Dovetails and box joints done over easy

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This article is from Issue 64 of Woodcraft Magazine.

Leigh RTJ400 Router Table Dovetail Jig

Tested by Joe Hurst-Wajszczuk

Think the world doesn’t need another dovetail jig? Maybe it’s time to think again. As a natural response to the plethora of router tables sporting precision power lifts and dust-collecting fences, Leigh Industries has created a dovetail jig designed to stand on its head. To find out how this table-riding template jig stacks up against the competition, I decided to run it through its paces. I discovered that the RTJ400 shares many similarities with its Leigh siblings, but is really in a league of its own.

Setup: I had the RTJ400 out of the box and making sawdust in about an hour, but jig owners know that assembly is only the tip of the iceberg. Unless you use your jig regularly, setup is a challenge every time you take it off the shelf. Realizing that months may pass between one set of joints and the next, the manufacturer provides instructions in three different formats: a spiral-bound guide, a 74-minute DVD, and five instruction strips (Photo A). 

The fully-illustrated book and DVD both provide detailed step-by-step instructions for all the joints. (I preferred following along with the DVD video on my laptop.) The instruction strips, designed to slide into the frame’s top bar, offer a brief in-use refresher course for each joint type. The strips are also intended for the user to record e-bushing settings.

Leigh provides three different aids to help set the jig. With a little practice, you’ll only need to glance at the strips.

Trial Run: Using dovetail and straight bits, the RTJ400 allows routing through dovetails in stock ranging from 1⁄4 to 1" thick, and half-blind dovetails in material from 1⁄2" to 1" thick. The jig’s maximum board width capacity is 151⁄2". Unlike the adjustable templates on some jigs, the fixed fingers on the RTJ400 dictate tail spacing, so you may have to design drawer heights and case depths to suit. That said, the instructions will help you select the right width and tail counts I was able to achieve tap-tight joints in a few attempts due to Leigh’s patented e10 bushing. This elliptically-shaped bushing and its etched-number face enable users to adjust a joint’s fit in .001" increments (Photo B) and then record the setting for future cuts. I found the bushing to be a special blessing for box joints–a joint that often requires much trial and error. Dialing in the bushing is significantly faster and easier than bump-adjusting a jig with a sliding stop.

The orange plastic blockers deserve special mention. Routing through dovetails and certain-sized box joints may require routing into every other finger and it can be easy to lose count. The blockers snap in between fingers (Photo C) to keep the bit from routing where it shouldn’t.

Although the RTJ400 is not outfitted with a dust-collection port, I quickly discovered that I could pull my router table fence into service to do the job, as shown in Photo C.

The e10 bushing takes the guesswork out of fine-tuning the joint fit. Draw a reference line on your router table insert for dialing in the proper setting.
The snap-in plastic blockers prevent routing between the wrong set of template fingers. Locating a router table fence dust port nearby extracts most of the dust.

Tester’s Take: Changing bits and setting bit heights with a table-mounted router takes more time than with a handheld router. In this instance, bench-mounted jigs have a slight edge, especially if you use one router for pins, and another for tails. But for single-bit box joints, this jig cuts as quickly as any other. (If the stock is 1⁄2" thick or less, you can rout two sides at once, cutting production time in half.)

The RTJ400’s main advantage over its bench-mounted brethren is its stability. Thanks to the 6 × 27" aluminum base and solid cam clamps, this jig can handle tall planks without any fear of tipping. (For longer boards, you could flip it over and use it with a handheld router, but how many projects reach that scale?) Theoretically, a user could let go of the handles and walk away in mid cut.

Having watched woodworkers fumble with handheld routers, I’m a fan of any setup that keeps spinning bits at a safe distance (in this case, on the opposite side of the jig). Experienced woodworkers may not feel the need for such protection, but accidents happen…I’ve seen quite a few dovetail jigs with a few knicked template fingers.

Dovetails are dandy, but I expect that this jig will bring box joints back into the regular repertoire of many woodworkers. With the included 3⁄8" straight bit, you can start cutting 3⁄8", and 3⁄4" wide box joints. Treat yourself to the 3⁄16" and 3⁄32" straight bits in the accessory kit (for matching-sized joints), and you’ll be set to tackle everything from cabinets to jewelry boxes.

The RTJ400 is a perfect partner to any router table, especially those equipped with built-in height adjustment and dust collection. After using this jig, I’m saving up for a router lift so that I can put it to full use.  

#160014, RTJ400, $329.00
#160015, RTJ400 Accessory Kit, $159.00

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