I can't remember how long its been since I bought all the parts for my Ox build and in that time I never noticed that the drive shafts on the Nema 23s don't have a flat side. I've got to the point of connecting everything up and placing the Ox on a 4' X 5' 18mm ply base, because the machine is 3' wide and 4' long so I could cut 2' X 3' sheets at a time. The Nema 17 has a flat side on its shaft, but the others haven't. I was wondering if this was OK to leave as is or the take them off and grind them flat. when ever I've used a grinder in the past people run for cover screaming their heads off so I would prefer the first option. Lastly, in mark's video, when he came to attach the Nema 23s to the machine he said he had already tapped the four holes in each one to accept the screws, but I found the m5 screw just slips through those holes. Is there enough room to use an M6 tap and use M6 screws instead Any one have the same problems while building their machines please let me know. Thanks.