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need to make a flat work surface about 2 x 4

I have settled into building solid wood baffles that are about 2 inches thick, face glued strips.
To flatten them, I use my router with a jig on a flat, smooth surface. 

https://drive.google.com/open?id=1APyxJcPluOFIPdICNC2OYXbzqDuBQpol

I need to be able to plane down larger baffles, so I'm thinking about building a special
flat work surface about 2' x 4 '   I have a lot of choice of materials, but I was thinking that
2 sheets of 3/4 MDF glued together and sealed with shellac and wax might provide a
very stable surface.  maybe use a laminate (formica) piece, but I'm not sure that  dissimilar
materials will be stable in the long run.

Or should I make up a matrix frame with 2x4s and screw down 3/4 inch baltic birch to the frame?

What do you shop experts think of this?  Thanks in advance.
Don, Donno, or "Hey you" all work for me, But never "Mr Johnson"
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Comments

  • I would recommend some sort of square reinforcement underneath. Square aluminum tubing can keep things surprisingly flat.

    A torsion box is one/another way.

    When I made the router circle-jig, I laminated HDF with aluminum reinforcement. It is flat and will stay that way. As long as you can laminate flat, this is a very rigid panel, as well as being very heavy. I used MDF boards to either side, and clamped the perimeter, then laid 25# weights on the center top while it laid atop my table saw- which is flat. For 2' x 4' and 1" thick of 8-ply 1/8" HDF, you will go through about a half gallon of Titebond. Use a blade or trowel to lay out the glue. As long as you have a straight edge clamped on one end, you can lay this up in one shot.

    I did this twice with 5-ply, and the second had a bit of bow with 5-ply when dried. So- I reclamped and added 3 more ply to flatten/counteract out the bow. This worked well.

    A layer of dry-erase marker-board for the top is inexpensive and durable.



  • edited January 2019
    I'm interested to see how you make out with this, for no particular reason ;).



    I've seen some jigs built online where you build a frame around your work piece, and then lay something similar to what you've already built over it to plane the board, but it assumes that you have a good flat table already that is bigger than the piece you intend to cut. I guess you could do it on the ground as well but that doesn't sound like a whole lot of fun.

    With the jig you have, you could basically keep it stationary, and feed the board through it as you make passes, I think that would work fairly well without a table that's big enough for the entire slab.



    I'm not deaf, I'm just not listening.
  • edited January 2019
    Scrap granite would be my first choice.  After that 2 layers of MDF or particle board glued together and "set" on a 2 x 4 frame with 1 foot spaced stringers across the 2 foot.  Get/ buy a decent 4 foot straight edge.  If you are at Lowes or HD hold a few levels together and look for light between them.  I've an old Craftsmen level with machined/ fly cutter marks across the edges.

    I'd let my MDF panel dry out a week, set it on the 2 x 4 frame then using the straight edge find the high spots in the panel, secure with a drywall screws and shim the low spots between the fame and MDF panel. After that flip it over and PL glue the edges of the 2x4s to the MDF panel.  That's gets you a basic flat work bench.  I'll be laminating mine with Formica. 

    I've been flattening some MDF panels by priming with Bin 123 shellac and sanding with 100 grit on a 9 x 11 inch MDF block, but that's for a veneer project.
     John H, thanks to JP I did get that email
  • edited January 2019
    You might consider a recycled solid core door if you have a Habitat Restore or similar near by. I use them for work bench tops. I've also found good deals at lumber yards that have damaged doors. My current bench is made from a door that's 1 3/4" thick and it's hard to bend.

    Ron
  • Thanks guys - all good suggestions, and possibilities that were/are on my list.
    At first I thought that Wolf nailed it, it's very unlikely that aluminum channel or steel angle iron would
    bend, so I checked prices for those at Lowes. Sheesh - "arm and a leg" - so I thought maybe black iron
    pipe - just as expensive! - So then I thought about used / surplus / scrap - and a local search found a 
    Habitat surplus store near where I work.  

