Heres a simple jig sent in by a reader that makes drawing arcs foolproof All you need are four nails and a couple scraps

Tedswoodworking Plans

16.000 Woodworking Plans

Get Instant Access

When it's time to lay out an arc (especially large ones like those used on the wardrobe on page 6), you practically need a degree in mathematics to calculate the radius. But Ben Rickey, of Arlington, Virginia, came up with an easier solution. He sent in a simple jig to draw perfect arcs. And the beauty of it is, you don't need to use any math at all.

Ben's jig is a couple of strips of wood and a few finishing nails. But the secret to making it work is where you place the nails.

layout. To find the location for the nails, you need a few layout lines to mark the length, height, and center of the arc, see Fig. 1.1 drew these lines on a piece of hard-board (Masonite) so it could be used as a template. They could be drawn right on the workpiece, but you'd be left with nail holes.

Once the layout lines are drawn, four finishing nails can be driven into the hard-board at points A', 'B', 'C', and 'D', see Fig. 1. These nails serve two purposes. First, they're used to help construct a sliding arm (the two strips of wood), see Fig. 2. Second, they guide the arm when drawing the arc. sliding arm. To construct the sliding arm, lay the wood strips against nails A', 'B', and 'C\ see Fig. 2. Where the strips overlap, join them together with a little glue and a few short brads, see Fig. 2a.

Now cut off the "ear" from the overlapping end of each strip and make a small notch on the outside corner where the pieces intersect, see Fig. 2b. This holds the point of your pencil when you use the jig.

But before you can draw the arc, nail 'C' has to be removed, see Fig. 3. It gets in the way when using the sliding arm.

using the jig. To use the jig, hold the arm against nails A' and 'B' and slide the arm along the nails to draw the first half of the arc. When one half is complete, simply move the sliding arm against nails 'B' and 'D' and finish the arc, see Fig. 4.

A band saw or a sabre saw can be used to cut out the arc. Then to smooth the edges, I sanded them by hand with a sanding block, see the tip on page 29. □

Like my workbench, this cutting board's laminated, maple top provides a solid working surface. And they're both built solid to keep them from rocking. But a cutting board has to "stand up" to one element that workbenches don't — water.

All this moisture expands and contracts the wood and eventually breaks down the glue that holds the top together. The result is the joint lines split open (usually at the ends), see the box at right.

To prevent this, I use water resistant glue when I know the wood will be in contact with water. But for this project, I combined a special woodworking technique in addition to the glue to prevent the top from splitting. This technique is to install butterfly-

shaped keys into the top.

These keys certainly make the cutting board more attractive. But from a practical side the keys tie or "lock" the pieces together. So even if the glue bond fails, the keys keep the joints from splitting completely open.

Before making the keys, you have to build the top. This isn't complicated. Just edge glue five boards together after cutting notches for the keys.

sizing stock. I wanted to reduce the amount of chipout when planing the boards to a final thickness of 1". So I spent some extra time sorting through my 5/4 maple stock picking out the boards with the straightest possible grain. I used five of my best

Joint separation. On many cutting boards the joints split open from excess moisture. To prevent the joint from opening completely, a dovetail-shaped key locks the pieces together. The strength of the key is in the grain direction. Since it runs perpendicular to the grain in the top, it won't split as the joint opens.

The butterfly-shaped keys on this cutting board look great, and they lock the boards together to prevent the ends from splitting.

pieces to make up the llW-wide x 16"-long top, see drawing at right.

If s also a good idea to make a couple extra pieces. They come in handy later as test pieces. Note: To ensure tight joint lines when the pieces are glued together, make sure the edges are smooth and square.

notch layout. With the stock planed to size, the next step is to shuffle the pieces so the best face is up. Later, these pieces are paired together so a pair of dovetail-shaped notches (one at each end) can be cut into the mating edges. Each notch forms a butterfly-shaped opening for a key to fit into.

