Table Saw Alignment

Introduction

It’s pretty common knowledge that the angle scales on most woodworking machines aren’t very accurate.  It’s why so many woodworkers avoid working with angles or resort to tedious trial and error methods.  Over the years a number of solutions have been sold in stores and catalogs that don’t offer any significant improvement.  Acceptance for products that do provide accurate angle measurement has been hindered by skepticism, cost or complexity.  So, when the low cost ($40) Wixey Digital Angle Gauge was introduced it became an instant success.  Not only is the price right, but the precision of a digital display is easy to read and gives the illusion of accuracy.

You won’t see test cuts or plastic drafting triangles in this review.  Unlike popular magazines and other web sites, this review will provide actual test data based on instrumentation with certified accuracy.  I’m not going to tell you that I did some test cuts that seemed pretty accurate because such a subjective judgement is virtually useless.  You have no way to judge if my idea of “pretty accurate” is adequate for your purposes.   That’s what makes this web site different.

It’s important to note that a number of clones have been introduced - some with an additional half digit (0 or 5) to the right of the decimal.  The transducers in these devices are all essentially the same.  So, while the brand and price may vary, the accuracy does not.

I purchased my Wixey digital Angle Gauge from the local Woodcraft store.  It comes packaged as shown above.  Two batteries were included (CR2032 button type).

The instructions are printed on the back side of the packaging paper insert.  That’s right, seven line drawings and a safety notice.

Most people are now familiar with what the Wixey Digital Angle Gauge looks like.  The whole unit measures about 2 inches square by 1.3 inches thick.  The front and back are plastic, the perimeter is plated metal (I would guess that it’s aluminum).  The bottom has three high strength rare earth magnets.

Testing

The most important aspect of any product is its ability to perform.  The maker claims vertical angle measurement accuracy to ±0.1° (6 minutes of arc).  I was eager to test that claim.

I used my Starrett AG16LM angle set as standards for the testing.  Unlike comparisons with a test cut of a piece of scrap wood, these solid chromium carbide angle blocks leave absolutely no doubt about the accuracy and validity of the testing.  These are the sort of instruments used by the NIST and other national standards organizations as master standards. 

For the first tests I chose the following angles: 45°, 30°, 15°, 5°, 3°, 1°, 30 minutes (0.5°), and I combined the 5 and 1 minute blocks to create 6 minutes (0.1°).

The Wixey was zeroed on the granite surface plate against a granite straight edge.  Then various angle blocks and combinations were placed underneath the Wixey using the same spot on the surface plate against the same spot on the straight edge.  Since the angle blocks are made of chromium carbide, the magnets in the bottom of the Wixey did not provide any attractive force.  So, on steeper angles the Wixey required support to prevent it from sliding off the angle block. 

Testing Data

The following photo gallery shows the results of these tests.

As you can see the display is occasionally off by 0.1° from the actual angle.  This was easily resolved by re-zeroing the display and testing the angle again.  But, in normal use the angle being measured would be unknown so the need to re-calibrate the device wouldn’t be obvious.

In addition to measuring known angles, I also performed threshold testing.  The goal is to determine how much change in angle results in a change on the display.  This tells you how much difference can exist between the actual angle and the number on the display.  Here are the results:

• Solid change of 0.1°: 3 minutes 40 seconds (0.0611°)
• Intermittent change of 0.1°: 3 minutes 39 seconds (0.0608°)
• Rare change of 0.1°: 3 minutes 38 seconds (0.0605°)

So, the actual angle could be anywhere between 0.061° and 0.160° and the display will still read 0.1°.

Summary

For the most part, the Wixey Digital Angle Gauge lives up to its maker’s claims (accuracy to ±0.1°).  If the threshold testing is included, then the display can be off by as much as 0.160°.  For maximum accuracy and reliability, I would suggest zeroing the gauge for each and every measurement.  The Wixey Digital Angle Gauge is accurate, handy, and easy to use.  It is certainly not the most accurate angle measurement device I own, but it sure beats the scales on all woodworking machinery I’ve seen.  And, except for my TS-Aligner products, it is considerably more accurate than just about any other such product made for woodworking.

To be sure, angle settings on woodworking machinery are some of the most challenging.  Since the Wixey Digital Angle Gauge relies on gravity to measure angles, it only addresses half of the problem (the vertical angles like table saw blade tilt).  For these it provides marginal accuracy for common work.  A 0.1 degree error on a 3 inch wide cut translates to an error of 0.0052 per cut.  For a four sided frame with square butt joints (four cuts) would have an accumulated error of 0.020 inches (a bit more than 1/64″).  If that frame has mitered corners (8 cuts) the accumulated error would be 0.042 inches (almost 3/64″). 

It’s also important to note that it takes more than just an accurate blade tilt to produce an accurate miter.  The Wixey Digital Angle Gauge doesn’t address any of these other adjustments which must be done properly to obtain accurate results.  It doesn’t address horizontal angles (like miter gauge settings).  And, it doesn’t provide the accuracy needed for more advanced work (multi-sided frames, segmented turnings, compound angles, etc.).

Ed Bennett
ejb@tablesawalignment.com