How ARC center, start angle, and sweep are calculated?

[KH0UJ]

Not sure who you are replying to, but there are no arcs in your code. It's all straight segments, which is typical of 3D g-code.
And this has nothing to do with the original question.

It`s definitely not you boss, im pointing my comment to the thread starter or the original poster, you are a 5 star General around here and im like aspiring to be private E-1 not even close to E-1

can anybody make a simulation video of what the OP meant on an ARC? my own understanding of an arc is it`s like a C or am I wrong?

[KH0UJ]

This is the simulation screenshot

Attachment 360188

So it`s like a letter C

[e-music]

It`s definitely not you boss, im pointing my comment to the thread starter or the original poster, you are a 5 star General around here and im like aspiring to be private E-1 not even close to E-1

can anybody make a simulation video of what the OP meant on an ARC? my own understanding of an arc is it`s like a C or am I wrong?

And I would emphasize again that, your answer had nothing to do with my question and you are totally in a different arena!

[ger21]

G02 X5.25 Y-1.5 I0 J1.75.......according to the notes I have......you would have to know precisely the diam of the cutter and also that it is not running out of round and so giving you a different cutter radius.

Every single line of g-code, whether a straight line or an arc, requires you to know the cutter diameter.
Unless you're using G41/G42 comp, in which case it doesn't matter, regardless of whether you're using IJ arcs or R arcs.

You're over complicating things. Or not understanding.

[handlewanker]

Every single line of g-code, whether a straight line or an arc, requires you to know the cutter diameter.
Unless you're using G41/G42 comp, in which case it doesn't matter, regardless of whether you're using IJ arcs or R arcs.

You're over complicating things. Or not understanding.

Well I thought using the R notation was simplifying things........using the R notation to create an arc at the corner of the plate does not require you to calculate the cutter diam (or radius) in the coding......that is up to Mach 3 to refer to the tool register when it creates the arc......using the I and J notation requires you to manually calculate the code with the cutter diam added to the X and Y values.

To refresh the memory.....

G02 X5 Y-1.5 R1.5 creates the radius and there is no mention of a cutter diam in that line of code......that is ultra simple as the tool diam is already in the Mach3 tool register.

It gets even more confusing if the part you are making is in Imperial dimensions (customers's drawing etc) and your cutter specs in the tool register are all Metric.

From post #15....... I get confused with the I value at 0....can't understand why this is so.
Ian.

[ger21]

Well I thought using the R notation was simplifying things........using the R notation to create an arc at the corner of the plate does not require you to calculate the cutter diam (or radius) in the coding......that is up to Mach 3 to refer to the tool register when it creates the arc......using the I and J notation requires you to manually calculate the code with the cutter diam added to the X and Y values.

X and Y are the start and end points They are what they are. You're not adding diameter to anything. Both R arcs and IJ arcs have the same X and Y coordinates.

[Jim Dawson]

Here is the shape I use for testing code. It has both G2 and G3 moves, with both full circles and arcs starting and ending at odd points. Put the shape in different quadrants and crossing quadrants. Allows testing of all possibilities. Also the G code contains both I, J and R, Start, End

Use ''Toolpath to Geometry'' to create a dxf from the G code.

