First post - gotta say, I agree about the instructions.
However, my experience with the S3 was that the extrusions all came with the ends cut out-of-square. Instructions weren't going to change that. It could have been a terminal flaw - the S3 wouldn't go together square and couldn't be made so.
No matter how many strap clamps you use to try to skew the frame (bad idea, btw), or holes you enlarge like on the videos. . . (and there's no good reason anyone should be doing any of that to something they've spent good money for), there's simply no way the machine can be brought into truth with out-of-square extrusions. After all, assuming the frame pieces are true, which they were on mine, the rails are the large scale definers of the machine's geometry and effect the overall precision of the thing. I mean, the whole point of a CNC cutter is supposed to be cutting accuracy, right?
Support was a little sluggish, but ultimately sent replacements that were even worse than the originals(!) After the second set of bad extrusions arrived and realizing I was unlikely to get anything better from C3D, I grimaced, made a jig for my bench belt sander (pretty analog, huh?), and trued the ends of the extrusions myself. With correct angles,the S3 went together perfectly square and now cuts beautifully.
I'm honestly amazed that C3D ships these things with that sort of fundamental flaw in the production process. I cut metal all the time on a cheapo Dewalt cut-off saw and can make square cuts. I have no idea what kind of setup they're using to cut the extrusions, but it needs careful evaluation. Talking with the support folks, it didn't even seem like anyone was particularly concerned about it. I've subsequently read S3 video comments about wonky extrusions, so it seems like it's been happening for some time.
I love the design of the thing, and the way it performs now that it's right - too bad that an issue like this could make it so difficult to get set up correctly. Oh well, now I have better jigs for my sander. . .