Project clampdown idea? Rare earth magnets

So, I’ve been pooling over some ideas in my head as to some neat work-piece hold down ideas and wanted to see what the community thought of the idea.

I’m cutting thin parts, mostly out of 1/8" birch ply. Trying to get the tabs cut through and removed nicely has proven to be…a suck factor. But the one time I tried to cut without them, the piece popped out and into the path of the spindle and got trashed.

I was thinking an interesting idea for holding them down would be some rare earth magnets. They’re rather thin (I saw some on Rockler that were 1/10 high) and have an amazing amount of holding power. I also have a box of old hard drives that I could scavenge a bunch just for testing…or Harbor Freight shows a cheap 10-pack of small ones for only $2.99.

So my questions to the community are:

Would you use 2 magnets - one under the wasteboard and one on top? Or would you just mount a strip of something to the bottom of the wasteboard that a magnet would try to stick to?

How much material would one think they could go through? Mounted to the bottom of the wasteboard (3/4" MDF) + up to maybe 1/4" hardwood on the work surface?

How would one “mount” these under the wasteboard? Standard serious glue like E6000 or Gorilla glue? Wood glue? Duct tape?

There is no way you would get enough holding strength through 3/4" of MDF. The attractive force of the magnets falls off very quickly as distance increases.

magnets do hold great but getting through 3/4"+ material is a stretch. also magnets only hold in 1 plane very well and tend to slide in the other plane. magnets would be a great idea but maybe used in conjunction with another method. again it depends on what your milling but you could always try insetting the magnets 1/2"from the back of the wasteboard and see how it works.

Thanks guys. Definitely seems like through the whole wasteboard is a bust.

Off to destroy an old non-working hard drive to see what I can get out of it.

Not Earth Magnets but there is a industrial CNC Routers working with Electra-Magnet. Creating Force field with adjustable strength between two metal bars and all parts stays between. Which… we’re looking at the price with high Dolars for High speed production. I know Earth magnet in 4" Diameter installed in two different work station into the materials, because you can’t get closer each other. It slams and generates deathly impact. I say lets stick with cheapest solution we’re already have success. Matter affect, I always stay away from Magnets and Magnetic fields which harms your body.

1/4" poplar was “sticky” but not very well. 1/8" birch ply was pretty good.

So I tore up a hard drive I had laying in the basement quick and grabbed the 2 magnets from that.

First test, I used a scrap piece of 1/4" poplar, cut a recessed pocket 1 3/4" x 1" x .084 (the magnet size was .0835) and just laid the magnet in the recess, then laid a sheet of the 1/8" ply on top and attached the magnet and then clamped down both pieces together. Note that the bottom magnet wasn’t glued, just laid in the recess.

First piece came out pretty darn good actually. No tabs needed, and it didn’t jump. Cut all the way through.

I’m going to go and glue the magnet down into the poplar for test 2.

Now, I do have some drives, but the time taken to try and rip them apart, I can get some magnets in a 10 pk @ Harbor Freight for $3. If test two continues to look promising, I think I’ll attempt a hole pattern that uses 2 of the smaller circular magnets farther apart but close enough to the edges to try and get the most bite where it’s needed.

If necessary, test 4 may be a 3-hole pattern.

If that all proves out, I’ll create a template board that’s 12x24 just like my ply and lay out the pockets for magnets for ~15 pieces on the board, and try cutting all 15 in a single file.

I may have to space out the gaps between the pieces and lay a few magnets around just to keep the center area good and down once half the pieces have been sprung loose. That will affect slightly my bottom line (less pieces per sheet of material), but if it improves the speed of not having to cut out the tabs and file them down…it’s worth it!

Did you check this Company for different variates.

Unless someone has a super fast and easy way to cut out and then relieve the tabs so I can get a good straight line, I don’t see how having tabs (while cheaper in not buying new equipment costs) is going to be any less expensive from a time/labor cost.

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Well, might be the good idea. Good discussion. I already started to search possibilities. Thanks Alan.

not for nothing, but one of my customers who does high-end production routing of plywood uses a vacuum system.

they have several holes in a sheet of steel that the work sits on… it sucks the material to the table top AND IT WON’T GO ANYWHERE!!

gotta use a vacuum pump and you gotta not poke a hole thru the material into one of the suction holes, but - no clamps!

So, if you have an old vacuum pump lying around… (shop vac probably not gonna do it)

Thanks Jay. That’s “on my list” - however is a much bigger upgrade for down the line if I continue to cut such small plywood. Though, I’m hoping that things will progress that a Laser Cutter will end up being a better upgrade than just building a vacuum table.