I was thinking about all these cheaper bench mills. How do you make them square?
Are they simply machined flat with a face mill/fly cutter? Then just bolted together?
Are they surface ground?
How square are machines made? Like a typical 45 sized bench mill?
How do you measure that 90degree angle to minute accuracy? 90.05, 90.002 degrees etc?
How are larger commercial machines put together? Do they have the base and vertical upright just bolted down?