There is nothing more frustrating than trying to assemble parts to a woodworking project and finding out they don't align properly. Many times we blame ourselves for not being more careful in our cuts or for not taking enough time to make proper measurements, but in many cases it's simply that the tools we are using have come out of alignment and need to be re-tuned or re-set.
On the table saw the item that needs to be re-set the most if ... of course the fence. It is the most used item on the table saw and is constantly being moved back and forth and tightened and loosened and all this activity, will, over time create a small amount of wear which results in the fence being out of alignment.
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Every fence for every table saw has some sort of adjustment mechanism. Some are better than others, but all of them can be adjusted. My first table saw has such and awful fence that even when I adjusted it, every time I moved it to a new location, I still had to check and set the front and back separately. It was terribly slow to use, but it was all I could afford and it did the job for me. More advanced and expensive fences are easier to set by simply turning a small set screw but regardless of the fence ... they ALL need to be checked and re-checked from time to time ...
There are many, many ways of checking the alignment of a table saw fence, the method I am using takes advantage of an older analog style, dial gauge that is highly accurate and can be adapted to many uses ... in this case, to checking the alignment of the table saw fence.
The particular unit that I have has a loop with through hole in the bottom and a bit of a raised portion around it, probably for better support. Because I want this gauge to lie flat on my support board, I needed to carve out that raised area so that the body of the gauge sits flat on the board.
After drilling a hole and inserting my hanger bolt, I found that because the bolt was already a snug fit through the hole in gauge, I need to do a bit of sanding so that the bold aligned with the gauge ... easily done in a few minutes.
The gauge will slide from side to side along the mitre slot, so the part that slides need to be smooth and fit snug in the mitre slot. I discovered years ago the trying to deal with wooden mitre gauge blanks was a constant battle with them shrinking and expanding depending on the time of year and the amount of moisture in the air, so I have long since gone to the extruded plastic blanks which I cut myself on the table saw.
For this version I also added a couple of adjusting screws in the side of the blank so that I could make it fit snug and therefore a very accurate reading.
After attaching my plastic blank to the wooden dock that also holds the gauge, I checked everything to makes sure there was no slop in the gauge, or in mitre slot the jig moved up and down the mitre slot ... everything was snug and firm.
The whole reason for this exercise was that I had not checked the fence for alignment for well over a year and recently, after making some cuts I felt that the fence might need to be re-adjusted. As I move the jig up and down and watched the needle, it move in the correct direction which meant the table saw fence was very slightly angled away from the blade, which is where it wants to be, and after a couple of checks, both with near identical results, it turns out the fence is not out of alignment. From end to end it is out about the thickness of 2 sheets of 20 bond computer paper. Well within the bounds of accuracy for woodworking. And now I have a jig for checking the fence ... quickly and easily ...
Copyright Colin Knecht