Introduction: Folding Plywood Router Table
Apartment living can be challenging for building projects. With a tool and bicycle storage area of 10' x 5', I don't have space for things like a typical router table. (I do have a balcony I actually work on, but storage is a real problem.) Fortunately 1/2" plywood is thin, relatively cheap, and readily available. This folding router table starts with a quarter sheet of plywood (4' x 2'). You'll end up with a table that can be folded up to 24" x 18" x 2-3/4"
Before you decide to start, you'll need to be sure you have some good way to attach your router to the bottom side of the tabletop. The base-plate on my router is removable from the collar with four bolts, so I only needed to buy slightly longer replacement bolts to deal with the variation in thickness between my router's base-plate and the 1/2" plywood. But in any case, just make sure you have a solution before your go out and buy materials.
A quarter sheet of 1/2" plywood (4' x 2')
12 feet of 3/4" x 1-1/4" wood strips
Two piano hinges approx. 10-1/2" long (or four shorter hinges)
Assorted screws (1", 3/4", 1/2")
Countersink bit (except for the hinge screws, I countersunk every screw hole to avoid splitting wood
(You may also need to purchase longer bolts to attach your router to the tabletop, but that depends on the actual router you use.)
Step 1: Cutting the Plywood
The diagram shows the approximate layout of each piece you'll need to cut. I say "approximate, because sometimes a quarter sheet of plywood is a bit smaller than a full 24" inches . If that is the case for you, you really only need to be sure that the sides and back of the base are precisely the same height. Mine turned out to be about 11-1/2" (vs. the 12" shown in the diagram).
After cutting the plywood, I went ahead and used my router to round the edges everywhere with the exception of the edges of the back, side pieces and hinge strip where the hinges would be installed. I wanted those edges to remain as square as possible to enhance rigidity. I also sanded everything.
Step 2: The Base
The pictures show the base both in its upright position and folded. The hinge strip is what allows the two sides to overlap cleanly when folded. I glued and screwed the hinge strip in place on one of the side pieces, making sure to leave 1" of space at the top for when the base would be inserted into the slots under the top.
I decided to use "piano hinges" to keep things really tight and straight. Naturally you could substitute. But because the piano hinges were precisely 12" long, I had to cut them down to about 10-1/2". It would be good to have precisely 1/2" long screws to install the hinges, or you'll need something to grind the tips off later. 'Nuff said. ;-)
Step 3: The Top - Holes for the Router Attachment
Cutting the holes to mount the router under the tabletop was simple enough for me. That was because my router's base is two parts: a metal collar with a plastic plate bolted to it. I unscrewed the plastic plate and used it as a template to mark the hole for the bit and the holes for the four bolts. I then cut out the router bit hole using my router freehand. (Take your time and it's not that hard to make it very round.) The bolt holes should not be too big. Snug is better. Naturally I had to countersink the bolt holes so that the bolt heads would not protrude above the tabletop.
I had to buy four longer bolts with flat heads because the 1/2" plywood is thicker than the router's plastic base-plate. And in the end, it all squared up well and could be tightened up nicely.
Step 4: The Top - Slots for the Base
After flipping the top over, I cut strips of 3/4" x 1-1/4" lumber to make the slots for the base to be inserted. Then each strip was glued and screwed in place in turn.
I first cut two strips for laying on the front and back of the top. These strips were 1" shorter than the overall width. I didn't round the corners very much at all, just smoothing all sides and edges with sandpaper.
I then set the base in place, centered on all sides. The back outside wood strip was then glued and screwed in place. (Don't do the front strip just yet.)
Note: to make sure the lumber strips would pull up tight, I pre-drilled all screw hole though the wood strips.
Next I measured the inside distance between the sides along the back piece of plywood. Remember that you should have clearance where the hinge strip meets this strip; there should be no contact between the hinge strip and the back inside slot wood strip
NOTE: I glued and screwed the back inside wood strip for the slot in place so that it held the base plywood in place snugly. That seems to have been a good decision. YMMV.
With the back slot finished, I glued and screwed the front strip of wood in place. But this time I did use a very thin piece of cardboard (like a cereal box thickness) to create a bit of space and not have things too tight when I went to take the thing apart. This seems to have been a good idea. YMMV. Naturally there is no reason to create a full slot at the font. There is no base on this side.
Finally I measured each of the spaces for the four slot strips for the side base pieces. I did use a square to make sure the side pieces were perpendicular to the back. I also use the cardboard spacer for both sides when I glued and screwed these strips in place. I think that without some spacing, this thing could be a real pain to get back apart.
Step 5: Final Thoughts and Options
There are any number of router table builds here on instructables that will help you add features to this table. I intend to build at least a fence. I might also add some sort of finish to the wood, but I think I'll just use it as-is for now. Finish is going to thicken the wood, so it might need some additional sanding to thin the top edge of the base where it goes into the slots. I might also add one peg per side that goes though the wood of the slots and the top edge of the side pieces of plywood. The idea is to make sure the base won't fall off when I pick up the top. But for now, everything seems tight enough not to fall apart when I do that.
One nice feature of having a removable base is that you can clamp the top to another table edge, or put it on top of two sawhorses, or even on top of a rubbish bin to catch the dust.