surface intercepts

DELFTship forum Hull modeling surface intercepts

This topic contains 18 replies, has 3 voices, and was last updated by  Denis Pratt 1 week, 4 days ago.

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  • #43463

    Denis Pratt
    Participant

    Hi,

    Trying to get the intrecepts of a radius sloping transom and various hard chine hull surfaces and getting a lot of difficulty.

    For the deck transom intercept part of the intercept appears but not all to the center line of the vessel.

    For the surface panels, the intercepts just please them selves whether or not to be determined.

    For the side plate and the transom panel no joy whatsoever.

     

    Anyone know what I am doing wrong?

    Denis

     

    Attachments:
  • #43470

    Maarten
    Keymaster

    Hi Denis,

     

    Based on just the image it is hard to say what happens. Do you think you could share the model, so we can have a look at it?

  • #43473

    Denis Pratt
    Participant

    Hi maarten,

    Tried to attach file intcepts.fbm of 24kb but your forum system tells me

    “Error!File type not allowed.

    Remove this file

    How do I get the file to you please?

     

    Will look further into it myself also.

    Denis

  • #43474

    Maarten
    Keymaster

    Hi Denis,

     

    I’ve added fbm as an allowed file type, you should now be able to upload.

  • #43475

    Denis Pratt
    Participant

    Maarten,

    Here is the file.

    Denis

  • #43476

    Denis Pratt
    Participant

    Maarten

    sent again

    intcepts

  • #43477

    Denis Pratt
    Participant

    Maaten,

    Hope you got the file this time. I have no way of checking if the file was received.

    I did send to info@……. as well.

    Denis

  • #43478

    Denis Pratt
    Participant

    Maarten, another go.

    Denis

  • #43479

    Icare
    Participant

    Hi Denis!

    English is not my mother tongue, but I tried to understand your problem.

     

    I’m still using an old version of FreeShip, but if nothing changed, the INTERSECTION function applies only to polygon’s edges. The software finds where a line crosses a surface, creates a point and connect it to the next intersection point. You have to understand it’s slightly different of the actual intersection of both surfaces.

     

    Do you want to draw a draw a transom based on a  sloping cylinder’s flank?

    If so, and without having my computer at hand, I’ll suggest you ask FS draw a cylinder wider than the hull, rotate it slightly forward or backward (say 5 or 10°), delete its front part, then ask FS to determine the surfaces’ INTERSECTION (Deck/Cylinder, Side/Cylinder, bottom/Cylinder).

    This will give you many points. Their connection may be somewhat weird, so you may have to redraw the intersection curve by drawing yourself the edges connecting the points.

    Once you’re satisfied with this curve, you can definitevely delete the hull’s excess part and the cylinder itself (it was just a template). Do not select the new edge meanwhile deleting the exces parts.

    Then close the hull by creating new polygons based on the hull’s aft edge.

     

    I assume this will give you a more or less developable transom.

     

    Note:

    On the old version I use, I noticed that asking the intersection of a surface by an other one (say the hull by the transom) doesn’t give exactely the same result than asking the intersection of the second surface by the first one (say the transom by the hull).

     

     

     

     

  • #43480

    Denis Pratt
    Participant

    Added 2 files as a trial. First is a .jpg and the second .fbm,  I am getting difficulty adding data files so thought I would see if both attach successfully.

    Attachments:
  • #43482

    Denis Pratt
    Participant

    Maarten,

    Still cannot attach .fbm files, it said it was not allowed for security reasons.

    Denis

  • #43505

    Maarten
    Keymaster

    Maarten,

    Still cannot attach .fbm files, it said it was not allowed for security reasons.

    Denis

    Awkward- I’ve added it to the list of allowed filetypes, but the back end doesn’t seem to accept it.

    If you mail me the file as attachement , to info at the domain of this site, I will have a look for you

  • #43507

    Denis Pratt
    Participant

    OK

  • #43517

    Denis Pratt
    Participant

    Maarten,

    I do not know if you received the .fbm file I sent by email.

    My ISP send me a message saying it had timed out and not delivered to [deleted] where you asked me to send to.

    Denis

  • #43521

    Denis Pratt
    Participant

    file sent per your instructions.

    Denis

  • #43523

    Maarten
    Keymaster

    Got your .fbm- I think I understand your situation a bit bettter now:

     

    The intersect function creates intersection points in all edges of a surface- your deck, at the intersection with the transom, is on single surface without edges.

    Create a few edges there, by selecting the last and the second-last edges in your deck and ‘split’ these. Repeat a few times to get the accuracy you want- you’ll end up with something like: Capture

    As for the ‘chine’ layers- there is no need (unless you want to use the unfold function later) to have each chine in its own layer. I’ve added them all to a single layer, so it’s easier and less work to intersect- i find no problem doing this.

     

    To add them all to a single layer, hold down the ctrl-key while clicking on the face belonging to each layer, until the are all selected. Then, in the layer drop-down, select the layer you want the entire selection  under.

     

    I hope this helps you on you way!

     

    • This reply was modified 1 week, 5 days ago by  Maarten.
    • This reply was modified 1 week, 5 days ago by  Maarten.
    Attachments:
  • #43527

    Denis Pratt
    Participant

    Thanks Maarten,

    I understand what you have said and now done it for myself on the original model.

    Got the decks, sides, chines and bottom intersects with the transom done and trimmed.

    Still to work out how to get the intersect lines on to the transom to trim that to the shape of the hull plates.

    Tried reversing the process and putting the intersect lines on the transom by nominating that surface first but my first attempt failed.

    All plates are to be developed for NC cutting.

    Denis

     

  • #43528

    Maarten
    Keymaster

    Hi Dennis,

    If you remember that intersect will only insert points in existing edges- and thenm where possible connect points with new edges, you can get a reasonable result. Although in this specific case some post processing is required;

    After the first intersect (I put all your non-transom layers in a single layer so I only had to do a single intersect) I ended up with this:Capture2 and decided this was not the way to go- too much work to make sure edges are where they’re needed.

    Instead, if you managed to trim the hull, simply close the transom in nice, regular sections.

    Good luck with your project!

     

     

    Attachments:
  • #43531

    Denis Pratt
    Participant

    Thanks Maarten,

    I did the same.

    After trimming the hull plates to the intersect lines, I discarded the old transom and made a new surface from the edges, four points at a time.

    One problem when building and ended up with a transom of two surfaces which would not join into one.

    Will join all the hull surfaces into one and try again.

    Denis

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