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  1. #1
    Dear CNC PCB guys,

    Inspired by the ideas from Poul-Henning Kamp [Height probing for PCB isolation routing with Eagle/pcb-gcode], I have created software to probe the surface of a blank piece of copper, then use the probed coordinates to adjust the Z height during the milling process, i.e. the tool height varies according to its X, Y position. I have also filmed the first test and also produced 2 identical circuits; with and without the autoleveling software running to demonstrate the results. Currently, I have tested with linuxCNC (it may or may not work in Mach3 at the moment, but definitely will in the future) and the GCode was originally generated with pcb-gcode. The software itself accepts a GCode file as input and outputs an optimised autoleveleled file.

    I know there is an autoleveler for PCB-GCode already but I couldn't get it to work and my software should work on any gcode file produced from any isolation software and should be easy to use too.

    Why wouldn't the copper be level?

    1. Table might not be level relative to the tool
    2. Blank copper might have significant flex


    Why is this a problem?

    1. Some areas of your board are lower than your Z zero while other areas are higher, leading to deep cuts in some areas and shallow cuts in other areas
    2. Occasionally, a very small ammount of the tip will break off if there is a lot of pressure from a deep cut. Then your tool won't touch the surface at all and you will need to re-touch-off Z and re-run all or part of the code
    3. Bits and boards are wasted


    To demonstrate this problem, here is a pic of a non-autoleveled circuit board:

    Click image for larger version. 

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    There is a huge area in the bottom left which is completely missing. This is with a leveled table so only the board flex is an issue here.

    This is the exact same 100x80mm circuit with my autoleveling software in operation (same pcb-gcode settings, same method of fixing the board down etc.):

    Click image for larger version. 

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    As you can see, this is much more consistent. The traces are thin but thats due to the settings in pcb-gcode and Eagle, not the autoleveler.

    I also filmed the whole autoleveled milling process. Here is the cut down video:



    Where can I get the software? As soon as I make a website to stick it on I will add a link. Assuming there is interest in this project?

    Happy Milling :),
    Daedelus.

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  3. #2
    Looks good Daedelus. Would it be possible to use this type of software instead of skimming the table. Possibly modifying the PP to add/subtract from the G-code programmed Z values instead of shimming the bed? G.

  4. #3
    Hi Geoffrey, when you say skimming the table, I presume you mean milling out an area to make it flat? In the video, you can see I have already done just that (the MDF sacrificial layer has been pocketed 1mm) but it still was not good as the first pic shows. But yes, you wouldnt even need to skim / pocket the table using this software.

    In fact, the Z height is calculated using a bilinear interpolation technique which gives a good result. You could probably get a good result with much fewer probe points (depends on the board size and quality). I would need to experiment to find out.

    best,
    James.

  5. #4
    Thanks Daedelus. Yes, I was asking if an unlevel (not necessarily uneven) table could be probed once and that information used to modify the Post Processor and add/subtract Z values for all future programs, not just for each individual program. Hope that makes sense. G.

  6. #5
    Quote Originally Posted by GEOFFREY View Post
    Thanks Daedelus. Yes, I was asking if an unlevel (not necessarily uneven) table could be probed once and that information used to modify the Post Processor and add/subtract Z values for all future programs, not just for each individual program. Hope that makes sense. G.
    Thanks Geoffrey, thats an interesting idea. Sorry, when you said PP I thought you meant "probe points" rather than "post processor". The problem is, by default, any information stored in GCode variables is lost for new sessions. In linuxCNC you can log stuff so I guess you could read the log file back in each time before starting a new job but then the Z information would be useless whenever you changed tool bit. Worth thinking about though, thanks.

    James.

  7. #6
    James, the way that I work and most pcb machines is that the tool length is always constant due to setting a collar on the 1/8th shank using a preset press. G.

  8. I am looking forward to see a download link, so that I can see if this will work with Mach3.
    "If first you don't succeed, redefine success"

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  10. #8
    What a musical machine, if it was mine I'd be forever trying to make it play Jingle Bells

  11. #9
    Noisy isn't it. and slow.

  12. #10
    The Autoleveller software is now available at www.autoleveller.co.uk so please feel free to download and try it.

    There are many changes planned but any feedback or questions are very welcome, good or bad.

    Most of the instructions are on the page but if there is anything confusing, or anything not explained, please let me know either in the comments section at the bottom of the page or here.

    enjoy,

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