I see machines that have double plates (one on either side) of the beams with the pulleys, and other with just one plate. Looking for pros and cons, as well as experiences for those options.
The idea is to add some stiffness to the wheels on the Y axis. Would be interested to see if anybody has data on how much improvement it brings.. The drawback is it makes securing the Y rails to the spoil-board impossible if the plate secures the lower and upper wheels together. IMO this is probably more important on longer Y axis machines, like 1000-1500mm machines (securing the rail to the board to prevent side to side movement). Another issue is having the plates makes side shields more difficult (not impossible) to add.
Makes the wheels MUCH stiffer as they are supported from both sides rather than being cantilevered. The down side is that you can only mount your bed to the main table linear rails at the very ends. If you have a heavy router or a very solid table I am not sure the trade off is worth it as connecting the main beams to the table can make the them VERY stiff.
