Getting the most out of the MTB angle set
Machinist's angle blocks can be used to enhance the angle measurement abilities of TS-Aligner and TS-Aligner Jr. The MTB Angle Set is custom made for us with this very purpose in mind.
How the Micro Tangent Bar works
The Micro-Tangent Bar is particularly unique. It provides the ability to set an angle anywhere between 0 and 5 degrees. The thumbwheel is graduated in minutes of arc and provides very quick and easy settings. However, since the tangent function isn't linear, there is some error involved in using the wheel for angle settings. In situations where more accuracy is needed a micrometer can be used.
The following formula can be used to determine the exact setting for a particular angle:
3.4377 * SIN(angle)Using this formula, you can see that the setting for a 5 degree angle should be 0.2996" but using the thumbwheel would result in a setting of 0.3000" for an error of 0.0004". The photos below show how this is done.
First, measure 3.4377" from the pivot point on the MTB. Scribe a line at this point on both sides of the MTB.
Next, measure the width of the fully closed MTB. This is your reference for zero degrees. Using a digital micrometer or calipers makes this step very easy.
Finally, open the MTB to the correct amount by measuring directly at the point you scribed in the first step. In this example, we set the MTB to 0.1200" for a 2 degree angle. Your choice of measuring device will determine the accuracy of your angle setting.
Using the thumbwheel will be more than adequate for virtually all woodworking applications.
Last revised: July 03, 2008.
