Join Date: Jan 2013
Location: Colorado Springs
If your slots are changing width, that may mean your dado blade is wobbling. The first thing I would do is actually analyze the error. I would use a dial caliper, digital or analog, don't care. Measure the actual space widths, starting from one end and progressing to the other. Write down the space number and the dimension. Next do exactly the same with the pins. This will tell you what problem to fight.
If, indeed the space widths are changing, look for run out on you blade. Your dado may also be changing width if the arbor nut isn't tight.
It may be that your pins are changing width due to inconsistent pressure against the key, either by your hand or because the saw blade wants to push it over. This can look like varying space dimensions.
Another thing you really want to check is to make sure your miter gauge is absolutely solid and perpendicular to your blade. If it is moving it will cause the space width to change. Miter gauge slot / bar slop could cause this, too. You start out with the board "tensioning" against the miter slot counterclockwise and end with it tensioning clockwise because of the length of the board and how you hold it and push the miter gauge.
Last edited by RogerInColorado; 04-21-2013 at 12:39 AM.
Reason: add second quote mark around "tensioning"