Hi Neale,

Glad it is of interest. I'm hoping that the method and setup is simple enough for others to try and compare to. I know Jonathan has measured something similar so perhaps others have too.

Yes the first figure (10,000N/mm) is the basic gantry stiffness and everything else drops away from this due to various factors you have mentioned. What you cannot see in these photos is that the Y axis ballnut screws to a wooden panel on the Y axis (!), so this probably accounts for some of the 10,000N/mm gantry side dropping to 5000N/mm on the Y plate. An upgrade to aluminium should help here. It's a carry-over part from an old design when I had less machining capability.

I've always felt I could have done a better job, especially on the Z axis, along the lines you have mentioned above plus other ideas. This data shows there is still room for improvement although I have been accused recently of only using the machine to make a better machine, and not actually making anything with it. Easy to get drawn in . . . .