The miter gage supplied with a table saw is sometimes useful, but for accurate, consistent work, a crosscut sled will make a big difference. Crosscut sleds have been around a long time. I can remember my father using one on his saw 50 years ago.
As with the use of any power tool, you need to be careful. It is difficult, or impossible, to use a blade guard when using a crosscut sled. The good news is that your hands can be kept far away from the blade and the fence at the rear of the crosscut sled prevents kickback. So watch where you hands are and use common sense when using the table saw and crosscut sled.
One of the biggest advantages the crosscut sled has over other guide systems is that it carries the work piece across the table instead of dragging it. This means that the tendency for the piece to torque while be pushed across the table is gone. If the piece is wider than the sled, and tends to drag on an extension table, a simple piece of material the same thickness as the crosscut sled can be clamped or taped to the extension tablet help reduce the problem.
I am presenting a general method for build your own crosscut sled. Size will depend on your needs.
This is a collection of crosscut sleds I use. The bottom sled is my main crosscut sled. It is as large as the table saw top and has a heavy rear fence. The rear fence has a T-Slot cut into it for the use of a movable stop block. The stop block is essential for repetitive accurate cuts. The T-Slot is handy, but the same can be done by just clamping a block to the rear fence. Other fences in the pile are a special fence for Dado cross cutting, Two special fences for cutting box joints, and the bevel cutting sled that will be detailed in this paper.
Here are the materials ready for assembly.
The most critical component of the sled is the runners. To make the runners I first milled a piece of stable hardwood (I use beech) to the proper thickness to smoothly slide through the miter slots on the saw. Most slots are 3/4” x 3/8”, so I mill the board to a thickness just under 0.750”. For my saw this thickness is 0.744”. To measure this, the board should be able to fit into the slot on the table with room for two pieces of paper.
After you mill the stock and check it for fit, rip two lengths from the board. The two strips should be about 5/16” thick. This measurement is not critical, but it should be consistent thickness. The reason that the strips (runners) are not as thick as the slot is deep is to allow clearance in the bottom of the slot for sawdust. You wouldn't want debris such as sawdust lifting the crosscut sled off the table. In this photo you can see some of the other parts. Save the remained material for future sleds.
The platform is made from 1/2” birch plywood. Baltic birch is excellent. Other materials may also work well. I used to build sleds using 1/4” material, but I found them to be too fragile. The front support holds the front of the sled together, so it must be a inch or so higher than the deepest cut you plan to make. The rear fence must be very straight, because it is the reference for the cut. Be sure it is high enough to remain strong even after it is cut through. I like to cut T-Slots in the rear fence for attaching stop blocks and other things. On my large sled, I made the area in the center of the rear fence quite high and cut down the areas to the left and right of center. See photo below. Notice also the block of wood glued on the rear fence. This helps your hands know where they are positioned. Never put your hand on this block, because that’s where the blade comes through. This block can be of any convenient size, and is glued in place during the last step.
I use the table saw fence as an easy reference for the positioning of the platform. Find a good place for the platform to ride, then bring the fence over and lock it down. The platform can be whatever size you feel will work. Cut the runner material the same length as the sled is from front to back.
Place the two runners in the miter slots on the table saw. Shim the runners from below so they come slightly above the height of the table surface. Using a couple thicknesses of paper, shim the left side of both runners. This assures that they are parallel to one another.
Put a bead of glue down the center of each runner. But before you do this, make sure your table is waxed enough so that glue will not stick to it.
Using the fence as a guide, lay the platform on top of the runners and clamp down using cauls. The cauls are just some 1x4 I keep around. The cauls should be directly above each table saw slot. This prevents distortion of the platform. Allow the glue to dry overnight. Note: On several descriptions I’ve seen about making sleds, the runners were either screwed or glue and nailed to the bottom of the platform. I prefer the pure glue technique because I think it is more stable than screws, and nails tend to cause the runners to widen, thus binding in the slots.
Scrape the extra glue along the rails and check to make sure the sled slides smoothly across the table. You may have to do some scraping to get it to glide nicely.
Now you can install the front support. Glue and brads work fine here.
Now you can place the sled on the table and make a stopped cut from the front and stop about 2” from the back.
Now some layout work for the rear fence. First extend the edge of the cut line to the back edge of the platform using a sharp pencil.
Then make a mark where you would like the back side of the fence to be. I usually make it about 1/2” from the back.
Using a square, and the mark you just made. Line up one blade for the square on the cut edge. Make sure the corner of the square lines up with the fence location mark. Make another mark on the platform some distance from the center. On this sled I made a mark 10” from the center. The mark is about an inch long.
Flip the square and do the same thing. Use the same cut edge and the same distance from center for the mark. Doing it this way will produce a good perpendicular line even if the square is not perfect.
Place some masking tape along the marks to make it easier to see them while gluing the rear fence. The glue squeezed out tends to cover the pencil lines.
Glue the fence and clamp it securely in place while the glue dries. Be very careful to get the fence lined up with the marks. You can also use brads to keep it in position. After the glue dries, you can make and attach a safety block to the rear of the fence.
I finish my sleds with a coat of shellac followed by paste wax on the bottom and runners.
Here's the sled ready for use.