DIY CNC mill from mainly salvaged and 3D printed parts

[NeverDie]

@dbemowsk
On my board,
M3 SP1000
spins the spindle at maximum speed. Just M3 by itself doesn't.
It's not obvious from looking at your board where the spindle OUT voltage is. Maybe on the opposite side? I guess you'll have to probe around to find it.

[dbemowsk]

@neverdie The SpnEn and SpnDir are control signals. For this board you need to have an external motor driver. After some looking, I may have found my answer. I am running GRBL 1.1. It appears that they swapped 2 of the pins. Pin 12 used to be the spindle enable pin in GRBL 0.9. In 1.1, they swapped 11 and 12 because pin 12 cannot be used for PWM which is how the controller limits the speed. I have not tried it yet, but I am going to try the Z+ pin which is pin 11. If that works, I may do a slight board mod.
Here is the post that explains it. https://github.com/grbl/grbl/issues/1187

[dbemowsk]

BTW, I am using an external H- Bridge to control the spindle.

[dbemowsk]

Just tried that and it worked perfect. I don't use SP though, I just use S. So M3 S1000 is full speed, M3 S500 slows the motor, and M5 stops it.

[NeverDie]

Yes, my typo, just S, not SP.

I do wonder whether some of the more "advanced" boards, like the Duet WiFi, actually perform better, or whether the results are the same.

I think I may get a RAMPS board, if only because it supports Marlin, and that's what the MPCNC uses.

On the other hand, there is a smoothieboard clone on aliexpress for $40. . Hmm... It's tempting....

The jump from GRBL 0.9 to 1.1 convinced me that the firmware can make a difference, that it's not just all equivalent.

[dbemowsk]

@neverdie I have always said, at least for 3D printers, that RAMPS was the way to go if you had to change your main board. Many of these 3D printer main boards have everything integrated into them. With RAMPS, it is all modular. If something dies, you are replacing 1 part rather than an entire board.

[NeverDie]

@dbemowsk I'll give it a shot. I ordered a mildly upgraded RAMPs board (so called "version 1.6"). It doesn't have the re-settable fuses, which I guess have a dodgy reputation (or so Tom Sanlanderer seems to imply).
https://www.aliexpress.com/item/Bigtreetech-upgrade-Ramps-1-5-Base-on-Ramps-1-4-3D-control-panel-printer-Control-Reprap/32822038995.html?spm=a2g0s.9042311.0.0.9zbnJj
I'll be curious as to whether it can accept either the TMC2130 or the TMC2660 modules.

[dbemowsk]

@neverdie I think most of those stepper driver modules run the same footprint. Check out this link. It is from Tom's 3D forum. People there are talking about those as replacements for the DRV88256's, which are the ones that I have. May be some useful info for you.
https://discuss.toms3d.org/hardware-f6/drv8825-vs-tmc2100-vs-tmc2130-vs-tmc2208-t250.html

[NeverDie]

@dbemowsk Short of making a very careful study of the datasheets, the other info that's available is awfully sketchy, so I ordered one of each module, and I'll see if I can get either one to work on the RAMPS board that I ordered. I'm not completely sure, but I get the impression that after they are properly configured, they can maybe just plug and play.

[dbemowsk]

So, here is the latest update with pictures. I have the whole setup mounted on a leftover piece of MDF. I am using an ATX computer power supply to run everything. The fan pulls air from the back of the setup and blows it over the heatsinks for all of the modules.

For spindle control I have 3 different modules. The first is a buck converter to boost the 12 volts to 24 for running the spindle motor.

Next I have a dual H-Bridge that I had in my parts bin. I am only using one side of it. This handles the motor direction and speed. One problem with it that I had to overcome was that it had separate logic inputs for forward and reverse. The problem was that the CNC shield had a single output for spindle direction. To overcome this, I made a simple not gate circuit using an NPN switching transistor which sends a normal logic level to one input pin and an inverted signal to the other. I then use the enable line to start and stop the spindle. This setup works well.


This is the entire spindle drive circuity.

Here is an angled front view.

[NeverDie]

Don't forget to include a snub diode on the motor, if you haven't already.

[dbemowsk]

@neverdie I thought that that was integrated on to the H-Bridge controller.

