re: New mitre sled

Ok here is what i did. I bought two miter bars from rockler. I’ve made all the miter bars in the past out of hardwood but, with a shop that goes throught to many humidity changes I’ve had to many offs. So i picked my ply shimed up the miterbars 1/32 above the table. put two very small pieces of carpet tape on bars to aid in holding the bars to attached them to the sled ply. (You want clearence under the bars so theres no drag on bars to miter slot) I squared the ply up to the rip fence of which is parallel to the miter slot. Then i laid the ply down onto the table, slid the ply back of which the bars should come with it because of the tape. Then fasten miter bars. Next, i made up my front & back support and fastened them from underneath with screws. Use carpet tape to hold them into place. Do long edge to long edge line up.
NOW the important stuff. What i did is square up two pieces of wood and do a half lap joint on one end. Its very important that this be precise and square. Glue up your half lap check it for square on the outside since this is the side you will be using for your miters. Now let that dry. Next, pull your sled back turn the saw on and make a cut with the blade you are going to use for your miters. Cut only to about11/2" from back fence. Dont go through. Now this is what i did.. i took my machinist 45° angle and set it along the saw groove just cut in the ply then i placed carpet tape on the underside of my 90° wood with the half lap and lightly put it on the ply and aligned it with the 45°trued it up with the outside & inside corners in the center of the saw kerf and pressed it down. I trippled checked it then slid the ply back added two clamps to hold the 90° wood to the ply rechecked it to make sure it was 45°to my saw kerf then screwed it down. Now you can use a bevel square to do this but you needto make sure you set a true 45.
after the 90°is screwed down run it through the saw again. Now you have a left zero clearance cut and a right zero clearance cut from the blade that is your mark. Put your pencil marks on the edge of the saw kerf a it will be exact.