It can get a little confusing cutting all these notches. Especially since the three pieces in the middle have notches cut on both edges. So to help keep track of everything, I numbered each of the mating edges, see drawing at right. Unless you like working jigsaw puzzles, this makes it easy to get all the edges realigned with each other after they've been routed.

routing notches. With the pieces numbered, the dovetailed notches can be routed next. A simple way to do this is with a W dovetail bit in the router table. But there's a small problem. Trying to make a full-depth cut (7/i6") with a dovetail bit can cause the workpiece to shift in the middle of the cut. So instead of starting with a dovetail bit, I used a V411 straight bit and left about Vi6" for the dovetail bit to clean up, see Fig. la.

I also added an auxiliary fence and stop block to the miter gauge. This way, the workpiece can be securely clamped to the

Sort boards with best face up

Numbered face is good face

NOTE:

Plane stock to 1" thick

Number mating faces to help locate position of notches fence to keep it from shifting. And the stop block keeps all the boards in perfect alignment with each other so the notches all end up in the same location. Note: See the box below for an alternate method of cutting the notches without a miter gauge.

Note: The test pieces also need this notch routed. They'll come in handy later when setting the depth of the dovetail bit.

One trick that I use when routing these notches is to rout two pieces at the same time. This is where the numbered faces really help. Simply fold two pieces together, number to number, and rout a notch in both pieces, see Fig. 1 and detail at right. There's a couple advantages to doing this. First, the notches will be aligned perfectly with one another. And second, there's less chance for chipout on the good faces.

Fold boards with numbered faces together

Start by removing the waste from the notch at one end. Then rotate the workpiece 180° and rout the other end. Note: When using a V4" bit to remove waste, make a couple of passes to reach the final 3/8M depth.

With the waste removed, the dovetail bit is installed in the router, see Fig. 2.1 used a test piece first to check the dovetail bit depth. And I set mine to cut 7/i6M deep, see Fig. 2a. Then rout the dovetail-shaped notch in all the pieces. Here again I paired-up the mating boards and cut the notch in both pieces at the same time.

Use stop block to locate workpiece

Workpiece

Stop block

Plywood sled replaces miter gauge straight bit

Clamp workpiece to auxiliary fence

Straight bit removes most of waste

Workpiece

Workpiece

3A"-thick hardwood fence

_-thick plywood base

Notch-cutting jig. You don't need to use a miter gauge to rout the notches for the keys. A small piece of plywood with an attached fence will do the same thing.

Adjust bit height to cut full depth with one pass

dovetail bit

Once the notches have been routed, the top pieces of the cutting board are complete. Now, keys can be cut to fill the notches.

KEYS

For this to work, it's important that the grain direction of the key runs perpendicular to the grain of the top, see photo on page 18. Otherwise, the key splits right along with the joint. But don't worry about getting the grain direction figured out. It's automatic when you crosscut the key blanks off the end of the board, see Fig. 3.

making blanks. I chose cherry for my key blanks because of the contrast with the maple top. But whatever wood you choose, the goal is the same. Getting a tight fit.

To do this, the first step is planing down a piece of stock to match the widest part of the notch cut in the top pieces, see Fig. 3. (In my case W.) I checked the fit after each pass through the planer. Once it fits tight, the blank can be cut to length.

The length of the key matches the height of the opening created by the paired notches. This opening is 7/s" on my pieces, so my keys are this length. Note: It's a good idea to cut extra blanks for setup pieces.

shaping keys. Now all that's left is to cut the butterfly shape. Unfortunately my router table wasn't setup for these small pieces. So I added an auxiliary table with a smaller hole for the bit, see Fig. 4. And for safety, I used a push block to rout the pieces, see Fig. 4a. (For more on this auxiliary table refer to page 29.)

With the bit set to cut 7/i6" deep, I made a shallow cut on all four sides of the blank, see Fig. 5. Then to check the fit, I dry clamped the top pieces together and inserted the key.

Finally, the keys can be cut to length from the blanks. You need eight keys to complete the cutting board top, but I made a few extra. My keys were also extra long (about IV2"). The extra length comes in handy later when trimming the keys flush, see Fig. 3.

glue-up. With the keys complete, I used a water-resistant glue (like Titebond II) to glue the top together. It sets up quickly, so I glued-up just one board and two keys at a time, see Fig. 6.

