I recently received a new 3-foot table from the April preorder, and it is a much more impressive experience than the end table! That said, I discovered that the Sisbot moved during shipping, an issue I did not discover until I tried running the table and found that the Sisbot arm was striking the gear on the off-axis motor because there was not enough clearance.
More precisely, when I ran the Erase pattern, I found that the table worked fine for about two-thirds of the radius, but when it reached a particular angle and distance away from the origin, suddenly the arm appeared to catch on something, and the ball would stop, move inward about a quarter to half inch, then continue on. This kept happening at the same spot, and then when the track finished, the table had lost position. When I tried running the track in reverse, I found that it was getting stuck in nearly the same spot. So I looked under the table and that's when I realized that the arm was getting caught on the motor, and that was because the Sisbot was too close to the underside of the table. But it was not evident by looking at the red flexible joints as described by the support documents, since they weren't bent. What I realized is that the metal supports welded to the circumference of the table had actually bent out of position during shipping.
As gently as I could, I adjusted these back and now the table works flawlessly. I measured the separation between the underside of the table and the ends of these support beams to make sure that the Sisbot was level, and found that it was off (tilted) by about 5 mm. I would estimate that the minimum separation to avoid the arm hitting the motor is about 35 mm as measured vertically from the underside of the table to the center of the screw that fastens the rubber joint to the metal support. At this distance, the clear plastic Sisbot arm looks like it is flexing slightly, like a leaf spring, pushing the magnet against the underside. I assume this is intentional, but am not sure. I would like to know if the separation should be larger than this.
Due to what I can only imagine was the rough handling of the table during shipment (the single FedEx delivery person simply carted it up to the doorstep despite the prominent label on the box saying that two people are required for lifting it), I would like to suggest that other people who receive their table, prior to operation, be instructed to check the underside for the proper separation distance as the Sisbot can become misaligned during transit. All it takes is a few millimeters. I realize that my experience may very well be exceptional, but I hope my findings will spare others from unnecessary worry.
Thanks so much for thoroughly investigating and documenting your problem (and fixing it!). You are spot on in all your assumptions. The coffee tables are far more massive, and also far more likely to be mishandled during shipping. We will indeed follow your suggestions, and add this pre-run check to our instructions!