1. #1
    Hi all,
    I have just partially run a 3D finishing tool path on a job in aluminium and due to some oddities have stopped it in case I am 0.2mm from catastrophe ;-)
    I have roughed out the shape fine using a 6mm end mill (single flute carbide) and left 0.2mm allowance for finishing.
    The toolpath I am half way through is a finishing pass in the X followed by a finishing path in the Y. I'm using a 4mm carbide ballnose (24000RPM and about 800mm/min - probably should be faster but I went for the least aggressive setting in Wizard).
    The reason I have stopped the job is at some points during the cut the toolpath essentially plunges into the material where there is a vertical surface aligned to the major direction of travel i.e. aligned to X and then tries to "profile" along that edge with much shrieking involved. So far the verticals have been fairly shallow e.g. 2mm or so, but I'm approaching a full depth edge which is at 16mm deep and I have a concern that unless Cut3D has vertical detection and some kind of compensation its going to "fall over that cliff" and try and profile 16mm deep and 0.2mm wide. This would obviously be bad, as for a start the flutes on the cutter are not that long and I doubt the tool could handle the forces.
    So the question is does Cut3D have vertical edge detect and compensation i.e. run into that area at whatever the tool depth setting is and use multiple passes rather than trying to take it all at once?
    I'll also post on the Vectric forum, but asked here as my spiritual home for all things CNC :-)
    PS. I'm going to try profiling the shape using a cut out path to take the material off of that area for safety, but asked in case I am worrying unnecessarily.

  2. #2
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 3 Hours Ago Has been a member for 3-4 years. Has a total post count of 591. Received thanks 79 times, giving thanks to others 5 times.
    I had a similar problem with cut3d, although I was working in wood. I worked round it by modifying the shape slightly so I had a slope just off vertical, although I was lucky that that suited the piece I was cutting. I would be interested to hear if there are any better fixes - I spent a lot of time modifying the stl model as the vertical face was curved in plan view and the original model came from a 3D scan and a very irregular mesh.

  3. #3
    Hi washout you should be able to see what cut3d is going to do when you run the program by previewing the toolpath ether in cut3d or mach3.
    CNC routing and prototyping services www.cncscotland.co.uk


  4. #4
    Thanks for coming back guys,
    I've just had a look at the finishing toolpath up close and I think I was right to stop the job, as Neale has confirmed.
    What I have done is import the Cut3D file into Cut2D and then select the "model" and run a more moderate profile using a 6mm End Mill. That has removed the 0.2mm allowance from the roughing pass on the vertical surface around the edge. So I think I can run the finishing pass now without the material being there, but still get all the nice curves on the shape I had originally intended.
    Or at least that's the theory and what the simulation is showing.
    If that doesn't work I picked up a trial copy of Deskproto last night, which I think does have a compensation function for vertical surfaces, as well as other strategies to try.

  5. #5
    i get round this problem in cut3d by using a ball end cutter instead of a ball nose cutter

    Click image for larger version. 

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    hope this helps

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