TurboCAD Mac Forum

TurboCAD Mac Categories => General Discussion => Topic started by: Colinh on November 14, 2017, 07:48:35 AM

Title: Joining two solids mac
Post by: Colinh on November 14, 2017, 07:48:35 AM
Hi Guys
Really struggling with joining the cross within the cowling to the main body. The whole thing is only two parts but they will not join.
Would love some advice as its wasting me loads of time.
Thanks for your help
Colinh
Title: Re: Joining two solids mac
Post by: mitchb on November 14, 2017, 06:01:57 PM
I tried to add the two solids together and got an "Unknown Error" so I moved the cross piece into the forcing cone away from the body and it worked, I judged that the many surfaces of both the cone and body just overwhelmed the "Add Solid" tool. Next, I cut the cone off the body and unioned the cone and cross then the cone/cross to the body, that worked.

After completing the above it struck me that the "Stitch" tool might do the job too, sure enough, it worked. I'll include a screenshot of the Stitch tool and the "take it apart and glue it back together" file.

Enjoy
Mitch
 
Title: Re: Joining two solids mac
Post by: Colinh on November 15, 2017, 02:39:33 AM
Hi Mitch
Your a star. I first moved the cross as suggested and tried the stitch tool and some weird things happened to the vertical mast.
Pic attached.
So again as suggested split the mast just below the cowl and it works.... relief at last from the head scratching. Thanks.
So was this a hardware/memory problem or a program overload.
Cheers
Colin
Title: Re: Joining two solids mac
Post by: Colinh on November 15, 2017, 03:05:22 AM
Hoping not to be a pain, but i have one other question now the stitching has been solved.
I need to run a tube down through the mast and out into the cowling ( to run wires through).
When i use the pipe tool the intersecting surfaces seem to block the pipe and it is not hollow. So i tried drawing
a cylinder and then subtracting it from the solid but get "decision to delete intersection graph was incorrect"
Once again flummoxed.
File attached
Title: Re: Joining two solids mac
Post by: murdic on November 15, 2017, 02:49:54 PM
I think that your original problem and perhaps this one is due to the way that you built the  pylon.  I'm unfamiliar with TC Mac versions, I'm using a windows version of it (long story), but does yours have verify menu?  I used verify|check object, and it told me that ACIS object 11102 has a zero-area surface somewhere.  When I passed a cut section through the middle of the nacelle, it revealed that the surfaces of the top of the pylon are within the nacelle, ie nacelle and pylon aren't a homogeneous solid.  I investigated further and exported the pylon as .stp, when the .stp was reimported, it returned as two objects, the pylon and the nacelle had separated.  The top of the pylon has a self-intersecting surface and its outer edges are what I would consider too close to coincident to the nacelle's skin.  I started trimming the top of the pylon, and that led to the skin on one side of the pylon rippling madly....
So....converted to surfaces and untrimmed the pylon.  The pylon surface is not sound.  There are gaps in the skin, it won't heal or thicken.  I think that you ought to rebuild the pylon cutting back the surfaces within the nacelle, and try to avoid coincident geometry, like the front flat surface of the nacelle and pylon.  If you want to shell the pylon or provide cable routing, it's a good idea to do that before you start adding details, bosses, holes etc, they complicate those operations.  Make pieces overlap when you add them, and trim them back afterwards with sacrificial objects.  Overlaps and trims  in solid booleans give more integrity and reliability in my experience, and you'll have a better chance of being able to shell the pylon or subtract a cable route through it.  I'd add the cross piece and subtract the mounting holes from cross piece and nacelle as one operation to avoid problems from coincident faces, too.
Rebuilding the pylon will eliminate your dramas, IMO.
*edit*  I passed cut sections through the pylon and checked the curvature of the  profiles, and it's mostly asymmetric.
Title: Re: Joining two solids mac
Post by: Colinh on November 16, 2017, 09:12:59 AM
Hi Murdic
Thank you for a very comprehensive reply. Yes the mac version does have check object, two pics attached.
The ACIS numbers seem different but i'm guessing its the 53856 that is the pylon. I tried the repair button but it failed. With my limited knowledge I struggle to understand how two bodies that have been joined into one can end up with one inside the other and at the same time making them inseparable. When i select the nacelle or the pylon and hit the hide button the whole assembly disappeares. I cannot see how to alter the height of the pylon.
The object report mentions lumps, is that a good thing?
Theres a lot to take in, ill have a go if i can figure out how to get it apart.
Do you think it would 3d print or crash out?
Thanks for your help
Colinh
Title: Re: Joining two solids mac
Post by: mitchb on November 16, 2017, 02:52:09 PM
Hi Colinh,

Quote
I first moved the cross as suggested and tried the stitch tool and some weird things happened to the vertical mast.
Pic attached.
I only moved the cross piece to help me troubleshoot the problem and understand why the Add Solid tool was failing. The Stitch tool was applied to your original posted drawing. Sorry for the confusion.

Thank you murdic for your analysis of this issue, please drop by more often, we can use your insight.

Colinh, do you use Autobackup? If so do you have an older backup pre-union to recover the parts as separate entities?

Lumps are common and okay. As to 3D printing, export it to a slicing engine and see if it likes it, I have no experience with that.

Enjoy
Mitch
Title: Re: Joining two solids mac
Post by: murdic on November 16, 2017, 07:56:24 PM
I did a quick rebuild of the pylon out of interest.  I passed cut sections through it, then used bounding boxes to draw frames, and found that the sections were very close to elliptical, so I drew diagonal ellipses across the frames, skinned solid through them and shelled the solid to 1.5mm.  I passed a cut section through the nacelle and revolved the section, the revolve adds to the pylon without a problem. 
Change the file .txt attachment to .tcd, your .tcd file opened in my program, I think this will open in yours.