Legs - their purpose and sizing (Can legs be bolted......?)
 

Copied from elsewhere:

The legs serve 2 main purposes . . . .

- The no-brainer purpose is to elevate the table off the floor. For that, even a 2x4 plank will do.

- But the second function is to stiffen the main beams from toppling over. Here the legs work in conjunction with the table cross-support beams 1010302, as well as vertical bearers 1010314. When taking cuts in the y-direction, there are forces which tend to topple the tops of the main beams in the y-direction. Not that there is a real risk of them ever falling over, but there is the risk of resonant vibrations reflected back as tool chatter marks on the job.

The tables I have built so far have always had the legs and vertical bearers welded to the main beams. The two tables in operation have the cross-supports welded as well. Within a few weeks we will have a table running with bolted cross-supports, but still with welded frames 1010310. So, I cannot personally vouch for the stiffness of an all-bolted construction, and more so if the bolting is to relatively flexible aluminium. My gut feel is that it would work, but I am nervous to state flat out that it is going to be good. (Those heavy main beams seam to vibrate all the same, irrespective of how I fixed them so far)