Routers are fantastic woodworking tools. And when you put a router in a router table or a Router Boss, you add new levels of accuracy, repeatability, and the ability to work safely with smaller pieces of wood. But, to gain accuracy on a router table, it needs to be set up correctly, to begin with.
Step One - Table Top
Whether a store-bought or home-made router table, the top needs to be flat so the wood doesn’t rock when running past the bit. That’s what a good straight edge is for. To adequately evaluate the flatness of the top, you need a reliably straight rule that is no less than 24” in length. A standard 12” rule doesn’t allow you to measure across the whole table. As all of the work is happening in front of the fence, you need only check flatness at the front of the table, but you should check side-to-side, front-to-back, and angled from corner-to-corner as well. Perfect is always elusive, but there should be little to no gap between the table surface and the bottom of the straight edge.
Step Two - Lift Plate
While we’re on the top of the table, this is a good opportunity to check the lift plate. Most router tables today employ a router lift to make adjusting the bit height easier. It’s important that the lift plate is flush, or possibly slightly lower than the surface of the router table. Again, the straight edge is a valuable tool for determining the proper alignment. In some instances, adjusting the plate height may require you to remove the lift, adjust, and replace it. This can get tedious, but it’s a step worth getting right, so take your time.
Step Three - The Fence
Next, make sure the fence is flat and square to the top. Once again, we start with the straight edge checking the fence along its length and also angling the straight edge to check for flatness. To make sure the fence is square to the table, you must tighten down the fence in its location. Checking against a loose fence does no good. Check along the length of the fence for square.
Again, perfect isn’t always possible, but very close is. Because many router table fences use wood faces, there can be slight variances, and there can also be dust or dirt behind the fence face keeping the fence from sitting square. If your fence isn’t square, investigate the possible issues and then check for square again.
Step Four - Adjustment to Bit
Router tables are often used with part of the bit set back behind the face of the fence, or fully exposed in front of the fence. Both techniques are standard, but everyday safety practices are needed to make sure the operation is safe, including using feather boards and appropriate guards. Conveniently, the fence doesn’t have to be parallel to any edge of the router table to make these cuts. The setup concerns are depth and height of cut, both of which are easy to gauge. When cutting in front of the fence, Setup Blocks can remove much of guessing and fiddling. After determining the proper offset distance to the fence, set the fence using a setup block or blocks. The setup blocks also solve the common issue of the fence opening, making measurement difficult with a standard rule.