How I designed and built my Dado Sled

At first glance, you might think that this sled isn't something I'd be very proud of having built. With its primary components made of redwood 2 x 4 stock, its certainly not a sled that's going to compete with my other sled for its looks, but for its utility and efficiency cutting all sorts of dados, grooves and lap joints on small, large and odd shaped materials it is a very useful piece of shop equipment for me that is going to get a lot of use.

Recently I built an adjustable dado jig for my router and it works fine. The problem is that routers are loud and they create a ton of very fine dust. Also, even though the jig I made locks in the width of the dado, the jig is still not as efficient to use as I would hope for large projects requiring a lot of dados. I have several projects coming up that I don't want to spend days building and they inspired me to come up with a better way. The projects include a complete walk in closet including the cabinetry and shelving and storage units for both the shop, my sons' closet, some storage in my shed and a version of the New Yankee Deluxe Router Table. Having made a garbage version of a router table myself, I remember cutting all those grooves. The desire for consistency alone on that one project was enough for  for the router table with a router was enough to inspire me to make this sled. What excited me about the thought of making a dedicated dado sled was that once the dado set was installed in my table saw, I could gain a lot more control over the saw other than the usual cuts with just a fence. For instance, it would be dangerous to plow a dado across the middle of a 25" wide shop cabinet side on the table saw because of the distance the fence would be from the blades. With a sled, the stock is supported and is unable to rotate so kickback is eliminated and with proper hold downs, the groove is ensured to be of consistent thickness. Lastly, by using a sled, stop blocks and the fence can be used in conjunction with the sled to make repetitive parts efficiently.

After I had completed my dado sled, I showed it to people on Woodnet and they suggested that I needed a way to hold down the stock. After a lot of head scratching and sketching of ideas, I came up with something that works really slick. I call them "hold down bars" and they eliminate the need for extraneous hardware. With the hold down bars, this sled is especially useful in its unique ability to cut grooves in odd sized/shaped pieces. Try cutting grooves in a bunch of pieces shaped like this with a router:

The two bars with tension knobs are hold down bars. they serve a dual purpose. When just cutting dados in sheet material, they prevent the material from lifting which ensures that the grooves are consistent and enables you to plow dados without sticking your hands near the blades. Secondly, for material that needs to be held down and secured when being cut, the tension knobs can be tightened and the bars then function like a clamp preventing the board from moving while being cut. Normally you don't need to tighten them which saves time but its great to not have to fuss with hold down hardware. 

The hold down system is what makes this sled work so well so I'll go into some detail about how I made it. First, I drove 5 1/2" combination screws with bolt ends into the front and back fence. The bolts are called closet bolts and I brought a jig knob to the hardware store to make sure I got one that would fit the knob. I stopped driving the screw end into the fence where the threads stop and using some candle wax on the threads helps. I predrilled the fences then hand drove the screws by hand using a threaded knob on the bolt. I made the hold down boards out of redwood and made sure that they could slide up and down the bolts with the springs in place without them binding on the fences. 

With these springs between the fence and the hold down bars, the bars don't fall and get in the way of your stock sliding parts and making dados, but when you need to hold down a piece because its small or odd sized you simply tighten the hold downs a bit to secure the piece and make your cut.

Here's a picture of the springs I bought at my local Orchard Hardware Supply. It took two packages to get 4 springs. 

I got a lot of satisfaction out of the design of this project and I figure its the best $25 I've spent so far in woodworking tools. I know I'll use it a lot for making shelves, bookcases, boxes, storage, cabinetry carcases and so on. If you decide to build one and you come up with any refinements, shoot me a picture of what you did to paulcomi@hotmail.com

Be safe!