Folding, portable breakdown table with sacrificial lattice top

Woodworking starts with taking big pieces of wood and turning them into little pieces. And the universal strategy for breaking down plywood is to get a piece of rigid foam board, lay your plywood down on it, and break out the saw. The foam panel supports the wood, provides a safe underlayer for the saw blade, and may provide a little bit of zero-clearance tearout protection.

Three or four projects ago, I had a bunch of cuts to do. And so I spent most of a morning standing over a 2" thick, rigid foam insulation board on the center of the driveway, going from kneeling to standing to kneeling and back again. Rotating the material, and clamping the straight-edges in place, and repeating - after my pieces were broken down, I was thinking about a solution that was not at ground level.

But I did not need a second workbench - the Dog Island shop has a table saw and a rolling work table and one more table devoted to handling plywood and making track saw cuts would just be overkill. Plus - not every project includes plywood breakdown. So a task that comes up infrequently demands a solution that isn't central and permanent.

So - something that takes up a minimum of space, and can still bring plywood up to a comfortable level for breakdown?

I am not alone in this type of thinking, and here I credit the sources and citations in my search for a good solution to this problem.

• Steve Maskery has a nice design for a table that knocks down, has a sacrificial lattice for supporting plywood, and can be built from a single sheet of plywood.
• Old Style Woodwork has a similar lattice cutting platform that is supported on sawhorses - bonus points for a track saw angle protractor for perfectly square crosscuts and/or crisp angle cuts across a full sheet of plywood.
• Izzy Swan made a workbench that folds laterally into a compact package, and has suspended hook arms for easily transitioning a full sheet of heavy plywood from the floor to the table.
• The Pneumatic Addict has a mobile workbench that folds into an impressively small size, and provides a solid platform given the overall length and width of the frame.

So I stole a little bit from each of the designs. Because this was going to be for breaking down plywood (and possibly the occasional glue-up, or paint job) I wanted a sacrificial grid of supports, similar to the foam panel surface. I didn't want to store a large table top (foam or otherwise) anywhere in the shop, so a lattice construction would be easier to break down and store. It would be nice if I could roll the table, so I was aiming for something with a frame and wheels instead of A-frame or sawhorse construction. And I wanted to get close to supporting a full 4x8 sheet.

Some of the above projects were constructed from 3/4" plywood. The May 2009 issue of Wood Magazine has a design in the Ideas section provided by Jeff Tobert of Alberta, CA.

Jeff's design is constructed from simple 1x4 boards and pocket screws. The ends fold in the middle with piano hinges and a hollow-core door is used as the table top.

This looked like a good starting point. I was a little nervous about connecting the frame uprights and the top/bottom pieces with pocket screws. So I started thinking about a way to make a rectangular frame that has some decent torsional strength. Also - for materials I did have two sheets of decent 1/2" plywood. So I thought about combining the thickness of stacked 1/2" pieces in the fashion of a lap joint.

A thin piece of 1/2" plywood on its side would be a little wobbly in a sacrificial lattice - but two pieces laminated into a 1" piece should have adequate strength.

So I started playing with dimensions for the major components - small square frames at the table ends, larger rectangular frames along the table sides, long lattice pieces to span the length, and short lattice pieces to cross the width. Eventually I ended up with dimensions that could be cut to fully utilize two sheets of 1/2" plywood - which was my target based on inventory.

Piano hinges at the ends provide some nice rigidity to keep the structure stable, both when fully assembled and when folded into storage mode. The 1/2" plywood pieces are overlapped at the corners with enough of a glued half-lap joint that the rectangular frames are quite strong - especially vertically when supporting heavier pieces of plywood.

I used lots of glue and brad nails, and clamped the frames with every clamp in the workshop. I considered adding dowel connections at the corners, but ultimately went with brad nails. If I do version 2.0, dowels will certainly look nice.

The long and short sacrificial supports for the top of this breakdown table were simply 92" and 44" strips of plywood, glued together to double the thickness and increase strength. (I refrained from brad nails considering that they would be cut with track saws.)

Once the rectangular frames were assembled, I had to prepare for a lattice connection. I marked the frames at regular intervals and then used the sliding table and fence to make dado notches where the lengthwise and widthwise sacrificial supports would go. 

Once the frames had their notches, I connected them with piano hinges and threw some casters on the bottom (with some thickness braces to get a good connection with the caster bases).

With the frame assembled, it was time to create the interlocked top from the length and width supports. I laid the sacrificial supports into the frame notches to mark their corresponding notch locations.

 Then I placed the length braces close to the width notches and marked the locations of the dado cuts that would be used to interlock the supports together. And here's the finished product.

I'm considering adding some hooked folding arms that will assist with moving plywood from the floor to the table. But for now it's been working great.

Plans are up for sale on the Dog Island Offcuts Etsy store!