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Rare Earth Magnets


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For those of you who have used these before:

I've seen in the build threads some folks using Rare Earth magnets to secure their control cavity & truss rod covers. Which magnets did you use? What type of glue did you use? I'm guessing that the 1/4"/6.4mm disk would be a safe diameter, but the thickness is up in the air. Any input?

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http://www.radioshack.com/product/index.js...rentPage=search

Something like that, you'd be looking for. I don't even think I glued them in, honestly, just drilled a hole and pressed them in. You can just use them for direct replacements for screws. They're strong, but they're no problem to get the covers off too. Just make sure that there's something for them to magnet to. I was impatient and broke off the heads off of some nails I had lying around, and hammered them into the body. It wasn't pretty, but it got the job done.

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I had almost finished my response with links and all a few hours ago and as I was finishing up the power died, ugh I hate that. I'm extremely happy that I finished my homework before it went out though.

Anyhow, I got mine at Rockler because I saw them there first. I grabbed the smallest ones they had and they are probably the biggest you'd ever want to use. I'd probably go smaller if I could. Here they are Rare Earth Magnets (Rockler). The worked just fine, though I didn't quite realized how strong they would be at that size, so I way over did my cavity cover. I used the 3/8" diameter X1/10"thick magnets. I believe you get 10 in a pack for less than $5. I installed my magnets with epoxy, I found a 3/8" forstner drilled it to the proper depth so it was about flush, then just used a dab of epoxy, which worked well because the forstner left that little extra deep hole where the epoxy could sit. It really worked out great. I think in some applications and for the really small magnets you could just use a tight fit, but honestly with the ones I used, I don't think they would stay in place. I've seen those magnets jump so far, they are amazingly strong, I can barely get my cavity cover off. I'd probably use epoxy or CA, either should be plenty enough to hold it in.

Magnets in cavity & cover

Cover in place

Cavity from a distance

I really dig the magnets idea, this was my first attempt so it's not perfect, but it looks and work fine. I'll probably try for the next one to find a bit smaller magnets, diameter wise or just use 3 sets instead of 5. There is no real issue with how many I used, there is just no need for that many. The thinner you can get them, probably the better otherwise you'll need to be very alert on the thickness of the cavity cover or truss cover. Well, best of luck. J

Edited by jmrentis
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They work great. I use 1/8" diameter ones. On this LP Jr I epoxied in a total of 4 - two in the body and two in the control cover. Just make sure the poles of the magnets are oriented correctly (like I didn't the first time :D ) otherwise your cover will be trying to pop out. I will probably never use screws again.

DSC_0005Medium.jpg

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Good point, I kept worrying myself about the polarity also, after rechecking the third time before glue up I decided to mark the backsides with black magic marker, so I could easily see how to place them. However with 1/8" I'd bet it'd still be tough see, where you marked them. I never thought to try magnets for truss covers as avenger63 suggested and with those 1/8" it would be easy and cool. I'm with Hydrogeoman on the never using screws again, too many cool things to do with magnets. Where did you find the 1/8" magnets Hydrogeoman? Are they thinner than 1/10" also? Good idea, like I said I way underestimated the strength on those little things.

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I wonder if you could search and locate a swallowed neodymium with another magnet on the outside... Talk about an awkward sensation.

I never tried this when I was building my first guitar, but do the neos stick to the copper shielding well? I'd go home and try it out myself, but I've got work all this weekend.

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i got some small ones when i got some mags for pickups from a localish place (happens to be about 1 minute from a luthiers supply place that i get fretwire and a few other things from). seem like a great way. small screws can strip, magnets will last for longer if youre always going in and out of the cavity.

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  • 2 weeks later...

I love this idea. Has anyone tried this: How about using magnets in the cover, and just iron in the guitar itself? If the grip is still strong enough, it seems like it might have some improvements. No worry about the polarities matching. And if you have trouble getting the covers off, you could use maybe lift it them off by using magnets on the outside.

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I use 3/16" diameter, 1/16" thick neodymium magnets. Five or six is enough for a control cavity.

I drill recesses for zinc screws into the ledge of the cavity, and screw them down so that they're recessed a little less than 1/16". Then I center a magnet on each screw, put a drop of CA glue on top of each magnet, and put the cavity cover in place. [Edit: Careful not to glue the magnets to the screws...]

When the glue is dry, all that's left is to remove the cover and tighten the screws down so the cover lies flush to the back.

If the magnets are holding the cover down too tight, you can also use the depth of the screws to adjust the strength of the hold.

Edited by Rick500
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