I have bought a Makita MLT100 table saw (TS) for my small workshop. The mitre tracks on this TS model are very small and the mitre gauge that is delivered with the saw is almost unusable because it has so much play in the tracks. The TS was useless to make any precision square cuts. The set up time of the mitre gauge was unbearable for poor results. However, since I've added this sled made out of scraps, my TS has become my go-to tool for presision cuts. It works like a charm and I'm now quite happy with this saw (cost vs quality). I will probably make a larger sled one day to cut bigger panels.
This is a simple sled that you can make in less than 2 hours. It does not have the little bells and whistles like a T slot for an adjustable stop. But that is easily compensated with a block of wood and a a small clamp...
There are plenty of youtube videos out there on how to make TS sleds. I just tried to integrate a number of features I liked and document the right tricks that allow you to have everything squared easily for a precise sled. The steps described in this instructable can be used on any TS that has mitre tracks.
I used my TS for 2 months without a sled and I can tell you this sled has been a life changer in my shop.
Step 1: Cut the Guide Strips
In this step, you need to take some hardwood scraps and cut thin strips that will fit in the tracks perfectly. The strip thickness should be less than the depth of the track. You don't want the base of the strip to rub or rest on the bottom of the track. The final strip should be longer than TS table top.
I used some short pieces to set up the fence and sneak in on a snug fit. then I cut the long strips.
Step 2: Nail the Base to the Guide Strips
Take the piece of plywood or particle board that you have selected for the base. It does not have to be perfectly square, but it should not look like a triangle... The size should be about the size of your TS top ideally. I used a scrap piece that happened to be the right size, but in retrospect, I would make the usable cutting width just over 60 cm (24in). the reason for this is that 60 cm is the standard width of a lot of furniture (cabinets, drawers...). Mine happened to be just under 24 in and it has been frustrating for some cuts. The nice thing is that you can make a quick rough cut of a panel with the circular saw and then easily square it up on the TS using the sled. So if you can have 26 to 28" of usable space, it would be perfect. I say usable space because we still need to add two fences on the base, so take that into account so the remaining space is 26 to 28" (65-70cm). Don't cut the base too small.
This being said, drop the strips in the mitre tracks. Lower the blade completely. Then put the board on top and visually align in with the edge of the TS top that is on your side. Then take some small nails and partially drive them through the base and in the guides. The goal here is just to secure the guides in position. Two nails in each guide would suffice. These nails will be removed if they are too long to be driven all the way through. Some people suggest doing this with double sided tape. The nails work fine for me.
Once the guides are secure, filp the base around and drive a 4-5 nails in each guide to secure it to the base. the nail length should be selected so that they do not point out on the other side.
Test the base, it should slide back and forth easily. Use sand paper to reduce any parts that may be causing a blockage. you can add wax or silicone spay to lubricate.
You now have a based perfectly fixed on 2 guides that fits snugly in the tracks.
Step 3: Lift the Blade Through the Base
Clamp the base down on the top, turn on the saw and lift the blade through the base. You can remove the clamps and push the base through a bit more, but do not cut the board completely.
Easy and gratifying step...
Step 4: Add the Fences
Now find some scraps for the fences. For the bottom (main) fence, you need to select a piece that is straight and that has at least 2 faces that have a good 90 degree angle.
I used a trim router with 45 degree guided bit to chamfer one corner of the main fence. This is for saw dust relief. How big should it be? not too big and not too small I guess...
Cut the fence pieces to lenght and position the main fence on the base and use a square (the larger the better) to position it at 90 degrees with the edge of the line cut by the blade. Once you are satisfied it is perfectly square, you clamp it down to the base.
Flip the whole thing around and secure the fence to the base using screws. Drill pilot holes and countersinks so that the head of the screw ends below the surface level.
It is not as critical for the second fence to be perfectly square like the main fence. The wood you select does not have to be as perfect either. Follow similar steps to fix it to the base.
Step 5: Add Some Safety Features
When you complete your cuts, the blade will stick out from the fence. Any finger in its path all also be cut perfectly squarely. This is why it is critical you add a blade guard. you need to find a way to fix it. You could put a plywood triangle on top and use it as a large bracket, you could drive long screws from the inside of the main fence... I had some small metal brackets lying around, so I used those. Whichever method you select to secure the blade guard, make sure the screws are short enough or positioned in a way so that the blade does not hit them, EVER!!!
During my search, on one sled model I saw, the maker had added 2 scrap strips to keep things (hands and fingers) away from the blade. Most designs I had seen before had some sort of removable or sliding plexiglass casing. I quite like the strip method because the material is readily available and it serves the purpose mostly. It is not as "hermetic" as a plexiglass casing, but it is very practical and you always have a nice clean view of your cut. The strips will also deviate any large piece that might might be projected by the turning blade. I feel it's a nice compromise.
I still need to modify the riving knife so it can be permanently fixed on the saw. The one delivered with the saw extends above the blade as it is meant to hold a flimsy blade guard. I need to cut it so it fits just below the blade.
A stop block can easily be clamped on the fence for repeaded cuts.
There you go... some simple tricks to easly build a precise sled for your table saw.
Enjoy the square cuts!