMG_2147.JPG)

With strong magnets, arc blow can become a problem.

Magswitch makes magnets that would do what you want if that's the route you want to go http://www.magswitch.com.au/magsquares/70mm-magsquare.html

I prefer this style clamp (no magnet):
http://www.stronghandtools.com/products/halfclamp.html

Edit - didn't see it was a cast iron platen, don't use the weld on half clamp idea.

I'm aware of arc blow, that's why I want the magnet on the table, not on my work. sort of like your second link, but with a magnet base. I can't tack stuff to my table, its not steel.

Second link is broken....

thanks though.

With strong magnets, arc blow can become a problem.

Magswitch makes magnets that would do what you want if that's the route you want to go http://www.magswitch.com.au/magsquares/70mm-magsquare.html

I prefer this style clamp (no magnet):
http://www.stronghandtools.com/products/halfclamp.html

Edit - didn't see it was a cast iron platen, don't use the weld on half clamp idea.

I'm aware of arc blow, that's why I want the magnet on the table, not on my work. sort of like your second link, but with a magnet base. I can't tack stuff to my table, its not steel.

Second link is broken....

thanks though.

If second link was broken how did you see pic?

If first link doesn't work, type "MagSwitch" into google
Got to site > products > industrial and welding > Magsquare

The Magsquares have threaded holes and would work for what you want to do. Sil-bronze a piece of plate to cut down cheap C-clamp and bolt to Magsquare. You could make a magnetic half clamp from one no problem.

sorry, I meant the first link...which now works..Those magsquares look like they would work. NOw I just need to find a bunch of them for cheap.. :D

It would be a lot cheaper to rent a Magnetic base drill and drill/tap holes in the table.