[usajet]

I have a Bridgeport J Head mill that I converted to a cnc. Installed ball screws on the x, y and z. I doubled checked my calibration on all axis and all is good.

I am using the Masso G3 Touch with these stepper motors, https://www.automationtechnologiesin...sbridgeportkit

Well every time I try to bore a hole in aluminum or steel it does not come out as a circle more like a freehand circle.

Since then I replaced my spindle bearings, shimmed my x and y gibs. I haven't looked at my knee gib yet.
I tried just doing hole boring after I did all the above with no luck.

I am running the spindle at 2720 rpm with a 8mm end mill and using a mister for lube and air.

Is there anything I could try or look at?

Thank you for the help, Nathan

[awerby]

Are you doing this boring with an endmill? Is everything but the Z axis locked down when you're doing it? Boring bars usually have a cutter like those in a lathe. Are you trepanning these holes with an endmill rather than boring them? Are you moving in Z with the knee, or the quill?

[Jim Dawson]

There are so many possibilities here it is difficult to know where to start. And I am just guessing here due to the limited information provided

Mechanical
Backlash or binding
Overloading the motors

Electrical
Bad Signals/noise

Tool path/G Code
Feed rate
Too aggressive tool path
Overall technique

If the machine is accurate otherwise, then I would have a serious look at how you are 'boring' holes. I suspect you are pocketing rather than boring, which is done with a boring head. Pocketing is done by interpolating with an endmill. It is good practice to rough pocket the hole, leaving about 0.5mm material, then finish contour with a helix tool path.

[usajet]

I am boring with an end mill using the quill as my z.

[usajet]

Mechanical
Backlash or binding, No
Overloading the motors, Not Sure

Electrical
Bad Signals/noise, No

Tool path/G Code
Feed rate
Too aggressive tool path
Overall technique


I have attached the G code..

(Bore)
(MACHINE)
( VENDOR BRIDGEPORT)
( DESCRIPTION 3-AXIS)
(T1 D=8. CR=0. - ZMIN=-9.53 - FLAT END MILL)
N10 G90 G94 G17
N15 G21






(BORE1)
N20 M5
N25 T1 M6
N30 S2720 M3
N35 G54
N40 G0 X13.824 Y-22.692
N45 Z15.
N50 G1 Z2. F3177.
N55 Z0.8
N60 G18 G3 X13.024 Z0. I-0.8 K0.
N65 G1 X12.624
N70 G17 G2 X11.824 Y-21.892 I0. J0.8
N75 X23.824 Z-0.349 I6. J0.
N80 X11.824 Z-0.698 I-6. J0.
N85 X23.824 Z-1.048 I6. J0.
N90 X11.824 Z-1.397 I-6. J0.
N95 X23.824 Z-1.746 I6. J0.
N100 X11.824 Z-2.095 I-6. J0.
N105 X23.824 Z-2.444 I6. J0.
N110 X11.824 Z-2.794 I-6. J0.
N115 X23.824 Z-3.143 I6. J0.
N120 X11.824 Z-3.492 I-6. J0.
N125 X23.824 Z-3.841 I6. J0.
N130 X11.824 Z-4.19 I-6. J0.
N135 X23.824 Z-4.54 I6. J0.
N140 X11.824 Z-4.889 I-6. J0.
N145 X23.824 Z-5.238 I6. J0.
N150 X11.824 Z-5.587 I-6. J0.
N155 X23.824 Z-5.937 I6. J0.
N160 X11.824 Z-6.286 I-6. J0.
N165 X23.824 Z-6.635 I6. J0.
N170 X11.824 Z-6.984 I-6. J0.
N175 X23.824 Z-7.333 I6. J0.
N180 X11.824 Z-7.683 I-6. J0.
N185 X23.824 Z-8.032 I6. J0.
N190 X11.824 Z-8.381 I-6. J0.
N195 X23.824 Z-8.73 I6. J0.
N200 X11.824 Z-9.079 I-6. J0.
N205 X23.824 Z-9.429 I6. J0.
N210 X21.496 Y-26.637 Z-9.53 I-6. J0.
N215 X14.152 Y-17.147 I-3.672 J4.745
N220 X21.496 Y-26.637 I3.672 J-4.745
N225 X20.374 Y-26.494 I-0.49 J0.633
N230 G1 X20.129 Y-26.178
N235 X20.065 Y-26.095 Z-9.523
N240 X20.003 Y-26.014 Z-9.503
N245 X19.942 Y-25.936 Z-9.469
N250 X19.885 Y-25.862 Z-9.423
N255 X19.831 Y-25.793 Z-9.365
N260 X19.783 Y-25.731 Z-9.296
N265 X19.741 Y-25.676 Z-9.217
N270 X19.705 Y-25.63 Z-9.13
N275 X19.677 Y-25.593 Z-9.036
N280 X19.656 Y-25.567 Z-8.937
N285 X19.644 Y-25.551 Z-8.834
N290 X19.64 Y-25.545 Z-8.73
N295 Z5.
N300 X39.756 Y-22.692
N305 Z2.
N310 Z0.8
N315 G18 G3 X38.956 Z0. I-0.8 K0.
N320 G1 X38.556
N325 G17 G2 X37.756 Y-21.892 I0. J0.8
N330 X44.756 Z-0.262 I3.5 J0.
N335 X37.756 Z-0.524 I-3.5 J0.
N340 X44.756 Z-0.786 I3.5 J0.
N345 X37.756 Z-1.048 I-3.5 J0.
N350 X44.756 Z-1.31 I3.5 J0.
N355 X37.756 Z-1.571 I-3.5 J0.
N360 X44.756 Z-1.833 I3.5 J0.
N365 X37.756 Z-2.095 I-3.5 J0.
N370 X44.756 Z-2.357 I3.5 J0.
N375 X37.756 Z-2.619 I-3.5 J0.
N380 X44.756 Z-2.881 I3.5 J0.
N385 X37.756 Z-3.143 I-3.5 J0.
N390 X44.756 Z-3.405 I3.5 J0.
N395 X37.756 Z-3.667 I-3.5 J0.
N400 X44.756 Z-3.929 I3.5 J0.
N405 X37.756 Z-4.19 I-3.5 J0.
N410 X44.756 Z-4.452 I3.5 J0.
N415 X37.756 Z-4.714 I-3.5 J0.
N420 X44.756 Z-4.976 I3.5 J0.
N425 X37.756 Z-5.238 I-3.5 J0.
N430 X44.756 Z-5.5 I3.5 J0.
N435 X37.756 Z-5.762 I-3.5 J0.
N440 X44.756 Z-6.024 I3.5 J0.
N445 X37.756 Z-6.286 I-3.5 J0.
N450 X44.756 Z-6.548 I3.5 J0.
N455 X37.756 Z-6.81 I-3.5 J0.
N460 X44.756 Z-7.071 I3.5 J0.
N465 X37.756 Z-7.333 I-3.5 J0.
N470 X44.756 Z-7.595 I3.5 J0.
N475 X37.756 Z-7.857 I-3.5 J0.
N480 X44.756 Z-8.119 I3.5 J0.
N485 X37.756 Z-8.381 I-3.5 J0.
N490 X44.756 Z-8.643 I3.5 J0.
N495 X37.756 Z-8.905 I-3.5 J0.
N500 X44.756 Z-9.167 I3.5 J0.
N505 X37.756 Z-9.429 I-3.5 J0.
N510 X40.041 Y-18.61 Z-9.53 I3.5 J0.
N515 X42.471 Y-25.175 I1.215 J-3.282
N520 X40.041 Y-18.61 I-1.215 J3.282
N525 X41.069 Y-19.083 I0.278 J-0.75
N530 G1 X41.208 Y-19.458
N535 X41.244 Y-19.556 Z-9.523
N540 X41.28 Y-19.652 Z-9.503
N545 X41.314 Y-19.745 Z-9.469
N550 X41.347 Y-19.833 Z-9.423
N555 X41.377 Y-19.914 Z-9.365
N560 X41.404 Y-19.988 Z-9.296
N565 X41.428 Y-20.053 Z-9.217
N570 X41.448 Y-20.107 Z-9.13
N575 X41.464 Y-20.151 Z-9.036
N580 X41.476 Y-20.182 Z-8.937
N585 X41.483 Y-20.201 Z-8.834
N590 X41.486 Y-20.208 Z-8.73
N595 Z15.