    As far as decibel's suggestion - it's theoretically possible to have a stationary router jig and slide the 
    work piece under it, but I think that the slightest "jiggle" in the work piece would cause a ripple in the 
    surface.  When I hot glue my baffles to the flat support, I can achieve a very smooth flat surface,
    so that's the model that I'm pursuing. Incredible live edge slab, though.

    So all possibilities are still on the table. Depends on what I find at the Habitat store. 
    I'll post build pics when I put it together.


    Don, Donno, or "Hey you" all work for me, But never "Mr Johnson"
  • If you're looking for angle iron look for a used bed frame. I just found a basic metal one on Craigslist for $5.

    Ron
  • Yeah, "pot to the kettle" - 30 years ago, I bought "this place" and it had an old bed  frame in the basement.
    Paid someone to cart it away. Of  course, now I need it... <grin>
    Don, Donno, or "Hey you" all work for me, But never "Mr Johnson"
  • Current plan is 3/4 BB on a steel angle iron or black pipe sub frame. Plan is to screw the BB to the pipes and use washers between the ply and the pipe if I need to level the fixture.

    Don, Donno, or "Hey you" all work for me, But never "Mr Johnson"
  • I really didn't think HD prices for Al square tubing were all that terrible.
  • edited January 2019
    rjj45 said:
    Incredible live edge slab, though.

    Thanks, I'm taking advantage of my new habitat, this stuff is local and cheap. The plan is to build a bench with it, using a pair of these:

    The bark unfortunately was barely attached, but it came off in one piece. I'm still debating whether I should glue it back on and keep it. The wife I think would rather do without for a less rustic look, as well the extremely coarse texture can be tough to keep clean.

    Since it'll just be a bench, the ultimate flatness isn't super important, so I may not end up planing it with a router, but I did find a nice article on building a jig:




    I'm not deaf, I'm just not listening.
  • Wolf said:
    I really didn't think HD prices for Al square tubing were all that terrible.
    Prices are not bad for aluminum. I immediately started searching for steel angles and tubing for some reason.
    (Reason, aluminum can and will bend, not so much for steel.)
    Now that I'm in full search mode, Nextdoor has a couple of "curb alerts" for bed (steel) rails.
    I might get lucky yet.
    Don, Donno, or "Hey you" all work for me, But never "Mr Johnson"
  • re: decibel.  That's a nice jig for large pieces. Having built 2 of these so far, I don't see the need for rectangular router plate. 
    it's easy enough to keep the router level.  On both of my jigs, I used some pieces of HDPE on the bottom, and they really 
    help the jig slide smoothly.
    Don, Donno, or "Hey you" all work for me, But never "Mr Johnson"
  • I'd seen that before - very nice stuff! Way overkill for my current needs.
    Don, Donno, or "Hey you" all work for me, But never "Mr Johnson"
  • My CNC frame is build out of 8020 extrusions.
  • A torsion box should work, You might get AL for the perimeter or a cross and the rest with MDF.
    Once assembled should be really hard to bend. Am old WW video:

  • Torsion tops are REALY strong. I dont think you need any metal.
  • A torsion box should work, You might get AL for the perimeter or a cross and the rest with MDF.
    Once assembled should be really hard to bend. Am old WW video:

    Very nice - I thought that idea might work out nicely.

    Don, Donno, or "Hey you" all work for me, But never "Mr Johnson"
  • "I love it when a plan comes together" , yeah, THAT guy.

    The Nextdoor "curb alerts" were all gone, but I found a Habitat store near my work and
    they had about a half dozen steel bed frames. I got an old, heavy angle steel Queen size
    frame for $10.  Figure I'll cut pieces with a jig saw. Perfect for my needs. They also had
    a bunch of light fixtures and tables that would be handy in the shop. 

    Thanks for all the suggestions!

    Don, Donno, or "Hey you" all work for me, But never "Mr Johnson"
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