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Thread: Looking to build more stable table

  1. #11
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    Heat isn't an issue. I already checked with a thermal camera.

    Wayne have you priced out phenolic? I've been seeing prices that get close to actually making buying aluminum extrusion seem with it.

  2. #12
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    Have you checked 80/20's eBay store? They offer odd sizes for about half price. The odd sizes can be over 8'. I've bought maybe a dozen of them over the years at that length. They're probably remnants from custom cuts.
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  3. #13
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    Unfortunately they closed that store earlier this year. Even at a discount you still need to get the hardware which roughly doubles the price. You're in the 2-3k range for that, plus I'd need to do some fancy cutting to get my vacuum plumbing in there.

    I do love the idea of a metal table, but I can't help but thinking that the benefits don't justify the cost.. which why I'm exploring extira...

  4. #14
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    I use MDO as a base which is much more stable than any other plywood that I have worked with. I put corian on top of that with the vacuum grid (4 zones) carved into it. The spoilboard tops off the system but it is doweled not glued. It stays quite stable for weeks at a time but if I am carving tight tolerances I dress the table fresh before carving. One thing to watch when dressing the spoilboard is the amount of vacuum you pull on wide open spoilboard as apposed to carving a sheet that has all of or most of the spoilboard covered. I cover as much spoilboard as practical as I dress it to keep the vac as high as I can.

  5. #15
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    Eric, please don't laugh, but I'd like to suggest you investigate using a type of concrete called "GFRC".

    I have long been interested in Glass Fiber Reinforced Concrete, "GFRC", (but failed to do anything with it ). It is used a lot in architecture to make exterior cladding for buildings, concrete counter tops, and various decorative items. It can be cast thin, and even will bend some. Plus you can embed hardware into it for securing your plenum layer. (They embed hardware when casting architectural panels, to facilitate attaching these to the building.) I have seen videos where they make panels that are just 3/4 of an inch thick. And some people mix in vermiculite to make the panels even lighter.

    There are tons of YouTube videos on the material. Here is a typical video, this one by Smooth-on: https://www.youtube.com/watch?v=wA3GygYmz0g.

    In addition to being stable, I believe that relative to your other options, that this is low cost. Of course there is the learning curve too...... You could probably find a concrete counter top fabricator in your area and see what he'd charge to make what you want. It should be right up their ally, as this would be just a big blank slab, requiring no sink or faucet holes. (Don't let them talk you into mixing in seashells or LEDs into your slab !)

    Thanks for your interesting posts, Chuck
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  6. #16
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    In 2005 /2006 I put in a 1.25" thick Paperstone bed. (I was cutting a lot of countertops at the time) If you are going to cut a vacuum grid into it (probably any phenolic top) you should keep in mind that it'll probably "warp" a bit because of all the stress relieved in cutting into the top over such a large surface (mine is 60" x 120 "). I had to flip it cut some grooves in the back to get it to relax back enough so when I flipped it and bolted it down there wasn't a lot of strain on the table frame. If I were to do it again I'd probably put it together out of four smaller pieces and biscuit / epoxy them into a solid table after having cut the grid into each of them. I think a lot of the problem I had was because it was one monolithic piece.
    Anyway the long and short of it is the table is very stable now. I find it's the spoil-board that causes the changes in height, as you pull through the board you introduce whatever humidity is in the air and that causes the fluctuations in thickness. It can very significantly across the board after only a couple hours. Of course using a vacuum-jig like you showed eliminates that issue, unless you are using the table vacuum to hold the jig down. ;-)

  7. #17
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    >> I find it's the spoil-board that causes the changes in height, as you pull through the board you introduce whatever humidity is in the air and that causes the fluctuations in thickness.

    That makes sense! Never thought of that before.
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  8. #18
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    Have you thought about granite for the base

  9. #19
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    Have you thought about granite for the base
    Surely that would be stable, but there'd be no reasonable way to cut a plenum into it.

  10. #20
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    Not only would GFRC be far cheaper than granite, and lighter depending on the ingredients, you could route a form in which to cast the plenum layer. For that matter, one could integrate the base and the plenum layer as one cast piece.
    Chuck Keysor (circa 1956)
    PRT Alpha 60" x 144" (circa 2004)
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