Hi guys - having been inspired by the stunning DIY CNC mill on 5bears.com, I am considering building a metal-cutting mill (mostly Al, but some steel) using aluminium extrusion and linear rails.
I have done some back of envelope calculations based on the cutting rates and accuracies I'd like, worked out the cutting forces they'd produce and used the deflection calculator to determine the size of profile I'd need to keep the deflection acceptable.
I am still working on the exact structure of my design, but so far, it's looking like it will come out at about 40-50kg for the structure without the milling head/motor which will add another 20kg or so. This is for a table size of about 750x250mm (30x12") and travels of about 500x300x300mm.
My worry is that it seems a bit light for its size. I have tried to ensure that my design is naturally balanced - i.e. no overhangs or massive cantilevers, so that it doesn't need a massively heavy base to keep it upright, but I am no mechanical genius, so I can't help thinking I've overlooked something!
Should I just trust my sums, or is there a good reason that mills are all rather heavy?
Cheers.