Simply spread an even layer on the mating edges, down in the slots, and a little on the keys. Then clamp two pieces together and tap in the keys. Note: A clamp in the center helps keep the pieces aligned.

leveling top. To complete the top, the keys must be trimmed flush and the glue squeeze-out removed. I used a chisel to pare the keys flush, see box at right. And then I finished up by sanding.

FEET

With the top sanded, you could stop here and have a perfectly usable cutting board. But instead, I added feet. They raise the cut-

▲ Carefully pare aware the key with a chisel until it's flush, with the top. Then sand smooth.
Foolproof Element Jig

SECOND:

Cut off %" wide - strip for key blank (height of opening)

Completed key blank

FIRST:

Plane workpiece to V2" thickness (width of opening)

NOTE:

Two or three keys can be cut from key blank

Stand blank strip on end to rout key profile

Use auxiliary table and featherboard to rout keys

Make push block from scrap stock

Auxiliary fence blank

Rout four sides of key blank to create butterfly profile

Step 4

Auxiliary fence blank

Rout four sides of key blank to create butterfly profile

Feet are joined to top with sliding dovetail

Straight bit removes most of the waste

Dovetail bit cleans up dado

ting board up and make it easier for me to pick up and move around.

What's special about these feet is they're attached to the top with a sliding dovetail joint. This helps keep the top from cupping. And because they're pinned in the middle, not glued, the wood can still move.

feet blanks. The feet start out as 3/4M-thick cherry blanks cut to finished size CUVW x IIV4"), see drawing above. Note: An extra blank (or two) is helpful when sizing the dovetail tenon cut on the top edge.

routing dadoes. Each of the tenons cut on the blanks fits into a long, dovetail-shaped dado in the bottom of the cutting board. Like routing the notches for the top,

I used a V4" straight bit to remove most of the waste, see Figs. 7 and 7a. And followed up with a W dovetail bit to finish up, see Figs. 7 and 7b. Note: After completing the dadoes, don't change the bit height. It's used next to rout the tenons on the feet.

routtenon. To rout this "tenon" simply run the blank past the bit taking a light cut off each side, see Fig. 8. The goal here is to get a tenon that fits in the dado and slides smoothly. Since the bit height wasn't changed, the only adjustment necessary is to move the fence to change the width. Note: When checking the fit in the top, don't push the feet in too far. They can be almost impossible to get back out.

taper. Once I'm satisfied with the fit, the ends are tapered next. Simply adjust the miter gauge to 30° and make your cut, see Fig.

9. The taper cut should intersect with the base of the tenon, see Fig. 9a.

arc. Finally, to complete the feet, an arc is cut on the bottom edge. This creates a small pad at each end to help the cutting board sit solid. The simplest way to lay out this arc is to use a piece of hardboard (Ma-sonite) and bend it into an arc shape, see Fig. 10. This is a three-handed operation, so while you hold the hardboard, have someone trace along the edge. Then use a band saw to cut out the arc and sand up to the line.

assembly. Now the feet can be installed in the top. To hold them securely, they're pinned in the middle with a V4"-diameter dowel, see Fig. 11.

Simply slide in the feet so the ends are flush with the top. Then drill a hole to match the dowel length and glue it place. □

Feet are joined to top with sliding dovetail

Feet cut from %"x VVw"x IVA" blank

Straight bit removes most of the waste

Dovetail bit cleans up dado

Adjust fence to change width of dovetail

Adjust fence to change width of dovetail

Cut miter flush with base of dovetail

Cut 30° angle on both ends of foot

Cut miter flush with base of dovetail

Cut 30° angle on both ends of foot

Feet fit flush with

How Put Solid Wooden Floors

Install dowel to pin feet in place

Feet fit flush with

Install dowel to pin feet in place

Was this article helpful?

0 0
Wood Working 101

Wood Working 101

Have you ever wanted to begin woodworking at home? Woodworking can be a fun, yet dangerous experience if not performed properly. In The Art of Woodworking Beginners Guide, we will show you how to choose everything from saws to hand tools and how to use them properly to avoid ending up in the ER.

Get My Free Ebook


Post a comment