Mike is correct. The deflection I gave was static. Tool forces also play a part of deflection. These effects can be minimized by slow feed rates and high spindle feeds. 12 lbs does sound light.
The static deflection formula for each rail is : ymax=PL^3/(48EI). for your setup the deflection = pounds on the rail * 0.01253 (example 7*0.01253 = 0.09 mm,
40 lbs would be 0.5 mm, 80 lbs would be 1 mm).
I have a cnc dremel and mill. The mill has a lot better tolerances and negligible deflection. However, the amount of deflection you can allow depends on what you are making. The dremel I have makes great looking parts with decent tolerances. |