Ok can you attach some code for me to look through, maybe I can see something there.

Yes the sim is the module works similar to what BobCAD, and others use.

Hood

;(Front Bushings .5625 Brass)
N20 G20 G18 G64 G80 G90 M49 G40 G49
; TOOL definition
N40 M09
N50 G0 Z1.0
N60  ( Twist Drill / Center Drill  0.1875" Dia )
N70 M06 T0202
N80 G97 S3000 
N90 M03 G94 F15.0
N100 G40
N110 G00 X0.0 Z0.05
N120 G01 X0.0 Z-0.085
N130 G00 X0.0 Z0.05
; TOOL definition
N150 G0 Z1.0
N160  ( Twist Drill / Center Drill  0.25" Dia )
N170 M06 T0303
N180 G97 S3000 
N190 G94
N200 X0.0 Z0.05
N210 G01 X0.0 Z-0.0552 F12.0
N220 G00 X0.0 Z0.05
N230 X0.0 Z-0.0052
N240 G01 X0.0 Z-0.1104
N250 G00 X0.0 Z0.05
N260 X0.0 Z-0.0604
N270 G01 X0.0 Z-0.1656
N280 G00 X0.0 Z0.05
N290 X0.0 Z-0.1156
N300 G01 X0.0 Z-0.2208
N310 G00 X0.0 Z0.05
N320 X0.0 Z-0.1708
N330 G01 X0.0 Z-0.276
N340 G00 X0.0 Z0.05
N350 X0.0 Z-0.226
N360 G01 X0.0 Z-0.3313
N370 G00 X0.0 Z0.05
N380 X0.0 Z-0.2813
N390 G01 X0.0 Z-0.3865
N400 G00 X0.0 Z0.05
N410 X0.0 Z-0.3365
N420 G01 X0.0 Z-0.4417
N430 G00 X0.0 Z0.05
N440 X0.0 Z-0.3917
N450 G01 X0.0 Z-0.4969
N460 G00 X0.0 Z0.05
N470 X0.0 Z-0.4469
N480 G01 X0.0 Z-0.5521
N490 G00 X0.0 Z0.05
N500 X0.0 Z-0.5021
N510 G01 X0.0 Z-0.6073
N520 G00 X0.0 Z0.05
N530 X0.0 Z-0.5573
N540 G01 X0.0 Z-0.6625
N550 G00 X0.0 Z0.05
; TOOL definition
N570 G0 Z1.0
N580  ( Grooving tool / Partoff blade )
N590 M06 T0404
N600 G97 S2200 
N610 G94
N620 X0.2889 Z0.002
N630 G01 X0.2593 Z0.002 F8.0
N640 X0.2593 Z-0.245
N650 X0.2609 Z-0.245
N660 G02 X0.286 Z-0.2701 I0.2609 K-0.2701
N670 G01 X0.286 Z-0.3401
N680 X0.286 Z-0.4024
N690 G02 X0.2609 Z-0.4275 I0.2609 K-0.4024
N700 G01 X0.2593 Z-0.4275
N710 X0.2593 Z-0.8275
N720 X0.2609 Z-0.8275
N730 G02 X0.286 Z-0.8526 I0.2609 K-0.8526
N740 G01 X0.286 Z-0.9194
N750 X0.286 Z-0.9817
N760 G02 X0.2609 Z-1.0068 I0.2609 K-0.9817
N770 G01 X0.2593 Z-1.0068
N780 X0.2593 Z-1.1655
N790 X0.2889 Z-1.1655
N800 G00 X0.3389 Z-1.1655
N810 X0.3389 Z0.002
N820 G01 X0.2297 Z0.002
N830 X0.2297 Z-0.245
N840 X0.2609 Z-0.245
N850 G02 X0.286 Z-0.2701 I0.2609 K-0.2701
N860 G01 X0.286 Z-0.3401
N870 X0.286 Z-0.4024
N880 G02 X0.2609 Z-0.4275 I0.2609 K-0.4024
N890 G01 X0.2297 Z-0.4275
N900 X0.2297 Z-0.8275
N910 X0.2609 Z-0.8275
N920 G02 X0.286 Z-0.8526 I0.2609 K-0.8526
N930 G01 X0.286 Z-0.9194
N940 X0.286 Z-0.9817
N950 G02 X0.2609 Z-1.0068 I0.2609 K-0.9817
N960 G01 X0.2297 Z-1.0068
N970 X0.2297 Z-1.1655
N980 X0.2593 Z-1.1655
N990 G00 X0.336 Z-1.1655
N1000 X0.336 Z0.002
N1010 G01 X0.2001 Z0.002
N1020 X0.2001 Z-0.245
N1030 X0.2609 Z-0.245
N1040 G02 X0.286 Z-0.2701 I0.2609 K-0.2701
N1050 G01 X0.286 Z-0.3401
N1060 X0.286 Z-0.4024
N1070 G02 X0.2609 Z-0.4275 I0.2609 K-0.4024
N1080 G01 X0.2001 Z-0.4275
N1090 X0.2001 Z-0.8275
N1100 X0.2609 Z-0.8275
N1110 G02 X0.286 Z-0.8526 I0.2609 K-0.8526
