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  1. #21
    Its my brain thats limited i think ;)

    Messing with various ideas now, as you said, thinking differently to get the job done that matters.

  2. #22
    Thanks guys, it seems the best way is indeed to duplicate that small area onto a new layer, convert it into a complete entity and cut as a separate process before the finish pass.

    I tried a few other options and none seemed to work correctly due to the odd shape of the slots but I think this method will do it.

    Certainly getting some practice at the CAD and CAM stages anyway ;)

  3. #23
    Seems to work in simulation, all the steps now make sense and total time in Mach3 was about 6m plus a tool change, not bad I think. :)

    How do you figure plunge rate? Same as cut, half as much etc??

    Its fascinating seeing the difference in manual machining and CNC, a real eye opener and I haven't even got to cutting a part yet;)

    I settled on 0.6mm DOC for the 2mm tool when pocketing the fine parts and 2mm DOC on the 5mm tool for hogging out the holes and roughing outside, then the final pass on the 2mm tool at 4.9mm DOC.

    I have high-helix carbide tools listed as suitable for aluminium etc.

    Hopefully good to go as soon as she's finished :)

  4. #24
    Quote Originally Posted by Davek0974 View Post
    How do you figure plunge rate? Same as cut, half as much etc??
    Think you know this already but if at all possible then don't plunge ramp or spiral into material. In Both cases you want to enter quickly possible to stop heat building up in tool so use same feedrate. If you must plunge then 50% feed.



    Quote Originally Posted by Davek0974 View Post
    I settled on 0.6mm DOC for the 2mm tool when pocketing the fine parts and 2mm DOC on the 5mm tool for hogging out the holes and roughing outside, then the final pass on the 2mm tool at 4.9mm DOC.
    When doing the pockets I'd spiral down full depth 5mm and cut full depth with 40% step over. Why waste the flute length.?

  5. #25
    Thanks Jazz, all noted.


    Dave

  6. #26
    Manual tool change...

    I have set sheetcam to park the tool at Y0, X150 which brings it nicely to the front and centre.

    Mach3 seems to lock the axes when tool-changing so how to handle the Z axis ?

    When parked the Z is at my rapid height of 20mm above the material, but it looks like the park commands are in work coordinates not machine coordinates so telling the Z to go to say 100 would not work if i have less than 100 spare (thick workpiece etc) If it was in machine coords, i could tell it to go to Z0 but there is no G53 in there.

    Whats a good way to get the tool to go to machine Z0 for manual changing ?

    :)
    Last edited by Davek0974; 17-03-2016 at 10:41 AM.

  7. #27
    Sorted :)

    Use Job Options -> ToolChange -> "run code before tool change" box and enter

    G53 G1 Z0 F1500

    or

    G53 G0 Z0

    Works perfectly
    Last edited by Davek0974; 17-03-2016 at 12:13 PM.

  8. #28
    Question...

    Truing the bed surface.

    In the wood forum it seems common to run a facing cut over the whole spoil-board to ensure the face is true to the tool, but what goes on when you have an aluminium bed plate??

    Try and face it true, assuming you can traverse the whole plate ?

    Try and shim the bed true using measuring equipment - DTI's etc.?

    Something else?

  9. #29
    Dave you do realise you can jog machine to any where on the table between tool changes. You don't have to have the G-code do it.?

    Regards the Bed then shim it tooling plate. Thou I think you'll find you may end up using a spoil board more than you think. For anything other than precision jobs that must have perfectly flat surface it's much easier to screw or stick material down into something like MDF or Ply. Clamps are ok but they don't always suit the job so what do you do then when can't clamp or find hole in Matrix of holes.?

  10. #30
    Thanks Jazz,

    I did not realise as I am doing most of my debugging and research on my laptop which has no motion output etc - just a laptop and Mach3 etc. I tried 'jogging' when in tool change but it did not move so assumed it was fixed for some reason, probably just did not move as it has no motion attached. :)

    I will find out this weekend what my parallel is like, I would never guess it would be perfect though, so shims is the way I would choose too.

    On the bridgeport i've used many odd ways including cutting a pocket into scrap aluminium, bits of plastic, wood, basically anything goes that will hold it down. Most of what I'm planning will be 5mm Alu sheet or thinner so pretty easy to mount, DS tape would likely work if i degrease the faces.

    Just trying to amass as much info as i can before I go throwing metal and cutters at it :)

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