[Micro Milling]

Hello everyone. Been a long time since I have posted here but my new hobby has me using my harbor freight milling machine again.

I have the habor freight mini mill.

I need to cut and shape about 1/4 to 1/2" inch steel plates. I am shaping steel to work as a torque arm on a bicycle so the cuts/edges do not have to be smooth.
I was wondering what is the best end mill size and type to use to shape it? The edges do not have to be perfect so should I use a roughing end mill?
Since I do not need to make any cuts in the middle of the steel, just trimming away the edges, what size would work best?


The reason I ask size is I know that if the end mill is too small it will break easily when you move it around. But I would think that a larger end mill will cut more away when all you want to do is trim away edges.

Should I use a 2 flute or a 4 flute?

[Superman]

For heavier work, & the ability to replace the cutting edges
I suggest a Ø16mm ( or 5/8" ) 4 flute tipped cutter. A larger radius on the corner would give stronger support the the actual tip ( say R1/32")
example link

For lighter work, & possible finishing ops
say Ø12mm ( or 1/2" ) endmill
example link

a greater number of flutes, allows for inceased feeds, a stronger tool ( a thicker cross section ), less flex when cutting, but a shallower area for the chips to roll into.

Always hold the tool as short as possible, use coolant or air to assist chip evacuation ( necessary for full width cuts),

Typically, the cutter size choice is that the cutter should be smaller than a corner radius it has to create ie internal corner rad of 1/2", rough with a Ø1/2" cutter, finish with a Ø3/8" . If you use a cutter the same size, it tends to give bad finishes in those corners.