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Thread: XYZ Probe modification

  1. #13
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    Very informative write up Ernie! Quite impressive and simple solution with most of the hard stuff worked out.

    I can see where the cross hair would suit close enough. Cutting a corner step locator into the bottom of the acrylic could work well to locate directly on a corner of the material. As long as at least one egde of the material were indicated in, should serve as a decent double edge finder in a one shot operation? Presuming the tube diameter is good and perpendicular to the base.


    My thoughts were a banana connector on each piece to swap out devices as desired. Lots of options there I suppose.

    Thanks for posting it.

    DC

    Learn cause and effect through experience. Mastering those relationships is the "Common Sense" ability within the art of any trade.


  2. #14
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    yea- this is just the starting point. You can make a plexiglass piece with an edge cut in the bottom, another with a corner cut in the bottom and yet another with a hole in the center that you plug various sized rods into for centering over holes.

    You can also imbed a pipe in your fixtures for automatically setting up your machine coordinates for the fixture. Or, you can imbed a pipe somewhere in your table and use it instead of homing switches to set up your table reference coordinates.

    I'm sure sure there are many other ways it can be used. Feel free to post your ideas and pictures of your plates.

    I cut my copper pipe on the lathe so it would be square. If the pipe is tipped over in the plexiglass you will not get accurate centering. You may also need to chuck up a round rod instead of using your bit to get good accuracy. Depending on the design of the flutes on your bit, you may not get an accurate center because of how they touch the inside of the pipe.

    -Ernie



  3. #15

    New Edgefinder Block

    I started to think about the possiblities of this probe idea for my K2CNC router and I came up with this idea (see pics.) You can probe in X, Y and Z all at the same time.

    Attached Thumbnails Attached Thumbnails -edgefinder-block-1-jpg   -edgefinder-block-2-jpg  


  4. #16
    Moderator ynneb's Avatar
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    A very worthwhile and concise thread.
    Keep up the great work, and thanks for taking the time to share the details with us.

    Regards Benny

    Being outside the square !!!


  5. #17
    Gold Member Mr.Chips's Avatar
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    Question

    Ernie,

    I'm new to custom screens and Mach 3 as well and have a question about it.

    In the link by the Aussie he listed the Gcode that drove the CNC to do the moving to determine the desired point.

    Does your modified blue screen already have gcode embedded to do the centering and Z axis finding?

    What kind of language is the screen written in? I seem to recall while I was downloading the Blue Screen a screen customizing utility. I didn't want to touch it, it might be too dangerious to me now, until I get more familiar with Mach3.

    Hager



  6. #18
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    Mr. Chips-

    I originally put this cook book up on Joe's 4 x 4 forum but I went into the gory details of using the various Mach screen editors and VBScript. I quickly decided it was much better to just post the already modified MachBlue.set file with the buttons and scripts already installed.

    I tried using several of the Mach screen editors and they all have various problems. I had the most success using the Mach3Screen version 2.7e with the MachBlue interface, but it crashes fairly often and you have to be very careful of where you click. It's like walking through a mine field. The programming environment is not very friendly. When you make a syntax error in your script it will not run and you get no feed back on what is wrong. You basically have to start out with 1 or 2 lines of known working code and gradually add on a line at a time. If the program stops working you back up to the last line you added and try to figure out what you did wrong. Kind of frustrating and definitely not the place for a beginning programmer to cut his teeth. And then the editor will crash and you have to start all over again.

    I had a hard time sorting this stuff out. The Mach community seems to be going off in many directions at once- Flash, html, Visual Basic, etc. and the documentation and tutorial threads are all mixed up. There doesn't seem to be a very clear sense of direction and the basic underpinnings of the user interface technology have obviously been added on to one too many times. It looks like it is a prime candidate for major house cleaning and a rewrite. Still it's pretty amazing what you can do if you have a lot of patience.

    If this hasn't scared you off, there is a nice Wiki with info on how to program - http://www.machsupport.com/MachCusto...itle=Main_Page and you can download the various screen editors from the "Screen Designer" section of this page: http://www.artsoftcontrols.com/artso.../downloads.htm

    The basic idea is that the Mach user interface is built from one or more background .jpg pictures that are overlayed with buttons, Led's, DRO's, labels and other specialized panels. All the overlay information is kept in a .set file. For instance the default screens you see when you first install Mach3 come from 1024.set. The MachBlue screen comes from MachBlue.set. The screen editors allow you to modify the .set files to add buttons, DRO's, Led's, labels and other specialized panels.

    A button can activate a canned Mach function, execute a G-Code program or execute a Visual Basic script. The Visual Basic scripting language has access to most of Mach's internal state variables and can read and modify them. VBScript can also execute G-Code instructions from within the script. Pretty powerful stuff.


