Re: [CAD_CAM_EDM_DRO] Calculating mechanical forces

cnc002@... wrote:

>
>
>In a message dated 8/1/2005 11:05:01 PM Eastern Daylight Time,
>elson@... writes:
>
>Think your round ways and linear bearings can keep the
>machine within it's tolerances with 332 Lbs of force? Well, maybe you
>have a
>smaller motor.
>
>Jon
>
>
>
>Jon:
>
>For years we ran round Thompson type bearings and ways on our CNC routers
>with 12 to 15 Horsepower motors, turning 20,000 rpm and cutting thru wood,
>

He was talking about flycutting steel, and I calculated a spindle speed
of 190 RPM.
So, that is 100 times slower, so the forces would be 100 times HIGER,
per HP.

>
>particle board, fiberboard etc. at speeds up to 400 inches per minute. We held
>+/- 0.001" tolerance with no problems on materials where you could measure
>that close. I think round bearings and ways would work just fine with a very
>small motor like most mills run. Plus, the cutting speeds are also slow.
>
>

Slower cutting speed means GREATER cutting forces. I also suspect wood
causes
much more friction between the tool, the chips and the workpiece than
when cutting
metal. That ends up as torque on the workpiece, rather than linear
force against the
face of the work. The round ways can probably handle torque better than
linear
force.

>
>

Jon