Years ago (certainly more than 10) I bought a Biesemeyer fence system for the saw I was using at that time. I eventually upgraded to a SawStop and was able to purchase it without a fence (I don't think they will do that anymore). I moved the Biesemeyer fence to the SawStop.
So I've used the fence for many years.
On a project recently, I was cutting a small piece of ebony and noticed that it was thicker on one end than on the other. So I started working to find out why.
Here's my fence setup (kind of messy, I know). I have a square on the side of the fence.
Biesemeyer01.jpg
Low and behold, the side of the fence is not square vertically. You can see daylight between the fence and the upper part of the square.
Biesemeyer02.jpg
Then I checked the other side of the fence. I never use that side.
Biesemeyer03.jpg
It's even worse, but it's in the opposite direction. So it appears that the fence was turned slightly when the fence was made. Through some trial and error, I found that if I put a 6" rule under one side of the "T" of the fence, the left side would be about square. But I can't keep slipping a rule under the "T" every time I use the fence - I need to find out why.
My first thought was that the plastic pads that the fence rides on might have worn more on one side. So I turned the fence over to examine them. You can see the two plastic pads on each end of the "T".
Biesemeyer04.jpg
Continued on next post due to the limit on number of pictures in one post.