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3 Great Router Jigs


Make your router a workshop workhorse.


by Tim Johnson






If you only use your router to rout decorative edges, you’re missing the boat. Your router can be the most versatile tool in your shop. The secret to unlocking your router’s potential is to use it with specialized jigs. A dovetail jig is a perfect example: With this jig, your router can do the same job as an expensive dovetailing machine. 


Fortunately, you can make many useful router jigs in your shop without spending an arm and a leg. I’ll show you three simple jigs that will expand your woodworking capabilities by leaps and bounds: one for dadoing, one for mortising and one for making shelf pin holes. Although these jigs have been around since the dawn of routers, they’re indispensable additions to any woodworking shop. 






Dadoing Jig


This jig (Fig. A, below) takes the guesswork out of routing dadoes, because setting the exact width is virtually foolproof. Being able to tailor the dadoes’ width to precisely match the thickness of shelves is a real blessing when you’re building cabinets with hardwood plywood, which is always undersize in thickness. 


This jig accommodates wood up to 24 in. wide. Its double T-square design guarantees dadoes that are square to the edges on both left and right cabinet sides. Positioning the jig couldn’t be easier—just line up the fixed fence with the top of each dado. This jig must be used with a pattern bit (see photo, left, and Sources, page 43). This combination is perfect for use with nominal 3/4-in.-thick plywood. It allows routing dadoes from 5/8 to 1-1/8 in. wide and up to 1/2 in. deep.





Make the Jig


1. Glue and screw the fixed fence (A) to the rails (B). Make sure the joints are perfectly square. 


2. Rout the slots in the adjustable fence (C) on a router table, using the router table’s fence and a 5/16-in. straight bit. 


3. Use the adjustable fence’s slots to locate the rails’ carriage bolt holes. Lay the fence on the jig, snug against the fixed fence and flush with the rails. Using a pencil, transfer the slot locations to the rails. 


4. Drill and counterbore the holes.


5. Install the carriage bolts. 






A pattern bit is a flush-trim bit with the bearing mounted on the shaft.  





Use The Jig



Photo 1: Position the fixed fence on a line indicating the top of each dado. Always orient the jig with the fixed fence at the top of the workpiece. Make sure the jig’s rail is firmly seated against the edge. Then clamp both pieces to your bench. 


Both rails are square to the fixed fence, so it doesn’t matter which rail registers the jig. Out of habit, though, I always register the jig against the front edge of the workpiece. 






Photo 2: Set the adjustable fence using offcuts from your shelves as spacers. This method guarantees that the dadoes will be exactly the right width. 







Photo 3: Rout the dado in two passes. During the cut, the pattern bit’s shaft-mounted bearing rides against the jig’s fences, so the dado it cuts is exactly the same width as the opening. Bear against the fixed fence during one pass and against the adjustable fence during the other. 















Mortising Jig 


If you have a plunge router with an edge guide, you can machine professional-quality mortises without buying an expensive benchtop mortiser. All you need is a plunge-routing bit (see photo, left, and Sources, page 45) and this jig (Fig. B, below). 


This jig accepts workpieces of any length. They can be positioned against one end of the jig or extend beyond both ends. Although it accepts stock up to 3 in. wide and 4-1/2 in. thick, this jig is invaluable for routing mortises in narrow pieces, such as door stiles or delicate legs, on which a large, top-heavy plunge router would be tough to balance. By fully supporting the router’s base, this jig makes mortising a breeze. 





Make the Jig


1. Glue two oversize blanks together. From the glued-up blank, cut the bottom piece (A) to final size. 


2. Glue on the sides (B), making sure they’re square to the bottom and level at the top. 


3. Fasten the clamp rail (C). 


4. Drill 1/4-in. holes and install the hanger bolts. Spin a nut all the way onto the bolt. Then use a wrench to thread the bolt into the hole. A doweling jig makes it easy to accurately drill the holes.


5. Make the end stop (D). To make the adjustable stop (E), drill start holes at the ends. Then rout the slots in several passes, using a 5/16-in. straight bit, your router table and a fence. Raise the bit in 1/4-in. increments.


6. Cut stop blocks (F) as necessary for each routing job.








An up-cut spiral bit routs a better mortise than a regular straight bit can. It cuts like a drill bit, lifting chips up and out as it spins, instead of jamming them inside the hole. Chatter-free operation and smooth-walled mortises are the result. 





Use the Jig



Photo 1: Clamp the workpiece in position. First, use shims to raise it flush with or slightly below the top of the rails. Install a stop block when you rout multiple pieces with mortises near the ends, such as this table leg. The width of the stop block determines the location of the top of the mortise. To accommodate wide stock, cut notches for the clamp heads in the back of the jig.






Photo: 2 Center the bit on the layout lines by adjusting the router’s edge guide. With the router unplugged, use the plunge mechanism to lock the bit in position just above the workpiece’s surface. Before you adjust the edge guide, orient the bit’s cutting flutes to span the mortise. 






