Extension Table, Part I

February 20, 2013 — 1 Comment

There are two kinds of people: people who will look at the following picture and say, “hey, nice tablesaw!”


…and people who will look at the picture above and say, “hey, what’s up with that gaping void between the fence rails?”

When we moved back to Chicago a few years ago, the only construction I had done to the house we purchased involved carving out a space for my woodshop. While planning the layout of the new shop, the best location for my tablesaw prevented me from keeping my Incra TS-LS tablesaw fence. I looked at alternative arrangements for the shop, but in the end I decided that as much as I liked the Incra fence, it wasn’t worth compromising overall shop layout and workflow for. So off came the Incra, and with it its custom-built router cabinet and Incra router-lift-equipped extension table. This is a picture of the old setup in my previous shop (circa 2007):


Rest thee well, Incra fence. You will be missed. In repeatable, accurate, 1/64th-of-an-inch increments.

Having sold off the original General fence and rails a long time ago, on went a new Beisemeyer tablesaw fence. The Beisemeyer rails sit more than an inch closer together and quite a bit lower than the Incra rails, rendering the Incra-made extension table surface useless. So the cabinet had to be rethought.

As I’ve mentioned several times before, the gaping void largely wasn’t a problem for the first two years in the house. I was almost never in the shop and could do just about all of my small house projects with other tools. But in the end-of-last-year push to get the shop up and running I decided I would:

  • not just cut down the exising Incra table; someone could use it (and its accompanying router lift) as-is
  • build a torsion-box top to make the table flat, sturdy, and make up for a height deficiency between the old fence and the new one
  • use microdot laminate to make the table durable and friction-free
  • reorient the router lift so that its length was parallel to the table’s length

So, after the joinery bench was done, I measured the Void Between Rails (aspiring musicians–there’s a great band name for you), subtracted the thickness of the laminate, then ripped and cut to length some baltic birch plywood. I decided that I wanted the new router lift to sit on top of torsion box ribs so that the table wouldn’t sag (I noticed a sag over time with the Incra MDF top–the router and lift together are not light). After figuring out where to place those inner ribs and cutting the appropriate notches, I basically had all the constitutent elements of the extension table:


Two sides, a front and back, and interior ribs, all of which would sit between two juicy slabs of MDF, wrapped in microdot laminate. Not unlike a wood, glue, and plastic chalupa. Delicious!

A little glue in the notched ribs, some pocket screws in the outer frame, and some glue and countersunk screws to hold it all together:


For the top and bottom, I placed a half-sheet of 3/4" thick MDF on top of the assembly and ran a track saw within an inch of the edges to trim down most of the excess.


I then marked the location of the ribs on the MDF with pencil and countersunk a bunch of screws along those lines, fastening the MDF to the assembly. Screws were placed outside the center square, not yet knowing exactly how that space would get cut out for the router lift.


I trimmed the remaining excess with a trim router and a flush-cutting bit. This step reminded me that I only love MDF in theory. In theory, MDF is a magical substance capable of being formed into virtually any shape, and unlike George Costanza, immune to seasonal shrinkage. In practice, even all the dust collection in the world does not temper my contempt for working with it.


One side done:


Lather, rinse, repeat for the other side.

Next was the job of clearing out the center of the extension table’s bottom surface to make space for the router (the opening on the top first required the laminate to be applied). 4 holes and a jigsaw did the trick, opening up the torsion box like a tauntaun on the ice planet Hoth.


Those large circles around the top-left and bottom-right of the hole? Thinking that MDF was, oh, like wood, I first tried a holesaw. And all it did was burn, leaving a stench in the shop which lingered well into the next day. All together now: and I thought MDF smelled bad…on the outside!

Another pass with a flush cutting bit in a regular router to clean up the edges.


Total shop time at this point: just over 3 hours I think, spread over a couple of days. I’ll keep better records next time.

Next up: laminating the assembly.

One response to Extension Table, Part I

  1. Nice floor.

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