Had a strange one or may be two today, first I put a sheet of 15 mill ply on the bed and did a 300 x 200 area clearance @ 5mm. All went fine no problems, until I put in an engineer square and it was out over the 200 length by 3mm! I took off the ply and put in a block of 200 x 250 @ 15 mm and did a profile 5mm in, all-round the edge of the block @ 5 mill deep, using the front of the bed to square up the material. The first time I did it at normal 72 feed it seemed to stick on the y axis (the bed moving Forwards toward me), then there was a sort of small bang and it went off again. The spindle returned to the origin and it was 6 mm off along the y axis. I reset and flipped the blank then dropped it to 60% feed rate, restarted the job. This time it ran perfect and all the angles on the job where correct, any ideas what’s going on?