achieving a smooth pocket

[Bob T]

Hi All,

I am cutting with a 1/2" end mill, removing 1/16-1/8" of material in a thin geometric shape, like you would for a topographical model. the pocketed surface I intend to finish, and is too tight for sanding easily. My endmill is leaving "starting scars," which I think I can clear up with a ramped start. but the bit is also leaving a "trail", I can see the path it has taken to clear the pocket. How do I minimize/eliminate this?

Thanks!

Bob T

[bleeth]

Make sure your end mill is defined as an "FEM" (Flat end mill that is made to minimize bottom mill marks due to the bottom geometry of the cutters).
Make darn sure your part is not moving at all and also that your z axis is dead perpendicular to your spoilboard. There is tons of stuff on here about squaring the z axis.
Best method is with a trammel in your spindle or router and feeler guages. If it is a router you can also see more marks due to collet runout.
You don't say what you are cutting, speed, feed, etc or what SB you have.