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Robin S. Robin S. is offline
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Default End Milling Into a Corner Without 'Snipe'?

On Feb 17, 10:25*pm, (Doug White) wrote:
The stainless makes taking light cuts
difficult, and the cosmetic issue means I really don't want a divot in
the corner.

Any suggestions or tricks?


Easy.

Before you begin cutting the pocket, move to each corner location of
your pocket (final dimensions!). Drill just under the endmill's
diameter (between like 1/64" and 1/16", depending on the size of the
endmill), and then plunge down with the endmill. Now you've created
your finished corners.

When you're machining your pocket, your cutter will actually come
completely out the cut as you reach the corners, instead of having a
*massive* chip load increase (as you're experiencing now) which flexes
the cutter.

You can't simply rely in "slowing down" at the corners. We're not CNC
machines - we're flimbsy, fleshy, squishy humans, and the machines
have backlash.

Climb milling is a good idea for your finishing cuts. When on a CNC,
you normally climb mill because it results in a better finish and
longer cutter life. Just make sure the machine is tight and you're
paying attention (listening, feeling and looking).

Additionally, climb milling should help with the issues associated
with taking light cuts in stainless. When you climb mill, the chip
load is at its max as the flute enters the work (good). When
conventional milling, the chip load is at its smallest as the flute
enters the cut (bad). This alone will let you take light cuts in
stainless successfully.

Lastly, make sure you know which way to turn the handwheel as you
switch your axis feed! This is no time to be second guessing! Draw
arrows on the machine just above the handwheels. *Always* think in
terms of where the cutter is going to go - not which direction the
axis will be moving (i.e. turn the handwheel clockwise to move the
CUTTER towards me). Different machines move in different ways so
always think in terms of cutter direction.

Regards,

Robin