( MADE USING CAMBAM - HTTP://WWW.CAMBAM.CO.UK )
( ARC TEST 12/5/2016 18:29:51 )
( T0 : 0.0 )
G20 G90 G64 G40
( ENGRAVE1 )
G17
M3 S1000
G0 Z0.125 W0.0
G0 X-3.9824 Y-1.9835 Z0.125 W0.0
G0 X-3.9824 Y-1.9835 Z0.0625 W0.0
G1 F10.0 X-3.9824 Y-1.9835 Z-0.015 W0.0
M7
G1 F30.0 X-7.9824 Y-1.9835 Z-0.015 W0.0
G2 F30.0 X-11.9824 Y-1.9835 Z-0.015 I-2.0 J0.0 R2.0 S0.0 E-180.0
G1 F30.0 X-13.9824 Y-1.9835 Z-0.015 W0.0
G3 F30.0 X-15.9824 Y-3.9835 Z-0.015 I0.0 J-2.0 R2.0 S90.0 E90.0
G1 F30.0 X-15.9824 Y-7.9835 Z-0.015 W0.0
G3 F30.0 X-13.9824 Y-9.9835 Z-0.015 I2.0 J0.0 R2.0 S180.0 E90.0
G1 F30.0 X-12.4319 Y-9.9835 Z-0.015 W0.0
G1 F30.0 X-12.4319 Y-9.4835 Z-0.015 W0.0
G2 F30.0 X-7.6911 Y-8.9835 Z-0.015 I2.4495 J-0.5 R2.5 S168.463 E-144.8849
G1 F30.0 X-7.6911 Y-9.9835 Z-0.015 W0.0
G1 F30.0 X-3.9824 Y-9.9835 Z-0.015 W0.0
G3 F30.0 X-1.9824 Y-7.9835 Z-0.015 I0.0 J2.0 R2.0 S-90.0 E90.0
G1 F30.0 X-5.9824 Y-7.9835 Z-0.015 W0.0
G2 F30.0 X-6.4824 Y-4.047 Z-0.015 I0.0 J2.0 R2.0 S-90.0 E-165.5225
G1 F30.0 X-1.9824 Y-4.047 Z-0.015 W0.0
G1 F30.0 X-1.9824 Y-3.9835 Z-0.015 W0.0
G3 F30.0 X-3.9824 Y-1.9835 Z-0.015 I-2.0 J0.0 R2.0 S0.0 E90.0
M9
G0 X-3.9824 Y-1.9835 Z0.125 W0.0
G0 X-13.0539 Y-5.6121 Z0.125 W0.0
G0 X-13.0539 Y-5.6121 Z0.0625 W0.0
G1 F10.0 X-13.0539 Y-5.6121 Z-0.015 W0.0
M7
G3 F30.0 X-14.4824 Y-5.1175 Z-0.015 I-0.9285 J-0.3714 R1.0 S21.8014 E98.1986
G3 F30.0 X-14.4824 Y-6.8495 Z-0.015 I0.5 J-0.866 R1.0 S120.0 E120.0
G3 F30.0 X-12.9824 Y-5.9835 Z-0.015 I0.5 J0.866 R1.0 S-120.0 E120.0
G3 F30.0 X-13.0539 Y-5.6121 Z-0.015 I-1.0 J0.0 R1.0 S0.0 E21.8014
M9
G0 X-13.0539 Y-5.6121 Z0.125 W0.0
M5
M30

[handlewanker]

Highly confusing........I need to understand how the coding sequence works......I'll have to gen up to get more knowledgeable or this thread will wander around in circles.....my fault entirely......thanks for your time, much appreciated.
Ian.

[KH0UJ]

Here is the shape I use for testing code. It has both G2 and G3 moves, with both full circles and arcs starting and ending at odd points. Put the shape in different quadrants and crossing quadrants. Allows testing of all possibilities. Also the G code contains both I, J and R, Start, End

Use ''Toolpath to Geometry'' to create a dxf from the G code.

