Building from Scratch or follow some plans?

[irving2008]

both!

Think about where the tip of the cutter will be when cutting...it'll be about 200mm below the y-axis (depending on how much y-axis clearance over the workpiece you want. So any sideways force on the cutter will be trying to bend the cutter.. but if that was solid it would be trying to bend the z-axis... but if that was solid it would be trying to twist the y-axis - the worst scenario being the twist in the X direction perpendicular to Y. Each of those components will deflect to some extent and transmit the forces back up to the component above them in the chain... and then the y-axis transmits them to the gantry sides and thence to the x-rails...

The easiest way to get a handle on the forces is to draw stick diagrams... some forces can be ignored generally, e.g. the twisting motion of the Y-axis on the Y-axis due to a sideways force on the cutter parallel to Y, although that force is also trying to push Y sideways and that is trying to rotate the bearings on the x-rails and that can't be ignored... at least initially... good bracing and gussetting helps, but you need also to keep the moving weight down...