Magnetic Clamp

[Omnimill]

Anyone on here able to help? I want to use some kind of switchable magnetic clamp to hold knives whilst sharpening. Trouble is some knives are quite small and many are stainless so not quite as easily held with a magnet. I've tried a couple of my switchable mag bases but they don't hold anywhere near well enough.

Anyone have experience of these:

http://www.magswitch.com.au/magsquares/magsquare-150-2.html

Or should I look at maybe making my own electro magnet? - would it have to have mains voltage or would say a 9 Volt battery be good enough?

I really need someone on here with a magnetic personality ... ! :big:

Vic.

 

[Omnimill]

Come on guys, 83 hits and no comment! Help me out here

Vic.

 

[websterz]

In cross-section I don't believe there is enough mass to really securely hold a knife blade magnetically. I grind a lot of small parts on my surface grinder and the thinner they are the less they seem to hold. I have to use metal packing strap pieces to dam the parts in otherwise they will slip. That's just my experience though.

 

[napoleonb]

In cross-section I don't believe there is enough mass to really securely hold a knife blade magnetically. I grind a lot of small parts on my surface grinder and the thinner they are the less they seem to hold. I have to use metal packing strap pieces to dam the parts in otherwise they will slip. That's just my experience though.

+1 on the damming.
I have used several magnetic clamps ranging from almost unused to completely abused the results were almost the same on small parts.
Made me set up a demountable fixture 1mm high at the end so it had nowhere to shift to, but be carefull on the return stroke!

 

[Omnimill]

Thanks for the replies guys, I agree about the low volume of steel being a problem. I should say however that there is only a small amount of pressure as it's only for sharpening an edge, not a large surface. I think some of the small rare earth magnets would be strong enough but of course you can't turn them off whilst positioning the blade! Also, the blade can be positioned against a back stop so sheer force shouldn't be a problem either.

Here's the setup I've got so far, it's just my own version of those available commercially:

In use, the blade is held largely in place by the downwards pressure of the stone but I still find it awkward when swapping sides.

Heres another shot of the jig:

Some sharpening systems use clamps but they often get in the way with small blades.

Vic.