[henrychan]

So, I'm building a CNC mill and I hope to cut steel with reasonable speed and quality. Word area is about 1000mm(x)*500mm(y)*500mm(z)

The machine will be mainly constructed using 3" .25" thick steel square tubes with .25" steel plates as reinforcements.
I am still at a very early stage of designing the machine, but some rough calculations and FEA of the frame assembly gives me about 1 thou deflection along x and y axis with 150lbs applied force.
Is that enough rigidity? I really can't find any useful information about how much load needs to be designed to withstand. Some sources say 200 safety factor while others say 1 million lbf per inch of deflection.

I also did some calculations to see how much force each member is subjected to if I were to make Z work area 750mm. It doesn't look that good, looking at about 4 thou deflection under 150lbs load on entire assembly.

Thanks.