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The Accurate Guide
Simple precision for any shop
Text & Photos by Tom Hintz
Cutting precise-fitting dados and sliding dovetails can be a daunting task, particularly for new woodworkers or those with small shops that lack the range of tools or space needed, especially when working with longer pieces like bookshelf sides. Dados become even more challenging when they are being cut to accept wood that does not match the bit diameter exactly.
For many, the Accurate Guide, from Accurate Woodworking Tools, LLC. (Pickett, Wisconsin) is an easy to use, affordable solution.
The Accurate Guide appears very simple but the engineering and machining behind it is not. The parts that make up the Accurate Guide are well made and cleanly finished. The mounting, often a sore spot with "bolt on" accessories, is very well done and matched our Bosch 1617 router base perfectly. Kits are available for most of the popular routers in use today.
How It Works
The Accurate Guide is essentially an expandable fence that uses small pieces of scrap, cut from the wood the dado is being cut for, to index the moveable half of the Accurate Guide fence outward. When the second pass is made, the bit opens the dado to perfectly match the width of the samples and the wood that will fit into it.
The Accurate Guide uses two bit sizes, ¼" and ½" cutters. Down cut, spiral bits work best and are what we used for the evaluation process. The ¼" size bit is used to cut dados for wood thicknesses from ¼" to ½" and the ½"-diameter bit to cut dados ½" to 1 ½"-wide.
The demonstration video (CD) that came with our Accurate Guide suggests it is so accurate that it literally cuts a dado that is exactly the same thickness as the sample wood. Often, a single piece of paper must
be added to the sample to create a slip fit of the wood into the dado that leaves room for glue. While that claim at first sounded a bit far-fetched, I had to add that piece of paper frequently while testing this tool in out shop.
Setup & Use
Setting up the Accurate Guide takes just minutes. Screw the included mounting bars into the fence and then mount the assembly to your router. Tighten the (included) screws to lock the bars into the router base and assembly is complete.
The last task is to measure the distance from the bits cutting edge to the face of the fence. In my case, with the Bosch 1617 fixed base, that distance was 4". This bit to fence dimension is the offset used to locate a clamped-on fence on the wood, against which the Accurate Guide rides.
The instruction sheet that accompanies the Accurate Guide is rather short, but complete. As we would find out, using the Accurate Guide is not difficult, thanks to the design that takes the guesswork and endless "fine tuning" out of cutting dados with a hand-held router.
Sliding dovetails are just as easy though the process is a bit different. The dovetail is cut into the sliding piece first and samples of that are inserted into the recesses on the Accurate Guide to make the second cut that sizes the dovetailed key way into which it slides. Use the same bit, set at the same cutting depth and the fit is perfect. If anything, the fit can be too perfect. All of the sliding dovetails we cut needed the piece of paper added to the sample to open the key way enough to slide in the dovetailed piece.
Accurate Woodworking Tools also offers the STG (Slot & Tail Gauge) as an accessory that eliminates having to cut sample pieces. The STG has a wide side that is fit to the wood that the dado is being cut for and locked in place. The other side of the STG is then placed in t he recesses of the Accurate Guide in place of the sample pieces of wood.
The fingers of the STG that go into the Accurate Guide recesses are machined 0.014" undersize. This allows the user to space them out as needed to perfect the dado fit. The logic to this design is sound, you can always take more wood off but it gets ugly when we try to put it back on.
The STG kit comes with two gauges and sells for $39.95 (2-9-2006) and like the Accurate Guide, will last forever with a little care.
In the Shop
The design of the Accurate Guide makes it very easy to use with remarkable accuracy. The combination of the 10"-long fence and the router base provide exceptional stability that lets the operator focus sliding it along the clamped-on fence. Most often, it takes longer to clamp the guide piece to the wood than it does to actually cut the dado.
Because the Accurate Guide follows a clamped on fence rather than key off the board it is cutting, it does not care how long the dado is or what angle it is cut at. The unique combination of capabilities makes the Accurate Guide an attractive alternative to other dado-cutting tools, especially in small shops and when the budget is smaller than we'd like.
Throughout testing, the Accurate Guide cut spot-on accurate dados, most requiring the addition of a piece of paper for a slip in fit. I did notice that if the stock that will be located in the dado is sanded before assembly, that small amount of wood loss usually produced a good fit. For this reason, it is a good idea to finish sand the wood before fitting the dados to it.
The one thing users will have to remember, particularly those who are relatively new to using a router, is that the second cut uses the near side of the bit. That means the feed direction for the second cut is right to left rather than left to right as used on the initial cut. Get this one point in your head and using the Accurate Guide is very simple. The same feed direction change applies to cutting sliding dovetails.
The Accurate Guide is as remarkable in how easy it is to use as it is accurate. The construction of the Accurate Guide is substantial, meaning it will last a very long time. The extensive capabilities of the Accurate Guide mean it can easily take the place of other dado0cutting tools. The Accurate Guide is also easier to use in the confined spaces of today's shops.
With a street price of $59.99 (2-9-2006) the Accurate Guide could very well be the most cost effective tool in your shop. Add the spot-on accuracy and solid construction and the Accurate Guide becomes even more attractive.
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