Trim the shoulders of the pivotblock tenons on

the table saw. With a stop block clamped to the miter gauge or cutoff box facing, the blocks are automatically positioned for the cuts. Note that the cuts are made with the blocks standing on edge.

block is positioned so the tenon contacts it. If only the waste touches the stop block, it will be useless when you go to trim the second end of a block.

If the plug cutler cuts a narrow groove around the tenon, the trim cuts may leave little nubbins of waste standing guard around each tenon.These can be pared off with a chisel.

4. Install tenon O-rings. The O-ring ensures that only the inner race of the bearing contacts the pivot block. This is important.








I MT-dia. bore, Ys" deep, houses outer race of bearing.

Off-the-shelf ball bearings, ft" bore, 1 ft" O.D., W long

Rubber O-ring shims bearing away from shoulder of pivot block.

I MT-dia. bore, Ys" deep, houses outer race of bearing.

Off-the-shelf ball bearings, ft" bore, 1 ft" O.D., W long

Rubber O-ring shims bearing away from shoulder of pivot block.

W-dia. bore. ft" deep, provides clearance for inner race of bearing.

ft"-dia. stub tenon. H" long, fits bore of bearing.

W-dia. bore. ft" deep, provides clearance for inner race of bearing.

ft"-dia. stub tenon. H" long, fits bore of bearing.

Consult the drawing f'irot Block Detail. You'll sec that if you would push the hearings all the way onto the tenons, the outer races would rub on the blocks instead of turning freely The solution to this problem is to slip a '/Mnch-diameter O-ring onto each tenon before installing thr bearings.The O-ring provides the needed clearance, as shown in the drawing.

An effective alternative to the () rings is a piece of stout cotton cord (about 'itrinch diameter) wetted with glue. Wrap it around the base of the tenon, and hold it in place with the bearing while the glue dries.

5. Drill the mounting-rod holes through the pivot blocks. These ^lo-inch holes are for the threaded rods that help hold the rig together. The hole must be in the ceiter of the block's face. To find the centcrpoint, draw diagonal lines across the pivot block face.

As you did in setting up to cut the tenons, align the pivot block under .1 drill bit. then clamp fences to the drill press table to hold the block secure while you drill. These fences will also serve to position the other blocks for drilling, so you only have to lay out the center of the first block.

Drill the holes.

6. Cut the beam parts. The beams are the top and boitom (roughly horizontal) members of the parallelogram th*t keeps the router in line with the stylus. The beam sides house the outer races of the bearings. The webs tie the pairs of sides together, forming the beams.

Check the dimensions specified by the Cutting list for the beam sides and webs, bearing in mind that the list presents the final dimensions of these parts. While the webs ultimately will be 5/x inches wide, you'll get a neater job if you trim the webs flush with the sides after assembly. Therefore, it's better to cut them 5'/i inches wide at this pont. The sides, on the other hand, must be cut to their fiml size now.

7. Bore the hearing recesses In the sides. These ret esses are stepped—counterbored. in effect—so they'll hold the bearing tightly but provide clearance for the inner race .The hole that houses the bearing is I % inches in diameter and inch deep.The clearance recess is concentric; it is \ inch in diameter and 'Ac inch deep.

Begin the work by laying out the centers of the two hearing recesses that must be bored in each side. The locations are shown in the Side View of the drawing Router Duplicator Plan Views. The holes are centered between the edges of the sides. This is convenient because it means that the four pieces arc identical rather than symmetrical. You don't have to keep track of almost-thc-same parts.

Drill the recesses on the drill press using a 1 ^inch-diameter I'orstner bit Clamp a fence to the drill press table to position the workpicccs.and adjust the depth stop so the holes will l>e exactly inch deep. Check and confirm the depth stop setting by pressing a bearing into a test hole.

Use a fence to locate the workpieces, and boring the stepped holes for the bearings becomes easy. Both holes are on the same axis. Take the time to set the fence carefully, so the holes are centered across the beam sides. Then drill all the bearing holes. After switching bits, drill all the clearance holes, as shown here.

The bearing should Ik- llusli with the beam side when it's fully seated in the hole.

After drilling all the bearing holes, switch bits and drill the inner-race clearance recesses. Don't move the fence; it's in the right position to give you clearance recesses that arc concentric with the bearing holes. Use a "*-inch Forstner bit. You don't need to remove a lot of material, remember. Just lio inch is deep enough.

