Teardrops n Tiny Travel Trailers

by **WoodSmith** » Wed Jul 15, 2015 3:18 pm

As I continue to digest all things Foamy, I'm interested in some feedback from those of you with more experience on making a table with Foamy techniques.

My family has recently joined a group that has several teams competing in the FIRST Lego League, http://firstlegoleague.org/ which uses a 4'x8' competition table area. All the current tables we have are made from a sheet of 1/2" plywood with 2x4 edges. These are difficult to transport, and usually requires help getting it set up. Surfing the web I find that some teams make tables out of a sheet of foam with a single, centered duct tape hinge, and simply dispose of them once they get too beat up.

I think that a table could be made in 3 parts and assemble fairly quickly using a tongue and groove type joint. I know that GPW is convinced that TBII, canvas and paint are all that is needed for a skin on trailers, but I'm wondering if students banging around with Lego bricks, repeated tear down and set up, and hard points for fasteners requires a stronger skin. I managed to purchase several sheets of 1/4" red oak plywood on sale for $8 (thrifty!) each for use on the playing surface, I'm pretty sure that this is necessary to mimic the regulation playing surface. I wonder if the bottom surface can be skinned more economically with canvas.

This method could also be used to make very portable tables for camping that could be put inside trailers and easily pulled out for setup. The three main sections nest into each other and contain the 4 side rails in such a way that the whole package is about 48x34x6 inches.

Attached should be some pics from my AutoCAD drawings.

: FLL table.JPG (53.92 KiB) Viewed 1105 times

This one shows the 3 sections, 2 with the top skin removed to show the detail inside, I have not bothered to draw the foam in. As designed, if you need a smaller area table for other use, the 2 end pieces may be joined, leaving the center piece out. The side rails are in 2 sections each and are sized so that one will complete the rail in the smaller configuration. These rails are also designed to span the table joints to help stabilize them, rather than rely on the tongue and groove for all of the support.

: FLL table joint.JPG (37.63 KiB) Viewed 1105 times

This shows the detail of how the sections join together. My intent is to use a clear SPF 2x4 (I actually found some!) joint it square, surface it and machine what I want, including matching the thickness of a sheet of 1x foam.

by **Fred Trout** » Wed Jul 15, 2015 6:40 pm

No reason why that would not work. Might I suggest you indent the tongue & groove width to eliminate a sharp corner since it is not needed anyway. We use the same technique to join roof panels and it works fine. I joined and removed my roof panels with the spline a number of times without issues so it will last a while.

I used a soldering iron with a piece of steel welding wire to hotwire out the panel edge - does not have to be too exact to work. Probably best to glue the spline in on one side for permanency.

by **WoodSmith** » Wed Jul 15, 2015 7:53 pm

I think I was not clear enough, The yellow pieces in the drawing are machined down from 2x4's. I see how your T&G works, but I think that these tables need a good solid structural joining area. One of the complaints of the fold-able and hinged tables is there is frequently a discontinuity at the joint. I'm hoping that between solid wood joints and perhaps some embedded T-Nuts, I can minimize the bump.

I'm not sure what you mean by "indenting the tongue and groove" , on each side I plan on a strip of 1 x 3/4 in which more t-nuts will be embedded to hold the side rails on. Unfortunately, leaving them in the picture makes it hard to see the joint. They will help align the T&G joint and will butt up against each other at each joint on the sides.

Glen

by **Fred Trout** » Wed Jul 15, 2015 10:23 pm

2x4s ? That should work well but make the piece much heavier than it need be. 1/4" ply is also more than required as well. 1/8 ply or Coroplast should both work well. Since the strength & resistance to flex of the panel is derived from it's composite nature and the rails, more wood is not needed.

You could use several biscuits or a plywood spline routed into 1 x 5/4 pine or hardwood as your spline and edge assembly mated to 1" foam and that would work as well. Canvas on the back side would be fine as well.

by **GPW** » Thu Jul 16, 2015 6:24 am

Wood , You might try a Test table (small sample ) to see the durability for yourself ... :thinking:

If you need something more durable , try some thin chipboard or poster board glued over the foam on the Use side and edges , then a light fabric ... should be pretty TOUGH...

Nobody believes me , so you have to test it for yourself...

by **WoodSmith** » Thu Jul 16, 2015 7:08 am

GPW, I looked into the chipboard, it tool me forever to figure out where you had posted it so I could figure out what it was called, and where to get it. When I found your post, I went to your artist supply place but they don't sell it in 34x48 inch pieces, which means I would have to buy more, and deal with a seam. I know that 1/4" is overkill, at least for the back, but it is tough to beat eight bucks.
I also want to take into account ease of construction and sourcing of materials if this works as well as I hope, teams of tweens and early teens may be building these. So far everything I need is available at every Lowes or Home Depot in the free country (California obviously not being a part of that with the ban on foam.)
Woodsmith

by **GPW** » Thu Jul 16, 2015 3:39 pm

Check Picture Framer suppliers , we've seen 4'X8' sheets of chipboard available , and it's not that expensive...

by **Tomterrific** » Thu Jul 16, 2015 4:52 pm

I think and build light weight. Since you have the 4x8 ,good price, my suggestion is to use a 1x2 at the fold with a hinge on the bottom. The plywood gives the surface. The foam gives the stiffness. The 1x2 gives the hinge screw's something to bite into.

Look at Lowes 1x2 furring strips for $1.09 each. Mine has enough straight ones that they could edge a 4x4 panel with 2 or three boards in the middle for stiff and light.

Tom

by **rowerwet** » Fri Jul 17, 2015 1:36 pm

If I was doing it I would bond 1" foam to the bottom of each 4'x4' half of each sheet of plywood after cutting them in half. I would use sections of aluminum angle to reinforce the edges.