Guiding Your Router, Part 2
Chapter 3, Lesson 3 of 3
GOAL: To understand the systems available for guiding a workpiece past the bit of a router mounted in a router table.
There are seven systems for guiding a router as its bit cuts a workpiece. Four are applicable when the router is handheld and passed over the top of a workpiece clamped to a table or bench; three involve pushing the workpiece past the cutter with the router mounted under a table. This lesson will explain the three guide systems for cutting with a table-mounted router.
In using each of the following systems, you must control the travel of the workpiece. It must be held firmly to the bed and fence or pilot bit on the router table. The router must be securely mounted under the table.
Guide System 5: One-part Fence on Router Table
The guide is the edge of the workpiece. It runs against the router table fence. The cutter is partially buried in the fence. The offset is the distance from the fence to the edge of the cutting circle.
When it's possible to make the cut you want with a one-part fence on the router table, it is the safest and simplest method of routing.
This method is accurate for cuts that do not remove the entire edge of the workpiece. If the cutter were to remove the entire edge of the workpiece, it would also destroy the guide surface, and the setup would be thrown out of control.
Work-holding sleds with fences that run on the front edge of the router table use the same guide method. With a one-part fence on the router table you can:
- Rabbet an edge.
- Mold part of edge.
- Slot or groove the workpiece.
Note that you can use pilot-bearing bits with the router table fence by setting the fence in line with the bearing or forward of it.
Guide System 6: Two-part Fence on Router Table
This setup is like a jointer turned 90°. The guide is the edge of the workpiece, which runs initially against the infeed fence. The offset is the distance from the infeed fence to the cutting circle. Once a cut of 4" to 5" is made, the workpiece must be kept in tight contact with the outfeed fence. The edge of the workpiece becomes a self-jigging fence that uses the outfeed fence as a guide. With this guide system you can:
- Remove all of an inadequate edge to make it straight and square to the face.
- Mold all of an edge.
Guide System 7: Pilot on Router Bit on Router Table
The pilot bearing is the guide. The fence is the workpiece edge or a template attached to the workpiece. The offset is the distance from the outside of the pilot bearing to the cutting circle. This setup always requires a starting pin.
With this method you can:
- Make a rabbet. One way to adjust the size of the rabbet is to change the bearing on the bit.
- Mold part of the edge of a board.
- Rout a groove or slot in the edge of a board.
- Make cope-and-stick frames for cabinet doors.
- Raise a panel.
To shape the full edge of the workpiece, you must use a separate template. The template can be mounted on top of the workpiece or below it.
Mounting the template below the workpiece allows the edge of a work-holding sled to act as the template. This makes a safe and stable setup for pattern-routing shaped parts, such as chair legs. Mounting the template on top of the workpiece gives you better visibility of the contact between guide and bearing. This calls for a bit with a tip-mounted pilot. When the pilot bearing is the same size as the router bit, the offset is zero and the setup reproduces the template. When the pilot bearing is not the same size as the router bit, the offset reduces or enlarges the template profile.
Shaping the Full Edge
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