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  1. Thanks, lead ins and outs pretty much like the plasma then.

    Radius makes sense, already use the different rad rule on the Bridgeport as that can get a bit vocal when it wants to;)

    Will apply to this as well, I was going 5mm rough and 2mm finish which fits ok i think, don't really want to go below 2mm unless really needed, but there are some features that are 2mm on the job so can't use bigger.

    Been researching fluids and seems pretty much anything goes, even Methylated spirits, but paraffin and oil mix seems popular - pretty much WD40 without the waxy residue ;)

    New power supply arrived today, will test it out tonight ;)
    Last edited by Davek0974; 15-03-2016 at 03:50 PM.

  2. #12
    Quote Originally Posted by Davek0974 View Post
    Will apply to this as well, I was going 5mm rough and 2mm finish which fits ok i think, don't really want to go below 2mm unless really needed, but there are some features that are 2mm on the job so can't use bigger.
    Unless Rad is critical then it's worth changing rad in Cad just 0.1mm makes difference to small tools and in most cases doesn't make jot difference to part. When designing I nearly always make my none critical rad's 0.1mm over size for this reason because most tools I'm using are round numbers.

  3. Good point, thanks

  4. On the left side of my part in the OP, there are three slotted holes on the diagonal face.

    After roughing the outside with a 5mm tool, these will obviously not be cut, but with my plan to finish-pass the outside with the 2mm tool in one pass, this will mean the 2mm tool taking the full depth cut on these features.

    Calculator shows speed for finish pass as 996mm/min as it's only taking 0.1mm off but here it shows speed as 380mm/min as full depth slotting cut.

    Options -
    run all outside at the slower rate,
    run outside as multiple pass contouring at the higher rate,
    try and get jiggy with path rules / action points in sheet-cam to slow down in that area,
    something else??
    Last edited by Davek0974; 16-03-2016 at 08:49 AM.

  5. #15
    Ger21's Avatar
    Lives in Detroit, United States. Last Activity: 6 Hours Ago Has been a member for 4-5 years. Has a total post count of 390. Received thanks 51 times, giving thanks to others 0 times. Referred 1 members to the community.
    Rough cut the 3 slots in multiple passes before making your full depth perimeter cut.
    Gerry
    ______________________________________________
    UCCNC 2017 Screenset

    Mach3 2010 Screenset

    JointCAM - CAM for Woodworking Joints

  6. But how to just rough the 3 slots?

    They are 2mm wide with a 3mm loop at the base, I was going to go in with the 2mm finish tool.

    Is it as simple as defining a second pre-finish pass with the 2mm tool but still leaving the same allowance after?
    But then that would not fit into the slot as its 2mm tool in a 2mm slot + 2 x 0.1mm allowance.

    Or are we saying go down to smaller tool?

  7. #17
    Hi Dave,

    If Sheetcam can do isolated lines as paths then ignore the next bit -
    I done something like this before and due to the limit Cut2D features I had to copy the dxf outline of the complete shape into a new CAM file, then used line creation and node editting tools to create a local closed off feature just in that area. Then deleted all the rest of the profile. So you end up with an enclosed local shape using the existing slot/loop features, plus some lines around the outside to make it enclosed. These extra lines are drawn in the scrap area outside the part. You can then select this little profile and do an inside roughing or finish pass to save running round the outside of the whole shape each time.


    As the slot is 2mm wide, and using <2mm cutter could be risky, it sounds like you will have to go straight to the finish pass. You could cnc spot drill the centre of the 3mm holes in the loop, then pistol drill dia 1.5mm freehand (as material is thin you should stay inside the hole boundary!) to relieve some of the cutting.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  8. #18
    Ger21's Avatar
    Lives in Detroit, United States. Last Activity: 6 Hours Ago Has been a member for 4-5 years. Has a total post count of 390. Received thanks 51 times, giving thanks to others 0 times. Referred 1 members to the community.
    I've never used SheetCAM, so can't help you there.

    What I'd do is draw duplicate geometry for the slots, and put them on a separate layer. Then just cut them by themselves first.
    Your perimeter cut can then either go into the previously cut slots, or go right past them (if you edit the geometry).
    Note that some CAM programs won't let you cut a 2mm slot like that with a 2mm cutter. You may need to enlarge it to 2.01mm
    AN alternative is to draw a straight line down the center, and cut a "rough" slot on the line.

    Hope this makes sense.
    Gerry
    ______________________________________________
    UCCNC 2017 Screenset

    Mach3 2010 Screenset

    JointCAM - CAM for Woodworking Joints

  9. I'm glad i titled this part as fairly advanced ;)

    Sheet cam can't isolate parts of paths, only complete entities.

    I have taken all the 3mm holes off the job now and will use a steel drilling jig to drill them as a second op, five of them must match up with another part that is drilled and tapped edge-on a strip of 5mm alu so this part must be jig-drilled and to make sure holes match both parts get jig drilled.

    That also speeds up the time on the mill.

    It seems i have 3 options now,

    1 - remove the loops at the ends of the slots and jig-drill after, cutting just a straight slot

    2 - as suggested, create a duplicate part of just that area and cut between roughing and finish passes.

    3 - Create a new layer and put three straight slots and smaller loops on the ends on it and cut that between rough and finish passes, allowing the finish pass to take the loops to final size.

    I think I would try opt 3 as a first go, seems to make most sense to me - 3 short slots opposed to a larger path.

  10. #20
    Several ways to do this and my way would be just like gerry's with operation just on that area before doing the final finish pass. Cam software makes how easy or hard this is to do but if you Cam program that is restrictive then it's easy enough to draw in geometry soley for the purpose of Caming the part.

    Like said before it's just knowing the Cam software and thinking a little differently to how Cam program might want to do it.
    Last edited by JAZZCNC; 16-03-2016 at 02:40 PM.

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