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Thread: Z-Zero

  1. #1
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    Z-Zero

    One of the recent updates I did to my CNC is automated zero of the Z axis. It's a fairly simple process and I finally took time to get it done.

    I planned to use a cutout from a PC board blank as the conducting part and place it in a 1/2" piece of wood. The hole at the peak of the piece is for hanging the assembly on the wall. The small hole in the pocket is for a wire that is soldered to the bottom of the PC board.

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    To operate the function, one lead is connected to pin A5 of the Arduino; the other to ground. In my case, the alligator clip goes to ground and the red wire to pin A5. A series of commands is then sent to the system to lower the bit to the plate. As soon as it touches, it stops and the position is stored in the system. I added a command to raise the bit 1/4" above the plate for clearance.

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    I use UGS for most of my projects, so I set up a macro to send the commands to zero the Z-axis.

    Here's a short video of it doing its thing:

    https://www.dropbox.com/s/7vy0brmq6s...ero_a.wmv?dl=0
    Bill Arnold
    Citizen of Texas residing in Georgia.
    NRA Life Member and Member of Mensa
    My Weather Underground station

  2. #2
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    Oh wow, very cool Bill. That's one project I need to do myself, been holding off until I rebuild my controller cabinet.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  3. #3
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    You are ahead of me.

    The osprey has the touch probe but is doesn't work right.

    I need to look at the macro routine.

    One of the things on my list.

  4. #4
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    Speaking of the macro, here's the one that makes this work in grbl:

    G20 G38.2 Z-.5 F2; G92 Z.5; G91; G0 Z0.25; G90

    Breaking it down:

    G20 = set system to inches

    G38.2 Z-.5 F2; = move Z down to Z-0.5 at 2ipm until it touches the plate (it never reaches -0.5, of course)

    G92 Z.5; = set the coordinate offset to 0.5", the thickness of the plate

    G91; G0 Z0.25; = set to relative mode and raise Z by 0.25" for clearance

    G90 = set system back to absolute mode
    Bill Arnold
    Citizen of Texas residing in Georgia.
    NRA Life Member and Member of Mensa
    My Weather Underground station

  5. #5
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    Quote Originally Posted by Bill Arnold View Post
    G92 Z.5; = set the coordinate offset to 0.5", the thickness of the plate
    Answered my only question right there

    Looks like a really nice feature to have.

  6. #6
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    I will need to look at the code in Mach3. Might be a little different.

    I will want at least two touches.

    Most of the machines touch 2-3 times. First at a little faster feedrate, then back off then touch again at a slower feedrate.

    Even in manual touch off, I like to hit the probe 2-3 times.

    I do like the coding, and I will set it up, but I need to work through my list.

  7. #7
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    Quote Originally Posted by Ryan Mooney View Post
    Answered my only question right there

    Looks like a really nice feature to have.
    It's a heck of a lot nicer than manually adjusting to a piece of paper!

    I've already seen an improvement in accuracy when doing light cuts like etching text.
    Bill Arnold
    Citizen of Texas residing in Georgia.
    NRA Life Member and Member of Mensa
    My Weather Underground station

  8. #8
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    I don't use a piece of paper anymore. I just turn the spindle with my fingers as I lower the "Z", until I feel the cutter touching the wood. Been doing that for about 3-4 years. I get it within a thou or 2 and it is really fast. Still the auto will be a good to have.

  9. #9
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    I've been doing the z-zero for a little while now on mine, Kind of had to when I was doing shallow engraving on aluminum when I was fooling around making 'coins'.

    I've fallen down a rabbet hole now and I want to set mine up to do X, Y, and Z probing to set the zero. So I created a jig for making my coins.

    Basically, it's piece of aluminum angle fixed into the tempate board that I will use to probe the x and z dimensions to set the center of the workpiece exactly everytime.

    The deeper rabbet hole I'm diving into is creating a 'widget' for Chilipeppr that will automate the probing of the x and y dimensions. It already has a real nice one for doing Z, but I need more.

    I've done some testing and the G38.2 command works just as well with the X and Y dimensions. Too bad I got started programming this widget before I finished testing out the other stuff. LOL.


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    If you haven't given Chilipeppr a shot, I'd highly recommend taking a look at it. It's been working really well for me.
    Last edited by Brent Dowell; 01-12-2016 at 02:24 AM.
    Programmer - An organism that turns coffee into software.
    If all your friends are exactly like you, What an un-interesting life it must be.
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  10. #10
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    Quote Originally Posted by Brent Dowell View Post
    I've been doing the z-zero for a little while now on mine, Kind of had to when I was doing shallow engraving on aluminum when I was fooling around making 'coins'.

    I've fallen down a rabbet hole now and I want to set mine up to do X, Y, and Z probing to set the zero. So I created a jig for making my coins.

    Basically, it's piece of aluminum angle fixed into the tempate board that I will use to probe the x and z dimensions to set the center of the workpiece exactly everytime. ...

    If you haven't given Chilipeppr a shot, I'd highly recommend taking a look at it. It's been working really well for me.
    I use the center of the project as X0, Y0 so I've been manually moving the router to that point. I can see where a jig would help that process also. I'll have to work on that - maybe leave the inside angle open so I can sit it over my center mark, run X and Y, then move it to run Z.

    I tried Chilipeppr a while back but had an issue I have since forgotten - senior moments! I'll give it another shot.
    Bill Arnold
    Citizen of Texas residing in Georgia.
    NRA Life Member and Member of Mensa
    My Weather Underground station

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