8. Assemble the beams. Assembly captures the bearings and pivot blocks, so you want to get the unit working smoothly IxTorc making this incarceration permanent. For this reason I sn*»|»csi yon assemble thr beams with screws only. After the duplicator is completely assembled and tested, but before you put it to heavy use. glue the webs and trim them.To do this, remove one web at a time, apply glue, and rcdrivc the screws in the same holes. This ensures that the web is being returned to its exact, tcstcd-and-proven position. After all the webs arc thus permanently fixed, use a router with a flush-trimming bit to shear the webs even with the sides (you cut the webs a little wide, remember).

But I'm getting ahead of us.

Ik-gin the assembly work by pressing a bearing fully into each recess in the Ix-am sides. Make sure they are flush with the surface of the beam sides and that the inner races turn freely.

Now install the pivot blocks, ("heck that your O-rings (or glucd-cord shims) arc in place on the tenons. With one of the sides laid flat on the bench top. insert a pivot block into each of its bearings. Set another side in place, seating

Assembling a beam doesn't really require three or four hands. Lay a side on the workbench, and insert bearings in the recesses. Press a pivot block into each bearing. Fit a second side, with its bearings in place, onto the pivot blocks. Right the assembly, and apply a clamp over each pivot block, as shown here, to hold the assembly while you screw the webs in place.

this side's bearings over the projecting tenons on the pivot blocks. Make sure the tenons go all the way into the inner races of the bearings so the O-rings contact both the tenon shoulders and the bearing inner races.

Right the assembly, and lightly clamp the sides together, placing the clamps directly over the bearings. This will ensure that there is absolutely no side-to-side play. Place two of the webs on the assembly, as shown in the Side View, and screw them in place. Use 1-inch drvwall screws. Turn the assembly over, and screw the other two webs in place. The pivot blocks should turn freely in the bearings when you are done and have removed the clamps. (If they don't, disassemble the beam and try again. This is why you don't glue die webs in place.)

Assemble the second beam in the same way.

9. Make a column blank. Although there are three different columns in the assembly, it is easiest to glue up one long column, then crosscut it into the three pieces needed.

Begin by milling and ripping three pieces of straight-grained hardwood stock to the thickness and width specified by the Cutting list. Each of these pieces should be crosscut to a 30-inch length.

Glue the pieccs together, forming a single U-scction column.The drawing Column Assembly Detail shows the arrangement of the parts.

If you find it more convenient to screw the parts together than to clamp them while the glue dries, make sure the screws don't lie in the path of the cuts you'll make in the next step.

10. Cut the columns to length. When the glue is dry, trim one end of the long column square, dien saw it into two 12-inch-long pieces and one i-inch-long piece.

When making these cuts, make sure your blade is perpendicular to the saw table and that your miter gauge fence is perpendicular to the miter gauge bar, because you want the cuts to be as square to the axis of the column as you can get them.

11. Assemble the beams and columns. Assuming that you bought a 36-inch length of threaded rod. saw it into one piece 14'/» inches long and one 18 inches long. Assemble the box beams, columns, and threaded rods as shown in the Router Duplicator Exploded View.

You'll have to make one departure from what you

Lay Ihe beams and columns on the workbench to assemble them. Line up these subassemblies, insert the threaded rods, and tighten the nuts finger-tight. After thus tying the parts together, refine the alignment of the parts as necessary, then drive screws through the pivot blocks into the columns.


see in the Exploded View: The longer rod can't screw into the T-nut on the platen because you haven't made those parts yet. Just thread an extra nut onto the rod for the time being.

With the nuts on the threaded rod snug against the pivot blocks but not overly tight, lay the assembly on its side on a flat surface, like your saw table. Now nudge and tap the columns into exact position, centered on the pivot blocks and not touching the box beams. When you have them just right, tighten the nuts to hold them securely in place, then drill pilot holes and screw the pivot blocks to the columns. The screws will keep the columns from twisting on the pivot blocks, thus main taining the accuracy of the jig, while the threaded rod will keep the screws from being pulled out of the end grain of the columns.

You can use glue and less hardware if you like, but then you won't be able to disassemble the duplicator for storage.

Was this article helpful?

0 0
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.

Get My Free Ebook

Post a comment