Magnetic question for FF....

[Mike Kolb]

Hi all ... after reading Franks article about magnetic clamps on Frets.com, I'm ready to construct a few just to (a). have some fun playing with magnets and epoxy, and (b). because they actually look pretty darned useful to have around for clamping-up cauls in weird places.

My question for Frank: you mentioned that 2 magnets over a steel bar would "complete the magnetic circuit" and make for a stronger pair. When placing the two magnets on the steel bar (prior to drowning 'em in goo) does attention have to paid to the polarity of the magnets with respect to each other? In other words, each one will grab the bar fine, but are they placed on the bar so that the "attracted" face of each one go flat to the bar... or does it matter? I'm thinking there might be an issue when constructing the mating clamp, being careful that nothing ends-up repelling instead of attracting. ....Or am I just overthinking the issue?! Thanks.

[Mike Kolb]

Hmmm, after reading more carefully, the first part of the article mentions adding the steel bar across -opposite- poles. But my question still stands because (being ignorant of such matters) how does one determine which poles are opposite, if either side of the magnet will affix itself firmly to the steel bar? I have the distinct feeling that the answer will show me for the magnetic ignoramus that I am! Anyway, here's the original reference....

( http://www.frets.com/FRETSPages/Luthier/HighTechDept/Magnets/MoldMa... )

[Tom Krebs]

Opposite poles attract. Similar poles repel.

[Mike Kolb]

Yes they certainly do; got that. But bear with me here.... you take 2 magnets, lay 'em at either ends of a steel bar. Both will, regardless of their individual orientation, attach to the bar. Now it's time to make another matching bar with another set of magnets, so that both bars (with magnets) will act as attracting forces and not repel. Oh heck, enough theory.... I'll just start the experiments!

[Bob Webster]

Ah, but here's the missing bit. When you attach the first magnet to the bar, the whole bar takes on the polarity of the first magnet. There is then only one way that the second magnet is going to go onto the other end of the bar.

Cheers,
Bob

[Tommy Kay]

I have been using the StewMac ones. I place them side by side with opposite poles up. Since they have a hole in them, I just screwed them into a thin piece of waxed scrap wood. This method has worked well on many cracks. If you stick them to steel or just place them next to each other; you'll find they 'want' to be organized this way. These are a huge help! Thanks to Frank and/or others that came up with this clamping idea!


Tom Krebs

[Mike Kolb]

Bob Webster: you nailed it, sir. I did some goofing-around with my magnets and bars this afternoon, and you're dead-on. I'm indebted!

[Jeffrey L. Suits]

I'm going to make an armrest, w/ 2 RE magnets where it would normally be stuck to the top w/ adhesive. I'm thinking that I can position it, tape/clamp in place, and put a couple of magnets inside, loose, that'll grab the armrest but good, but still be easily removable.

[Bob Webster]

There's something about this idea that rings right, nearly. How, really, are you going to get those gonzo magnets apart? I suppose that, depending on the design of hte armrest, you might be able to slide them apart but what about scratching the finish? I need some coffee.

Bob

[Jeffrey L. Suits]

I'm talking about 3/8 x 1/4 RE mags; I should be able to lift the armrest off, and the internal mags would just drop.

Maybe I'll cobble this up, today...

[Mike Kolb]

Maybe you could superglue or epoxy the internal magnets in place so they wouldn't be rolling around inside... then they're always "at the ready" for securing the armrest in place again.

[Jeffrey L. Suits]

...Or I could just scoop them up.

If they're glued, that would limit somewhat the placement of the armrest...which
I didn't get to, today.

[Christian Johnson]

Hey, I made some of these epoxy magnet clamps following Franks method on Frets.com to the letter. They worked great, just don't let them slam together. Mine are now in pieces because too many folks let them slap together and they eventually shattered. They will pinch fingers!