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IndustryArena Forum > CAM Software > BobCad-Cam > Can’t get the right surface
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  1. #1
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    Apr 2018
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    Can’t get the right surface

    Designing an intake runner which changes shapes from oval to circle. I have the dimensions in and have done every option on bobcad v29 and can’t seem to get it right. I can connect lines between the two dimensions creating the runner wall, but it ignores the lines I draw. I’ve done cross section without those lines and results are always the same. When you look down the throat of the design the port is shrouded by the program’s extrapolation every time.

  2. #2
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    Re: Can’t get the right surface


  3. #3
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    Re: Can’t get the right surface

    use ruled surface
    draw your circle at one level in Z
    draw your ellipse at the other level of Z
    break divide by 2
    use ruled surface on 1/2 of the circle and half of ellipse
    mirror image,,then stitch

  4. #4
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    Quote Originally Posted by jrmach View Post
    use ruled surface
    draw your circle at one level in Z
    draw your ellipse at the other level of Z
    break divide by 2
    use ruled surface on 1/2 of the circle and half of ellipse
    mirror image,,then stitch
    Can’t for the life of me find that option. Searching, googling or YouTube videos.

    Good lord. 30 seconds after making this after looking for who knows how long lol

  5. #5
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    Re: Can’t get the right surface

    the help menu within bob covers it

  6. #6
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    Re: Can’t get the right surface

    Quote Originally Posted by boosted67 View Post
    Designing an intake runner which changes shapes from oval to circle. I have the dimensions in and have done every option on bobcad v29 and can’t seem to get it right. I can connect lines between the two dimensions creating the runner wall, but it ignores the lines I draw. I’ve done cross section without those lines and results are always the same. When you look down the throat of the design the port is shrouded by the program’s extrapolation every time.
    Cross Section is what you want. It will allow you to add defining sections for your throat, as opposed to just 2 entity skin...

    The issue with what you show, will be, you want your entities to have "EQUAL" segmentation. (You'll want to break/divide your circle to match the little throated piece.

    Here are a couple examples. The first zeroed one, is just a default circle and elipse. So just a straight cross section, produces good results.

    The second 2, I created you lower throat, that has "6 segments" in it... I divided the arc to 6 then, and got these skins.... (bbcd file attached)

    The last thing is when doing these skinning functions, be sure to work with the shift click, instead of just windows select. Do your work so the chain start/end can be in the same place on both entities.

    Attachment 418810

    If you need more direction, maybe someone else can jump in to show this. I am ill and cant play at a high level right now....

  7. #7
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    Apr 2018
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    Quote Originally Posted by jrmach View Post
    the help menu within bob covers it
    Massive PITA. I broke the circles down by 2 but the chains still start where ever they want. Since the circle at the top is larger, the chains start and cover more ground per click. So like a curtain, it’s pulling closed at the top more than the bottom. As the chain starts around the bend it’s shrouding the lower section. There is no editing the chain length up top. You click and it lights up. Half the time in the wrong direction and clicking the arrow most times won’t change the chain direction. I have to reselect the ruled surface and start over again.

  8. #8
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    Quote Originally Posted by BurrMan View Post
    Cross Section is what you want. It will allow you to add defining sections for your throat, as opposed to just 2 entity skin...

    The issue with what you show, will be, you want your entities to have "EQUAL" segmentation. (You'll want to break/divide your circle to match the little throated piece.

    Here are a couple examples. The first zeroed one, is just a default circle and elipse. So just a straight cross section, produces good results.

    The second 2, I created you lower throat, that has "6 segments" in it... I divided the arc to 6 then, and got these skins.... (bbcd file attached)

    The last thing is when doing these skinning functions, be sure to work with the shift click, instead of just windows select. Do your work so the chain start/end can be in the same place on both entities.

    Attachment 418810

    If you need more direction, maybe someone else can jump in to show this. I am ill and cant play at a high level right now....
    Seems easy enough. I may need to break more on the top since it is a longer line. Should keep them straight like yours. My bottom is a rectangle I snapped some circle to and trimmed. I’m using shift click but the arrows pop up now and absolutely flat refuse to change directions by clicking on them.

  9. #9
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    15

    Re: Can’t get the right surface

    Something was wrong w that particular file. It stopped even highlighting lines. Went back to my base file, broke top in 12 segments and lower into 6 and it cross sectioned no problem.
    I’ve been this far before believe it or not lol. I’m just trying to get better at the software. I offset .250 and .187 top to bottom for runner thickness and cap. Now to figure out how to radius the inside at the top. Yeahhhhh. Lol
    And bobcad crashes and closes again. Jfc

  10. #10

    Re: Can’t get the right surface

    Regular saves with version numbers on the end of your file help when something goes wrong and you need to roll back to a version that's not broken.
    A fast PC with a good graphics card and lots of RAM makes a difference.

  11. #11
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    Jun 2008
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    1838

    Re: Can’t get the right surface

    Quote Originally Posted by boosted67 View Post
    Something was wrong w that particular file. It stopped even highlighting lines. Went back to my base file, broke top in 12 segments and lower into 6 and it cross sectioned no problem.
    I’ve been this far before believe it or not lol. I’m just trying to get better at the software. I offset .250 and .187 top to bottom for runner thickness and cap. Now to figure out how to radius the inside at the top. Yeahhhhh. Lol
    And bobcad crashes and closes again. Jfc
    BobCAD won`t fillet the solid in this instance, (it is quite normal for it to crash trying to do this operation,) what you need to do is go to the "Utilities" tab and use the "Stitching > Unstitch Solid to Surfaces" then you can use the Fillet under the "Surfaces" tab, you can select one slope and the corresponding vertical, set a value for the radius and then it will radius, a bit labour intensive/PITA and when you have done the rads go back to the "Utilities > Stitching >Stich Surfaces to Solid" and you should be back to having a solid with rads between your circle and your oval.

