Router Second Pass To Enlarge Dado

Here's a familiar problem. You want tc make a series of ^inch-deep dadoes in some cabinet sides.

As every routerhead knows, the machine is a trimmer, and you shouldn't really cut deeper than about Y* inch per pass. Your router is a fixed-base machine, so for each dado, you set the depth of cut to V\ inch and make a pass, then advance the setting to ¥* inch and make a second pass.

When you are done, you assess the process. Adjusting the router twice for each dado took a lot of time. And it didn't give you consistent results: Some dadoes are Ys inch deep, but a few are shy of that, and several others are deeper. Moreover, the play in the adjusting mechanism throws some didoes off, leaving the dado too wide at the surface, with a ridge along one wall near the bottom. (See Ridged Dadoes.)

PLÄV IN nil ADJUSTMENT MLCUÀWI3M LEADS TO RIDÇED DADOES

The double-bar dadoing guide offers a.single solution to all these woes. Slot the spacer to give it an extra dimension.

After you trim the spacer to the proper width, rout a slot the same way you would a dado. When using the guide, set your fixed-base router for the final depth, but make the first pass with the spacer in place. You can cu: up to about Yi inch deep in two passes that way.

You have only a single adjustment to make, so you save time. All your dadoes will be of a consistent depth, and play in the mechanism won't displace parts of dadoes.

A hard hoard or plywood spacer makes il easy to set the movable fence for a particular width of cut. Make a set for cuts of common widths, and prominently mark each. If you rout a slot in the spacer, it can help you make your cuts in two steps, without having to adjust the router's depth of cut.

ZERO EDCE

EDGE

BASEPLATE (RÏ

fractionating baseplate will add new dimensions to your straight bits!

This baseplate looks like a square, bur it's a trickster developed by Nick Engjer, one of my favorite woodworking writers. The measurement from the axis of the bit to each of the four baseplate edges is different. With this baseplate, you expand the cutting width of any straight bit in your collection, and you give yourself the ability to produce a greater incremental range of cuts.

Cutting a %6-inch-wide dado, or a Winch-wide dado, or an Wo-inch-widc dado is as simple as turning the router to reference a different edge against the guide fence. Use a Winch straight bit and make a pass with the "zero" side against the fence. Turn the router so the "+'/&" side is against the fence, and make a second pass. The additional V« inch between the bit and the fence adds '/« inch to the width of the cut.

Using a Winch bit with this base gives you dado widths of V* inch, inch. % inch, and inch. A Winch bit yields widths of 'A inch, Vit» inch, Ys inch, and 'Ao inch.

If you are really clever, you'll sec that Nick's idea is an inexpensive solution to undersized plywood. One of the shortcomings of plywood, especially hardwood stuli. is that it's often (usually?) a 64th or a 32nd undersized. Three-quarter ply is more likely 2Vk inch or inch. So it rattles in the dado you cut for it with your Winch straight. Maddening.

One solution is to buy special dadoing bits that are % inch. But a less costly solution is to make a version of this fractionating baseplate that'll allow you to make those off-sized dadoes in two passes with a Winch or Winch bit.

To make the baseplate, cut a square of plywood or acrylic. Drill mounting holes using the factory baseplate as a template. Screw the plate to the router, and bore a Winch bit hole by switching on the router and advancing the bit into the baseplate. Now remove the baseplate from the router. Measure from the bit hole to the edges

Make a pass with the "zero" edge of the fractionating baseplate against the fence; the cut will match the hit's diameter. Tunt the router so a different edge rides the fencc, and make a sec ond pass. The bit is repositioned farther from the fence, widening the cut.

ZERO EDCE

EDGE

BASEPLATE (RÏ

fractionating baseplate will add new dimensions to your straight bits!

Fractionating Baseplate spacers. Each spacer is a strip that's the length of the fences. 1 drop it between the fcnces. snug the movable fence against the spacer and in turn the spacer against the fixed fence, then lock down the movable fencc.

