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unusable groove toolpaths v26 lathe

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This topic contains 2 replies, has 2 voices, and was last updated by  nick 2 years, 10 months ago.

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    I’ve been having issues with the grooving toolpaths calculated by v26 lathe. it seems that no matter what it doesn’t know how to compensate / calculate for both sides of a groove tool. Making a grooving path is not rocket science and there is no reason why the toolpath should be undercutting or just plain not cutting radii. And why when everything from the drawing and the tool geometry is nice round whole numbers is it giving me numbers in the .0001-.0009 range and making all sorts of taper moves and straight features? None of it adds up.

    After a week of going back and forth with tech support I still have no answer as to why bobcad is unable to generate a usable groove path. The tech guy kept telling me it looked great in the simulator even though the numbers in the post don’t add up. Then he says when he zooms in on the sim he can see the undercut/step im talking about. I pointed out the numbers in the post that are causing it to undercut and he tells me he does not know how to read g-code! How are you working tech support for a computer aided machining system and don’t know anything about g-code programming? Anyway… that aside he convinced me he’d have someone else look at it with him and he would get back to me. I just spoke with him today and all he did was draw a representation of the groove tool, plot points along the toolpath at the posted numbers, and line the theoretical tool tip along with the drawn tool up to the plotted points which did nothing to solve the toolpath. All it did was prove that the calculated path is still wrong because now you can actually see the tool representation overlapping the part geometry where it undercuts. The we go through changing the system tolerances all the way down to .0001 (the lowest it can go) and re-calculating and re-posting it all and just gives the same bad toolpath. His final statement after wasting all this time is that he still doesn’t understand why this is happening and he will try some more things with somebody else’s help.

    This issue has caused a lot of wasted time and effort already and I feel as if bobcad-cam might just be that. A waste of time and effort. If anybody can prove me wrong (and I sincerely hope someone can)
    then please do. I’m attaching the file with the tool representations in the layers here so anybody can take a look at it. If this problem cant be solved and bobcad-cam is incapable of producing usable toolpaths in their lathe module then my company will be seeking a refund or to sell our software and seats to somebody who doesn’t mind having a cam system that puts out paths that need to be completely re-written by hand.

    • This topic was modified 2 years, 10 months ago by  nick.
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    I took a look at the model and was unable to find an issue in the simulation when plotted against the solid model. The code, albeit with the post that was defined in your part file, plots correctly also. Would you please give me a call at 727-489-0003 and ask for Sean so we can get this issue sorted for you.

    Sean Daugherty
    BobCAD-CAM Technical Support



    If you zoom in to the solid model you can clearly see the how it cuts the radii on the edges of the groove real funky. And how can you say this code plots correctly? It will not give the desired result it should look something like this…

    G0 X1.05 Z-.61
    G1 X1. F.015
    G2 X.98 Z-.6 R.01
    G0 X1.05
    G1 X1.
    G3 X.98 Z-.55 R.01
    G1 X.9
    G0 X1.05
    Not this…

    N7G00 X1.325 Z-.608
    (start point should be z-.61)
    N8G00 X1.05

    N9G01 X1. F.015

    N10G01 X.9968 Z-.6047
    (why 2 linear moves before starting radius?)
    N11G01 X.9953 Z-.6037

    N12G02 X.9907 Z-.6016 I-.009 K-.0077
    (why is a .005r being broken up into 2 arc moves?)
    N13G02 X.9805 Z-.6 I-.0062 K-.0104

    N14G01 X.9

    N15G01 Z-.5504
    (why is it feeding to within .0004 of left finish shoulder?)
    N16G01 X.95

    N17G00 X1.0473
    (why is it not going to specified clearance value x1.05?
    N18G00 Z-.545
    (start point should be z-.54)
    N19G01 X.9973
    (this move will cause a .00135 step per side of part)
    N20G03 X.9805 Z-.55 I-.0089 K.0055
    (n20 seems to be ok)
    N21G01 X.9

    N22G01 Z-.5504
    (only a .0004 blend?

    This code is not correct and will not make the intended feature to acceptable standards. Our parts are required to have very specific finish and edge break tolerances and that program will not do it. If you can somehow manipulate that file to put out something that looks more like what I wrote at the top and will not cause steps, flats, and undercuts where radii should be I would like to see it. (and yes im aware that it is the post processor that determines whether I’s and K’s or R’s are used)

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