Table Saw Sled Homemade Machines & Jigs
A table saw sled is something that I really haven’t had a need for, since my homemade table saw had a sliding table attached for cutting larger stock. For all miters and cuts less than 12″ wide, I use my sliding miter saw. After dismantling my homemade table saw, I needed a way to make 90 degree cuts in wider stock, so I figured it was time to make a simple sled for that purpose.
I had a few design features that were important for me:
- Lightweight. If it’s too heavy, I’m a lot less inclined to use it.
- Big enough to crosscut 16″+ at 90 degrees.
- A thin base to reduce weight and maximise depth of cut.
- A removable centre section, so that I can use the sled for dado cuts.
- Well made and accurate, without throwing the features above out the window.
I made two videos covering the complete build:
The sled is made from two thicknesses of plywood, 1/4″ fir for the base and 3/4″ Baltic birch for the fence rails. The advantages of using plywood are many, with very few disadvantages. Good plywood is flat, consistent thickness and dimensionally stable. It doesn’t warp or twist under normal circumstances. Solid wood can be used, but may move due to seasonal expansion / contraction. Another consideration is that where I live, high quality Baltic birch plywood actually costs less than an equal quantity of good quality, clear hardwood.
One of the key features of my sled design is the replaceable centre section, where the blade cuts through. I want to use this sled with a dado blade as well, and would like to swap out the centre section for that purpose. To accomplish that, I made the insert wide, about 5″, and cut the edges to key into a V-groove in the sled. The V-groove keeps the insert in line on the top and bottom of the jig:
Since I will need more than one insert, I cut three during the build and then marked the exact dimensions on the bottom, so that I could easily set up the saw to cut a new one when I need it.
The front fence is a three piece build up, with two vertical parts and one horizontal. This L-shape produces a fence that stays straight, due to the strength axis of the plywood parts at 90 degrees to each other. In carpentry, this construction is called a ‘strongback’ and is often used to strengthen and straighten ceiling rafters.
Here, I’ve cut the parts to width and length:
Prior to assembly, I took the time to cut two rabbets in the vertical parts to receive the metal shelf standard after the fence is put together and installed on the sled.
The fence is assembled with wood glue and 1-1/2″ nails, being careful not to put any fasteners where the blade will cut though the fence:
The red arrow points to a block that holds the fence square while the glue dries. There is one in each end and these will be removed after the clamps come off.
After about one hour of dry time, the fence is glued down to the base. To do this, I used polyurethane glue and clamped the whole thing down to the (very flat) outfeed table on my saw. There is a lot more detail on this in the first build video, including my reason for using that particular glue:
The back fence is also glued on. I have tape on the removable insert to prevent it from being glued in.
I gave the glue overnight to dry. After taking the insert out and removing the tape, I slid it back in and and put four screws in to secure it. I also marked the correct orientation for it with an ‘X’, but this was not necessary, since the screw locations will do that:
The basic sled is now assembled and all that’s left to do is line it up accurately and attach the runners. As a starting point, I used the table saw fence to line it up and clamped it down:
The runners are made from UHMW plastic and for the initial setup, I only have one installed. I marked the centre of the runner on the sled, then drilled countersunk holes to drive screws through the top into the runner:
With the first runner attached, I made adjustments to get the sled cutting as close to 90 degrees as possible.
This picture shows the ‘five cut method’ of checking the sled (more detail in the second video).
After several adjustments, I got the sled cutting to an acceptable level of precision. A few thousands of an inch difference in the strip after the last cut is perfectly fine, and as far as I took this.
When I was happy with the alignment, I installed the second runner, then added more screws to keep the runners in place. These plastic runners slide very smoothly, but are flexible and need a lot of support to keep them straight. Metal runners, steel especially, would be a better choice.
To add a level of safety, I glued and nailed plywood fillers where the blade comes through the fence. The sled should never be pushed far enough ahead to cut through these blocks:
The final step is to give the whole thing a coat of polyurethane to keep the moisture out and make the bottom a bit slicker.
The finished sled:
I made a simple adjustable stop block to go with the fence:
So, that’s it. Not a lot to it, but a project well worth making.