N600 M30

[machinehop5]

...try mill cutting a 45 degree angle for test with the same cutter

[Jim Dawson]

I think this might be your problem

N50 G1 Z2. F3177

Try setting F = 300

I'm surprised your machine is not walking across the floor at 3177

From the post format, it looks to me like you are using Fusion 360.

Choose 2D pocket as your roughing operation, and 2D contour as the finish operation.

Make my life easy here and tell me what size hole you are cutting?

[usajet]

I think this might be your problem

N50 G1 Z2. F3177

Try setting F = 300

I'm surprised your machine is not walking across the floor at 3177

From the post format, it looks to me like you are using Fusion 360.

Choose 2D pocket as your roughing operation, and 2D contour as the finish operation.

Make my life easy here and tell me what size hole you are cutting?

I lowered the feedrate and I tried 300 down to 160 and that didn't fix my issue. It got a little better but not 100%. I did adjust the knee gib but haven't tried it. Plus I do have servos now and will be removing the stepper motors.

[Jim Dawson]

I lowered the feedrate and I tried 300 down to 160 and that didn't fix my issue. It got a little better but not 100%. I did adjust the knee gib but haven't tried it. Plus I do have servos now and will be removing the stepper motors.

Servos are good

[usajet]

I have my servos and I want to set them up what do I have to do?

[Jim Dawson]

I have my servos and I want to set them up what do I have to do?

Install the motors on the machine.
Mount the drives in your electrical cabinet
Wire the drives to the motors, power, and your controller per the documentation supplied with the servo system
Confirm proper operation
Tune the system.

Make chips.

[usajet]

Install the motors on the machine.
Mount the drives in your electrical cabinet
Wire the drives to the motors, power, and your controller per the documentation supplied with the servo system
Confirm proper operation
Tune the system.

Make chips.

What control mode do I use? It has position, velocity and torque.

[Jim Dawson]

What control mode do I use? It has position, velocity and torque.

Normally torque mode works well.

[usajet]

I replaced the steppers with servos and it still stops during milling process at 12 o'clock, 3 o'clock, 6 o'clock and 9 o'clock. Plus the circles are still not round.

[Jim Dawson]

I replaced the steppers with servos and it still stops during milling process at 12 o'clock, 3 o'clock, 6 o'clock and 9 o'clock. Plus the circles are still not round.

Rather than run a Bore operation, make the same cut with a Contour operation with the Ramp check box checked on the Linking tab. Around a 2 degree ramp. Should give you about the same tool path, but the G code is much different. Maybe your controller will like that better.

[usajet]

Rather than run a Bore operation, make the same cut with a Contour operation with the Ramp check box checked on the Linking tab. Around a 2 degree ramp. Should give you about the same tool path, but the G code is much different. Maybe your controller will like that better.

I redone the backlash with the servos and no more problems with the circles. Thanks for the help.