Thread: Tiddy CNC.

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  1. #81
    It's great when a problem is solved, say "hi" to Peppa Pig for me
    Last edited by EddyCurrent; 03-08-2014 at 09:46 PM.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  2. #82
    Oink! Oink!

  3. #83
    Some teething problems I think, seems to be Z axis...?

    I'm using Cambam but only really want to draw on the MDF bed of the machine at this stage. I've defined my stock as 5mm thick but the arcs lines etc are set to profile to only -1mm in the cambam dialogue. The G Code for the test is below, the machine homes just fine. when I Jog the machine I see Z- going in the direction of the bed. So I get a post-it and manually jog the Z until it bites the paper and then back it off say 0.650 mm and then set Z to 0 in mach. The theory being that the -1mm "cut depth" will push the biro into the mdf bed.

    However when the program runs the pen seems to move up not the 1mm down I want it to go. I did some googling and changed the Z motor direction in Mach and that didnt feel at all right, homing went backwards (expected really). So my question, should I have selected a + z move (cut depth) in Cambam or is there a clue in the G Code below that the machine is set up wrong? Advice as always welcome. Thanks.

    ( Made using CamBam - )
    ( CNC_Template 9/3/2014 10:17:13 PM )
    ( T6 : 6.0 )
    ( FROM/0,0,5 )
    ( Select dummy tool to avoid warnings )
    ( TOOL/MILL,1,0,20.0,0 )
    ( STOCK/BLOCK,500.0,500.0,5.0,0.0,0.0,5.0 )
    G21 G90 G91.1 G64 G40
    G0 Z3.0
    ( T6 : 6.0 )
    ( Tool Taper coming soon )
    ( TOOL/MILL,6.0,0.0,0.0,0 )
    T6 M6
    ( Profile1 )
    M3 S1000
    G0 X207.0 Y120.0
    G0 Z0.2
    G1 F300.0 Z0.0
    G2 F1500.0 X196.5 Y113.9378 Z-0.1667 I-7.0 J0.0
    G2 Y126.0622 Z-0.3333 I3.5 J6.0622
    G2 X207.0 Y120.0 Z-0.5 I3.5 J-6.0622
    G2 X196.5 Y113.9378 Z-0.6667 I-7.0 J0.0
    G2 Y126.0622 Z-0.8333 I3.5 J6.0622
    G2 X207.0 Y120.0 Z-1.0 I3.5 J-6.0622
    G2 X196.5 Y113.9378 I-7.0 J0.0
    G2 Y126.0622 I3.5 J6.0622
    G2 X207.0 Y120.0 I3.5 J-6.0622

  4. #84
    It is more common to set the home for Z at the top, that means all cuts will be -Z. So when you zero your Z at the bed a command to cut would be a -Z move.

    You can tell Mach to home in any direction. ..Clive

  5. #85
    Dont know if this will double post? Thats how its set up Clive. the code looks ok to me too I think, start of Z3 as a positioning move, moves down to Z0.2 still just above bed and then gets to Z-1.0 4th line up from the bottom. so why is the spindle not actually going down but going up?

  6. #86
    The Z as Clive said should be 0 at the Top and go down with negative sign.

    Do you recalculate the toolpath? When set working Z0 i mean.

    Ok Zero at the middle of the air. Then in the mdi window write Z-1 and hit enter. It should go down from there 1mm/ becarefull if in inch cause will go 1 inch down /
    Last edited by Boyan Silyavski; 03-09-2014 at 10:25 PM.

  7. #87
    Thanks chaps. I did the MDI -1 and it does come down 1 mm.
    Maybe I'll start again with cambam and see if that helps.

  8. #88
    Try it using the Mach3-CutViewer post processor as you are, then try it with just the Mach3 post processor, see if there's a difference.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  9. #89
    Thanks Eddy, I did change the post processor and reset Cambam to start from scratch. I think its the stock to cut relative to the Z that had me confused.

    I created two tests. For the first I created a simple shape in Cambam than had a depth of 5mm relative to 0 and marked the Z axis depth on a post-it note. I stopped the program when it was at depth and although I didnt measure it accurately I'm OK that it ran a clearance height plus Z and ended up around -5. The camera work on the first video is pretty awful, makes you realise that those who do youtube videos well put some work into it :) should be at

    For the second test I tried manually adjusting the Z and ran the program, It using a hacked Biro and the ink tube slips a little as well as bing not the smoothest line. I found that around 1.05 into the video the pen caught for a few secs, I think its down to replacing the cut down biro with a felt tip now. This video is still not great but has the virtue that I'm not really trying to do too many close-ups.

    For those on thier journey to making a machine, I can say it is very satifying when it starts to move and it does kind of sing a bit during arcs. More videos and stuff in a few weeks when I get another chance to play.
    Last edited by TonyD; 05-09-2014 at 12:52 AM.

  10. #90
    And for my next problem.. :)
    I'm getting comforatble jogging the machine around now, I'm about to use it to drill some holes through the MDF bed and into the Steel base structure prior to tapping the steel and using a Forstner bit on the MDF to counterbore it so I can firmly fix the bed prior to checking the gantry for good geometry, surfacing etc and.. I cant seem to get the VFD (& Spindle) running and have Mach communicate with the PLCM control board. Interesting enough I did have issues a few weeks ago where I would lose comms to the control cabinet whenever I closed the control box, which was most weird and I bypassed the problem by removing the USB chassis mount and just running the USB cable direct from the PC to the control board through a hole in the box. This all leads me to suspect earthing as a culrpit? Any ideas how I would trace the issue, sorry its a bit vauge, I can post pictures and update the electrical schematic if that would help. Any advice, as always, much appreciated. Thanks.

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