Guide Bushings

Fundamentals of Woodworking: Guide Bushings

My use of guide bushings differs from what you most often read about in magazines and online. Predominantly, articles on router bushings focus around using the router accessory for pins and tails when using dovetail jigs. My use, however, is more outside the box, although I do some dovetail work using the bushings, too.

What are guide bushings? They are small tubes of varying diameters (and lengths) that fit into a router baseplate through which a router bit extends. They are sometimes referred to as template bushings, too.

When run against a template, pattern or dovetail fixture, the side of the bushing keeps the bit spaced a constant distance away (the offset, or the distance from the outside of the bushing to the cutting edge of the router bit).  To calculate the offset, take the guide bushing outside diameter, then subtract the bit diameter and divide by two.

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6 thoughts on “Guide Bushings

  1. What angle of dovetail bits do you use? Or do you use different angles for different situations? Also, do you ever hog out the material first with a straight bit prior to using the dovetail bit, as I was taught to do?

    1. Mitch,
      When routing the sliding dovetail sockets I use a 14° dovetail bit. I cut my pins and tail by hand using a 12° slope, which I like as a design – not to little of an angle and not too much as well. But I cannot find a 12° dovetail router bit, so I move up to 14°, which is easy to find. Additionally, I find removing the majority of waste using a straight bit a waste of time. With a sharp dovetail router bit, there’s no need to use a straight bit first.

  2. Good tips, and the accompanying videos really clarified the info. One thing I’ve wondered about is why would you use a guide bushing in any application where a pattern bit would work, thus avoiding all the offset issues? And maybe my eyes are going bad, but I’d appreciate it if you guys would use higher resolution cameras 🙂

    1. Michael,
      Video in the article is one of the great features that make online woodworking publications special. In areas where you can use a pattern bit instead of a guide bushing, it makes sense to do so. There are times, however, when a guide bushing may be the better choice. If my pattern has many small, tight radii or inside curves, I can see using a guide bushing with a smaller diameter router bit. Finding a small diameter pattern bit is not easy. Whiteside makes a 1/4″ bottom-mount bearing which could take care of most applications. Whiteside has an 1/8″-diameter too, but it has a solid pilot (burn potential) and the cutting length is 3/8″ only.) As for top-mount bearings, a 1/2″ diameter is all I can find.

  3. Good article on a superior technique for shelf holes (IMHO). My question is where do I get one of those safety shield eye protectors? Looks handy. Thanks

    1. Good eyes. You’re the first person to comment on that face shield. It is a great product from RayGear (https://raygear.com/index.php/). The piece I have here in the shop is a X-Shield: Full Face non-vented clear. They have a bunch of choices. I like the fact that the shield goes on and off as simple as glasses. You should check them out!

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