The Bosch Miter Finder replaces the frustrating plastic angle finders with ease and accuracy. Click image to enlarge

Bosch DWM 40 L Miter Finder

A common problem solved

Text & photos by Tom Hintz

   A common and often frustrating task in woodworking is cutting accurate miters. Whether cutting the complicated compound miters necessary to install crown molding or simply wrapping an edge around a square panel, clean fitting miters are difficult to achieve if we do not know the exact angles involved. Assuming a "square" corner is actually 90-degrees can and does get us in trouble.

   Many of the newer high-end miter saws have detents for the bevel and miter angles necessary to fit crown molding to perfect 90-degree corners. The problem is true 90-degree corners are not as common as we like to think, in our homes and in our projects. A perfectly cut 90-dgree miter will show a gap when applied to an 89-degree corner.

Cool Tool Solution

A pair of spirit vials are included to extend the usefulness of this tool a little more. Click image to enlarge

   The Bosch DWM 40 L Miter Finder makes cutting accurate miters easy, including the complicated crown molding cuts. Simply put, the Bosch DWM 40 L Miter Finder is an electronic protractor capable of measuring angles from 0 to 220-degrees with an accuracy of +/- 0.01-degree. The findings are displayed on the large LCD screen down to a tenth of a degree.

   The Bosch DWM 40 L Miter Finder also has a pair of built in spirit level vials 90-degrees to each other with an accuracy of +/- 0.057".

   The 16"-long Bosch DWM 40 L Miter Finder is built from sturdy aluminum extrusions and a heavy cast knuckle that houses the angle-measuring sensor. The upper arm closes over the lower at 0-degrees but has a cutout window over the LCD screen that allows reading small angles.

   The unit is powered by four AA-size batteries that apparently last a very long time. When the "low-battery" indicator appears in the LCD window you still have 1 to 2 hours of power left.

   The LCD screen is a generous 2 ½"-long and 7/8"-tall with large, easy to read numerals that my 50-something eyes can make out easily at most angles. There is a duplicate LCD screen on the back side of the Bosch DWM 40 L Miter Finder that allows reading the information directly in most situations.

Controls

The control panel is simple to use but solves complicated math problems. Click image to enlarge

   Operating the Bosch DWM 40 L Miter Finder involves three buttons. An "On/Off", a "Hold" button that retains a measured angle, and another marked "BV/MT" that activates the really trick part of the electronic functions.

   The "On/Off" button does just what the name implies, but for when we forget, the computer shuts the unit down after five minutes of non-use.

   The "Hold" button freezes the angle reading for when the object being measured prevents seeing the display directly. Hold the Bosch DWM 40 L Miter Finder with its arms against the two surfaces and press the Hold button. The miter finder can then be moved to view the screen without losing the reading if the arms are disturbed. Pressing the "Hold" button again clears that measurement.

Crown Molding the Easy Way

Applying crown molding to inside or outside corners is easy when the Bosch Miter Finder tells you exactly how to cut for corners that are not exactly 90-degrees. Click image to enlarge

   The really trick part of the Bosch DWM 40 L Miter Finder's electronics is the BV/MT function. Whether installing crown molding on walls or as decoration on cabinets, the on- board computer reduces this once complicated mathematical process to a few pushes of the BV/MT button.

   Measure or set the spring angle (the angle at which the crown molding is to the wall) and push the BV/MT button. The instructions show how to measure spring angle with the Bosch DWM 40 L Miter Finder. Measure the angle of the corner to which the molding is being applied and then push the BV/MT button again. Push the button twice more and the Bosch DWM 40 L Miter Finder displays the bevel and miter angles down to the tenth of a degree for cutting the molding flat on your compound miter saw.

   If we always dealt with 90-degree angles, the detents built into some better dual bevel compound miter saws would suffice. However, in the real world corners are not always what they are supposed to be, a condition new Bosch DWM 40 L Miter Finder owners are quick to confirm. Taking a walk through your home and measuring corners with the Bosch DWM 40 L Miter Finder can be a revealing experience. The results of such an impromptu inspection usually demonstrate the value of the Bosch DWM 40 L Miter Finder in no uncertain terms. To form clean fitting moldings on many corners, the joints must be custom cut, and the Bosch DWM 40 L Miter Finder will tell you exactly how to do it.

In The Shop

Applying face frames or molding with tight miters is simple if you know exactly what the angles are. Click image to enlarge

   While the Bosch DWM 40 L Miter Finder may have been designed with the home improvement market in mind, I find it is very useful in the workshop. I find myself using it often, and not only for cutting crown molding.

   I have several small angle finders that are far more frustrating than helpful. The tiny scales make reading or setting angles a guessing game at best. On several occasions corners that appeared to be 90-degrees according to those little numbers produced miters that didn't fit. I went back to re-check some of these with the Bosch DWM 40 L Miter Finder and discovered they were actually off by a degree or two. The Bosch DWM 40 L Miter Finder instantly showed what the tiny numbers on the low-buck plastic angle finders could not define.

Using a simple carpenter miter gauge to transfer angles from inside small spaces to the Miter Finder is accurate and fast. Click image to enlarge

   The Bosch DWM 40 L Miter Finder is very handy for laying out a wide range of angled cuts. Whether copying an angle or following a plan, the Bosch DWM 40 L Miter Finder makes it simple to transfer those angles to the work piece accurately.

   At times, the 16" arm length of the Bosch DWM 40 L Miter Finder makes it difficult to measure an angle in smaller projects. In those cases, I use a simple carpenters angle gauge to transfer the angle to the Bosch DWM 40 L Miter Finder on the bench. The results are dead on.

   While the computer does not calculate simple miters, the accuracy of the tool means you need only read the display and divide by two. Even I can handle that.

Conclusions

   The Bosch DWM 40 L Miter Finder is a worthy tool for any woodworker interested in precise layouts and angle cuts. This easy to use tool will dramatically increase the accuracy of these often frustrating tasks found in

Checking assemblies for square before allowing to dry is far more accurate with the Miter Finder. The more I use this tool, the more uses I find for it. Click image to enlarge

many projects. Being able to so clearly read angles with this level of precision substantially reduces the guesswork involved in cutting virtually any angle needed.

   Using the Bosch DWM 40 L Miter Finder allows me to cut highly accurate miters quickly, virtually eliminating the series of test cuts and tweaking that were usually necessary in the past.

   Since bringing the Bosch DWM 40 L Miter Finder into my shop, those little plastic angle finders remain unused in the drawer, serving as reminders of the old days when tight miters were a matter of guessing, experimentation and often luck.

   Maybe the best news of all is you can get a Bosch DWM 40 L Miter Finder for under $125!

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