You are right. There isn't really anything holding the gantry down other than the leadscrew and gravity. On the other hand the router wasn't meant to mill steel. I haven't noticed any problem on the parts that I have cut.
The pipe rails are bolted thru the base and the support. I used 1/4" bolts but I think a larger size would be better. Since the pipe is soft the threads can strip out.
Chris |