My Sharpenatrix was working well enough but having to tighten the screws holding the blade each time was a bit annoying. So I bought some stainless-steel non-magnetic screws and a bunch of neodymium magnets to play with. And some of those magnets were small cylindrical magnets with a screw, and those were ideal for a quick upgrade of the Sharpenatrix.
Here is a composite picture of the upgraded thingy.
© Charly, all rights reserved. Click for full size.
I screwed three magnets into the end of a 5 mm strip of aluminum, glued on it another strip to make a continuous plane with the magnetic side of the magnets and I used the non-magnetic screw to make an end-stop to lean the back of the blade against. Spanning the blade is now a matter of seconds and whilst the magnets do not hold it extremely strongly, they do hold it strong enough to keep the constant angle during sharpening. And they allow me to adjust the blade position slightly and quickly, giving me greater versatility.
© Charly, all rights reserved. Click for full size.
The screw can be adjusted to the thickness of the blade but its purpose is not to hold the blade firmly – that is done solely by the magnets – but to avoid levering/twisting the blade off the magnets when I lean it against the belt. The side with the screw is now significantly thinner than the side with the magnets, which allows me to sharpen at a constant angle blades that were too narrow for the previous version.
© Charly, all rights reserved. Click for full size.
I have not actually tested it yet, I do not have any knives that need sharpening right now but I see no reason why it should not work.
I have also bought 500 5x5x5 neodymium magnets for making more sophistimacated magnetic chucks in due course.
I’ve been peripherally involved with bonding grids of strong magnets to a metal base. And I’ve also used them in products.
So I would suggest being careful. If you are placing powerful magnets like this in a grid, sometimes placing one magnet can destabilize the whole thing. This leads to a big clump of magnets and shards flying.
It can help to make a nonmagnetic gripper to place the magnets. More specifically, you need a material with a relative magnetic permeability close to 1, like brass. That will at least reduce the change of squished fingers.
@rsmith, safety should not be underestimated, you are right about that. That is one of the reasons why I bought a buncha of small magnets instead of fewer bigger ones. I should get enough holding force with no risk of fingers getting squished during assembly. And I will have to make some aluminium/brass tools for assembling my jigs.