Photo 3: Install stop blocks. For the table leg shown here, the end stop determines the top of the mortise and the adjustable stop determines the bottom. 


To rout mortises in the middle of a long workpiece, such as a bedpost, remove both stops. Install a second adjustable stop and relocate the first, using the alternate hanger-bolt holes (Fig. B). Center the mortise between the stops when you clamp the workpiece in the jig. If you only have a couple mortises to rout, don’t bother with the stops. Just rout to the layout lines.






Photo 4: Plunge-rout the mortise in several shallow passes. After routing, square the mortises with a chisel if your tenons are square-shouldered.










Shelf-Hole Jig


Forget about tedious drill press setups or using pegboard as a not-so-accurate template: This jig (Fig. C, below) eliminates the onerous task of drilling adjustable shelf holes. And because you plunge-rout the holes, you won’t have any of the unsightly tear-out that drill bits frequently cause.


To use the jig, you need a plunge router equipped with a 1/4-in. bit and a template guide (see photo, left, and Sources, page 47). Your router’s plunge mechanism must slide smoothly; side-to-side play will result in oversize holes. Operate at a slow (9,000- to 12,000- rpm) speed and use a steady plunge rate.  


It’s easy to modify this jig. For example, the holes can be spaced differently from the edges or clustered in groups. You may need a shorter version to fit inside a cabinet. 





Make the Jig 


1. Before you make the jig, test-fit your template in a hole drilled with your Forstner bit. The guide should fit snugly without binding.


2. Lay out the holes. 


3. Drill the holes on your drill press, using a fence and a 1/2-in. Forstner bit. Before you drill, set the depth stop so only the center point of the bit goes all the way through the jig.


4. Flip the jig over to finish drilling the holes. This two-step drilling method ensures clean holes on both faces of the jig. 


5. Make the alignment pin:


-Joint one side of a 2x4 and clamp it to your drill press, jointed side down. 


-Using a Forstner bit, drill a 1/2-in. hole all the way through the 2x4. 


-Seat a 1-3/8-in. length of 1/2-in. dowel in the hole so it sits below the 2x4’s surface.


-Without starting the drill press, lower the bit to mark the dowel’s center, using the walls of the 1/2-in. hole to guide the bit. 


-Install a 1/4-in. bit and drill a 1/2-in.-deep hole in the dowel, using the center mark you’ve just made to guide the bit.


-Glue a 1/4-in. dowel in the centered hole. Then trim it to final length.






A spiral down-cut bit eliminates tear-out around the edge of the hole, thanks to the bit’s downward shearing action. This bit works especially well with veneered plywood, which tears out easily. 





Make the Jig



Photo 1: Position the jig flush with the top and the front edge of the cabinet side. Securely clamp the jig and you’re good to go. To rout the back row of holes, flip the jig over and align it flush with the top and the back edge. You can also use this jig inside a completed cabinet. Just register it against the cabinet’s top or bottom. If you need to allow room for an inset door or Euro-style hinges, use a pair of setback guides (Fig. C) to move the holes farther back from the front edge. 






Photo 2:  The template guide precisely fits each hole, locking the router in position, so every hole you rout is perfectly located. The guide’s collar must extend less than 1/2 in. so it doesn’t protrude beyond the 1/2-in.-thick jig. The guide must exactly fit the holes in the jig, but the size of its outside diameter isn’t critical. To use a 1/2-in. template guide like the one shown here, drill 1/2-in.-dia. holes; to use a 5/8-in. guide, drill 5/8-in.-dia. holes.






Photo 3: The alignment pin makes it easy to reposition the jig on long cabinet sides. Installing the pin aligns the jig’s top hole with the last hole you’ve routed. With the pin installed, clamp the jig flush with the front edge and you’re ready to rout additional holes.




















Porter-Cable, (888) 848-5175,  1/2-in.-o.d. template guide (most routers accommodate Porter-Cable template guides), #42033, $7. • MLCS, (800) 533-9298,  1/4-in.-dia. solid-carbide spiral down-cut bit, #5177, $14. Freud Tools, (800) 334-4107,  1/4-in.-dia. up-cut spiral bit, #75-102, $21. 5/16-in.-dia. up-cut spiral bit, #75-104, $45. 3/8-in.-dia. up-cut spiral bit, #75-106, $42. 1/2-in.-dia. up-cut spiral bit, #75-109, $74. • Rockler, (800) 279-4441,  1/4-in. x 3-in. hanger bolts, #24463, $2 per package of eight. 1-in. round knobs, #34095, $1 ea. 7/8-in. 3-star knobs, #68064, $1 ea.  Amana Tool, (800) 445-0077,  5/8-in.-dia. x 1/2-in. flush-trim plunge-routing (pattern) bit, #45469, $21. • Rockler, (800) 279-4441 5-star knob, #23804, $1 ea.






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