Welcome to Our Community

Some features disabled for guests. Register Today.

Ask Grbl CNC questions here.

Discussion in 'Control Software' started by Sonny Jeon, Aug 12, 2015.

  1. Fish4Fun

    Fish4Fun New
    Builder

    Joined:
    Apr 14, 2016
    Messages:
    3
    Likes Received:
    2
    Thanks David!

    So I don't bury the lead:

    my Front-End was at fault ...

    You are 100% correct about (re) reading the wiki

    ... I started this project back in the Spring ... got the basics of a front-end I have used for years modified to work pretty much the way I wanted with grbl... then my computer crashed, life happened and 5 months passed ... I forgot a lot of what I had read AND that my code-writing session ended in a computer crash ... so what I remembered was that "I had it working when last I worked on it", and I ***-u-med that I was now receiving some type of non-ascii error messages that had not been present previously. As I re-read the wiki and reviewed my code I remembered the crash and realized how many "stubs" there were in my front-end code .... obviously I lost more than a few changes in the crash ...

    So, I spent a few hours filling in enough of the stubs in my code to keep a steady flow of g-code flowing, but something Peter said in a PM kept nagging at me,

    While I have been anxious to try grlb on a traditional 3-Axis machine using a real PC, this project is simply not a good fit .... This project is a single Axis machine that only needs a couple of modes of operation .... literally a "speed knob", a "min - max" travel knob, a Direction Switch and a SPDT momentary switch .... (FWIW, I am building a stepper-based Tapping Head ... the head uses gravity and the Tap itself for "feed rate" ... an operator lines the Tap up with a pre-drilled hole and holds the momentary switch "down" to tap, and "up" to remove the tap .... the "speed" adjusts how rapidly the tap spins, the "min - max" travel adjusts how many steps the Tap travels forward before reversing to break/clear chips ... the "Direction Switch" is for left/right hand tapping....)

    I have a "mock-up" (that uses a PC // Arduino to control the stepper driver) and using a 10:1 Gear Reduced NEMA-23 Stepper can tap 3/8-16 holes in 1/2" 1018 steel in just over a minute ... smaller sizes and aluminum are quick/easy. My thought with grlb was that using g-code to create "settings" based on material//tap size and stored in a second Arduino host would make fine tuning easier ... but a laminated piece of paper with the approximate analog speed/travel settings in a chart is all that is truly requisite. While the precise acceleration // deceleration algorithms in grbl would be nice, because "lost steps" and "extra steps" are trivial in this application, simple acceleration // deceleration routines hard-coded in firmware should be sufficient .... Finally, though I have muddled my way through the start of a functional front-end on a PC in a high-level language, I feel confident I would run into more problems porting that front-end to an Arduino than I would simply replacing the PC in my existing mock-up with a few analog inputs.

    Again, Thanks for your response! Sorry I posted before going back and re-reading the wiki ( AND my own front-end code).

    Fish
     
    David the swarfer and sharmstr like this.
  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Resident Builder Project Maker Builder

    Joined:
    Mar 1, 2017
    Messages:
    2,166
    Likes Received:
    1,081
    Still, instead of two Arduinos and Grbl, if its just one axis, just control it directly from your own sketch. See OpenBuilds/ArduinoStepperDriver
    (interface your switches and knobs in the sketch directly)
     
    David the swarfer likes this.
  3. 50Special

    50Special New
    Builder

    Joined:
    Sep 14, 2019
    Messages:
    2
    Likes Received:
    0
    Hi, I'm not sure if this is the right topic, maybe you can redirect me if i'm wrong.
    BTW, i'm always asking myself if GRBL can lose step due to gcode coordinates resolution.
    I mean, I'm creating the gcode files through Fusion 360 CAM packet, and on gcode I can see example X12.345
    and i've 0,01mm of resolution (1/4th microsteps,200-step motors, 8mm t2 leadscrew).
    Can this resolution difference give me problems?
    I'm building an MPCNC but having problems with Y (double motor) and X axes shifting some step,
    so I'm searching for the problem.
    If someone can also explain me (roughly) how grbl handle this resolution difference, i will be grateful.

