What is the best way to cope with a table saw that has an uneven table?
I noticed inconsistent cut depths with my table saw so did some test cuts on a piece of oak known to be straight and measured the depths. Cuts were like this:
I made the cuts in a random order to rule out the possibility of the blade height drifting. I also noticed no play in the blade position or angle with my hands.
Results were like this (leading and trailing edge depths measured about 0.25" from respective edge, note x axis is mirrored wrt above picture, "throat plate far edge" is where the edge of the wood crosses the far edge of the throat plate):
The blade has angled teeth, and I measured to the center of the cut. I made the full set of measurements 3 times and found my results only varied by at most 0.0005", so I believe the relative measurements to be accurate.
The first thing I discovered was that I did a poor initial job adjusting my throat plate height (as evidenced; it was too low), so I fixed that. However, I closely inspected the table with a square (a friend lent me a Starrett) and found that it is not completely flat. There are large, smooth, ever so slight bends and dips in it, and the bit to the right of the throat plate is a few hundredths of an inch higher than the left side. I am presuming this is the cause of my inconsistent cut depths. I also can feel with my fingers that the miter slide's rail is slightly higher than the table although I'm not sure how this affects things.
I noticed an identical trend with a piece of MDF and a piece of poplar as well (this is actually what prompted me to do this experiment) although I did not make a full measurement set on those.
What is the best way to cope with this (or are my expectations too high; the saw is a Ridgid R4513†)? I have not yet built any sleds. It seems like a sled with a nice flat base will solve the issue for cross cuts. I did read this great answer, however, I am still unsure what to do for non-through rip cuts, where the material is longer and I want to use the fence.
† After reading grfrazee's answer, I contacted Ridgid and they claim a ±0.016" manufacturing tolerance; further inspection of the table appears to verify it is within their tolerance. So it seems my expectations may be too high for this particular saw.