N1120 G01 X0.286 Z-0.9194
N1130 X0.286 Z-0.9817
N1140 G02 X0.2609 Z-1.0068 I0.2609 K-0.9817
N1150 G01 X0.2001 Z-1.0068
N1160 X0.2001 Z-1.1655
N1170 X0.2297 Z-1.1655
N1180 G00 X0.336 Z-1.1655
N1190 X0.336 Z0.002
N1200 G01 X0.1706 Z0.002
N1210 G02 X0.171 Z-0.0001 I0.1659 K-0.0001
N1220 G01 X0.171 Z-0.245
N1230 X0.2609 Z-0.245
N1240 G02 X0.286 Z-0.2701 I0.2609 K-0.2701
N1250 G01 X0.286 Z-0.3401
N1260 X0.286 Z-0.4024
N1270 G02 X0.2609 Z-0.4275 I0.2609 K-0.4024
N1280 G01 X0.171 Z-0.4275
N1290 X0.171 Z-0.8275
N1300 X0.2609 Z-0.8275
N1310 G02 X0.286 Z-0.8526 I0.2609 K-0.8526
N1320 G01 X0.286 Z-0.9194
N1330 X0.286 Z-0.9817
N1340 G02 X0.2609 Z-1.0068 I0.2609 K-0.9817
N1350 G01 X0.171 Z-1.0068
N1360 X0.171 Z-1.1026
N1370 X0.171 Z-1.1649
N1380 G02 X0.171 Z-1.1655 I0.1659 K-1.1649
N1390 G01 X0.2001 Z-1.1655
N1400 G00 X0.336 Z-1.1655
N1410 X0.2889 Z-1.1655
N1420 X0.2889 Z0.002
N1430 X0.287 Z0.0009
N1440 G01 X0.1664 Z0.0009
N1450 X0.1664 Z-0.25
N1460 X0.2609 Z-0.25
N1470 G02 X0.281 Z-0.2701 I0.2609 K-0.2701
N1480 G01 X0.281 Z-0.3401
N1490 X0.281 Z-0.4024
N1500 G02 X0.2609 Z-0.4225 I0.2609 K-0.4024
N1510 G01 X0.1664 Z-0.4225
N1520 X0.1664 Z-0.8325
N1530 X0.2609 Z-0.8325
N1540 G02 X0.281 Z-0.8526 I0.2609 K-0.8526
N1550 G01 X0.281 Z-0.9194
N1560 X0.281 Z-0.9817
N1570 G02 X0.2609 Z-1.0018 I0.2609 K-0.9817
N1580 G01 X0.1664 Z-1.0018
N1590 X0.1664 Z-1.1655
N1600 G00 X0.331 Z-1.1655
N1610 X0.287 Z-1.1655
N1620 X0.287 Z0.0009
N1630 G97 S2200 
N1640 G94
N1650 X0.331 Z0.0009
N1660 X0.331 Z-0.5825
N1670 G01 X0.0 Z-0.5825 F6.0
N1680 G00 X0.331 Z-0.5825
; TOOL definition
N1700 G0 Z1.0
N1710  ( Twist Drill / Center Drill  0.25" Dia )
N1720 M06 T0303
N1730 G97 S3000 
N1740 G94
N1750 X0.0 Z-0.5325
N1760 G01 X0.0 Z-0.6377 F10.0
N1770 G00 X0.0 Z-0.5325
N1780 X0.0 Z-0.5877
N1790 G01 X0.0 Z-0.6929
N1800 G00 X0.0 Z-0.5325
N1810 X0.0 Z-0.6429
N1820 G01 X0.0 Z-0.7481
N1830 G00 X0.0 Z-0.5325
N1840 X0.0 Z-0.6981
N1850 G01 X0.0 Z-0.8033
N1860 G00 X0.0 Z-0.5325
N1870 X0.0 Z-0.7533
N1880 G01 X0.0 Z-0.8585
N1890 G00 X0.0 Z-0.5325
N1900 X0.0 Z-0.8085
N1910 G01 X0.0 Z-0.9138
N1920 G00 X0.0 Z-0.5325
N1930 X0.0 Z-0.8638
N1940 G01 X0.0 Z-0.969
N1950 G00 X0.0 Z-0.5325
N1960 X0.0 Z-0.919
N1970 G01 X0.0 Z-1.0242
N1980 G00 X0.0 Z-0.5325
N1990 X0.0 Z-0.9742
N2000 G01 X0.0 Z-1.0794
N2010 G00 X0.0 Z-0.5325
N2020 X0.0 Z-1.0294
N2030 G01 X0.0 Z-1.1346
N2040 G00 X0.0 Z-0.5325
N2050 X0.0 Z-1.0846
N2060 G01 X0.0 Z-1.1898
N2070 G00 X0.0 Z-0.5325
N2080 X0.0 Z-1.1398
N2090 G01 X0.0 Z-1.245
N2100 G00 X0.0 Z-0.5325
; TOOL definition
N2120 G0 Z1.0
N2130  ( Grooving tool / Partoff blade )
N2140 M06 T0404
N2150 G97 S2200 
N2160 G94
N2170 X0.331 Z1.0
N2180 X0.331 Z-1.165
N2190 G01 X0.0 Z-1.165 F6.0
N2200 G00 X0.331 Z-1.165
N2210 X0.331 Z0.0
N2220 X0.0 Z0.0
N2230 M05 M30
 

There is nothing in the code, that I can see anyway, that will fluctuate the spindle RPM. The calls are G97 which is Revs per Minute, so no CSS calls at all.

Hood

That was my conclusion as well. It may be noise in the motor controller. I don't normally run the lathe. My Son and his Wife does. They probably would not realize the spindle is acting differently.

I am considering putting a servo motor on it instead of the DC motor that is on there now.
Much better control of the spindle speed that way as well as direction then. It could finally be able to do some threading.
I used to take care of threading with a little 7/14 manual lathe. That motor control burnt out, so it isn't running.
I think I would much rather do cnc threads instead.

Judging from the time it took my mill to burn through the brushes on it's old DC motor (similar) then this one is getting close to needing replacements sourced anyway.
I had always intended to do threading eventually, so it is about that time.

Servo's are relatively new to me so I'll have to research them a bit. Any recommendations?

You can thread with any motor as long as it is powerful enough and relatively steady in RPM. Sounds however like you may be needing new brushes in it, so if you fix them you should manage threading fine.

Regarding servos, well I just pick mine up on eBay so cant really recommend any. One warning, if its AC servo then it is best to make sure the motor and drive are a pair as AC servo drives often can not be set up with motors they are not intended for.

Hood

I did buy the spindle encoder that uses a hole in a disk, but never installed it. It is partially a trust issue I think. I think I would trust a servo setup more and it would be more precise than the motor I have on it now.
It doesn't have any braking on it.
I am currently running the steppers off of Gecko 203V's. 72 VDC 12 Amp PS. The lathe is only 110 VAC right now, but it sits close to the circuit panel and I could runn 220 to it as well to run a spindle from. My question now is if I did use a 220 VAC and chose AC servo's, could it use the same BOB as the DC steppers? Right now, the motor controls are inside the control panel on the larthe.


There is a need now to find an answer before my little motors quits completely, but I haven't decided to go with servo's yet. I was unable to locate brushes for my old mill motor, but I may be able to find them for this one. That would give me more time.

You dont need braking for threading on a lathe as the spindle never halts from pass to pass.
Are you talking about rigid tapping instead of threading? If so then Mach does not natively support rigid tapping, it can be done with some external controllers however.
If you have a servo spindle then you can do rigid tapping with Mach via the parallel port but it is a work around and requires SwapAxis()

Regarding the BOB, yes as long as the drive is capable of Step/Dir command then it will work from the same drive. Most industrial servos prefer differential Step/Dir signals although most can be connected single ended. It is however easy enough to put a line driver on the Step/Dir output of the BOB to give differential signals and would be the preferred option.

Hood

Right. I was thinking rigid tapping. Not having done threading on a cnc lathe, I confused myself with it.

Spindle keeps turning the same direction for use with a threading tool.

I will try to do a CAM part that maintains one speed throughout and see how the spindle reacts.
It is still stopping and starting, but never gets a chance to stop completely.
The Check box for CSS in not lit in Mach 3, but it does flash numbers beside it when it's running and those do change.
Honestly I have never really noticed those before.

I dont use the standard Turn screen so afraid I ave no idea weter te CSS DRO sould display numbers or not.

Hood

Thanks, Hood.
Definitely something still going on with it. I'll investigate further and let you know if I get it sorted out.