form drilling 4330

[shrektaylor]

trying to form drill three angles and a .021 radius three inches deep, keep breaking the tips

[ProProcess]

More information would be helpful, such as...
Coolant through the tool
Carbide, HSS, Indexable, Cemented ect...
Drilling into solid or pre-drilling/boring shape

This should get us started.

[dookie2022]

More details would be nice but have you checked alignment of drill (square and on centre line to spindle)

[shrektaylor]

have tried carbide through coolant hss two flute with a pre drilled hole leaving .005 for cleanup in x axis, waiting for carbide twist drill and hss with carbide tip to arrive

[cogsman1]

One trick I have used often, is that when I reach the depth I need, I dwell slightly and then FEED back away from the bottom before doing a rapid out. That stops the shock that could be there from backlash. This has proven itself many, many times to stop chipping/breaking my tools.

[hacdlux]

i would look at the straightness and center of your predrill

also. you don't state a diameter on your tool but it sound pretty skinny.

generally with my form tools i drop the feed during the last .100 of the hole(whenever you hit the drill point from your predrill) when the tool starts to engage on all its faces

ex: .250 cbore .720 dp
.230 cbore .760 dp
.120 thru
in 6061
feed to .720 @ .003 ipr
feed to .850 @.0008 ipr
dwell x.1
feed out .003 (no withdraw marks allowed

also i do all my critical form work on my sub
i don't run ground bar so the GB tolerances make it difficult to keep things from bell mouthing

[shrektaylor]

drill dia is .231 feed at .003 to .1 from pre drill point followed by pecking at .01 dp .001 per rev feeding out, no rapid movements.