Help! What's wrong with this program?

[mwbridgwater]

I wrote this simple program today for finishing a slot (I've omitted the first part which is roughing.). Please see the sketch and code I wrote. One problem which I can't figure out: The finished slot measures the correct width (.280) but the length is exactly .015 short at each end (2.220 inside the ends of the full radii instead of 2.250). Using a .250 end mill with D code at .250 diameter. Funny, that the amount the ends are short is the same as the amount that the sides are over 1/4", but I don't see how that can be related. See PDF sketch: Starting at point "A", CCW loop, finishing at point "B". Gotta figure this out by the morning! Thanks for any insight.

N23 X2.3 Y0
N24 G01 Z-.5 F80.
N25 G41 D04 X2.345 Y0
N26 G03 X2.485 Y.140 I.140 J0
N27 G01 X.515
N28 G03 X.515 Y-.140 I0 J-.140
N29 G01 X2.485
N30 G03 X2.625 Y0 I0 J.140
N31 G40 G01 X2.3 M09
N32 G00 G91 G28 Z0.
N33 M30

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[Superman]

??? some controls require Dvalue to be 1/2 cutter diameter ...ie D=0.125

maybe your cutter is comped wrong
... try setting D=0 & running the path above the job.... does it follow the profile ?
no... fix program....
yes... now run it above, with the Dvalue

[mactec54]

I wrote this simple program today for finishing a slot (I've omitted the first part which is roughing.). Please see the sketch and code I wrote. One problem which I can't figure out: The finished slot measures the correct width (.280) but the length is exactly .015 short at each end (2.220 inside the ends of the full radii instead of 2.250). Using a .250 end mill with D code at .250 diameter. Funny, that the amount the ends are short is the same as the amount that the sides are over 1/4", but I don't see how that can be related. See PDF sketch: Starting at point "A", CCW loop, finishing at point "B". Gotta figure this out by the morning! Thanks for any insight.

N23 X2.3 Y0
N24 G01 Z-.5 F80.
N25 G41 D04 X2.345 Y0
N26 G03 X2.485 Y.140 I.140 J0
N27 G01 X.515
N28 G03 X.515 Y-.140 I0 J-.140
N29 G01 X2.485
N30 G03 X2.625 Y0 I0 J.140
N31 G40 G01 X2.3 M09
N32 G00 G91 G28 Z0.
N33 M30

Sorry that would not work what I suggested you could try this though and change what you need to run this on your machine

%
O3483
N1G17G40G80
T4M6
M8
G54
S2850M3
G90G0X-.005Y.0863
G43Z.1H4
G1Z-.5F20.
G3X-.015Y.0763J-.01F14.
G41G1Y-.985D4
G3X.015I.015
G1Y.985
G3X-.015I-.015
G1Y.0763
G3X-.005Y.0663I.01
G40G0Z3.
M9
G91G28Z0.
M5
M30
%

Without cutter comp

%
O3484
N1G17G40G80
T4M6
M8
G54
S2850M3
G90G0X-.005Y.0863
G43Z.1H4
G1Z-.5F20.
G3X-.015Y.0763J-.01F14.
G1Y-.985
G3X.015I.015
G1Y.985
G3X-.015I-.015
G1Y.0763
G3X-.005Y.0663I.01
G0Z3.
M9
M5
M30
%

[mwbridgwater]

??? some controls require Dvalue to be 1/2 cutter diameter ...ie D=0.125

maybe your cutter is comped wrong
... try setting D=0 & running the path above the job.... does it follow the profile ?
no... fix program....
yes... now run it above, with the Dvalue

No, pretty sure that's not it. I know the machine uses the diameter for the D value, and the width of the slot is perfect - only the ends are each .015 short - that's what's so strange.

[mactec54]

No, pretty sure that's not it. I know the machine uses the diameter for the D value, and the width of the slot is perfect - only the ends are each .015 short - that's what's so strange.

To ways to fix it add .015 to each end of your slot and see what happens

Or rewrite it without the cutter comp and you should be ok

[rcs60]

try this
I don't think that the first radius is complete
by starting on one side completing the arc then coming back to it it should be complete
the other thing that you could do is enter the finish cut on one side before the radius then when you are at the end of the cutting just g40 off the part to the center of the slot



N23 X2.3 Y0
N24 G01 Z-.5 F80.
N25 G41 D04 X2.485 Y-.140
N26 G03 X2.485 Y.140 I.140 J0
N27 G01 X.515
N28 G03 X.515 Y-.140 I0 J-.140
N29 G01 X2.485
N30 G03 X2.485 Y.140 I0 J.140
N31 G40 G01 X2.3Y0. M09
N32 G00 G91 G28 Z0.
N33 M30

[shaiyya]

My guess is your finish pass is too fast on both ends. In my experience when cutting a slot, with cutter comp active, if the side/width is correct but the length is short then it is a finish pass speed issue. Simply slow down finish speed pass should fix this issue.