    Thanks in advance,
    50Special
     
  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Resident Builder Project Maker Builder

    Joined:
    Mar 1, 2017
    Messages:
    2,166
    Likes Received:
    1,081
    Less likely Grbl, more likely choice of drivers. Let me guess, some variant of underpowered pololu footprint?
    Replace it with some decent drivers like our DQ542MA Stepper Motor Driver

    Wiring instructions:


    Oh, and seeing as you mentioned MPCNC, if Open Source and all it stands for is important to anyone reading this, watch this: (or if you just like watching drama hehe)
     
    sharmstr likes this.
  5. 50Special

    50Special New
    Builder

    Joined:
    Sep 14, 2019
    Messages:
    2
    Likes Received:
    0
    Dear Peter,
    First of all thanks for the reply.
    I forgot to mention that drivers are DRV8825 (I'm from Italy so i think that buying from pololu site or out of UE, i will pay duty and shipment more than drivers itself, so I bought them from local Amazon.it, I don't think they are genuine).
    From when I wrote the first post and now, I've switched from 12V supply to 24V supply, and I've noticed so much heating and stepper drivers resets every 3-4 seconds.
    Other thing, not really needed, it's an MPCNC but designed from scratch by me, not available online. I've checked all leadscrews and couplings, no frictions or lockings on movements.
    Now i'm printing a new case with 2 fans, trying to solve overheating.

    Thanks for the attention
    50Special
     
  6. phil from seattle

    phil from seattle Well-Known
    Builder

    Joined:
    Mar 17, 2017
    Messages:
    126
    Likes Received:
    47
    A couple of thoughts.

    First, GRBL in absolute mode will "accumulate" any lost precision your machine will have. You can test this by doing a series of short moves in one direction, say 20 moves of 5.005 mm, and compare to a single 100.1 mm move. They should be the same length.

    If you haven't already bought the drivers, look at trinamic step sticks (assuming you are using that format). They run a lot cooler and are significantly quieter than the Allegro based drivers. Not that much more expensive, either.

    Try running at 1/8 step for better resolution.

    For a CNC machine, you might want to consider better drivers not in the stepstick format. The stepstick format maxes out around 1Amp and were really designed for 3D printing. CNC has higher power needs.
     
    #966 phil from seattle, Sep 15, 2019
    Last edited: Sep 15, 2019
  7. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Resident Builder Project Maker Builder

    Joined:
    Mar 1, 2017
    Messages:
    2,166
    Likes Received:
    1,081
    Look for DQ542ma or DM542 at a local vendors, they are really popular
     
    David the swarfer likes this.
  8. phil from seattle

    phil from seattle Well-Known
    Builder

    Joined:
    Mar 17, 2017
    Messages:
    126
    Likes Received:
    47
    Those certainly will work and are an excellent choice, if your budget allows. There are other driver that are quite a bit less expensive - TB6600 based, for example. - that will work a lot better than a stepstick. If you think you are going to be continuing on with a more powerful CNC machine, the 542s make sense as you can use them on fairly powerful motors. Lots of choices for different budgets.
     
  9. Ian Marshall

    Builder

    Joined:
    Sep 18, 2019
    Messages:
    1
    Likes Received:
    0
    Hi Everyone,

    Currently at the beginning of a new project and I have been playing with GRBL 1.1.

    I am planning to drive the table with 4x stepper motors using 4x DM542 controllers. I was plannning to wire the controllers in parallel back to the 3 pins on the UNO (Enable, Direction and Pulse) however I got to thinking about whether the Uno could handle the signal current. From the data sheets the typical current draw for the signal inputs on the DM542 is about 10mA so if I wired 4 in parallel it would be equal to 40mA which is double the current that the Uno can support (So I'm expecting to see the magic smoke if I did it that way).

    I then got to thinking, it is typical (I believe) to wire the 3 controllers (in a 3 axis machine) to the Enable pin which would draw 30mA on the pin which again is over the 20mA upper limit the UNO can support !! I haven't seen this issue raised before so assume its not a problem but I'd be grateful for any views about this.

