Thanks for your posts. It was good to hear that someone else was seeing the same thing I was with the cameo. Here's an update:
I called silhouette-america tech support asking why I am seeing the rotated rectangles and squares with bowed-out edges. The first call ended since I didn't have the latest version of sil-studio. So I loaded it, and gee, same thing. So I called back and they wanted pics and such, which I was happy to provide, and I fired off an email with pics, a dxf file and the resulting studio file, and another studio file in which I used their drawing tools to create arrays of squares. I told them I have tried two different knives, that the knife was properly seated and clamped, that the mat is loaded properly and centered with the rollers in the proper position, and that the mat release lever was in the clamped position. I told them that the mat was very secure under the rollers (I could not move it after load), and that I had the latest sil-studio software. I told them that I was cutting polyester (mylar) overhead transparency sheets that I mic'd to about 0.004", that my blade depth was the minimum (1), that the speed was the slowest (1), and that I tried force (thickness) settings over a varying range, with the same result. I told them that I tried cutting on 0.007" (65lb) cardstock, at settings appropriate for that media, with the same result. I told them that many other folks with cameos are cutting rectangles down to 10-mil-wide with 10-mil space (~0.5mm pitch). I told them I would be happy with rectangles that were 15-mil-wide with 10-mil space (TSSOP ~0.65mm pitch). I told them that I could not even do rectangles that were 25-mil-wide with 25-mil space (SOIC 50-mil pitch) with the test I ran.
They replied, "Can you confirm whether you see this problem with a sheet of regular printer paper?" Which I did, and told them so, and I will never load thin paper again as it not only gets ripped up, but leaves a fibrous mess on the mat.
Then they requested pictures of my media loaded on the mat, and pics of me loading the mat into the machine. I replied that I would not be at the machine until Thursday, and asked how either a slightly-rotated media sheet or even a rotated mat load would result in the hole-to-hole pattern problems, and that I did not care how the entire pattern was oriented wrt to media edges.
They replied that if it cannot be resolved, that they will swap out the machine, which is great, but am now wondering whether that will result in the same problem.
I asked them if they had tried cutting the test files that I sent them, to see if it happened on one of their machines, whether they had a test file for me to try cutting, whether four line segments cut differently than a rectangle, how I could change a rectangle in sil-studio to four lines, and whether there was any special mode I could use to cut much slower than speed 1.
They replied that my hole sizes were too small to cut well on this material type (it is the same on all materials). Maybe they tried cutting my test files, I am not certain. They didn't answer any of my other questions, but asked me to cut some squares that are 1" and 0.5" size. Not sure what that will tell them. I am certain this is just going to end up with an answer of "not our problem; it's not designed for that use." Which is true, but I think they are missing a technical market. I'm feeling like my questions were not escalated to someone who could actually recognize the error and offer a solution, but it may never get that far. I can likely get them to swap out the machine, but I am not convinced that will help.
I am wondering whether the dxf file exported by the eagle ulp actually has four cut lines instead of a rectangle. I don't have autocad, and have only looked at it with an online dxf viewer. When the dxf is imported into sil-studio, I can only select it as a rectangle, not line segments, so perhaps it was not actually four lines, or perhaps the sil-studio import converted it into a rectangle. If that is the case, it would explain why it cut just like the test of studio-drawn squares.
I was actually happy to hear that you saw the same problem and found a solution. I am trying your fix, but I will continue this in another post.