First, check the alignment of the blade to the miter slots.
The idea is very simple, I make part of the sled, cut the kerf and refer to it as a reference point (or line) to position the "Back Fence" square to the kerf by "locking" everything together.
I discovered that the plastic drawing triangles are very, very accurate, and I use them to locate the fence (actually, as you will see, I'm using the shop-made triangles that were "copied" from the plastic one).
By cutting the Runners 1 mm narrower than the miter slot width, it's very easy and fast to cut the runners and, I think, will eliminate any binding due to expansion with humidity changes.
My table saw is different and has only one miter slot, so I made some kind of "fiction" miter slots for the guys with the "normal" table saw...(I think everybody except me)
It took me around 1½ hours to make it (including 148 pics), so I assume that it should take you 2~2½ hours, considering that you have to prepare the parts (I used scraps from around the garage).
This looks like a very good method. A similar method that is not quite as accurate, but a little bit easier to do since you don't need a kerf-thickness shim is as follows.
Attach a long scrap to the bottom of the sled before you cut the kerf, so that you cut the long edge of the scrap away. Now you have a well-anchored edge to hold your square against while you position your fence. Then remove the scrap. This only allows you to use one square to align the fence, rather than Niki's two, but it works pretty well.
I showed you the thing I sent a friend it was on Thompsons gouges & I added words like you showed me to do just like on your tutorials.
Thanks for the help your directions were perfect. I use Windows XP version.