I'm wondering what kind of misalingment in a circular saw base plate
Mine is a right-blade depth-adjustable (Porter Cable 447K), and at
some depth settings the rear of the saw blade is about 1mm closer to
the farther (left) edge than the front of the saw. If I try to do
anything like this:
then the saw will either track away from the guide or the blade will
score the workpiece about 1mm more than I intend to cut. (And the
misalignment varies w.r.t. depth as well!)
(The front is 5in from the edge of the kerf dead-on, as touted by the
With the blade fully extended, use a square and see if the blade is
perpendicular to base, both front and rear. Adjust accordingly and then
lower the blade some and recheck. Once satisfied that the blade is staying
perpendicular at all blade settings, now you can check the distance from the
edge of the base to the blade - front and back. Just a couple of
thousandths off can cause the problem you're experiencing when the saw is
being referenced against a fence.
I'm not sure about the adjustments on that model so I can't tell you how to
do it but the Porter Cable site should have a manual available if you don't.
Here's the link
Took a quick read and they do not have a procedure for checking or adjusting
the blade to base edge for being parallel. Make the measurements as above
and if they're off see if there are any screws on the base that can be
loosened that would allow the base to be shifted slightly. That's a molded
base, maybe the one edge is off?
Thanks for your comments.
The base is not adjustable. I exchanged it and got one which is
almost perfectly aligned, only about a paper-thickness worth of
difference (maybe 3 thousandths?) along the length, at various depths,
in this sample.
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