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Thread: Joining 2 sheets of plywood together smoothly

  1. #1
    Join Date
    Apr 2005
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    Rockville, MD
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    1,100

    Joining 2 sheets of plywood together smoothly

    My grandson got a train set for Christmas and it will take 2 sheets of plywood to accommodate the track. I figure to put the plywood on 2X4's to make it rigid and some sort of stand. But I haven't figured out an elegant way to join them together smoothly for the track, that can be undone for storage when needed. Run bolts through the 2X4"s? Anybody have to join 4X8 plywood together to form a smooth edge, their ideas would be appreciated!

  2. #2
    Quote Originally Posted by Don Morris View Post
    My grandson got a train set for Christmas and it will take 2 sheets of plywood to accommodate the track. I figure to put the plywood on 2X4's to make it rigid and some sort of stand. But I haven't figured out an elegant way to join them together smoothly for the track, that can be undone for storage when needed. Run bolts through the 2X4"s? Anybody have to join 4X8 plywood together to form a smooth edge, their ideas would be appreciated!
    One of many to come. (The fun of woodworking)
    Place the panels next to each other and run a router with 2 straight edges.
    A home-made jig.
    ( Or one commercially bought router guide)
    Leave 3/8" space between the panels and use 1/2" straight router bit.
    Even if the straight edge or your jig is off...no problemo.

    We use the same technique for laminates and melamine.
    SECURE all non moving pieces. Plywood and jigs.
    good luck.

  3. #3
    Dino has the answer, but to elaborate: you may want drill dowels between the two sheets in which only one side (or neither side) would be glued. This would help with alignment. Also you could screw a cleat on the underside of the sheets that would keep the joint closed.

  4. #4
    Join Date
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    ft walton beach, fl
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    I have scarfed half sheets of plywood but not a whole sheet. I did it by stacking the 2 sheets at an offset. For instance to get an 8:1 scarf on half inch plywood they would be offset 4 inches. The top piece has the best side up, the bottom best side down. Mark 4 inches on the top piece and then with a belt sander and coarse sandpaper, sand them both down so there is a continuous surface. They then can be flipped and glued together. It worked for a 2 foot wide piece. May be tough to do on a 4 foot wide piece. Also does not knock down. Perhaps you can modify this in some way.

  5. #5
    If you have a slotting cutter for your router (3/16 works fine) rout a slot in one edge of both pieces and make a spline to fit then use "titejoint fasteners" on the back face to pull the two pieces together. these are used in countertops all the time.
    Steve Jenkins, McKinney, TX. 469 742-9694
    Always use the word "impossible" with extreme caution

  6. #6
    Join Date
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    Medina Ohio
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    I use drawtite fasteners some look like dog bones and some are just a long bolt with a block on one end drilled oversize like a washer and a block on the other end drilled and tapped.

  7. #7
    Join Date
    Jan 2010
    Location
    Bellingham, Washington
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    All the responses sound good, but if you don't want to do all the work, why not try t&g plywood (subflooring)?

  8. #8
    Quote Originally Posted by David Helm View Post
    All the responses sound good, but if you don't want to do all the work, why not try t&g plywood (subflooring)?
    Bingo.
    Also put a couple of glue blocks on the bottom, and clamp them together.

  9. #9

    Smile Plywood

    Use Dino or biscuits or dowels to line the plywood and get a couple of the table leaf clamps that you can put underneath to hold it together. I think you can find those table leaf clamps at Rockler ( look a lot like double-hung window locks.) Should be easy to take apart and put back together when ever you need to.
    Thanks John
    Don't take life too seriously. No one gets out alive anyway!

  10. #10
    Join Date
    Feb 2008
    Location
    Northwestern Connecticut
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    6,249
    I've had good luck using a spline joint made with a 1/4" slot cutter in a freehand router with a bearing set to give 1/2" depth. I'd use 1/4" MDF for the spline, or rip a strip of 1/4" hardwood perhaps. You could also make your own T&G joint and skip the spline, though IMO the spline is easier to make, or use T&G floor underlayment as your substrate.

    For quick knock down connection between sheets Rockler and others sell the hardware for table leafs which do a fine job of pulling two parts of a table top together tightly.

  11. #11
    Peter - Great minds think alike.
    Thanks John
    Don't take life too seriously. No one gets out alive anyway!

  12. #12
    Quote Originally Posted by Don Morris View Post
    .... I figure to put the plywood on 2X4's to make it rigid and some sort of stand...... Run bolts through the 2X4"s? Anybody have to join 4X8 plywood together to form a smooth edge, their ideas would be appreciated!
    For simplicity sake, your idea is the best. Just run bolts and wing nut through the 2 X 4's.

    Ok, here is where I differ from your plan. If you cheap-out, you will most likely have problems lining up the edges of the boards.
    1) Step One.....stay away from the BORG's.
    2) Go to a quality lumber yard where the local cabinetmakers go and get 2 sheets of 3/4" cabinet grade lumber. It might surprise you that the quality stuff may actually be less expensive than the BORG.
    3) Dont use construction grade 2x4's, they will eventually twist and take the plywood with it. Buy 4/4 red oak (failrly inexpensive) and cut into 3" Boards. Stand them on edge and they will stiffen the plywood substantially.
    4) Have fun

  13. #13
    Join Date
    Apr 2005
    Location
    Rockville, MD
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    1,100
    Tony,

    I know enough to stay away from the BORG's for plywood. I helped my #1 grandson (different than the one with the train set) build a full sheet plywood form for a Robotics competition using a Microsoft chip placed in individually designed Lego's. I used a good Hardwood source nearby for 3/4" Maple plywood, but the competitions design called for four 2x4 supports around the sides and three crossing underneath. That seemed fine. I am anticipating using 3/4" Maple ply again. While at the hardwood source, they had some fir (I think) which I priced, but again, the "go by" said 2 X 4's so I just went with what the BORG had and it seemed to be OK. Have to think about upgrading to something else.

  14. #14
    Join Date
    Nov 2007
    Location
    Manassas, Virginia
    Posts
    266

    A different approach

    Besides doing woodworking, I have some experience with model trains and I have several friends that are very much into it. Now, I do not know what kind of trains your grandson has, but for most, plywood is too stiff and yes, too noisy to serve as a base. Also, 2x4's are too heavy.

    Typically, we build track in sections using 1"x4" lumber to build modular frames (module size can be 2' by 3' or more - depends) then topping them with something like Homasote (spelling?) mounted on top which makes for easy attachment and quiet running and to a common height so modules can be attached to one another. (Some guys stiffen it with very light plywood underneath - I never did.) My point is that trains and scenary are not that heavy, but the ability to fasten track to the surface and make the trains run more quietly is normally more prized than a stiff two ton platform - even if we are talking about LGB G scale (or Playmobile) or even Lionel O scale.

    You do not have to mount your frames - they can even be flat on the floor, but the approach I mention is suitable for almost any kind of train and if there is wiring invlved, it is the best method. Once you build a module, you just bolt it to the next and so on. The legs need to be sturdy and we often level with t-bolts, but there is a certain elegance to the whole thing. As hobbies go, trains are almost as addicting as woodworking, but I do like woodworking more.

    You can see these modules at train shows, Model RR clubs, etc., or Model Railroading Magazine.

    I agree with the approach not to use wood that warps - that is too much agony.
    Last edited by Thomas Pender; 01-18-2010 at 10:52 AM. Reason: dimension could mislead

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