To use the guide, measure and mark just the top of each dado. This is easy to do with a square to extend lines across the work: All you need is a little tick-mark.

fhc trick here is the notch routed in the crossbar. Because only one router and bit is ever used with the guide, that notch tells you how close to the fixed fence one edge of the cut

To positron the guide, use the notch made in the crossbar. Align the edge of the notch that's closest to the fixed fence with the edge of the dado you want to rout.

fhc trick here is the notch routed in the crossbar. Because only one router and bit is ever used with the guide, that notch tells you how close to the fixed fence one edge of the cut

To positron the guide, use the notch made in the crossbar. Align the edge of the notch that's closest to the fixed fence with the edge of the dado you want to rout.

This teardrop-shaped baseplate is a cam. The radius of its edge's arc is steadily changing, soyou can alter the hit's position in relation to the fence by turning the router. Once you calibrate the baseplate, you can widen a dado or groove by any fractional amount between zero and 'A inch simply by twisting the machine and referencing a different spot against the fence during a second pass.

of the baseplate, as indicated in Fractionating Baseplate. Trim the baseplate »produce the desired result. Remount the baseplate and you're ready to cut some odd-sized dadoes.

Cam Baseplate

Taking Nick's idea one step further. Fred made a baseplate whose circumference is a curve of steadily increasing tadius. The baseplate is thus a cam that displaces the bit by Y-* inch when you rotate the router three-quarters of a turn.

The theory is: If you cur and mount the baseplate accurately, you should have no trouble cutting a dado or groove of the oddest width to an exact lit. When you make the first pass, set the base's zero point against the fence. You'll get a cut the width of the bit. Then you just "dial in" the amount by which you want to increase the width of the groove, by rotating the router and making a second pass with the appropriate spot against the fence.

To make the baseplate, begin with a 10- to 12-inch square of Winch I baseplate material. Fred used a piece of white acrylic plastic, but you can use pl^vood. polycarb, phenolic, or whatever you have rhat's appropriate. Using the router's factory' baseplate as a pattern, drill mounting-screw holes (only) and mount the blank on the router. Using a Winch-diameter straight bit. bore a bit opening through the blank.

A stnng compass is used to scribe the circumference of the baseplate. (You can do this with the blank still mounted on the router, though you do have to remove it to cut it.) Tape the end of the string to a Winch dowel or router-bit shank. Insert this swing point—you don't actually pivot the dowel or bit—in the bit opening. Wrap the string around the dowel or bit several times, then tic the free end around a pencil or marker. Set the marker on the blank and swing an arc of about 270 degrees (three-quarters of the way around the blank). As the arc is made, the string unwinds from the dowel and bccomcs longer. (Don't let the dowel turn as you scribe.) Instead of having a fixed radius, the curve you scribe has a steadily changing radius.

On the table saw, cut down the blank so you have one 90-degree comer forming tangents to the ends of the

This teardrop-shaped baseplate is a cam. The radius of its edge's arc is steadily changing, soyou can alter the hit's position in relation to the fence by turning the router. Once you calibrate the baseplate, you can widen a dado or groove by any fractional amount between zero and 'A inch simply by twisting the machine and referencing a different spot against the fence during a second pass.

arc, as shown in Fractionating Baseplate. Use a saber saw or band saw to carefully cut to the curved line. Sand the sawed edge smooth.

Remount the baseplate on die router, and use a larger-diameter bit to enlarge the bit opening. Then make a series of test cuts to calibrate your baseplate. The zero point should be with one flat side against the fence, the maximum offset with rhe other flat side against the fence. Maybe you want to mark the plus jAtr, plus W, and plus Mo-inch spots. Plus Ya inch will lie roughly midway between the % and Yit marks.

will be. Align the notch's edge with your tick-mark. If you're going to make a cut wider than Vi inch, the extra width is going to be toward the

If you don't have a plunge router, the double-bar guide helps you make do with your fixed-base router. Instead of tipping the bit into the work, start with it in the crossbar notch.

will be. Align the notch's edge with your tick-mark. If you're going to make a cut wider than Vi inch, the extra width is going to be toward the

If you don't have a plunge router, the double-bar guide helps you make do with your fixed-base router. Instead of tipping the bit into the work, start with it in the crossbar notch.

movable fence. (Unless you have a different T-square for each bit, you can't reliably use a T-square's crossbar notch to line up the work like this.)

