DIYbanter - View Single Post

In article .net,
says...
Ned,

Rough the part from both ends to the middle reorienting as required to
avoid climb milling, then finish with light cuts the whole length. The
final can be a very light climb, if that gives you the best finish.

Dumb question: what happens in the middle? For any given pair of "half
passes", won't the first half of thecut leave the second half breaking
out of the material? Or is the point that when it happens, there is
material under (and in front of) the endmill?

Yes, in order to create a defect in the middle you'd have to pull a
divot out of the part, whereas on the end you're chipping off a sharp
outside corner.

If that is the idea, would you take a large endmill and cut almost full
depth (up/down)? How much would you take front to back on each pass?

Depends on how well you can hold onto the part and, especially in this
case dealing with acrylic, how much heat is generated. Unless I was in a
big hurry to make a number of parts, I'd probably use a dead sharp 5/8"
2-flute endmill taking perhaps 1/8" off both surfaces on each pass, and
make adjustments depending on what's happening in the cut. Finish with a
pass of .005"-.010" on both surfaces simutaneously.

Ned Simmons