questions about rare earth magnet settings

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Hey All, I am attempting to make a small clam shell type presentation box (for a pen and pencil set I turned) using rare earth magnets to hold it shut. I resawed a nice piece of cherry and routed two opposing grooves on each of the bookmatched faces. The 1/4 inch diameter magnets will be positioned in each corner of each half so I would need four pair of magnets to hold the two halves together. I want the magnets hidden too so I thought I would place them as close to the inside face as possible from the outside and plug the holes with a cocobolo dowel (the same wood as the pen bodies) . I did a few test mounts drilling the 1/4 inch hole and leaving 1/8 inch wood face. The 1/4 inch magnets will not hold very well with two 1/8 inch layers of wood. They will attract when placed across 1/2 inch cherry but I know the strength of their attraction is less than the strength necessary to hold two pieces of wood together. (The magnets are placed so they attract.) I only have 1/4 magnets right now but can pick up larger ones tomorrow although I am not inclined to go over 3/8 inch. So I'd like to know if anyone here has any suggestions about the thickness of wood (2 pieces) or the size of magnets needed to hold stuff together. The faces are 7 by 4 inches so it's not a lot of weight but I think the 1/4 inch magnets are insufficient to do the job. I would prefer to keep the wall thickness 1/8 inch because I am concerned about damaging it when trying to seat the magnet. Would using two magnets in series in each hole make the attraction stronger? I did not test that set up yet. Any suggestions are welcome and thanks in advance, Marc
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In my experience putting 2 mags together only gives a slight improvement...may be enough...may not. Look at lee valley for steel cups to put mag in...it directs/focus's the mag force...you will need to drill a larger hole tho.
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On 12/13/2011 8:18 PM, marc rosen wrote:

Can you stack the magnets? Like batteries stacked end to end both will increase in strength.
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the lee valley cup sets are the way to go... you can use epoxy to hold the magnets in if the wood is too thin for screws. You might just need the very small magnerts
shelly
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On Tue, 13 Dec 2011 23:31:28 -0800 (PST), " snipped-for-privacy@stny.rr.com"

Put the magnets as close to the surface as possible and hide them with felt buttons. Rare earth magnets are extremely strong.
Think NO GAP when mating magnets. -Much- stronger.
-- However beautiful the strategy, you should occasionally look at the results. -- Sir Winston Churchill
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On Wed, 14 Dec 2011 06:44:42 -0800, Larry Jaques

And then don't forget to have a screw driver handy when you need to pry the box open. <g>
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I cannot really answer your questions but do want to mention that the strenght of these magnets can differ even for the same physical size. I do not recall the units that are used to describe their strength but it shouldn't be too hard to google up a reference.
--
There are no stupid questions, but there are lots of stupid answers.

Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf. lonestar. org
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On 12/14/2011 4:40 PM, Larry W wrote:

gauss
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wrote:

or tesla. ;-)
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Well, my goal was to have hidden magnets but after several trials none of the combinations would hold the two test boards together. I bought some 3/8 inch magnets, confident the 1/4 inch would not be strong enough, and set them in the boards leaving only slightly more than 1/8 inch of wood and air gap (the taper of the drill point). I used 6 magnets in each board and the holding power was so weak that you could not pick up one board with the other. I then tried stacking more of them in each hole but that too proved useless so I had to abandon the invisible magnet approach and go to exposed magnets with the metal pocket. Two, 3/8 inch magnets, medially located 5/8 inch from the ends on each face and you'd think the boards were velcrowed together. The box still looks nice andI'm certain the recipient will be very pleased but it would have been nice for me to have only wood showing. I'm the one who wanted no "hardware" showing, not the folks who asked for the pen set anfd box. I'll try experimenting with 1/2 inch magnets after Christmas and maybe it will work. Thanks anyway to those who responded. And to all of you out there, I hope you have a great time this winter season. Merry Christmas or Happy Chanukah. And to my Zappa friends, Happy Zappadan. Marc
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On Wed, 14 Dec 2011 19:23:14 -0800 (PST), marc rosen

Yeah, and electrical plugs taped onto the outside of an outlet deliver zero electricity, too.

Happy Zappadan! Now go cover those exposed mags with sticky felt, or something else really thin. Dis -ain't- rocket surgery, mon.
P.S: Close only counts in horseshoes, hand grenades, and RE magnets.
-- However beautiful the strategy, you should occasionally look at the results. -- Sir Winston Churchill
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On Thu, 15 Dec 2011 20:29:28 -0800 (PST), Father Haskell


http://www.youtube.com/watch?v
-p9TSDngg Do not miss this!
-- Silence is more musical than any song. -- Christina Rossetti
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wrote:

Thanks for that Larry. So, are you one of us? Marc
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On Fri, 16 Dec 2011 20:13:51 -0800 (PST), marc rosen

I'm a Zappa fan, having cut my teeth on Hot Rats, if that's what you mean. Otherwise, what is one of y'all?
-- Silence is more musical than any song. -- Christina Rossetti
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And to all of you out there, I

Hi Larry, Hot Rats is a great place to start. Thanks for the reply, that's all I want to know. By the way, magnets and felt worked and it looks good to me. The recipient gets his pen set on Tuesday. As soon as I get my Dad's Birthday turkey in the oven it's back to the basement shop to continue working on my dining room table (as I steer the thread back on topic. Hope you all have productive weekends too! Marc
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On 12/17/2011 7:49 AM, marc rosen wrote:

Ever heard the Tinseltown Rebellion version of "Peaches En Regalia"? Fun stuff.
--
Any given amount of traffic flow, no matter how
sparse, will expand to fill all available lanes.
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Hi Steve, Thanks. I have the entire Zappa catalogue and that's all I listen too. TR Peaches is a great tune.
Marc
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On Sat, 17 Dec 2011 08:07:19 -0800 (PST), marc rosen

-1
-- If you're trying to take a roomful of people by surprise, it's a lot easier to hit your targets if you don't yell going through the door. -- Lois McMaster Bujold
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Translation: TR = Tinseltown Rebellion, Peaches = Peaches en Regalia, Great Tune = really fun music to listen to.
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On Sun, 18 Dec 2011 04:40:40 -0800 (PST), marc rosen

-1 meant that I didn't particularly like the TR version. Too much electronic noise vs the original musical theme. It sounded to me as if it were made during the first year of MIDI's existence, when accurate sounds of musical instruments weren't yet anywhere close to being produced.
-- If you're trying to take a roomful of people by surprise, it's a lot easier to hit your targets if you don't yell going through the door. -- Lois McMaster Bujold
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