    I'd also be grateful for any suggestions about changing my design; perhaps putting 2 stepper motors in parallel on to one controller (and then using 2 controllers in parallel to get 4 steppers in total). I realise this doubles the load on the controller so 2x2A motors would put a 4A load on the controller.

    I've also toyed with the idea of putting in a simple transistor circuit after the Uno to act as a buffer between the Uno and DM542.

    Anyway, any comments gratefully received

    Ian
     
  10. Fish4Fun

    Fish4Fun New
    Builder

    Joined:
    Apr 14, 2016
    Messages:
    3
    Likes Received:
    2
    Thanks David!

    That is exactly what I am doing ... except the part about 'sketch' .... sadly C is still on my "round-to-it list" .... While grlb would have made development easier, the complication of controlling grlb from a second microcontroller would have negated any time savings ....

    So, leaving grbl out of the loop, I have everything working on an ATTINY2313A (have plenty of them on hand). As expected, it took some time & fiddling to get acceleration / deceleration worked out ... (there is still room for improvement) ... but the time to benefit ratio is getting steep. Mostly what I tap is Aluminum, generally 5/16-18 or smaller ... and the ATTINY2313A code is adequate for most of those tasks ... not as fast as the same mechanical & driver set-up using a "real" controller with a tweaked script run on a PC, but in most cases faster than hand tapping. With the ATTINY2313A all that is requisite is a 12V wall-wort, the Stepper Power Supply and the stepper driver ... I replaced the "speed knob" & "travel knobs" with three pairs of momentary switches (the 2313 doesn't have an ADC...) and they are easy enough to use.

    Perhaps after some real-world use (and//or I find a "round-to-it" for learning C), I will revisit the controller and a more robust target.

    Thanks for your help!

    Fish
     
  11. Tajudeen

    Tajudeen New
    Builder

    Joined:
    Aug 27, 2019
    Messages:
    35
    Likes Received:
    2
    I was able to connect the black box to windows 10 about 12 hours ago. Now I cannot get it connected any more. Please what shall I do?. USB not recognized
     
  12. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Resident Builder Project Maker Builder

    Joined:
    Mar 1, 2017
    Messages:
    2,166
    Likes Received:
    1,081
    Disconnect everything except USB and then test again, let us know if it connects then.
     
  13. Tajudeen

    Tajudeen New
    Builder

    Joined:
    Aug 27, 2019
    Messages:
    35
    Likes Received:
    2
    @Peter thanks for your reply. I have disconnect and reconnect severally. I can no longer see the ftdi driver on the usb port menu. Please what can I do next?
     
  14. brentmccabe

    Builder

    Joined:
    Oct 6, 2019
    Messages:
    1
    Likes Received:
    0
    Hello, as new as new can be. I will apologize ahead of time if I am not supposed to ask control s-ware questions here. I couldn't find another place to ask. I just purchased a "toy" CNC router to teach an old dog new tricks. It is just a cheap little router, I figured if I destroy something, I better start out small and inexpensive. I have programs that I downloaded from the site I purchased the little router from. It has 3 axes. I have downloaded gbrl control s-ware and my machine works. I have loaded g code program and my router performs fine. My question is: is there a way I can open the project and change some of the code, to see how this works and learn? I didn't buy this to just download other people' programs and not learn anything. Thank you ahead of time.
     
  15. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Resident Builder Project Maker Builder

    Joined:
    Mar 1, 2017
    Messages:
    2,166
    Likes Received:
    1,081
    Duplicate thread Black box not working anymore please only continue in the thread posting in multiple threads about the same issue just makes things confusing
     
  16. CHarmon

    CHarmon New
    Builder

    Joined:
    Oct 16, 2019
    Messages:
    1
    Likes Received:
    0
    Hello!
    Pardon if this isn't in the write place, but I was looking for guidance as to if Grbl would be the right solution for a particular project I am undertaking (Senior Mechanical Engineer in College). I am essentially making an 3-axis (XYZ) machine that needs to drive screws into pre-made holes to a particular depth. Due to very tight depth tolerances (0.005"), I may have to us a laser to tell the machine when to stop driving the screw and move onto the next. Would Grbl support such a sensor integration?
    I am a bit out of my usual area of expertise, so I greatly appreciate any sort of guidance possible.
     
