Mill Vise Problems

Mill Vise Problems

I have never been able to get the mill vise on my Sherline vertical mill to hold pieces of aluminum tight enough to actually do any milling. It doesn't matter how tightly I clamp a piece of aluminum (and often, this is true for Delrin and other hard plastics)--one I start milling anything, it either pulls it right out, or loosens it enough that it is no longer in the same position it was before. I'm using a four flute end mill. Is this perhaps the problem? Even taking off a .010" layer is sometimes as much as I can do. The only way to get around this to hold the workpiece in place with my hand--which is definitely not a recommended procedure!

I'm wondering if a different mill vise might be a better choice--or perhaps there is something wrong with my technique. Aluminum is pretty gooey stuff, and climb milling is even less happy than conventional milling.

UPDATE: Yes, two flute end mills are the preferred method of cutting aluminum. I'm still not happy with how this vise works, but it's better with the right endmill.