Simple to extravagant, they all serve the same basic purpose. Mine is a mid-point model; 3/4" BB ply base, solid glued and screwed front bridge, t-bolt attached and adjustable rear fence, dummy block where the blade comes through, ZCI inserts for the blade path and the rear fence face.
The same sled (and same basic design in 3 others) has served me for years. I have a bunch of ZCI parts which I have very professionally (read, felt tip marker) labeled for 80T blade, dado widths, box joints and so forth. I use 1/4" melamine for the inserts as this makes blade position visibility very easy on my old eyes.
I have used commercial aluminum, UHMW and QSWO runners, all with equal success and reliability. Your location and weather could effect the stability of organic runners. The replaceable inserts and adjustable fence are necessities as far as I am concerned. I finished my parts in dewaxed shellac, sanded the bottom to 400 grit and paste-waxed it. I have yet to need a re-wax but, I keep my tablesaw top pretty well maintained so the sled could just be getting "auto-waxed" from use ;-) I have very few other items that take only a few hours to make and get used so much.
You'll wonder how you got by without one. My main user has a 22" front to back capacity and is about 36" wide IIRC. Two thirds of the width are to the left of the blade for me but, this will vary depending what you use it for. I didn't bother with track for hold downs on my main user or my larger sled. I do find them useful on a sled I made for bevel cutting small box parts. I made all my rear fences a standard height so my stop blocks and such can be used on any of the sleds.
Last edited by glenn bradley; 11-22-2010 at 03:55 PM.
Any sufficiently advanced technology is indistinguishable from magic.
- Arthur C. Clarke