  17. element

    element New
    Builder

    Joined:
    Mar 9, 2019
    Messages:
    2
    Likes Received:
    0
    I'm new. I assume, to ask a GRBL-related, I'm supposed to just reply to this thread.

    My question: I have a laser-engraver type machine, Chinese, ~55 cm X axis, aluminium extrusions, 2mm-pitch T belt, Nema 17H3430 motors, one mechanical homing switch for X, Arduino-based.The X-axis accuracy is not up to par. When I make a mark on the X axis and jog to that mark (after homing), depending on the day, the position varies within ~4mm or so from G00 X-418 to G00 X-422. I checked the belt tension, it is seems OK, not too tight, not too lose. Is there something else I should check? Another idea I have: put a homing switch on the other end of the X-axis, then home both ends of the X axis, measuring the difference in machine position (assuming I can measure it), then modify the steps/mm value for each session to force to command that puts me on the mark to be constant (e.g. G00 X-420). Any other ideas? Thanks.
     
    #977 element, Oct 21, 2019
    Last edited: Oct 21, 2019
  18. Alex Chambers

    Alex Chambers Master
    Moderator Builder

    Joined:
    Nov 1, 2018
    Messages:
    1,048
    Likes Received:
    517
    If the results are inconsistent then it will not be corrected by adjusting the grbl setting for steps/mm. Can you tell us what stepper motors (I'm guessing nema 17 - but give us any numbers printed on them) and what drivers you have (again guessing - if they have any numbers printed on them it says A4988 or something similar). You could also check that various machine movements are smooth - DON'T TURN THE STEPPER MOTORS BY HAND - disconnect the drive pulleys from the motor shafts before checking that each axis moves smoothly. Also check that the drive pulleys are firmly attached to the motors - a fixing screw in the pulley should grip the flat on the motor shaft.
    Let us know if you find anything.
    Alex.
    Sorry - just read your post again - you told us what motors you have - what drivers are you using?
    Alex.
    PS I suspect this will turn out not to be a grbl question - if so I will move it to another thread.
     
    #978 Alex Chambers, Oct 21, 2019
    Last edited: Oct 21, 2019
  19. phil from seattle

    phil from seattle Well-Known
    Builder

    Joined:
    Mar 17, 2017
    Messages:
    126
    Likes Received:
    47
    It's possible something is loose or binding. Carriage, motor coupler, motor mount, frame. When checking axis movement binding, do the whole length. If the the carriage always moves less than it should, you could be losing steps - turning up your motor current could be the solution if there is no binding in the X movement.
     
  20. element

    element New
    Builder

    Joined:
    Mar 9, 2019
    Messages:
    2
    Likes Received:
    0
    Thanks for the reply. Yes, the motor model is mentioned above (Nema 17H3430), the (2) drivers are TMC2130. Y axis is mirrored (2 motors, one driver, twice the current of X axis). Microstepping is 16. Bought for their quiet operation. Indeed, the motors are 100% silent and move smoothly (at least, to my eyes). Someone mentioned that the issue could be missed steps. Hm, now I vaguely recall reading somewhere that TMC2130 by default are in some "StealthChop" mode, which makes the motors weaker and MAY lead to missed steps. I'll look into this. Hard to tell (yet) what problem this is, it could be mechanical (belt), electronic (steppers) or software (GRBL).
     
  21. phil from seattle

    phil from seattle Well-Known
    Builder

    Joined:
    Mar 17, 2017
    Messages:
    126
    Likes Received:
    47
    I agree with alex, it's very unlikely to be GRBL unless the differences are highly repeatable.

    I like those drivers - amazingly quiet. I've used them in a couple of projects (not cnc, though). Try switching to 8:1 microstepping to see if the problem goes away. I tried 16:1 in a star tracker I built and didn't like the result, switch to 8:1 and it was excellent.
     