    You can open up the .set files with the screen editor and then double click on any of the buttons and see how they are set up. The programming code is all there for you to read and modify. Make sure you make back up copies of the .set file before you make any modifications.... Here is the VBScript I put in the centering button:

    Rem VBScript to center probe inside a pipe

    If GetOemLed (825) <> 0 Then 'Check to see if the probe is already grounded or faulty
    Code "(Probe plate is grounded, check connection and try again)"
    Else
    FeedCurrent = GetOemDRO(818) 'Get the current settings
    XCurrent = GetDro(0)
    YCurrent = GetDro(1)

    Code "G4 P1" 'Pause 1 second to give time to position probe plate
    Code "F4" 'slow feed rate to 4 ipm

    Rem Probe left

    XNew = Xcurrent - 3 'probe 3 inches to left
    Code "G31 X" &XNew
    While IsMoving() 'wait for the move to finish
    Wend
    XPos1 = GetVar(2000) 'get the probe touch location

    Code "G0 X" &XCurrent 'rapid move back to start point
    Rem Probe right

    XNew = XCurrent + 3 'probe 3 inches to right
    Code "G31 X" &XNew
    While IsMoving()
    Wend
    XPos2 = GetVar(2000)

    XCenter = (XPos1 + XPos2) / 2 'center is midway between XPos1 and XPos2
    Code "G0 X" &XCenter 'rapid move to the x center location
    Rem Probe up

    YNew = YCurrent + 3
    Code "G31 Y" &YNew
    While IsMoving()
    Wend
    YPos1 = GetVar(2001)

    Code "G0 Y" &YCurrent
    Rem Probe down

    YNew = YCurrent - 3
    Code "G31 Y" &YNew
    While IsMoving()
    Wend
    YPos2 = GetVar(2001)

    YCenter = (YPos1 + YPos2) / 2
    Rem move to the center

    Code "G0 Y" &YCenter
    While IsMoving ()
    Wend

    Code "F" &FeedCurrent 'restore starting feed rate
    End If

    Attached Thumbnails Attached Thumbnails -centerbutton-jpg  
    Last edited by erniebro; 04-10-2008 at 03:27 AM.


  7. #19
    Gold Member Mr.Chips's Avatar
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    Smile

    You'r very right, this is not the place for me to start working. At least not now.

    I see the code in embedded in the screen itself. That was one of the things that was confusing me about the Aussy thread, I saw the gcode but didn't understand how it fit. I need to go back now and reread his thread.

    I think I now see why you didn't specify a pipe dia, 3/4" or 1 1/4" would be just fine as it will move up to 3' looking for the side, find the other then divide by 2 to get the center. And because it is round it doesn't matter if the probe is started off center as the center is always the same.

    But then you need to know (in code) the diameter and thickness of the wall of the pipe to rise up and move to the center of the edge and then down to set the Z. Don't think the Z code is in this. That's OK though.

    Thanks for taking the time to explain this, I'm sure others will also appreciate and be stimulated to tackle one.



  8. #20
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    That's why I split out the z depth code from the centering code. I knew people would be using different size pipes and bits. I didn't want to explain how to modify the the button and I didn't want to clutter up the user interface with a bunch of offset fields you had to fill in. This solution is insensitive to fixture and bit dimensions.

    By the way, the probe moves only 3 inches, not 3 feet.

    -Ernie



  9. #21
    Registered Mike F's Avatar
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    Hi,

    Any one know what has happened to the videos? I get a message saying they are no longer available.

    Great thread though - excellent work.

    Mike



  10. #22
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    Very nice thread erniebro!!!!
    I have had a similar idea for a while. I'd like to have a cylinder either mounted permanatly to my table or eaisly relocated to exact same position (dowel pins) for tool diam. and length setting. It would be very much the same as yours. It would add the functions of doing the math to find tool diam. and length and set those in your tool library for current tool number. I think it would need an airblast to clean all chips off just before probeing as well.

    You may also need to chuck up a round rod instead of using your bit to get good accuracy. Depending on the design of the flutes on your bit, you may not get an accurate center because of how they touch the inside of the pipe.
    You may be able to get around this by running your spindle in reverse direction of tool at a very low speed.

    eibbor



  11. #23
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    eibbor-

    If you know the ID of the pipe you can get the tool diameter. In the code above, just insert a line after

    YCenter = (YPos1 + YPos2) / 2
    ToolDiameter = PipeID - YPos2 + YPos1 'change PipeID to your value

    I thought about rotating the spindle while doing the centering, but I didn't want my hand anywhere near a moving cutting tool! Plus, the probe circuit actuates very quickly and I'm not sure there is any guarantee that it would detect the the proper edge of your bit even if it was spinning. I guess it would depend on how fast you jogged in, the rotation speed of the bit and the amount of "debounce" in the probe circuit.

    -Ernie



  12. #24
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    eibbor-

    It would be cool if you can get that to work. You could measure tool wear and automatically compensate on the next use of the tool. Great idea!

    -Ernie



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