Interior furniture in Rhino

[catsketcher]

Hello all,

I am drawing a 7 metre cat which is a development of a little 5.9 metre folding cat I have built. I want to CNC cut this next boat rather than cut it out by hand so I have to get DXF files.

I have imported a Freeship hull into Rhino with Iges and have started to get quite a nice hull, much like her smaller sistership. I have quite a lot of trouble getting the bulkheads and furniture to trim easily. Am I doing something wrong like not offsetting the hull skin and then putting all the interior skin into one layer? Sometimes I can't even get the bulkheads to trim even after splitting and selecting all items as cutting objects. This is done in desperation after nothing trims properly.

I quite like Rhino as it is like Autocad which I have some background with but what is the easiet way to develop interior patterns from a hull? Trim seems hard work.

And another thing, sometimes my decks don't curve properly but go segmented on me. I seem to have fixed it but I don't really know why.

Thanks in advance - Oh yeah, I am supposed to start building in 8 weeks.

cheers

Phil

[Windvang]

I use the section command to draw bulkheads in Rhino. Make a section at the place you want a bulkhead. Clean up the cross section you just have created, draw in holes, doors etc. (make sure there are nog gaps!, join all borders) Finally make the bulkhead a solid at the desired thickness.

You can offset the hull, or, slightly less accurate, offset the hull in the cross-section. This is much easier and cleaner than trying to trim a surface.

[Tim B]

I've had similar problems when importing from external code, but it's not Rhino's fault.

Check that you can actually make one closed polysurface with the hull/deck before you start splitting things. You may have to change the accuracy (properties page - I use about 0.00001 units). Use the edge analysis tools and see if you can find any offending edges. Usually it is the hull centre-line and it is then often easiest to export all the surface control points, clean up the edges, import the clean points and re-build the surface by hand.

Once you have clean geometry you can offset the surfaces by the structure thickness, and use contour to draw sections which you can then surface to form bulkheads etc.

Incidentally, don't use Rhino like Autocad. Too many people think like that and have poor results to show for it. Your thinking needs to be in 3D all the time. It takes time, practice, and understanding.

Also, split tends to be more useful than trim.

Tim B.

[SailDesign]

Originally Posted by Tim B

Also, split tends to be more useful than trim.

Tim, my boy, you are wise beyond your years. Or is that "behind your ears"? Either way, you speak the truth. Trimming surfaces inhales. Deeply!
Steve

[dougfrolich]

All good Points. Another usfull tool is intersection. This may also help identify why your surface won't trim or split.

[catsketcher]

Thanks for giving me some way out of my problems. According to Tim I have to make all of the interior surface of the hull one polysurface. I should also check intersections, use split and the section command (I didn't even know there was a section command) I can understand that it is probably some difference in intersections that is causing me grief.

If I can then ask another question, How well have CNC kits come out in the build process? I have heard of people forgetting about hull thickness and all the bits either being a hull thickness too big or too small. What I really am thinking is this - When I built my other boats I used epoxy's wonderful gap filling qualities to a fair bit of use. In fact many designers would rather a bulkhead too small rather than too big and pushing out on the hull. In my 38ft cat I hung the bulkheads off the gunwales and lowered them into 5 mm approx of glue which then coved into a lovely looking join. Glassed over it has sailed thousands of miles very well.

Can computer design and CNC cutting be so accurate that I should reduce the bulkhead size all around by 3mm for this epoxy bed or should I just cut what is drawn because it is usually pretty rough anyway? How close does this process get when you build it?

Thanks for all the help so far. I really appreciate it. By the end of this I should be able to help a newby a little.

cheers

Phil

[Windvang]

Originally Posted by catsketcher

Thanks for giving me some way out of my problems. According to Tim I have to make all of the interior surface of the hull one polysurface. I should also check intersections, use split and the section command (I didn't even know there was a section command) I can understand that it is probably some difference in intersections that is causing me grief.

If I can then ask another question, How well have CNC kits come out in the build process? I have heard of people forgetting about hull thickness and all the bits either being a hull thickness too big or too small. What I really am thinking is this - When I built my other boats I used epoxy's wonderful gap filling qualities to a fair bit of use. In fact many designers would rather a bulkhead too small rather than too big and pushing out on the hull. In my 38ft cat I hung the bulkheads off the gunwales and lowered them into 5 mm approx of glue which then coved into a lovely looking join. Glassed over it has sailed thousands of miles very well.

Can computer design and CNC cutting be so accurate that I should reduce the bulkhead size all around by 3mm for this epoxy bed or should I just cut what is drawn because it is usually pretty rough anyway? How close does this process get when you build it?

Thanks for all the help so far. I really appreciate it. By the end of this I should be able to help a newby a little.

cheers

Phil

I found it to be amazingly acurate, 1mm to big and it won't fit anymore!