One popular way of guiding a router is to follow a template or pattern attached to the work piece. To keep from cutting through the template, a bushing with a fixed collar of a larger diameter than the bit is used. One advantage to using a bushing, rather than a bearing or pilot attached to the bit, is that the bushings position is independent of the depth of cut. This is ideal for cutting out copies without the need to go full depth on the first pass.
Because the bushing must have a larger diameter than the router bit, there is a fixed "offset" between the edge of the bushing and where the router bit will cut. It is important to account for offset when making a template or pattern. Choosing an bit and bushing pair that gives a standard fractional offset, such as 1/8" or 1/4", makes everything go more smoothly, which is exactly the reason it is so handy to have a full set of bushings.
This set contains 7 bushings that will fit router bit diameters of 1/4" to just over 1/2". The bushings and hardware are made of brass, so they'll ride smoothly over a range of template materials. The bushings attach to your router using a large knurled nut (two supplied) and will fit most American routers. The collars also fit the Festool 1400 router using the universal plate which is included with each machine. The inner diameter of the bushing that fits through the base of the router is 1 1/8". The shoulder which sits flush into the base of the router is 1 3/8" in diameter and about 3/32" thick.
Each set contains the following:
| Inner Diam. | Outer Diam. | Length |
| 1/4" | 5/16" | 5/32" |
| 9/32" | 3/8" | 5/16" |
| 11/32" | 7/16" | 5/32" |
| 13/32" | 1/2" | 1/2" |
| 5/8" | 51/64" | 1" |
| 17/32" | 5/8" | 9/16" |
| 21/32" | 3/4" | 9/16" |
| 2 lock nuts |
| Plastic Storage Case |
