A miter lock router bit cuts matching tongues and grooves into a workpiece to create a strong angled joint. Not only does this bit increase the glueable surface area of a joint, but it also automatically aligns the opposite pieces, reducing the need for special clamps. You can use the common 45° bit to create parallel or perpendicular joints, for such projects as drawers, boxes, and frames.
In order to use a miter lock bit, you’re going to need a router with a 1/2″ collet, and a router table equipped with a fence. I also advise beginner and intermediate woodworkers to order a set-up jig with their miter lock bit, to ease the learning curve.
Once you’ve set it up properly, run one side of the joint along the router table so the center of the stock is aligned with the centerline of the miter-lock bit. Then, run the opposite side of the joint along the fence to create a matching contour. For thicker materials, you may want to complete the cut in several passes, to protect the bit and achieve a smoother cut.
You can choose from two main bit sizes — one for thin panels, and the other for 3/4″ stock and thicker. You can also get 22.5° bit sets, which can make parallel or 45° joints. Many reputable router bit manufacturers offer decent quality miter-lock bits, with prices ranging from $40 to $100 for the 45° style.
If you’re looking for great quality, consider MLCS’s Katana bit which costs $53 (or $44 for the smaller size), and carries a lifetime guarantee. MLCS also offers regular-quality and 1/4″ shanked bits — but for the extra few dollars, stick with their Katanas. For excellent quality, consider Freud’s bit, which is currently going for $70 on Amazon after 25% discount. No matter which brand you go with, be sure to check out the helpful instructional video at MLCS and their detailed article.
Miter Lock Bit [MLCS]
Miter Lock Video [MLCS]
Miter Lock Instructions [MLCS]
Miter Lock Bit [Freud]
Street Pricing [Google Products]
Freud 45° Bit Via Amazon [What’s This?]
Freud 22.5° Bit Via Amazon [What’s This?]