PECK DRILLING CYCLE ISSUES: CHIP BREAK DISTANCE / FORCED RAPID MOVEMENT!!!!

[Anonymous]

I THINK I FOUND WHY I'VE BEEN BREAKING VERY DELICATE AND EXPENSIVE DRILLS.... NOT HAPPY.

I am having to drill small diameter holes and using the peck drilling cycles to get it done, I have broken several carbide drills in the troubleshooting phase.  I switched back to cobalt drills so I could get the job done, not drilling at $12/hole!!....

I think I have found the reason:  Fusion is outputting a forced move to .005" that is a rapid movement in the downward direction!!!

obviously i know i have hole clearing issues due to the small diameter, so I would increase the chipbreak distance to a higher increment to allow the drill to clear and then get back to cutting, and that's when I noticed Fusion forces a RAPID back to .005" then feeds down.  With chips in the hole that is not enough space.

Look at my simulation and see the points on the toolpath.  In the first setup it is wrong as Fusion is doing its thing (.010" CB specified).... the second set up has the motion that is needed, but needs to honor the chipbreak the user inputs (I had to enter .003" to keep it less than the .005" fusion defaults).   Want to see something stupid?, enter in .005" as a chipbreak and fusion still inputs a unneeded rapid to -.000079 (my third example).  

Please expose these small default values and let them be visible and editable... there is no reason to have this .005 a default and not apparent to us users/operators,  I have thought this was a matter of drill quality, slop in my z axis, feeds/speeds, insufficient coolant, and caused me to ultimately do the job in the RED with lesser tools that took 4min/cycle longer (1000parts @ 15/cycle = 66 setups x 4min = 4.5hours wasted).   

[Steinwerks]

What post processor are you using? Sounds like the post is set up to expand the drilling cycle into point moves instead of a canned cycle which may be part of the issue. Machines like Haas and Fanuc use a chip break distance specified in a parameter, not output in code (Fadal uses a P value), so if you want it to be something specific on a machine that handles it like this, it will expand the cycle. And yes it will use rapids because that's what gets used in most generic drilling cycles. Most machines also do not perform accumulated depth cycles, but if yours does a post can be edited to use it.

Now I went ahead and posted your example 3 without changing anything using the generic Haas post and got this:

%
O01001 (Example)
(Using G0 which travels along dogleg path.)
(T1 D=0.2344 CR=0. TAPER=118deg - ZMIN=-0.228 - center drill)
(T20 D=0.125 CR=0. TAPER=135deg - ZMIN=-0.8 - drill)
N10 G90 G94 G17
N15 G20
N20 G53 G0 Z0.

(Center Drill -.100 5)
N30 T1 M6
(CENTER DRILL #4)
N35 S1467 M3
N40 G54
N45 M8
N60 G0 X0. Y0.
N65 G43 Z0.4 H1
N70 T20
N80 G0 Z0.3
N85 G98 G73 X0. Y0. Z-0.228 R0.2 Q0.228 F2.934 <--Normal canned cycle with a starting plane of .2"
N90 G80
N95 G0 Z0.4
N100 M5
N105 G53 G0 Z0.

(Top Drill 4)
N115 M9
N120 M1
N125 T20 M6
(1/8" 0.125 Norseman 240-UB)
N130 S1070 M3
N135 G54
N140 M8
N155 G0 X0. Y0.
N160 G43 Z0.4 H20
N165 T1
N175 G0 Z0.3
N180 Z0.2 <-- start of expanded cycle
N185 Z0.08
N190 G1 Z-0.25 F2.139 <-- everything past here almost conforms to the toolpath
N195 G0 Z-0.245 <-- rapid to chip break distance
N200 G1 Z-0.35 F2.139 <-- feed to -.05 from previous peck depth
N205 G0 Z0.3 <-- rapid to retract height
N210 Z-0.27 <-- rapid to some built in meterial clearance, this one's weird, but shouldn't cause any actual issues
N215 G1 Z-0.4 F2.139
N220 G0 Z-0.395
N225 G1 Z-0.45 F2.139
N230 G0 Z-0.445
N235 G1 Z-0.5 F2.139
N240 G0 Z-0.495
N245 G1 Z-0.55 F2.139
N250 G0 Z-0.545
N255 G1 Z-0.6 F2.139
N260 G0 Z-0.595
N265 G1 Z-0.65 F2.139
N270 G0 Z0.3
N275 Z-0.57 <-- again with the .08 clearance
N280 G1 Z-0.7 F2.139
N285 G0 Z-0.695
N290 G1 Z-0.75 F2.139
N295 G0 Z-0.745
N300 G1 Z-0.8 F2.139
N305 G4 P500 <-- dwell at the bottom of the hole
N310 G0 Z0.3
N315 Z0.4

N320 M5
N325 M9
N330 G53 G0 Z0.
N335 X0.
N340 G53 Y0.
N345 M30

%

I don't see any rapid moves to -.000079 in the code or toolpath. Can you take a screenshot of this issue?