A Simple Jig for Smaller Router Bits
To complete the building of the jig, install a router bit into the router, set the depth of cut to a bit stronger than the hardboard or plywood, then with the router base running against the fence, make a cut. The newly created edge is the exact cutline of the router bit and aligning this jig is as easy as clamping to your layout lines.
A Simple Straightedge Jig
Not all the best shop-made jigs are pieces of plywood arranged in some design. One of the most useful jigs is simply a straight piece of stock or two pieces stacked together, what I call a straightedge jig. There are a couple operations where these shine. One use is for simple straight cuts on pieces too large or too awkward to hoist onto the table saw. A second use is to create a tenon for installing breadboard ends on a tabletop. Or, you can use this to create everyday, run-of-the-mill tenons.
Each of these operations works with a pattern bit; the depth of cut determines the layers of plywood needed for the jig. If I plan to create a smooth cut across an edge, a single thickness of plywood is best. This style of jig allows the standard pattern bit with a 1″ cutting length to extend completely through a 3/4″-thick workpiece while the bearing rubs the jig.
For example, if I were trying to cut the angled slope on a case side of a slant-lid desk, it would be nearly impossible to hoist the panels up to a band saw, or to control a panel at a table saw. But trim close to the line with a jigsaw, clamp a plywood straightedge at the layout line, then make a pass using your router while the pattern bit rides smoothly along the guide. The completed cut is square and needs little sanding or smoothing before finish – it’s that smooth.
The same operation is perfect for squaring large panels, too. You know how hard it can be to trim a large top with a panel-cutting sled. Once you achieve parallel sides at a table saw, use a square to lay out one end cut, position a plywood straightedge at the layout line, clamp the jig in place and trim the end square. Repeat the same steps at the opposite end of the top.
I don’t like to perform this operation with a circular saw – as you may have seen done a number of times – due to the sometimes-wonky finish of the cut. It’s easier to sand a routed cut than that of a circular saw – but I will trim the end close with a jigsaw prior to routing.
Change the Thickness, Change the Cut
If you require a cut that’s not a through cut such as making a tenon, you will need to stick two pieces of plywood together because of the cutting length of the router bit. A single thickness of plywood is sometimes not thick enough to allow the bearing to ride against the guide without cutting into the workpiece too deeply. A second thickness of plywood remedies that problem. Now it’s possible for the bearing to ride the jig and set the depth of cut where needed.
I use this two-piece setup to create tenons on large panels or tabletops. I cut a 1 1/4″ -long tenon to create a breadboard end (the 1/4″-thick tenon slides into a matching slot formed in the breadboard end). To do this, just set the two-thickness guide on your layout lines, adjust the depth of cut on the router, then waste away the excess from each face, leaving a tenon intact and centered. By using a pattern bit and plywood jig or guide, you clamp directly on your layout lines and go for it. That’s much easier than determining the offset for the router base.
More Work for a Pattern Bit
As you can tell, I use a pattern bit with plywood jigs for many operations. And bit diameter is not important. I use a 3/4″-diameter bit as well as a 1/2″-diameter router bit. Additionally, I use bits with either a top- or bottom-mount bearing.
Until now we’ve primarily discussed work accomplished with straight jigs. However, plywood is also where I turn for intricate work with patterns. I’ve built quite a few tea tables over the years and the most fancy was a Massachusetts design with extremely scalloped aprons at both ends and sides.
Instead of transferring the design onto each apron separately, I drew the design one time onto plywood – use a piece that’s 1/2″ thick at minimum – and used that to repeat the layout on each piece. But the plywood pattern did double duty. Not only could I use the piece to trace the pattern onto the aprons, I used the plywood and a pattern bit to cut the intricate design at a router table.
If you attach the plywood pattern on top of the workpiece, you’ll need a bottom-mount bearing, but a top-mount bearing is used if the pattern is positioned below the workpiece. As you make the jigs for this type of work, make sure to extend the ends of the pattern an extra inch or more to allow contact between the bit and pattern prior to cutting the work.
There are a number of techniques where this setup works great other than table aprons. Before I added a spindle sander to my shop, I would create a pattern for bracket-style feet and cut the design using my router. It’s more efficient to create the feet other ways, but this works if needed. Furthermore, I use this technique for high chest aprons and sculpted drawer dividers such as those on block-front or serpentine chests.
Running in Circles
Step into most woodworking stores and you’ll find many commercially made jigs for cutting circles of all sizes. In fact, these jigs are so involved that you have to read the instructions before beginning work (something we all hate to do). For the most part we use a few sizes of circles specific to our work. We don’t need all those settings. I looked for something different.
My first circle-cutting jig was an elongated base added to my plunge router. I used the existing bolts to affix the base to the router, then cut a circle. Seemed easy enough. But I ran into an issue. With the router bolted to the jig, there’s a point as you rotate and make a cut that you have to let go of the handles in order to complete the circle because the router doesn’t turn as you spin the jig. Your hands should always be in control as you use a router.
To eliminate the handle problem, I turned to a guide bushing. Again using plywood, I fashioned a jig for circle cutting. This time, instead of affixing the jig to the router base, I positioned a ¾”-diameter hole where the router bit would be located. The hole, which could be sized to match any size guide bushing, allows the bushing that’s installed in the router to spin freely as a circle is cut. The ability to spin during use means my hands stay in contact with the router throughout the cut.
Using the jig is a walk in the park. Select a guide bushing that matches the hole in the jig, then install the desired router bit and the bushing to the tool. Measure accurately for your needed diameter and pin the jig to the workpiece with a dowel. All that’s left is to cut a circle. Use a plunge router for this technique and step through the cutting process; don’t try to complete the cut in a single pass.
You don’t need scads of money. You don’t need complicated commercial jigs. You don’t even need to keep the jig once it serves its purpose. All you need is a few pieces of plywood used in conjunction with certain router bits and you can increase productivity in your shop. It’s as simple as plugging in a router.
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