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  1. #1
    Join Date
    Nov 2013
    Posts
    5

    Chinese 3040 - buy cheap buy twice…

    Hello all,
    i just joind this great forum to get some help and advise...

    I have this machine for 3 months, so far, not a single decent cut.
    Mainly the long axis (Y) is skipping step once in a while. It was hard to turn, I removed the end bearings and noticed a band/miss-alignment of about 2mm or so, without the end bearing it run freely, turns easily and smoothly. I kept it out for testing.
    But still skipping steppes, I reduced acc` and speed to few inches, cutting 2mm of MDF, still skipping steps. Didn’t find shielded cable next to me so I tried to isolate the spindle cable by routing if far from the stepper motors cables pack, no luck.
    Next is to try the capacitors on pins 15, now it become useless, one of the cap`s bridged after few min` and I burned the 5A fuse, replaced them, burned again immediately, removed all the caps, new fuse – burned again immediately. I do not see damage on the board but still any fuses burn immediately on power up.

    All I wanted is a nice CNC for home use… any ideas?

  2. #2
    Join Date
    Dec 2007
    Posts
    2134
    The drivers on ALL these variant Chinese are known to be garbage (with the exception perhaps of Carving CNC), bite the bullet and buy a Gecko G540 would be my suggestion. You could spend months trying to get the drivers working, but they are all based on an inferior and unworkable design that leaves them open to problems with noise immunity, not to mention the high likelihood of blowing the IC's because of the very particular power/down sequence required by them. Simply put, these controllers are not worth spending/wasting time on, as the end result will always be inferior no matter how much effort you put into it.

    cheers, Ian
    It's rumoured that everytime someone buys a TB6560 based board, an engineer cries!

  3. #3
    Join Date
    Oct 2008
    Posts
    2100
    I bought a cheap Chinese router off Ebay knowing it was probably not well built. It was not square. It was not in tram, and it would only work reliabley at about half the claimed speed. I rebuilt it and retrofit it with a G540 and some bigger steppers. I tested it at over 600 inches per minute after that and locked it down at 300. I spent about the same as if I had bought a better router. LOL.
    Bob La Londe
    http://www.YumaBassMan.com

  4. #4
    Join Date
    Dec 2013
    Posts
    9
    One of the other members "Helloagain" has puzzled out how to fix a lot of the issues's with the cheap/poorly built controllers that come with them. His modifications also update the parallel port so that a USB to parallel port converter and a more modern computer can be used. Should fix many of the cheap ones issue's. Ask me again in about six months. Search for his posts on the YOOCNC branded CNC 6040. I know the same solution applies to the CNC 3040 but it has a little different board set up in it. Same chips, same repairs to fix it. CNC 3020 probably in the boat as well. Hope this helps. Bo

  5. #5
    Join Date
    Dec 2007
    Posts
    2134
    I know some people spend an inordinate amount of time trying to fix the issues with these crappy controllers, but I really don't see the point, apart from an exercise in education.

    No matter what fixes are used, there's no getting around the fact that the commonly available design is still based on an inferior layout, is still prone to random blowing of the IC's due to the particular power up/down sequence, and still delivers a max VDC that's often far below the optimal amount required for the steppers supplied with the machines.

    Meaning the steppers will never be able to operate at peak performance.

    The problem with the opto-isolation and logic level shifting issues is another problem altogether.
    cheers, Ian
    It's rumoured that everytime someone buys a TB6560 based board, an engineer cries!

  6. #6
    Join Date
    Nov 2013
    Posts
    5
    well, did it again, I was thinking that a non-Chinese setup will cost around $300-$400 so I’m going to try once more with a Chinese board, about $50. This time I found a board witch appear to have a layout that easier to handle. Looks like two layers, some nice vias or through holes next to the outputs and more space between components.
    I`m working for the T&M industry so I arranged I nice scope for few weeks. I`ll spend some time on this maybe it will work…
    Will keep this post updated...
    thanks

  7. #7
    Join Date
    Dec 2013
    Posts
    6
    I have cnc3040 too and the capacitors help for me.
    I thinking to buy a spare board so i waiting for your experience.
    I also thinking about to change to USB driving with this board:
    4 Axis 3 0A 15kHz USB CNC Stepper Motor USB Driver Board TB6560 Controller | eBay

    Best
    Thomas

  8. #8
    Join Date
    Nov 2013
    Posts
    5
    OK, the board arrived, I have the equipment, here are the first measurements…
    First the setup, too cold to work outside, I set everything up in my study, the scope is Agilent 9000 series, really an over kill for this but this one was available..