    See attached example, might be of some help to you

    Regards
    Rob

  12. #12
    Join Date
    May 2013
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    701

    Re: Can’t get the right surface

    I have done stuff in the past using the Skin function and seems to work well
    Seems to break into segment automatically

    RAF

  13. #13
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    Jun 2008
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    Re: Can’t get the right surface

    What we really need is a "Loft" option that can be found in several other softwares, it would be nice if BobCAD could look at including this in the next version (V32?).

    I have attached a short video that shows how very simple, easy and time saving this option can be for lots of designs, it may not be suitable for all but I think a lot of people would make good use of it, anyway on to the video with the rubbish comentary, I only just installed this video capture software today so this is a first attempt at a video, please be kind
    It is in .mp4 format that should open and play in Windows Media player that is in most PCs by default

    Hope it is of some use, if anyone wants me to have a go at creating something similar and don`t already have access to software that will do this then just supply a .DXF file with the shapes and I will endeavour to come up with something for you

    Regards
    Rob

  14. #14
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    Quote Originally Posted by The Engine Guy View Post
    What we really need is a "Loft" option that can be found in several other softwares, it would be nice if BobCAD could look at including this in the next version (V32?).

    I have attached a short video that shows how very simple, easy and time saving this option can be for lots of designs, it may not be suitable for all but I think a lot of people would make good use of it, anyway on to the video with the rubbish comentary, I only just installed this video capture software today so this is a first attempt at a video, please be kind
    It is in .mp4 format that should open and play in Windows Media player that is in most PCs by default

    Hope it is of some use, if anyone wants me to have a go at creating something similar and don`t already have access to software that will do this then just supply a .DXF file with the shapes and I will endeavour to come up with something for you

    Regards
    Rob
    Rob,
    Cross section "IS" loft.... our issue in bob is a few fold. A weak modeling kernel which doesnt make much available to the feature (or devs just havent got around to lower priority stuff like that)

    "Chain selection" for our CAM software we like, is good thing, and it keeps track of so much more than just "modeling", but it makes for rigidity in other areas....

    Cant wait to see your video. It may take me a couple days. Mucho thanks! Keep doing it and you'll be abale to pump one out in 3 minutes.... they make for some fantastic comms....

  15. #15
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    Jun 2008
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    1838

    Re: Can’t get the right surface

    Hi Burr

    Yep, I fully agree with you re the "Cross Section" in effect being a version of "Loft", it does work and is very accurate in that as you rightly point out working with lines/arcs is good, more labour intensive but as in my earlier post shows the shape is very accurate in the other software using their "Loft" the user is pretty much at the mercy of the software regarding the actual shape of radii which isn`t such a great thing, but it is much faster and easier so if accuracy isn`t priority then OK, I have found that a little practice with the shapes re number of and heights then it is possible to get pretty close to an accurate required shape, but, nothing is for nothing that also requires some extra labour, again !!

    The video is pretty rubbish, particularly the commentary, but it may be of interest to some, never make it as a News Reader that`s for sure, I`ll just stick with the machines, they don`t care what I say or how I say it

    Regards
    Rob

  16. #16
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    Re: Can’t get the right surface

    Quote Originally Posted by The Engine Guy View Post
    Hi Burr

    The video is pretty rubbish, particularly the commentary, but it may be of interest to some, never make it as a News Reader that`s for sure, I`ll just stick with the machines, they don`t care what I say or how I say it

    Regards
    Rob
    lol. Talks to the machines at night!!! "Hello Darlin.... Make some sweet chips tomorrow, and I'll oil you!!!!"

    I want to hear your crusty old voice, so I have a better idea of who I chat with!!!!

  17. #17
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    Apr 2018
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    15

    Re: Can’t get the right surface

    Definitely something w that particular file. Computer is slow to highlight or do anything. Open up anything else and it’s fine. So I redrew it in a couple minutes no problem now that I know how to do it. Thanks a ton. May need more soon. Solid fillet isn’t radiusing the inside of the runner at the top. Try a few things here.




    https://i.postimg.cc/sXYpkcng/7-E7-F...0088-F2-B6.jpg


    https://i.postimg.cc/mgnNChzB/BC8-C9...-B9139-BBB.jpg

  18. #18
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    3376

    Re: Can’t get the right surface

    Burr,in this particular case,why is "Rule" not a good choice ?
    Say I break both entities in 12 0r 24 places,,it seems alright,,maybe an illusion ?
    Sure is fast with chain select

  19. #19
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    Quote Originally Posted by jrmach View Post
    Burr,in this particular case,why is "Rule" not a good choice ?
    No, not "not a good choice"....

    Opinion. But for "why my opinion" it is beacause of his design. Kind of a port, throat/airway thing. So for me, those are engineered more by "station than waterline". So ruled is like a sweep, which is a curve calculated along a path. Cross is a loft from station to station, where all your defining numbers and traits are

  20. #20
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    Apr 2018
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    15

    Re: Can’t get the right surface

    Getting the same garbage results. When you turn to a solid you can see how terrible it really is. You can start the chain in similar location, break the top ellipse into 360 if you want, nothing changes




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