[johnmastri]

New to CNC -

Just tried the follow and the bit broke after ~1" inch on the tool path.

Software: Aspire
Material: .020" brass
Tool: O flute up cut (Amana) 1/8”
Cut Depth for pass: .02"
Spindle: 14000rpm
Feed: 15ipm
Plunge: 30ipm


Ramp: 1” (smooth)


I applied A9 cutting fluid to the area the profile was being cut. The tool proceeded down the ramp then snapped off approximately at the end of the ramp.


Any ideas?

[awerby]

That feedrate and spindle speed would be good for a 2-flute cutter, but with a single flute you should slow down to half as fast. Here's an online feed-speed calculator you might try: Feed Rate Calculator Usually you would plunge slower than you feed; this was the opposite. Also, while those O flute cutters are good for plastics, for brass a negative rake is indicated. Another thing that could cause problems is the thinness of the material. It sounds like the break happened just as the tool broke through. When that happens, there's a tendency for a cutter to grab the material and pull it up, which puts a lot of stress on the tool. How are you holding this stuff down?