Re: [CAD_CAM_EDM_DRO] CNC'ing a Mini Mill

ezko.laurila@... wrote:

>Hi!
>
>Hi!
>This is not right on the nail but good to know, here is how to count the ~rpm and the ~feed for a mill.
>
>rpm = 20*1000 / pii * D
>mm/min = rpm * pii * tooth feed (to be sate use .05mm to start with)
>
>A gross value for HSS is 20 m/min, so with your 25mm 2 flute? (tooth) HSS the rpm would be ~250 rpm and the table feed ~25 mm/min.
>
>
>

Yup, these are far more practical parameters for a lighter machine.
Really, using a 25 mm end mill may not be a good idea in a mini-mill.
They are just too flexible, and the larger cutters put a greater moment
arm on the spindle. This could cause severe chatter to develop. I've
never even tried anything over 10 mm on mine, and that had the whole
machine shaking pretty bad. It seems the mini-mill I have (the ~70 Kg
model) is about 10 times more flexible than my Bridgeport.

Jon