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Homing Question

Discussion in 'CNC Mills/Routers' started by Solly747, Oct 19, 2019.

  1. Solly747

    Solly747 New
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    Hey folks,
    I have a 1000x750 workbee, well it's made by sharpcnc but it is the exact same machine.
    Anyway, I have just finished building it and trying to setup the homing. So the way I have my axis setup is:
    As I'm looking at the front of the machine,
    • when Y comes towards me, it's negative
    • when X goes to the left, it's negative
    • when Z goes down, it's negative
    I want to home to the negative (left front of machine), but no matter how I try to configure it, I either get Y & Z homing to +, or if I invert homing, I get X homing to +.

    Is there a way I can configure each axis homing direction separately?

    Why is this happening?

    I am running a basic GRBL setup (nano with screwshield and TB6600 drivers running on 24V.

    Any advice would be awesome. Thanks
     
  2. Alex Chambers

    Alex Chambers Master
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    $23 is the grbl setting
    Read https://www.google.co.uk/url?sa=t&s...AwAXoECAcQCQ&usg=AOvVaw0Qv75ELfQOjQy5zl0eMkkX
    Scroll down to step port invert mask which explains how the mask works. Scroll down further to read how homing direction invert works. The mask is in binary - convert the binary number for the directions you want into decimal and that is the number you put after $23 in your grbl settings.
    Alex.

    On my PC now so can give more detail

    Mask to invert directions is

    Invert mask.png

    $23 - Homing dir invert, mask
    By default, Grbl assumes your homing limit switches are in the positive direction, first moving the z-axis positive, then the x-y axes positive before trying to precisely locate machine zero by going back and forth slowly around the switch. If your machine has a limit switch in the negative direction, the homing direction mask can invert the axes' direction. It works just like the step port invert and direction port invert masks, where all you have to do is send the value in the table to indicate what axes you want to invert and search for in the opposite direction.
     
    #2 Alex Chambers, Oct 19, 2019
    Last edited: Oct 19, 2019
  3. Solly747

    Solly747 New
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    Thank you Alex
     
  4. Solly747

    Solly747 New
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    Got it all sorted, thanks very much.
    Now if I can just ask another question unrelated to this, would openbuild control work on my machine (any GRBL machine) or does it have to be specifically an openbuilds machine? Like I said, my cnc is basically an openbuilds sold by someone else.
     
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  5. Alex Chambers

    Alex Chambers Master
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    Openbuilds control is not my area of expertise, but I believe it will work. Your TB6600 drivers might prove disappointing. What stepper motors do you have? If your control electronics do turn out to be underwhelming have a look at the blackbox controller - best stepper drivers commonly available.
    Alex. :thumbsup:
     
  6. Christian James

    Christian James Journeyman
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    Why?
     
  7. Alex Chambers

    Alex Chambers Master
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    If you search for TB6600 on the forum you will find many posts from people who have found them disappointing. The drivers in the blackbox are definitely better.
    If @Solly747's set up works for him that's fine, if not there are alternatives.
    Alex.
     
  8. Solly747

    Solly747 New
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    @Alex I've been eyeing out the blackbox for a while now. I also believe the TB6600 or variants are unreliable. Many reports that they often miss steps etc. Only reason I have them is because they came with the complete kit. Gonna play around with it as is for a while before ordering the blackbox I think
     
    Alex Chambers likes this.
  9. Christian James

    Christian James Journeyman
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    There are many people out there who are very happy with the 6600 based drivers. There are also posts from people who are disappointed with the Black box. Which is best?. I don't know but we need to keep an open mind before suggesting that one is " definitely better" than the other There are thousands of CNC machines out there - you would need to poll all of them to find an answer.
     
  10. Solly747

    Solly747 New
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    I'm sorry @Christian James but I'm going to disagree (my opinion). If I hear multiple reports that a product is not reliable, I won't use it. It doesn't mean it's unreliable for everyone, but I'd still rather not risk it. I think of it like boeing with their max8 aircraft. Do you need to see more of them fall from the sky before making up your mind? Like I said, just my opinion!
     
  11. Christian James

    Christian James Journeyman
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    Yes, that's fair comment Solly747, but I can't see a company like Toshiba - one of the biggest companies in Japan, sending unreliable drivers to the market. A business can't survive doing that.
     
  12. Solly747

    Solly747 New
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    Yeah, well for now my 6600's are staying on my machine. Eventually I'm hoping to move to a different control system, but for now it's not bothering me as I'm still testing the machine's capabilities
     
  13. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    The chinese breakout PCBs with slow optocouplers, odd current reduction circuitry and a host of other things that go againt the Toshiba datasheet... That's the problem, not the chip.

    Unfortunately china doesnt market it as a unique name so TB6600=bad because almost all the breakouts are. There are exceptions, just know who you buy from.
     
  14. Christian James

    Christian James Journeyman
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    Yes Peter, and it did make me wonder if the Chinese are also making their own cloned 6600 chips?
     
  15. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Would not be surprised (;
     

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