( MADE USING CAMBAM - HTTP://WWW.CAMBAM.CO.UK )
( ARC TEST 12/5/2016 18:29:51 )
( T0 : 0.0 )
G20 G90 G64 G40
( ENGRAVE1 )
G17
M3 S1000
G0 Z0.125 W0.0
G0 X-3.9824 Y-1.9835 Z0.125 W0.0
G0 X-3.9824 Y-1.9835 Z0.0625 W0.0
G1 F10.0 X-3.9824 Y-1.9835 Z-0.015 W0.0
M7
G1 F30.0 X-7.9824 Y-1.9835 Z-0.015 W0.0
G2 F30.0 X-11.9824 Y-1.9835 Z-0.015 I-2.0 J0.0 R2.0 S0.0 E-180.0
G1 F30.0 X-13.9824 Y-1.9835 Z-0.015 W0.0
G3 F30.0 X-15.9824 Y-3.9835 Z-0.015 I0.0 J-2.0 R2.0 S90.0 E90.0
G1 F30.0 X-15.9824 Y-7.9835 Z-0.015 W0.0
G3 F30.0 X-13.9824 Y-9.9835 Z-0.015 I2.0 J0.0 R2.0 S180.0 E90.0
G1 F30.0 X-12.4319 Y-9.9835 Z-0.015 W0.0
G1 F30.0 X-12.4319 Y-9.4835 Z-0.015 W0.0
G2 F30.0 X-7.6911 Y-8.9835 Z-0.015 I2.4495 J-0.5 R2.5 S168.463 E-144.8849
G1 F30.0 X-7.6911 Y-9.9835 Z-0.015 W0.0
G1 F30.0 X-3.9824 Y-9.9835 Z-0.015 W0.0
G3 F30.0 X-1.9824 Y-7.9835 Z-0.015 I0.0 J2.0 R2.0 S-90.0 E90.0
G1 F30.0 X-5.9824 Y-7.9835 Z-0.015 W0.0
G2 F30.0 X-6.4824 Y-4.047 Z-0.015 I0.0 J2.0 R2.0 S-90.0 E-165.5225
G1 F30.0 X-1.9824 Y-4.047 Z-0.015 W0.0
G1 F30.0 X-1.9824 Y-3.9835 Z-0.015 W0.0
G3 F30.0 X-3.9824 Y-1.9835 Z-0.015 I-2.0 J0.0 R2.0 S0.0 E90.0
M9
G0 X-3.9824 Y-1.9835 Z0.125 W0.0
G0 X-13.0539 Y-5.6121 Z0.125 W0.0
G0 X-13.0539 Y-5.6121 Z0.0625 W0.0
G1 F10.0 X-13.0539 Y-5.6121 Z-0.015 W0.0
M7
G3 F30.0 X-14.4824 Y-5.1175 Z-0.015 I-0.9285 J-0.3714 R1.0 S21.8014 E98.1986
G3 F30.0 X-14.4824 Y-6.8495 Z-0.015 I0.5 J-0.866 R1.0 S120.0 E120.0
G3 F30.0 X-12.9824 Y-5.9835 Z-0.015 I0.5 J0.866 R1.0 S-120.0 E120.0
G3 F30.0 X-13.0539 Y-5.6121 Z-0.015 I-1.0 J0.0 R1.0 S0.0 E21.8014
M9
G0 X-13.0539 Y-5.6121 Z0.125 W0.0
M5
M30

Here`s a freestyle version of your shape sir drawn and routed under 2 minutes, I cut the circle first to be more realistic then the outline, I added an auto zero to reload material to the jig and start all over again

( T0 : 0.0 )
G21 G90 G91.1 G64 G40
G0 Z3.0
( T0 : 0.0 )
T0 M6
( 1 )
G17
M3 S1000
G0 X34.755 Y-105.2152
G0 Z1.0
G1 F30.0 Z0.0
G1 X34.1887 Y-103.9064
G1 X33.7056 Y-102.5647
G1 X33.3078 Y-101.1953
G1 X32.9967 Y-99.8036
G1 X32.7736 Y-98.3951
G1 X32.6394 Y-96.9753
G1 X32.5946 Y-95.55
G1 X32.6394 Y-94.1247
G1 X32.7736 Y-92.7049
G1 X32.9967 Y-91.2964
G1 X33.3078 Y-89.9047
G1 X33.7056 Y-88.5353
G1 X34.1887 Y-87.1936
G1 X34.755 Y-85.8848
G1 X35.4025 Y-84.6142
G1 X36.1284 Y-83.3867
G1 X36.9299 Y-82.2073
G1 X37.804 Y-81.0805
G1 X38.747 Y-80.0108
G1 X39.7554 Y-79.0024
G1 X40.8251 Y-78.0593
G1 X41.9519 Y-77.1853
G1 X43.1314 Y-76.3838
G1 X44.3588 Y-75.6578
G1 X45.6294 Y-75.0104
G1 X46.9382 Y-74.4441
G1 X48.2799 Y-73.961
G1 X49.6494 Y-73.5632
G1 X51.0411 Y-73.2521
G1 X52.4496 Y-73.029
G1 X53.8693 Y-72.8948
G1 X55.2946 Y-72.85
G1 X56.72 Y-72.8948
G1 X58.1397 Y-73.029
G1 X59.5482 Y-73.2521
G1 X60.9399 Y-73.5632
G1 X62.3093 Y-73.961
G1 X63.651 Y-74.4441
G1 X64.9598 Y-75.0104
G1 X66.2304 Y-75.6578
G1 X67.4579 Y-76.3838
G1 X68.6373 Y-77.1853
G1 X69.7641 Y-78.0593
G1 X70.8338 Y-79.0024
G1 X71.8422 Y-80.0108
G1 X72.7853 Y-81.0805
G1 X73.6593 Y-82.2073
G1 X74.4609 Y-83.3867
G1 X75.1868 Y-84.6142
G1 X75.8342 Y-85.8848
G1 X76.4005 Y-87.1936
G1 X76.8836 Y-88.5353
G1 X77.2815 Y-89.9047
G1 X77.5925 Y-91.2964
G1 X77.8156 Y-92.7049
G1 X77.9498 Y-94.1247
G1 X77.9946 Y-95.55
G1 X77.9498 Y-96.9753
G1 X77.8156 Y-98.3951
G1 X77.5925 Y-99.8036
G1 X77.2815 Y-101.1953
G1 X76.8836 Y-102.5647
G1 X76.4005 Y-103.9064
G1 X75.8342 Y-105.2152
G1 X75.1868 Y-106.4858
G1 X74.4609 Y-107.7133
G1 X73.6593 Y-108.8927
G1 X72.7853 Y-110.0195
G1 X71.8422 Y-111.0892
G1 X70.8338 Y-112.0976
G1 X69.7641 Y-113.0407
G1 X68.6373 Y-113.9147
G1 X67.4579 Y-114.7162
G1 X66.2304 Y-115.4422
G1 X64.9598 Y-116.0896
G1 X63.651 Y-116.6559
G1 X62.3093 Y-117.139
G1 X60.9399 Y-117.5368
G1 X59.5482 Y-117.8479
G1 X58.1397 Y-118.071
G1 X56.72 Y-118.2052
G1 X55.2946 Y-118.25
G1 X53.8693 Y-118.2052
G1 X52.4496 Y-118.071
G1 X51.0411 Y-117.8479
G1 X49.6494 Y-117.5368
G1 X48.2799 Y-117.139
G1 X46.9382 Y-116.6559
G1 X45.6294 Y-116.0896
G1 X44.3588 Y-115.4422
G1 X43.1314 Y-114.7162
G1 X41.9519 Y-113.9147
G1 X40.8251 Y-113.0407
G1 X39.7554 Y-112.0976
G1 X38.747 Y-111.0892
G1 X37.804 Y-110.0195
G1 X36.9299 Y-108.8927
G1 X36.1284 Y-107.7133
G1 X35.4025 Y-106.4858
G1 X34.755 Y-105.2152
( 2 )
S1000
G0 Z3.0
G0 X67.0153 Y0.0
G0 Z1.0
G1 Z0.0
G1 X67.0573 Y-1.9778
G1 X67.1832 Y-3.952
G1 X67.3927 Y-5.919
G1 X67.6856 Y-7.8754
G1 X68.0612 Y-9.8177
G1 X68.5189 Y-11.7422
G1 X69.0579 Y-13.6455
G1 X69.6772 Y-15.5243
G1 X70.3757 Y-17.3751
G1 X71.152 Y-19.1946
G1 X72.0049 Y-20.9795
G1 X72.9328 Y-22.7266
G1 X73.934 Y-24.4327
G1 X75.0067 Y-26.0948
G1 X76.149 Y-27.7099
G1 X77.3588 Y-29.2751
G1 X78.634 Y-30.7874
G1 X79.9721 Y-32.2444
G1 X81.3709 Y-33.6432
G1 X82.8278 Y-34.9813
G1 X84.3402 Y-36.2565
G1 X85.9054 Y-37.4663
G1 X87.5205 Y-38.6085
G1 X89.1826 Y-39.6813
G1 X90.8887 Y-40.6825
G1 X92.6358 Y-41.6103
G1 X94.4207 Y-42.4632
G1 X96.2402 Y-43.2396
G1 X98.091 Y-43.9381
G1 X99.9697 Y-44.5574
G1 X101.8731 Y-45.0964
G1 X103.7976 Y-45.5541
G1 X105.7398 Y-45.9297
G1 X107.6963 Y-46.2226
G1 X109.6633 Y-46.4321
G1 X111.6375 Y-46.558
G1 X113.6153 Y-46.6
G1 X115.593 Y-46.558
G1 X117.5672 Y-46.4321
G1 X119.5343 Y-46.2226
G1 X121.4907 Y-45.9297
G1 X123.4329 Y-45.5541
G1 X125.3575 Y-45.0964
G1 X127.2608 Y-44.5574
G1 X129.1396 Y-43.9381
G1 X130.9904 Y-43.2396
G1 X132.8099 Y-42.4632
G1 X134.5948 Y-41.6103
G1 X136.3419 Y-40.6825
G1 X138.048 Y-39.6813
G1 X139.7101 Y-38.6085
G1 X141.3252 Y-37.4663
G1 X142.8903 Y-36.2565
G1 X144.4027 Y-34.9813
G1 X145.8596 Y-33.6432
G1 X147.2584 Y-32.2444
G1 X148.5966 Y-30.7874
G1 X149.8718 Y-29.2751
G1 X151.0816 Y-27.7099
G1 X152.2238 Y-26.0948
G1 X153.2965 Y-24.4327
G1 X154.2977 Y-22.7266
G1 X155.2256 Y-20.9795
G1 X156.0785 Y-19.1946
G1 X156.8549 Y-17.3751
G1 X157.5534 Y-15.5243
G1 X158.1727 Y-13.6455
G1 X158.7116 Y-11.7422
G1 X159.1694 Y-9.8177
G1 X159.545 Y-7.8754
G1 X159.8378 Y-5.919
G1 X160.0474 Y-3.952
G1 X160.1733 Y-1.9778
G1 X160.2153 Y0.0
G0 Z3.0
G0 X159.8167
G0 Z1.0
G1 Z0.0
G1 X250.2
G1 X250.6916 Y-0.0039
G1 X251.1832 Y-0.0154
G1 X251.6744 Y-0.0347
G1 X252.1653 Y-0.0618
G1 X252.6558 Y-0.0965
G1 X253.1456 Y-0.1389
G1 X253.6347 Y-0.189
G1 X254.1229 Y-0.2468
G1 X254.6102 Y-0.3123
G1 X255.0964 Y-0.3854
G1 X255.5814 Y-0.4661
G1 X256.065 Y-0.5544
G1 X256.5472 Y-0.6503
G1 X257.0279 Y-0.7538
G1 X257.5068 Y-0.8648
G1 X257.984 Y-0.9833
G1 X258.4592 Y-1.1094
G1 X258.9324 Y-1.2428
G1 X259.4035 Y-1.3837
G1 X259.8722 Y-1.5319
G1 X260.3386 Y-1.6875
G1 X260.8025 Y-1.8504
G1 X261.2638 Y-2.0206
G1 X261.7223 Y-2.198
G1 X262.178 Y-2.3826
G1 X262.6307 Y-2.5743
G1 X263.0804 Y-2.7731
G1 X263.5269 Y-2.9789
G1 X263.9701 Y-3.1917
G1 X264.4099 Y-3.4115
G1 X264.8462 Y-3.6381
G1 X265.2789 Y-3.8716
G1 X265.7079 Y-4.1118
G1 X266.133 Y-4.3588
G1 X266.5542 Y-4.6124
G1 X266.9714 Y-4.8725
G1 X267.3844 Y-5.1392
G1 X267.7932 Y-5.4124
G1 X268.1977 Y-5.6919
G1 X268.5977 Y-5.9778
G1 X268.9932 Y-6.2699
G1 X269.384 Y-6.5681
G1 X269.7701 Y-6.8725
G1 X270.1514 Y-7.1829
G1 X270.5277 Y-7.4993
G1 X270.8991 Y-7.8215
G1 X271.2653 Y-8.1495
G1 X271.6263 Y-8.4833
G1 X271.9821 Y-8.8226
G1 X272.3324 Y-9.1676
G1 X272.6774 Y-9.5179
G1 X273.0167 Y-9.8737
G1 X273.3505 Y-10.2347
G1 X273.6785 Y-10.6009
G1 X274.0007 Y-10.9723
G1 X274.3171 Y-11.3486
G1 X274.6275 Y-11.7299
G1 X274.9319 Y-12.116
G1 X275.2301 Y-12.5068
G1 X275.5222 Y-12.9023
G1 X275.8081 Y-13.3023
G1 X276.0876 Y-13.7068
G1 X276.3608 Y-14.1156
G1 X276.6275 Y-14.5286
G1 X276.8876 Y-14.9458
G1 X277.1412 Y-15.367
G1 X277.3882 Y-15.7921
G1 X277.6284 Y-16.2211
G1 X277.8619 Y-16.6538
G1 X278.0885 Y-17.0901
G1 X278.3083 Y-17.5299
G1 X278.5211 Y-17.9731
G1 X278.7269 Y-18.4196
G1 X278.9257 Y-18.8693
G1 X279.1174 Y-19.322
G1 X279.302 Y-19.7777
G1 X279.4794 Y-20.2362
G1 X279.6496 Y-20.6975
G1 X279.8125 Y-21.1614
G1 X279.9681 Y-21.6278
G1 X280.1163 Y-22.0965
G1 X280.2572 Y-22.5676
G1 X280.3906 Y-23.0408
G1 X280.5167 Y-23.516
G1 X280.6352 Y-23.9932
G1 X280.7462 Y-24.4721
G1 X280.8497 Y-24.9528
G1 X280.9456 Y-25.435
G1 X281.0339 Y-25.9186
G1 X281.1146 Y-26.4036
G1 X281.1877 Y-26.8898
G1 X281.2532 Y-27.3771
G1 X281.311 Y-27.8653
G1 X281.3611 Y-28.3544
G1 X281.4035 Y-28.8442
G1 X281.4382 Y-29.3347
G1 X281.4653 Y-29.8256
G1 X281.4846 Y-30.3168
G1 X281.4961 Y-30.8084
G1 X281.5 Y-31.3
G1 Y-56.45
G1 X186.4945
G1 X184.8787 Y-56.4834
G1 X183.2656 Y-56.5835
G1 X181.6581 Y-56.7503
G1 X180.0588 Y-56.9833
G1 X178.4706 Y-57.2822
G1 X176.896 Y-57.6464
G1 X175.3378 Y-58.0755
G1 X173.7987 Y-58.5685
G1 X172.2813 Y-59.1248
G1 X170.7882 Y-59.7433
G1 X169.3219 Y-60.4229
G1 X167.8849 Y-61.1626
G1 X166.4798 Y-61.961
G1 X165.1088 Y-62.8168
G1 X163.7744 Y-63.7285
G1 X162.4788 Y-64.6946
G1 X161.2242 Y-65.7134
G1 X160.0128 Y-66.7832
G1 X158.8466 Y-67.9021
G1 X157.7277 Y-69.0683
G1 X156.6579 Y-70.2797
G1 X155.6391 Y-71.5343
G1 X154.673 Y-72.8299
G1 X153.7613 Y-74.1643
G1 X152.9055 Y-75.5353
G1 X152.1071 Y-76.9405
G1 X151.3674 Y-78.3774
G1 X150.6877 Y-79.8437
G1 X150.0693 Y-81.3368
G1 X149.513 Y-82.8543
G1 X149.02 Y-84.3934
G1 X148.5909 Y-85.9515
G1 X148.2266 Y-87.5261
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G1 X147.6947 Y-90.7136
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G0 Z3.0
G0 X0 Y0
G0 Z0
M5
M30

