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  1. #1
    Using an eMach EM900 machine with the pendant controller

    Can anyone improve the route below ?

    I'm trying to remember how to set-up the work and axis before starting cutting, watched a few U Tube clips and have decided on the route I have written...

    In VCarve (Or your program for designing etc) set machining datum to TOP of workpeice for eachmaterial at material CENTRE for X & Y for all work designs

    Insert pointer rod into tool collet to use as alignment tool for workpieceedges along X axis, mark workpiece centre using lines across from corners with a pencil.
    Align workpiece edge along X axis using pointer and handsetrapid along workpiece edge and move work to align with x Axis before clampingetc
    Clamp, stick, or whatever the workpiece to wherever requiredon table/platen
    Using handset find drawn centre marker, jog to exactly the centreof the X marked on job eyeing up the cross lines.
    Remove pointer after zeroing WORKPIECE axis X & Y todatum centre drawn lines in your pendant or software
    Fit required cutting tool for the job into collet ready for Z Axissetting
    Using handset set tool to “Touch Off” at job top face. Justkissing the top face
    Zero Z axis using pendant or your software. Axis setting is now complete.
    Ensure workpiece is fixed ready for use.
    Reduce feed rate, start machine after loading required G code/Design and watch for issues, increase rate whensatisfied all is Ok.
    If you can't fix it with a hammer you've got an electrical problem !

  2. #2
    That's fine for jobs that work about a centre line e.g. guitars, but I would think most jobs are referenced to the bottom left corner, the X0,Y0 corner
    If you are doing repeat work you might want to think about 'fixtures' using G55 - G59 coordinate systems.
    Last edited by EddyCurrent; 28-08-2014 at 02:08 PM.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  3. #3
    There's not right or wrong way or better or worse it's all down to preference.

    My setup is mostly done from lower left corner but in the case of a circle I may use the centre it all depends on the job and material it's coming out of. Often i'm cutting parts out of existing sheets and with a circle working from centre is easier regards waste and fitting into available space etc.

    If your mostly using square sheet material then I'd setup reference bump stops or edges along each axis so can work from same X0 Y0 WORK coordinate and cut this process out. Only needing to set the Z ZERO. (if using same thickness material won't even need to do that.!)
    You should be able to set the G54 WORK OFFSET in the control. G54 is often the default OFFSET and will be the last place you set the WORK ZERO if the OFFSET was saved before closing down the control. So you can predefine a spot on the table and save as G54 default which will always be the same unless explicitly changed by you or G-code.
    On first startup you should always HOME the machine first before doing anything. Then after this the Control nows the OFFSET's and because G54 is the default then it will be set to the spot on the table you designated ZERO for G54. Which is be the corner of the material when against the bump stops.

    Even if you change the G54 OFFSET in g-code while working so long as you don't save the WORK OFFSET when finishing cutting session the machine will start backup at the spot you selected after homing.

    One thing I will mention with smaller jobs is not to work on the table in one spot all time but to move the smaller stuff around the table to lower wear on the ballscrews in one area.

  4. #4
    Thanks Jazz for the advice.

    I set a 19mm sacrificial board on the machine today and on top of that I set a small 200 x 120 x 13mm thick piece of ply

    After setting the machine to "HOME, I then, using my procedure above, brought the arm axis's to the centre of my workpeice. Positioned the cutter to the correct marked centre and zero'd X & Y.

    Then I brought the head down and jogged until the cutter (A 3mm dia single flute end mill) just touched the surface and zero'd Z

    In my V Carve software I set the XY to centre of the work, and the height of the material as 13mm. Reference start for Z axis was top of workpiece at centre.

    When I started the machine and set it all in motion the X & Y axis travelled to the exact set point in the middle of my piece as expected, but the Z rapid plunged into that point to the collet nut depth ! (Until I hit the E Stop button)

    What did I do wrong? I'm missing something here and feel a little dumb.... Newbie cock up I know... Loooong time since I did this and it's a fun learning curve again
    If you can't fix it with a hammer you've got an electrical problem !

  5. #5
    By default V carve sets the material z position to the bottom of the job. Did you change it to the top?
    Also did you have the "model in material" set to "gap above model". .. Clive
    Last edited by Clive S; 29-08-2014 at 06:08 PM.

  6. #6
    Quote Originally Posted by Clive S View Post
    By default V carve sets the material z position to the bottom of the job. Did you change it to the top? Clive

    Hi Clive, yes I did change it to the top. The diagram shows as you say the default at the bottom of the workpiece, (Which I also tried) but irrespective of how I set it the Z axis is wrong... I'm wondering now if I am sending the wrong G code to the machine.
    The PP asks for a file with extension .nc
    So I use the first available .nc choice as my machine is not listed.
    Perhaps I'm doing that wrong ?
    If you can't fix it with a hammer you've got an electrical problem !

  7. #7
    Well if you want to be sure have a look at the gcode it produced you can open the file by renaming it to .txt ..Clive

  8. The Following User Says Thank You to Clive S For This Useful Post:

  9. #8
    Thanks Clive, I may try that and post the results here. I'm fairly new to G code, as when I were t'prentice the programming and such was done by the clever office bods :-)

    How would I detect if the code is wrong please?
    If you can't fix it with a hammer you've got an electrical problem !

  10. #9
    If you post the top 20 line of code it should be easy to see. you just look for the g1 z!!! parts. Did you re read my edited post lower down for the position of the model in material. ..Clive

  11. The Following User Says Thank You to Clive S For This Useful Post:

  12. #10
    I'll got to my machine tomorrow and get the file. I'm not sure what you mean about the position of the model in the material though. Sorry if this seems a bit dumb, but I did think I could remember more ... Maybe not
    If you can't fix it with a hammer you've got an electrical problem !

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