A router sled for flattening slabs or end grain cutting boards is a useful jig in any shop. You can go to a store and purchase a pre-made jig for hundreds of dollar, but spending only $40 sounds way better! Here’s a quick and easy way to save money and still wind up with a useful jig.
- (2) – 3/4″ x 2′ x 2′ MDF Board ($5.73)
- 2″ x 96″ Aluminum Angle, 1/16″ Thick ($26.56)
- #8 – 1.5″ Wood Screws ($4.24 for 50)
- Wood Glue ($3.97 for 8 oz. of Titebond II)
- Small scrap pieces of 2×4
Let’s Get Started – The Platform
Using one piece of MDF, cut two 2.5″ strips from the SHORTER edge. Although the nominal dimensions of the MDF are 2′ x 2′, one side will actually be a half inch longer than the other. These will become the side rails, which your router jig will slide on. Because of that, it’s critical that these two strips are exactly the same width, with perfectly straight (and parallel!) edges.
The second piece of MDF will be your platform. Next, clamp one of your 2.5″ strips on its edge along one side of the platform. With the clamps in place, flip the piece over and pre-drill 4 holes, being sure to countersink the holes. Now remove the clamps and add wood glue to the edge before reclamping. Drive four screws into your pre-drilled holes to secure the rail to the platform, then wipe off any glue that squeezed out. Now repeat that whole process on the opposite edge with the other rail.
The Router Sled
The aluminum angle bars will be the base of the sled on which your router rides. First, take a precise measurement from the outside edge of one rail to the other – This should be roughly 24”. Depending on the size of your router, it’s good to have 4-5” of overhang on each side when we cut the aluminum pieces to length. This overhang will allow you to use the full width of your platform. Since you want that overhang on each side, cut your aluminum stock to 10″ longer than the width you measured earlier. This should give you two 34″ long pieces of aluminum angle bars.
Measure the width of your router base – then add 1/8″ to it. This will be the distance between the two vertical pieces of aluminum, with the extra 1/8″ ensuring that your router slides freely and doesn’t bind. Take some scrap 2×4 – or any other scrap in your shop – and cut two pieces to that length.
Clamp those pieces inside the aluminum angle as pictured below, and check that your router slides freely through the sled. If there’s too much gap between the router base and the vertical pieces of the aluminum, trim some length off of your scrap. If your routergxets caught in the router sled or is difficult to move, add some shims to the end of one or both pieces of scrap to widen the sled a little bit.
Once you have a good fit, go ahead and flip your router sled over with the assembly still clamped in place. Drill and countersink holes through the aluminum into the scrap wood, and then use screws to fix the whole assembly in place. One screw in each corner of the sled will work fine! Now you can remove the clamps and place the sled back upright on the rails.
At this point, you have a perfectly functional router sled, but I’ve added one extra feature to mine. Two more pieces of scrap wood attached to the underside of the sled will help keep your sled on the rails! Few things would be as disastrous (not to mention dangerous!) as having your sled fall off the rail and watching your router bit take a huge chink out of the middle of your workpiece.
The other nice thing about this router sled is that it’s very easy to adjust the dimensions to fit the type of work that you do. If you flatten a lot of long slabs, then make a longer version. If your usual material is thicker, then you can make the rails taller, although you’ll want to add some thickness/support to the rails if you go too much taller.
Now Go Flatten Something!
And there you have it. A cheap and easy way to flatten anything! If you’ve used a sled like this in the past, or have a better way to do it, let me know in the comments below.
Now that you have the jig complete, all you need is a router and a flattening bit – but that’s a discussion for another day.