[Jim Dawson]

Here`s a freestyle version of your shape sir drawn and routed under 2 minutes, I cut the circle first to be more realistic then the outline, I added an auto zero to reload material to the jig and start all over again

Converting to line segments is one way to solve the I,J confusion. But really doesn't answer the question.

[handlewanker]

LOL.......OK, I just worked out how the radius is coded.......it came in a flash and is logical once you realise that the radius dimensions are INCREMENTAL values while the actual other moves along the straight lines are all ABSOLUTE.........and you don't need to know the cutter dimensions for the coding as the specs for the cutter called up will be in the tool register that Mach 3 automatically refers to and applies to the code.

So.........starting from the left side of a hypothetical 100mm square plate as 0.0 and with a 20mm radius on the right top corner.....the shortened coding movement from 0.0 start would be......

G01 X80
G02 X0 Y-20 I0 J-20.....etc etc as you go round the bend and on down the - Y axis.

If this is also wrong I'll have to fall on my sword and take up knitting to wile away the hours....LOL.
Ian.

[RCaffin]

Fwiiw, I prefer the R format. I dig out a lot of holes with two semi-circles:
Starting at X0 Y0:
G02 X2 Y0 R1
G02 X0 Y0 R1
Usually with Z spiralling downwards.

Ian - feel free to email me direct if you need more help.

Cheers
Roger

[handlewanker]

Hi....sounds interesting....I'll add it to my notes......just gotta fathom out what the code values represent.

Can you expand on that code with values for a real hole size....just the circular interpolation part.......say if you want to make a 20mm diam hole with a 10mm diam cutter.....what would the code look like and where does the Z value for spiralling down occur...........I assume you would go to the next line with G01 and a Z depth value with a feed rate?

I'm looking to see where the code values change as it creates the two semi circles to get the bigger hole size you want from a smaller cutter diam.......that would definitely be a boon for bigger holes than using a boring head.
Ian.

[RCaffin]

Hi Ian

20mm diam hole with a 10mm diam cutter... and 10 mm deep with a 1 mm cut, centred on X=15 Y=25

#1=10.00 % 10 mm deep
#2=fup[#1/1.0] % number of 1 mm passes needed
#3=[10.0/#2] % depth of each pass
% to be sure, you could skip most of this, until you want a hole 5.28 mm deep ...
#4=0.0 % Z start
#5=[20.0/2-10.0/2] % radius of cutter circle needed (do the maths)

g0 z20
g0 x15 y25 % circle centre
g0 x[15+#5] y25 % one side of circle
g0 z#4
m98 p10 L#2 % cut N circles while ramping down
g0 z20
m30

o10
#4=[#4-#3/2] % target Z half a step down
g2 x[15-#5] y25 z#4 % cut a descending semicircle
#4=[#4-#3/2] % ditto
g2 x[15+#5] y25 z#4 % ditto
m99

Load this into Mach and look at the cutter path, and study.
Cheers
Roger

[handlewanker]

Hi Rog....the format you showed is a puzzle to me.....not what I'm used to with straight G code........at the moment I'm making room in the garage by Ebaying and sorting out the junk to sell on Ebay, so no time to go to Mach 3 for the present.
Ian.

[RCaffin]

Hi Ian

It is NIST standard g-code, but CAM programs never produce anything like it. They can't: they don't have the intelligence.,

Cheers
Roger

[handlewanker]

AAAAhhhhgghhh.........now I'm completely lost, I'll stick to simple hand written G code as I am making some sense of going around in circles now......helical interpolation and thread milling looks interesting and the CNC cookbook has a tutorial to achieve it.

Just to digress off topic for a moment.......just been on EBAY and bought a couple of ER11 chucks with some collets sets too.

The chucks are the type with a plain back and an 8mm hole to mount on a motor shaft, as in the high speed water cooled spindles on the CNC routers etc.

The point is, the body is 16mm diam, 37mm total length and that makes it suitable to hold in a 16mm collet in the ER32 chucks I have on my mill and is more compact than a drill chuck.

This makes it suitable with the small extra stick out length to hold small diam drills, as a 2mm drill in an ER32 chuck is lost when it gets down to ground level.

Reason?.......well the chuck cost $7 and a set of 13 collets cost $12,.....(a small 6mm keyless chuck cost $45)....... and that makes it good to hold drills up to 7mm diam and very accurately too compared to the small drill chucks that seem to run out.

I've gone off thinking in terms of drill chucks for drill holding for now.

This happens to coincide with a drill job I'm planning to do on the mill and the G code to do it.......there will be four 5mm holes in line on a block approx. 75mm long, and there being 9 blocks that makes quite a few drill cycles to write up..
Ian. .

[RCaffin]

I do have a 0 - 3 mm chuck on a 15 mm shank for real small drill bits, but the bigger use of such a chuck is that I can get into smaller spaces with it, compared to a full-sized ER32 or ER25 collet face.

As for there being 9 blocks: that is what subroutine calls are for, along with an origin shift each time.

Cheers
Roger

[handlewanker]

Hi, a sub routine is not needed as this is a one off job and the separate blocks will just be located in the vice one at a time.

It's a simple operation, 4 holes in line etc, first to spot and chamfer the position on all blocks, then change over tools and repeat the sequence for the second tap drill size.

I think that simplifies the coding by repositioning the blocks against a stop each time..

I'm puzzling out the Gcode solution for a hole you posted in post #15......you stated that it was done with 2 semi circles.

Starting with the tool on X0 Y0....

G02 X2 Y0 R1
G02 X0 Y0 R1

Can you elaborate on how the 2 semi circles occur with this code sequence.....I can only imagine how a corner radius is formed when a 1/4 circle is coded.
Ian.

[RCaffin]

Hi Ian

Starting with the tool on X0 Y0....
N1 G02 X2 Y0 R1
N2 G02 X0 Y0 R1

N1 describes an arc starting at 0,0 and going to 2,0 with a radius of 1 in the CW direction. It's an upwards bump with a centre at 1,0
N2 describes an arc starting at 2,0 and going to 0,0 with a radius of 1 in the CW direction. It's an underneath bump with the same centre.

Stick it into Mach and look at the tool path. Run in simulation mode to see it happen.

Cheers
Roger