It is the height of my 3" border that is off.
I wouldn't recommend buying a 28mm rotary cutter if you are in the market for a new one, but there was a Quilting Start-Up Kit years back when I started quilting that came with a mat, ruler, square & 28mm rotary cutter. It typically works just fine. Olfa says it can cut through up to 5 layers of fabric at a time & I've had no problem cutting through 4 layers with a standard ruler/square. The 28mm replacement blades seem to consistently be much cheaper than the 45mm blades, so that's one advantage. The irony is that I was debating whether to buy a 45mm rotary cuter or the ShapeCut. I figured since my rotary cutter works fine, I'd delay that purchase & get a ShapeCut instead. Apparently, that was the wrong order in which to purchase them.
