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  1. #21
    I sometimes use 6mm 2 flute carbide tools with a 45 degree helix, but they are a little more expensive.

    The more standard 30 degree helix also works but the 45 degree angle is supposed to be more tailored to aluminium cutting.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  2. #22
    Quote Originally Posted by Davek0974 View Post
    So i have a g-code file from SheetCam and it was programmed for say a 6mm roughing cut leaving an allowance for finish, do i need to make a second file for the finish cut or do you use the same cutter but just program a final cut for the finish pass??
    Just one file for both operations.
    If corner radius are larger than the roughing cutter and the flutes edges are good enough for finish then use same tool. If not then just use smaller tool for the finish so it can clear the corners, always use a tool just little smaller than the corner radius. But in both cases it can all be done in one file.

    Quote Originally Posted by Davek0974 View Post
    One job i have in mind has some 3mm holes in it, i would be looking at ramping in with a 2 or 2.5mm tool for them and then do the outside profile with a larger tool maybe - I am lacking knowledge of how you change tool and get back to exactly the right place OR do you use the tool dia offsets in Mach3
    With circler pockets or holes Spiral rather than ramp if possible.
    When you change tools the G-code file just stops tells you to change the tool and waits for you. You then can jog the machine to easy position to change the tool. After changing the tool you reset the new Z height by touching off the material again and setting zero. Then just press cycle start and the cutting continues.
    The Cam software will have taken care of tool offsets when created the g-code.
    Last edited by JAZZCNC; 19-02-2016 at 09:54 PM.

  3. Great so I can pretty much ignore the tool offsets in Mach as it's all done in cam - program roughing cut on tool 1, program tool change, program finish cut on tool 2. Mach3 runs the roughing cut, stops and requests a tool change, I change tool and re-zero Z, press go and drink coffee ?

    Now it makes sense, gets confusing when you have tool charts etc in Mach, I presume they are meant for g-code where the tool offset is not pre-programmed in cam?

    Yes i meant spiral cut not ramp.

    Thanks BTW
    Last edited by Davek0974; 19-02-2016 at 09:59 PM.

  4. #24
    Quote Originally Posted by Davek0974 View Post
    I presume they are meant for g-code where the tool offset is not pre-programmed in cam?
    No tool offsets are for machines that have spindles with tool holders that can be changed. In this case you measure the tool length offset which is the distance from the tool tip to the surface on the holder that contacts the spindle nose. You also have the option to enter diameter for when doing tool compensation. Say for wear or under size tools.

    On manual tool change spindle without repeatable holders, like ER collet system on most routers then it's not used and just leave empty. It's actually important that you don't have any values in these because if the Cam calls for G43H which is tool length compensation and theres value in that tools offset it will be applied to the tool length and change the Z height.

    To see this happen do a test. Set tool #1 in tool offsets to height of 10mm and save. Then zero out the Z for tool #0 which will be the default tool when first starting mach and all offsets are referenced from.

    Now using MDI type g43 H1 T1 (space between them) and you'll see the Z dro change to -10. G43 applied the tool length offset and now mach thinks the tool is at different height.! . . . Very dangerous when not being used correctly.

    Don't forget to go back and set tool #1 to zero.!!
    Last edited by JAZZCNC; 19-02-2016 at 10:57 PM.

  5. Great, thanks for that, its all starting to make sense now, surprising differences between plasma cutting and milling.


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