Cutting occurs outside region curve


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    Default Cutting occurs outside region curve

    I have a circular region curve and so expect not to see cutting outside of it. But I do. Is there an explanation?

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    Default Re: Cutting occurs outside region curve

    Some cutters stay inside the region curves and some don't.



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    Default Re: Cutting occurs outside region curve

    OK then. I'll try to work around the flakiness of remachining and region curves.



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    Default Re: Cutting occurs outside region curve

    Other inexplicable phenomena (in addition to the frequent ineffectiveness of region curves):
    1. Excessive number of radius leads on what should be continuous cuts. Changing cut-link distance does not fully address this. In addition, if cut-link distance is greater than the tool diameter, isn't there a risk of a collision with uncut material?
    2. In the re-machining dialog, why does the previous cutter radius default to half the cutter diameter if the previous cutter is a flat end mill?
    3. Re-machining doesn't work correctly if the previous cutter radius is set to 0 which is what I would expect it to be for a flat end mill.
    4. If previous cutter radius and overlap are set to 0, re-machining does not occur in places that it should.
    5. Toolpath recalculation does not remember all parameters of the toolpath that it is recalculating.



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    Default Re: Cutting occurs outside region curve

    If it's a boundary curve without island curves, it should stay inside the curve. It can be problems sometimes depending on the quality of the curve. It can help if using the curve rebuild function in Rhino.

    /Joakim



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    Default Re: Cutting occurs outside region curve

    1. There is no risk for collission if encreasing the cut-link distance. If there would be a collision with a straight line connection, it will automatically produce a connection toolpath that follows the model surface.

    2. The re-machining only calculates from a previous cutter as a ball with the diameter of the previuous cutter. It can be more precise if using a 3D stock model for remachining.

    3. It doesn't matter if you have a flat or ball cutter as your prevoious cutter. It will still calculate the rest regions from a ball.

    4. The overlap is calculated by increase the radius of the previous cutter.

    5. Only the parameters from each toolpath calculation dialog are remembered plus some other parameters like clipping planes, reagions, drive surface and angle limits.

    If you still are having trouble, please send your model with toolpaths to madCAM and we will have a look.

    /Joakim



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    Default Re: Cutting occurs outside region curve

    Quote Originally Posted by JOM View Post
    1. There is no risk for collission if encreasing the cut-link distance. If there would be a collision with a straight line connection, it will automatically produce a connection toolpath that follows the model surface./Joakim
    Could you explain the reason to set the cut-link distance and why it is even a parameter? Wouldn't it be best to have all the cuts linked (i.e. cut-link distance greater than the size of the stock)?

    Quote Originally Posted by JOM View Post
    2. The re-machining only calculates from a previous cutter as a ball with the diameter of the previous cutter. It can be more precise if using a 3D stock model for remachining.

    3. It doesn't matter if you have a flat or ball cutter as your prevoious cutter. It will still calculate the rest regions from a ball. /Joakim
    If re-machining always assumes that the previous cutter was a ball, what does the radius parameter do?

    Quote Originally Posted by JOM View Post
    4. The overlap is calculated by increase the radius of the previous cutter./Joakim
    This probably isn't important, but it seems like overlap would be generated by doing the calculation by decreasing the radius of the previous cutter.



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    Default Re: Cutting occurs outside region curve

    1. It is very useful in some cases, for example if engraving text. Then it's important that the toolpath doesn't travel on the surface. Even if it doesn't cut into the surface, it can leave unwanted marks that you don't want for a distinkt text or pattern.

    2. 3. That was my mistake in my previous reply. madCAM does calculate for a previous cutter as a ball, flat or corner radius cutter. Below are two examples.

    Previous cutter flat end 10 and remachining cutter flat end 6.
    Cutting occurs outside region curve-remavhining1-jpg

    Previous cutter ball end 10 and remachining cutter flat end 6.
    Cutting occurs outside region curve-remachining2-jpg

    It is also possible to control the steepness or flatness of the surfaces that should be cut by setting the angle limit parameter.

    4.What I meant was that the overlap adds an offset to the previous cutter that will make it bigger to leave more material for the remaching cuts.

    Regards,

    Joakim



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    Default Re: Cutting occurs outside region curve

    Quote Originally Posted by JOM View Post
    If it's a boundary curve without island curves, it should stay inside the curve. It can be problems sometimes depending on the quality of the curve. It can help if using the curve rebuild function in Rhino.

    /Joakim
    It looks like if the boundary curve is not convex, then cutting can occur outside of it. I think this must be what you mean by island curves? So maybe the cutting stays within the convex hull of the boundary curve points?



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    Default Re: Cutting occurs outside region curve

    The curve direction doesn't matter if using region curves for 3D toolpath operations. If you have one or several closed boundary curves, toolpaths will stay inside each boundary curve.
    Cutting occurs outside region curve-regions1-jpg

    If having a boundary curve that containes other closed curves inside (island curves) the boundary, toolpaths will be created in between the boundary curve and island curves.
    Cutting occurs outside region curve-regions2-jpg



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    Default Re: Cutting occurs outside region curve

    I don't understand what I'm seeing then. In the attached, I have a region curve in red and cuts occur outside of it.Cutting occurs outside region curve-cut-outside-region-jpg



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    Default Re: Cutting occurs outside region curve

    That looks like a traverse curve. Traverse curves are not controlled to stay inside region curves. That wouldn't work in every case, for example if having two separate boundary regions.

    If you decrease the cut-link distance, the curve you see, that is crossing the bounday curve, will probably be replaced with a rapid traverse.



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    Default Re: Cutting occurs outside region curve

    Quote Originally Posted by JOM View Post
    That looks like a traverse curve. Traverse curves are not controlled to stay inside region curves. That wouldn't work in every case, for example if having two separate boundary regions.

    If you decrease the cut-link distance, the curve you see, that is crossing the boundary curve, will probably be replaced with a rapid traverse.
    My basic problem is that I have no mental model for how this works. What I'd like is for cuts to be linked as much as possible while staying within a boundary curve. You're suggesting that I should decrease cut-link distance until I see all cuts stay within the boundary? Besides undesirably breaking up cuts isn't this also potentially risky if I miss something in a more subtle case?

    I also still don't understand the use of cut-link and when it would be used. When engraving doesn't the cutter traverse between letters and cut-link wouldn't be needed? And why is cut-link a parameter of the cutter instead of the operation?



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    Default Re: Cutting occurs outside region curve

    Quote Originally Posted by JOM View Post
    That looks like a traverse curve. Traverse curves are not controlled to stay inside region curves. That wouldn't work in every case, for example if having two separate boundary regions.

    If you decrease the cut-link distance, the curve you see, that is crossing the bounday curve, will probably be replaced with a rapid traverse.
    Now I realize I also don't understand what a traverse curve is and what makes it different from a cut or a rapid.



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