    Attachment 212752

    Attachment 212740

    First measurement is the 28V output from the power board to the controller board, this is feeding the stepper motors eventually. Spindle power is off:

    Attachment 212742

    Same 28V output when spindle power is on, notice the ripple about 0.4v:

    Attachment 212744

    Same 28V output when spindle power is on and on max, notice the ripple about 0.7v:

    Attachment 212746

    Attachment 212748

    Attachment 212750

    So first, i think i need a clean power source to the board and a seperate one for the spindle..

    Thanks,
    Yoram

  9. #9
    Join Date
    Nov 2013
    Posts
    30
    Keep us posted. Interested in your progress. My 3040 with the same stock controller you had will be here next week.

  10. #10
    Join Date
    Nov 2013
    Posts
    5
    New update – not working well 
    Still skipping steps, the motors act like crazy, here are the pics:

    Attachment 215048

    Attachment 215050

    Attachment 215052

    Attachment 215054

    current decay set to fast, this yield the best results, subdivision set to 1, less than that and the motors act like crazy again.
    Load noise from all the motors and they are becoming really hot after few min` with no load, I limited the current to 0.8A, didn’t help.
    Any ideas?

  11. #11
    Join Date
    Oct 2008
    Posts
    2100
    I don't have any help to suggest. I did like you did when I was experimenting and I tried a Chinese "red board" and a "blue board" because they were cheap. Both of my current stepper controlled machines are running on Gecko G540s. The red board and the blue board both went in the trash. The CNC conversion I am working on for my mini lathe is going to use Leadshine (Keling Labeled) drivers.

    I couldn't get satisfactory results out of either of the cheap boards I tried, but... they were cheap. I know its frustrating because you get your hope up, but atleast the lesson is cheap.

    I've got one servo controlled machine as well, and I like it so much better I doubt I'll build or setup another stepper based machine. It costs more, but I think its worth it. In fact I plan all servos on the rigid gantry router I am buiding now too.
    Bob La Londe
    http://www.YumaBassMan.com

  12. #12
    Join Date
    Jan 2007
    Posts
    1795
    compact drives in my opinion behind... compared with controls where all axis has separated drive..

    USA Free SHIP Promotion 3Axis Wantai Nema23 Stepper Motor 425oz in 4 2A Cncmill | eBay

    these motors can drive a lot larger router..

    this control working with mach3..

    you also can buy a ncstudio for 50 dollar.. then don't have to buy mach3..

    tough for this need assembly, and a box.. but in case a faulting axis, you change only one drive.. not the whole control..

    it also can be mixed with larger motor.. like 3 pcs nema 23 and one nema 34

    so in my private opinion it could be better deal than any compact drive..

  13. #13
    Join Date
    Dec 2013
    Posts
    6
    In my opinion the skipping steps and the motor hot/noise is two different problem. If the motor gets noise and hot the setup in mach 3 is wrong. Try to find out the correct settings.

  14. #14
    Join Date
    Nov 2013
    Posts
    5
    Hi, Thanks for the replay…
    The motors are getting hot with hi-freq sound even without the Mach3 running, no connection to the host PC, no load or movement and current limited to 20% (0.8A-0.6A).
    I can adjust the current decay and the resolution, to achieve the best behavior, ie lowest noise and kind of controlling the motors the settings are:
    Current - 20%, current decay- Fast (slow, 25%, 50%, fast), resolution - 1 (1, 1/2, 1/8, 1/16)
    Pls look at the pic`s, do you see anything odd in the waveforms?
    Yellow is AP but I couldn’t hold the probe, Green is AM, Blue is BP and then BM.
    The voltage levels are about 45V, but pls look at the noise levels which are 4-5V, wonder if this is the issue…

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