  22. Metalguru

    Metalguru Veteran
    Builder

    Joined:
    Dec 29, 2015
    Messages:
    682
    Likes Received:
    472
    Sounds more like a mechanical problem than an electronic one.

    Make a little g-code program (macro?) that is just G0 X+200, G0 X-200. Center the axis, make sure you are set to relative co-ordinates, and run the program several times in a row. It should end up back exactly where it was. If it does not, there is definitely a repeatability issue.

    Check all belt anchors, belt should be quite tight, but don't bend the motor shafts. Make sure there is no play in the axis. Grab the carriage and jiggle it back and forth along the direction of the axis. If it moves AT ALL, or feels loose, there is a loose component somewhere. Make sure motor mounts are tight, pulley screws are tight and on the shaft flat, belt holder on the carriage is tight, etc.

    If you eliminate all the mechanical possibilities, it is likely too low a motor current or microstepping is set too high.

    MG
     
  23. Chris Preece

    Builder

    Joined:
    Oct 21, 2019
    Messages:
    3
    Likes Received:
    0
    Hi I just got the leed 1010 and we have made a file with solid works but are having trouble importing it into the open build controller. We have saved it multiple way and we still can’t get it to work. It keeps giving us errors or unsupported code.


    I know we need to use a post processer for solid works to make it into a grbl file but have not been able to make it work.


    we also can’t seem to import 3D files into the open builds cam program. It only wants to accept 2D files or pictures.


    any suggestions?
     
  24. David the swarfer

    David the swarfer OpenBuilds Team
    Staff Member Moderator Builder

    Joined:
    Aug 6, 2013
    Messages:
    1,333
    Likes Received:
    676
    So you want to generate Gcode from your own drawings ....
    OpenBuilds CAM Gcode Creator - Public Beta

    Alternately Sketchup Make 2016 and the SketchUcam plugin
    SketchUcam Howto - YouTube
     
  25. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Resident Builder Project Maker Builder

    Joined:
    Mar 1, 2017
    Messages:
    2,166
    Likes Received:
    1,081
    OpenBuilds CAM is aimed at beginners and is thus 2.5D

    Best option for 3D work is offered in the store: VCarve Desktop or https://openbuildspartstore.com/aspire-1/
    Alternatively you can use Fusion360, or any of many other commercial options, just make sure to use a Grbl compatible post processor. For Fusion see: https://openbuilds.com/threads/fusion-360-grbl-post-processor-install-the-easy-way.14402/
     
  26. Chris Preece

    Builder

    Joined:
    Oct 21, 2019
    Messages:
    3
    Likes Received:
    0
    So We down loaded Fusion 360 and used it to make our build and then ran our file through the post processor you suggested and it still wont fully work? The simulation works fine but when I hit run job it just does small circles on the board... the code seems right so I'm not sure why we are having so many issues.

    If I attach a file would it be easier to see any flaws?
     
  27. DarkPenguin

    Builder

    Joined:
    Sep 16, 2017
    Messages:
    72
    Likes Received:
    15
    Attach a file.
     
  28. Alex Chambers

    Alex Chambers Master
    Moderator Builder

    Joined:
    Nov 1, 2018
    Messages:
    1,048
    Likes Received:
    517
    Hi @Chris Preece, in Fusion you can export a Fusion archive file. Zip it, together with your nc file from Fusion and post it here.
    Alex.
     
  29. Henk Schooms

    Builder

    Joined:
    Mar 25, 2019
    Messages:
    4
    Likes Received:
    0
    HI All the GBRL masters.

    Im looking for the best software that i can control my gbrl with for very long toolpaths for my rotary setup.

    As this are now then i run it through UGS it reaches a freezing point in the software and just stops, then i need to check the line and edit the gcode which is a hassel.

    Does anyone have advice PLEASE.
     
  30. phil from seattle

    phil from seattle Well-Known
    Builder

    Joined:
    Mar 17, 2017
    Messages:
    126
    Likes Received:
    47
    Better to get your Post processing in order to avoid generating the offending op codes.

    With grbl panel you can hit continue to get past an unsupported GCode but that's not the preferred option.
     
    Peter Van Der Walt likes this.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice