I’m impressed. Look forward to the photos and a source for the magnets.
John
i use magnets from old hard drives and they do a great job of pinning down warped wood. and if you leave them on the metal plates, you can put the magnet directly on the crumb tray and have the play resting on top of the edge of the material, getting a stronger hold.
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Ah, sources. Amazon. Specifically:
and
The discs are rated with an N number, the bars aren’t. I get the feeling that the bars, while strong, aren’t as strong as the discs – they may be N35 instead of N52, if I were to order more, I might look for N52 bars (if they exist).
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I designed some T-pins for the PRU, but wasn’t real happy with how they worked, so let it go and tried something else. 
I’ve bought a bunch of magnets from here. You have a very wide range of shapes, thicknesses, pull-direction and strengths. And they’re priced decently too
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Did no one think about or try out finishing nails?
I haven’t tried it myself, but I was working on a cheese board this morning that I now realize I could have use them instead of using all my magnets to try and keep it in place.
I wonder if we have any finishing nails in the garage…
I use this method when magnets won’t do.
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Cotter pins - brilliant - I must see what’s in the workshop here, and start experimenting. Must have plenty of warped plywood in UK with the current weather pattern !
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You can make a quick pin bed using small neodymium magnets (like the 3-4mm ones) and brads or small nails. drop the magnets on the base where you want your pins and then place a nail on each pointy side up. Easy to throw a dozen on there quickly, no need for precises placement and then when you’re done, pull off the nails and use a bigger magnet to suck up all the little ones from the bed.
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Now thinking of neo magnat on the base holding a machine screw, up through the honeycomb, with a wing hut bearing down onto a wooden hold down piece just clamping the edge.
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Have magnets that you really like? Where do you get them? I have some rare earth ones that are small enough, they aren’t too much of a paint to get them to release, but still have a LOT of holding power. I might use those.
Scroll back, I listed my sources.
Sorry…missed it. I thought I had read through the whole thread.
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I started with the small neodymium magnets I had from a craft store. I ended up using tape to wrap them. Use a larger strip of tape, place magnet in middle, and press the ends of the tape together. You end up with a magnet with a flag, basically. Now I can easily get them to release, from the bed or from each other. And since then, I haven’t pinched my fingers between magnets snapping together, either.
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I don’t have any problem removing even the large neodymium magnets from the bed but that’s just me. The wife’s fingers are likely not strong enough.
Where I had a problem was laying them down and having another magnet jump 4 inches to pinch my fingers. So I screwed a steel socket rail to my bench to place the magnets.
I slid the socket tabs off the rail. 99cents at Harbor Freight.
Thought about using the front pass thru shield instead. Not like I will ever use it.
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That’s a really good idea to wrap them with tape.
Brilliant solution! I’m going to do this. I think I have the same magnets…they’re about 1 1/8" diameter and quite strong!
My latest thought for a simple hold down is a wood screw through a wooden ‘washer’ strip, down through the honeycomb, and screwing into another wooden strip/ block underneath.
Two of these at opposite sides of the highest point of the warp, clamping the work down flat, and with sacrificial tops if they are not well positioned !
Mine are from the craft store, and really tiny, less than 1/4" across. I was having problems removing them from the honeycomb and the floor of the Forge. Neuropathy sucks.
I used to design a lot of products that relied on magnets. I found that the easiest way to increase the strength of a magnet is by encasing it in a Steel “cup”. It increases the magnet strength by about 4x by focusing the magnetic field to point only forwards. It works kind of like head of a flashlight, where a single LED’s light is redirected to all shine forwards.
Anyway, you can buy steel cupped magnets quite easily. Sometimes they are called steel cupped magnets. Other times they are called encased magnets. I bought a set of 8x from McMaster. Part number 5685K26
They cost around $2.35 each and hold 20lbs each.
When used together, my set works great and will flatten most any slightly warped thin plywood.
Tip: not all encased magnets or steel cupped magnets have a hole in the back of the cup. If it does, they say that the hole is for “mounting”. It certainly works for that. I will also point out that the hole makes it easy to lift the magnet off the crumb tray using the dentist pick that you are probrably already using for weeding your parts. Also, it makes it possible to push the magnet out of the cup if you want to. Without that hole, no way you are getting that magnet out of the cup.
Hope this helps,
Jason
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