Now clamp rhe jig in place on the work. Set the movable fence, and you're ready to go. Make a pass from left to right, cutting a Winch dado; then return from right to left, widening the dado from Vi inch to your final width.

PE-NCIL

MOCWTlMC-SittW HOLE-POJITWN 50 KOU1LA WILL

STRING

BASEPLATE

DIAL IN" TUE CUT WIDTH VtTW THIS CAM BASEPLATE

AS PENCIL Ii SWUNG AROUNO DOWEL,STRING UNWINDS, BECOMING LONGER. RADIUS Or ARC THUS BEÍ0HES GREATER. _____

LAYING OUT THE BASEPLATE

GROOVING WITH AN EDGE GUIDE

CUTTING LIST

Piece

Number

Thickness

Width

Length

Material

Fences

2

Vi"

3"

36"

Birch plywood

Crossbars

2

Ya"

2'/2"

15"

Hardwood

Spacer

1

Va"

variable

36"

Lauan plywood

Hardware

8 pes. #8 X I" flathead wood screws

2 pes. 'A" X

Wi" flathead machine screws with washers and nuts

2 pes. V«" wing nuts

1. Glue and screw the fixed fence to the crossbars. A right angle between the fence and crossbars is essential.

2. Rout the slots in the movable fence.

3. Cut a 'A-inch by 36-inch plywood strip. Rip it to the width that exactly matches the diameter of the router baseplate. The edges of the plywood spacer must be parallel.

4. Butt the spacer against the fixed fence, then butt the movable fence to the spacer. Trace the slots onto the crossbars. Mark the center point for the fence's machine screw "stud" at the end of the slot that's fanhest from the fixed fence. Then drill a fi-inch-diamcter counterborc about Mft inch deep. Bore a 'A-inch hole for the stud. Countersink the bottom of the crossbar.

(NOTE: The spacer's utility goes beyond its use in making the guide. The guide's basic cut is the '/¿-inch dado, and though you won't need the spacer to set the fences for that cut. you may want to use it as a spacer in making two-pass cuts. See "Problem Solver" on page 229.)

5. Drive a machine screw into cach hole, fit washers on the screws, and tighten the nuts down into the coun-terborcs.

6. Drop the movable fence over the studs, add the washers, and cinch the assembly in place with wing nuts.

To make a spacer:

1. Clamp the jig to a scrap work-piece.

2. Determine the width of the dado. Because you will always use a '/2-inch straight bit with this guide, that's the width of cut you get when the distance between the fences equals the diameter of the router's baseplate. To get a cut wider than Vi inch, subtract'/»inch from the width, then add the difference to the router baseplate's diameter. The sum is the width of the spacer.

Example: To make a spacer for a 7/«-inch dado, subtractVi inch from 7/a inch. The difference is Y* inch. Add Ys inch to the diameter of the

Using the dadoing baseplate is a lot like using a pattern hit and template. but with-out the router tippiness. Line up the fence directly on the edge of the dado. The bit will ait right along the fence's edge. This setup is especially good where, as here, the cut skews across the workpiece, rather than being square or parallel to an edge.

router baseplate. If it is 6 inches, then the spacer must be 6V* inchcs wide.

3. Cut the spacer and use it to set the movable fence. Remove the spacer from the jig. Mnke a test cut in a scrap piece. Measure the dado's width. If it is too wide, trim the spacer and repeat the test procedure. If it is too narrow, cut a new spacer, making the second wider than the first. Repeat the test procedure. If it is right on. return the spacer to the guide and rout the slot.

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Woodworking Tools and Installation Tips

Woodworking Tools and Installation Tips

There are a lot of things that either needs to be repaired, or put together when youre a homeowner. If youre a new homeowner, and have just gotten out of apartment style living, you might want to take this list with you to the hardware store. From remolding jobs to putting together furniture you can use these 5 power tools to get your stuff together. Dont forget too that youll need a few extra tools for other jobs around the house.

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