[NeverDie]

@dbemowsk If that's what it is, then I guess you're covered. :)

[NeverDie]

I like the idea of recycling an old PC power supply with a boost converter. For instance, a lot of the 48v power supplies don't come with regular 110VAC plugs, and you're even left with semi-exposed 110VAC wiring, so this kinda works around that. It's a bit ungainly, but it works.

The only problem is you probably can't get to more than 240w, as that would be 20amps at 12v to the input of the boost converter. Actually less than 240w because of conversion inefficiency. At best probably just 0.85*240=204w. Maybe it would be good enough for milling PCBs though.

[dbemowsk]

So I am trying to test the new machine and am having some trouble. I am running into an issue with some gcode I am testing. The gcode was generated from inkscape and I am including the gcode below. The way I am testing this is just using a terminal connection to the CNC and pasting the gcode into the terminal window. If there is a better way to test this let me know.

When I paste in the gcode below, the CNC runs through part of it and then stops. If I then hit enter in the terminal window I get this:

error: Invalid gcode ID:35

From my research on this error I found this:
A G2 or G3 arc, traced with the offset definition, is missing the IJK offset word in the selected plane to trace the arc.

After testing in chunks, I have found the line that appears to be causing the error.
This will cause the error:

G01 Z-0.125000 F100.0
G03 X44.448347 Y19.159901 Z-0.125000 I-203.958107 J224.353401 F400.000000
G03 X45.751092 Y20.363421 Z-0.125000 I-235.328819 J256.037427
G03 X47.053649 Y21.586232 Z-0.125000 I-48.170466 J52.617095
G03 X47.737750 Y22.275812 Z-0.125000 I-14.623944 J15.191857
G03 X49.369789 Y24.042092 Z-0.125000 I-12.444180 J13.135542
G03 X50.077180 Y25.172247 Z-0.125000 I-4.326712 J3.494655
G03 X50.505064 Y26.430623 Z-0.125000 I-5.413285 J2.542606
G03 X50.652755 Y27.790183 Z-0.125000 I-6.183798 J1.359560
G03 X50.459010 Y29.287714 Z-0.125000 I-5.884361 J0.000000
G03 X50.002913 Y30.259582 Z-0.125000 I-2.876467 J-0.756965

If I run it just to the line that ends in J0.000000, I don't get the error. From all the testing I am doing, it almost seems like a problem with the version og GRBL that I am running. If anyone can help, it would be greatly appreciated.

Here is the full gcode file I am trying to run.

 %
(Header)
(Generated by gcodetools from Inkscape.)
(Using default header. To add your own header create file "header" in the output dir.)
M3
(Header end.)
G21 
G00 Z5.000000
G00 X43.225993 Y18.042555


G01 Z-0.125000 F100.0
G03 X44.448347 Y19.159901 Z-0.125000 I-203.958107 J224.353401 F400.000000
G03 X45.751092 Y20.363421 Z-0.125000 I-235.328819 J256.037427
G03 X47.053649 Y21.586232 Z-0.125000 I-48.170466 J52.617095
G03 X47.737750 Y22.275812 Z-0.125000 I-14.623944 J15.191857
G03 X49.369789 Y24.042092 Z-0.125000 I-12.444180 J13.135542
G03 X50.077180 Y25.172247 Z-0.125000 I-4.326712 J3.494655
G03 X50.505064 Y26.430623 Z-0.125000 I-5.413285 J2.542606
G03 X50.652755 Y27.790183 Z-0.125000 I-6.183798 J1.359560
G03 X50.459010 Y29.287714 Z-0.125000 I-5.884361 J0.000000
G03 X50.002913 Y30.259582 Z-0.125000 I-2.876467 J-0.756965
G03 X49.239064 Y30.916004 Z-0.125000 I-1.644692 J-1.141216
G03 X48.146224 Y31.169360 Z-0.125000 I-1.092840 J-2.230286
G03 X47.289509 Y31.048092 Z-0.125000 I-0.000000 J-3.086831
G03 X46.475200 Y30.686621 Z-0.125000 I0.908316 J-3.144182
G03 X45.866393 Y30.136858 Z-0.125000 I1.149043 J-1.884428
G03 X45.713957 Y29.684007 Z-0.125000 I0.596437 J-0.452850
G03 X45.985338 Y29.064178 Z-0.125000 I0.843529 J-0.000000
G03 X46.679436 Y28.792797 Z-0.125000 I0.694099 J0.751942
G02 X47.335454 Y28.673230 Z-0.125000 I-0.000000 J-1.859443
G02 X47.812019 Y28.365758 Z-0.125000 I-0.474548 J-1.258585
G02 X48.135474 Y27.903550 Z-0.125000 I-0.880288 J-0.960310
G02 X48.257626 Y27.288877 Z-0.125000 I-1.485457 J-0.614672
G02 X48.104631 Y26.518211 Z-0.125000 I-2.017507 J0.000000
G02 X47.682050 Y25.896359 Z-0.125000 I-1.707278 J0.705676
G02 X47.046759 Y25.486928 Z-0.125000 I-1.345892 J1.390756
G02 X46.270965 Y25.339351 Z-0.125000 I-0.775794 J1.965345
G02 X45.292182 Y25.503034 Z-0.125000 I-0.000000 J3.008278
G02 X44.544242 Y25.933491 Z-0.125000 I0.740151 J2.151068
G02 X44.042842 Y26.629349 Z-0.125000 I1.319262 J1.479165
G02 X43.857268 Y27.530245 Z-0.125000 I2.093979 J0.900896
G02 X44.053076 Y28.610069 Z-0.125000 I3.075347 J0.000000
G02 X44.637076 Y29.609740 Z-0.125000 I3.204798 J-1.201795
G02 X45.497064 Y30.450999 Z-0.125000 I4.328411 J-3.564579
G02 X46.382366 Y30.983691 Z-0.125000 I2.558297 J-3.249731
G02 X47.382290 Y31.355341 Z-0.125000 I3.964670 J-9.135984
G02 X48.109089 Y31.522132 Z-0.125000 I1.448687 J-4.645789
G02 X48.873231 Y31.617913 Z-0.125000 I1.459799 J-8.550217
G02 X49.724411 Y31.652101 Z-0.125000 I0.851180 J-10.578908
G02 X51.889847 Y31.372996 Z-0.125000 I0.000000 J-8.539831
G02 X53.549194 Y30.649487 Z-0.125000 I-1.488545 J-5.678518
G02 X54.704159 Y29.414339 Z-0.125000 I-1.811549 J-2.851516
G02 X55.127380 Y27.753048 Z-0.125000 I-3.048959 J-1.661291
G02 X54.936373 Y26.631768 Z-0.125000 I-3.386657 J-0.000000
G02 X54.384704 Y25.636421 Z-0.125000 I-3.198858 J1.122406
G02 X53.586077 Y24.796888 Z-0.125000 I-4.668650 J3.641547
G02 X52.750815 Y24.225335 Z-0.125000 I-2.952589 J3.418787
G02 X51.827360 Y23.791569 Z-0.125000 I-7.103306 J13.922514
G02 X49.947214 Y23.018488 Z-0.125000 I-24.534815 J56.996312
G03 X48.140362 Y22.212394 Z-0.125000 I6.972211 J-18.056198
G03 X47.867719 Y21.960175 Z-0.125000 I0.309378 J-0.607900
G01 X47.867719 Y21.885905 Z-0.125000
G02 X48.332245 Y21.916706 Z-0.125000 I1.362590 J-17.031956
G02 X48.926032 Y21.941607 Z-0.125000 I1.463551 J-27.806724
G02 X49.538817 Y21.955270 Z-0.125000 I1.159694 J-38.263217
G02 X50.225717 Y21.960178 Z-0.125000 I0.686900 J-48.074419
G01 X53.159290 Y21.960178 Z-0.125000
G03 X54.047826 Y22.036865 Z-0.125000 I0.000000 J5.185830
G03 X54.440406 Y22.182978 Z-0.125000 I-0.196020 J1.127129
G03 X54.758038 Y22.451881 Z-0.125000 I-0.663402 J1.105664
G03 X54.978847 Y22.814255 Z-0.125000 I-1.019962 J0.869964
G03 X55.149683 Y23.228183 Z-0.125000 I-5.791228 J2.632369
G03 X55.275917 Y23.612631 Z-0.125000 I-4.868337 J1.811474
G02 X55.407546 Y24.001962 Z-0.125000 I45.628782 J-15.209704
G02 X55.498720 Y24.262473 Z-0.125000 I20.519916 J-7.035405
G01 X55.740088 Y24.262473 Z-0.125000
G01 X54.551808 Y17.912589 Z-0.125000
G01 X43.225993 Y17.912589 Z-0.125000
G01 X43.225993 Y18.042555 Z-0.125000
G00 Z5.000000

(End cutting path id: path4518)


(Start cutting path id: path4516)
(Change tool to Default tool)

G00 Z5.000000
G00 X35.980838 Y21.607403

G01 Z-0.125000 F100.0(Penetrate)
G01 X35.980838 Y25.190815 Z-0.125000 F400.000000
G01 X35.999408 Y27.233175 Z-0.125000
G03 X35.574593 Y26.748497 Z-0.125000 I52.703425 J-46.622391
G03 X34.773990 Y25.822090 Z-0.125000 I191.750900 J-166.520630
G02 X33.983162 Y24.922179 Z-0.125000 I-36.848082 J31.584152
G02 X32.917298 Y23.761165 Z-0.125000 I-62.405165 J56.220956
G02 X31.819666 Y22.649912 Z-0.125000 I-29.726417 J28.264352
G02 X30.726405 Y21.625970 Z-0.125000 I-26.328768 J27.015589
G01 X33.028700 Y21.607400 Z-0.125000
G01 X35.980838 Y21.607403 Z-0.125000
G00 Z5.000000

(End cutting path id: path4516)


(Start cutting path id: path4516)
(Change tool to Default tool)

G00 Z5.000000
G00 X40.399760 Y21.607403

G01 Z-0.125000 F100.0(Penetrate)
G01 X42.590657 Y21.607403 Z-0.125000 F400.000000
G01 X42.590657 Y20.809024 Z-0.125000
G01 X40.399760 Y20.809024 Z-0.125000
G01 X40.399760 Y20.084915 Z-0.125000
G03 X40.407178 Y19.750985 Z-0.125000 I7.520648 J-0.000000
G03 X40.436895 Y19.249405 Z-0.125000 I17.002115 J0.755670
G03 X40.546108 Y18.791102 Z-0.125000 I1.970229 J0.227339
G03 X40.696833 Y18.543863 Z-0.125000 I0.702969 J0.258990
G03 X40.941182 Y18.384755 Z-0.125000 I0.600616 J0.655210
G03 X41.290973 Y18.283925 Z-0.125000 I0.555297 J1.269242
G03 X41.662590 Y18.250282 Z-0.125000 I1.978264 J19.782188
G03 X41.977950 Y18.228226 Z-0.125000 I1.153236 J14.223609
G02 X42.293361 Y18.222789 Z-0.125000 I0.000000 J-9.150730
G02 X42.516390 Y18.209656 Z-0.125000 I-0.158205 J-4.587139
G01 X42.516390 Y17.912583 Z-0.125000
G01 X33.715674 Y17.912583 Z-0.125000
G01 X33.715674 Y18.209656 Z-0.125000
G01 X34.198412 Y18.209656 Z-0.125000
G03 X34.458043 Y18.231591 Z-0.125000 I-0.716004 J10.022311
G03 X34.959656 Y18.283923 Z-0.125000 I-3.655306 J37.467340
G03 X35.448552 Y18.416918 Z-0.125000 I-0.290338 J2.032389
G03 X35.683768 Y18.580993 Z-0.125000 I-0.249659 J0.608548
G03 X35.843078 Y18.850674 Z-0.125000 I-0.547342 J0.505231
G03 X35.962270 Y19.416503 Z-0.125000 I-2.408402 J0.802798
G01 X35.999405 Y20.809021 Z-0.125000
G01 X29.723789 Y20.809021 Z-0.125000
G01 X29.723789 Y21.198928 Z-0.125000
G03 X31.120862 Y22.513291 Z-0.125000 I-26.402073 J29.463183
G03 X32.713060 Y24.151066 Z-0.125000 I-39.419679 J39.915522
G03 X34.252508 Y25.840106 Z-0.125000 I-70.593355 J65.887243
G03 X36.017970 Y27.864447 Z-0.125000 I-99.645628 J88.684620
G03 X37.748161 Y29.937732 Z-0.125000 I-142.627488 J120.783656
G03 X39.025809 Y31.522129 Z-0.125000 I-82.011066 J67.440569
G01 X40.399760 Y31.522129 Z-0.125000
G01 X40.399760 Y21.607403 Z-0.125000
G00 Z5.000000

(End cutting path id: path4516)


(Start cutting path id: path4514)
(Change tool to Default tool)

G00 Z5.000000
G00 X18.865337 Y24.225335

G01 Z-0.125000 F100.0(Penetrate)
G01 X20.480658 Y31.559267 Z-0.125000 F400.000000
G01 X20.647760 Y31.559267 Z-0.125000
G03 X21.301879 Y31.370938 Z-0.125000 I4.220657 J13.429377
G03 X22.207381 Y31.150795 Z-0.125000 I6.684447 J25.522464
G03 X23.141733 Y31.001820 Z-0.125000 I1.740292 J7.910320
G03 X24.249741 Y30.946556 Z-0.125000 I1.108007 J11.079935
G03 X25.672326 Y31.009030 Z-0.125000 I0.000000 J16.228010
G03 X26.570605 Y31.150795 Z-0.125000 I-0.580218 J6.593308
G03 X27.163172 Y31.377624 Z-0.125000 I-16.345032 J43.587248
G03 X27.758887 Y31.614966 Z-0.125000 I-17.300215 J44.288718
G02 X27.874660 Y31.545070 Z-0.125000 I-0.000000 J-0.130829
G02 X27.944556 Y31.262194 Z-0.125000 I-0.537466 J-0.282876
G02 X27.858000 Y30.728811 Z-0.125000 I-1.686705 J0.000000
G02 X27.517517 Y29.981077 Z-0.125000 I-3.699295 J1.233098
G02 X27.036658 Y29.338516 Z-0.125000 I-2.958736 J1.712955
G02 X26.087865 Y28.477160 Z-0.125000 I-6.317281 J6.005326
G02 X24.999472 Y27.947358 Z-0.125000 I-1.799138 J2.313175
G02 X22.968624 Y27.697349 Z-0.125000 I-2.030848 J8.123382
G02 X22.023587 Y27.724483 Z-0.125000 I0.000000 J16.470844
G02 X21.353303 Y27.790183 Z-0.125000 I0.479583 J8.344780
G02 X20.698448 Y27.945130 Z-0.125000 I0.823870 J4.943211
G02 X20.090753 Y28.180087 Z-0.125000 I1.386162 J4.488536
G01 X19.496612 Y25.562154 Z-0.125000
G02 X20.420767 Y26.277720 Z-0.125000 I3.544856 J-3.623633
G02 X21.371870 Y26.694735 Z-0.125000 I2.068978 J-3.425688
G02 X22.425760 Y26.915093 Z-0.125000 I1.767117 J-5.821095
G02 X24.045505 Y27.010372 Z-0.125000 I1.619745 J-13.720196
G02 X26.002310 Y26.698984 Z-0.125000 I-0.000000 J-6.304103
G02 X27.684619 Y25.822090 Z-0.125000 I-1.793851 J-5.493667
G02 X28.853132 Y24.429454 Z-0.125000 I-2.426172 J-3.222266
G02 X29.262806 Y22.721416 Z-0.125000 I-3.355793 J-1.708038
G02 X28.719685 Y20.623608 Z-0.125000 I-4.322955 J0.000000
G02 X27.201879 Y19.008034 Z-0.125000 I-3.955337 J2.195212
G02 X25.055324 Y18.043352 Z-0.125000 I-4.247338 J6.580391
G02 X22.467318 Y17.689786 Z-0.125000 I-2.588006 J9.294965
G02 X20.516310 Y17.965951 Z-0.125000 I-0.000000 J7.029654
G02 X19.125274 Y18.655265 Z-0.125000 I1.211062 J4.192136
G02 X18.167632 Y19.798729 Z-0.125000 I2.094628 J2.726975
G02 X17.844157 Y21.124661 Z-0.125000 I2.555779 J1.325932
G02 X18.001470 Y21.835020 Z-0.125000 I1.682496 J0.000000
G02 X18.475432 Y22.480048 Z-0.125000 I1.845992 J-0.859776
G02 X19.163765 Y22.908353 Z-0.125000 I1.503460 J-1.648961
G02 X19.942218 Y23.055620 Z-0.125000 I0.778453 J-1.983804
G02 X20.910521 Y22.903307 Z-0.125000 I-0.000000 J-3.154065
G02 X21.668941 Y22.498615 Z-0.125000 I-0.744739 J-2.308701
G02 X22.184274 Y21.866063 Z-0.125000 I-1.061617 J-1.391084
G02 X22.374483 Y21.031827 Z-0.125000 I-1.734336 J-0.834236
G02 X22.212395 Y20.170622 Z-0.125000 I-2.368924 J0.000000
G02 X21.780342 Y19.509343 Z-0.125000 I-1.793062 J0.699732
G03 X21.254269 Y18.887006 Z-0.125000 I3.449199 J-3.449189
G03 X21.186201 Y18.673830 Z-0.125000 I0.299780 J-0.213176
G03 X21.278233 Y18.397734 Z-0.125000 I0.460159 J0.000000
G03 X21.576106 Y18.153956 Z-0.125000 I0.643932 J0.482949
G03 X21.992550 Y18.027396 Z-0.125000 I0.884662 J2.162523
G03 X22.393050 Y17.986856 Z-0.125000 I0.400500 J1.958017
G03 X23.573351 Y18.312863 Z-0.125000 I-0.000000 J2.299628
G03 X24.286875 Y19.119436 Z-0.125000 I-0.912880 J1.526457
G03 X24.642008 Y20.282923 Z-0.125000 I-4.628727 J2.048777
G03 X24.788181 Y21.941607 Z-0.125000 I-9.337783 J1.658684
G03 X24.614609 Y23.704630 Z-0.125000 I-9.040542 J0.000000
G03 X24.156906 Y25.116548 Z-0.125000 I-6.224224 J-1.237565
G03 X23.309525 Y26.128896 Z-0.125000 I-2.201031 J-0.981541
G03 X22.133113 Y26.490499 Z-0.125000 I-1.176411 J-1.732823
G03 X20.931989 Y26.297380 Z-0.125000 I0.000000 J-3.831820
G03 X20.220721 Y25.859224 Z-0.125000 I0.566382 J-1.715806
G03 X19.619208 Y25.205500 Z-0.125000 I7.557493 J-7.557497
G03 X19.403778 Y24.893745 Z-0.125000 I1.484653 J-1.256244
G03 X19.256083 Y24.552361 Z-0.125000 I3.008082 J-1.504041
G03 X19.143841 Y24.188203 Z-0.125000 I3.312064 J-1.220236
G01 X18.865337 Y24.225335 Z-0.125000
G00 Z5.000000

(End cutting path id: path4514)


(Start cutting path id: path4512)
(Change tool to Default tool)

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(End cutting path id: path4512)


(Footer)
M5
G00 X0.0000 Y0.0000
M2
(Using default footer. To add your own footer create file "footer" in the output dir.)
(end)
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[NeverDie]

@dbemowsk said in DIY CNC mill from mainly salvaged and 3D printed parts:

The way I am testing this is just using a terminal connection to the CNC and pasting the gcode into the terminal window. If there is a better way to test this let me know.

This may be your problem, or at least a contributing factor. Try using a gcode sender, such as ChiliPeppr, instead.

[dbemowsk]

@neverdie Thanks a million. I tried the online version of chilipeppr and it seem s to be working.

[dbemowsk]

So I did a test run of an old style font carving my house number into a piece of wood. I created the gcode using Inkscape which is a popular vector graphics program. For a test run I think it went fairly well.

I did a video of it carving. The spindle is spinning much faster than it looks like in the video. It has to do with the recording frame rate on my phone.
https://www.youtube.com/watch?v=S2wdsbMfSeM&t=46s

[NeverDie]

Looks like your spindle may have really bad runout.

[dbemowsk]

@neverdie I don't think it's runout. If you look, a lot of the video is shaky. I think it is vibration from the V bit cutting into the wood. The tip of that bit may be bent a little which would cause vibration like that. I guess I'l find out when I try cutting a PCB. When I do one, I'll change to a new bit. I ordered a pack of 10. I have to see if I have any copper clad laying around.