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Render of Swept Part doesn't match wireframe
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* July 12, 2017, 02:33:08 PM
I have just recently started using TurboCad again after a several year hiatus, and I'm having a problem with rendering and hidden line mode that I'm  hoping that someone can give me some help with.  I did a search of the forums without finding a similar issue, but I might have not used the right search terms.

First, a little background:

The project that I'm working on is a homebuilt Fokker TriPlane from a plan set by Ron Sands (http://www.ronsandsreplicas.com/Fokker_DR1_Plans.htm).   This plane has a steel tube fuselage and tail group, and I am using TurboCad to create a solid model of the various tube components.  I've found a company (http://www.vr3.ca/) which will profile and bend the tubes based on the solid model, and I believe that will save me a lot of work when it comes time to actually start building the plane.   

My method is to use various lines, 3D splines, and 3D polylines to draw the center lines of the framework components, and then sweep a pair of concentric circles representing the outside and inside diameters of the tubing along the various component paths and then use the various 3D Boolean operations to trim, intersect, etc. the various components to get the right end profiles of the tubes so they will fit together properly when it comes time to weld the frame up.

I'm not sure how to have an inline image in this post, but I've attached a file called FuseFrame.png which shows the current status of my work. 

However,  I'm having some issues when I try to render the model using either hidden line mode or quality rendering.   I've attached a .TCW file (ProblemIssue.TCW) with one component (Lower right fuselage longeron) for reference.  The two circles representing the OD and ID of the tube, the 3D spline path of the tube, and the resulting tube are in this drawing.

The attachment, Problem.png is an image constructed of several screenshots showing the issue.  Going from right to left in this image are: 
  • The wireframe representation of the part.  Everything looks good here
  • The hidden line representation of the part.   This looks just like two straight tubes with a kink,  the curve is gone.
  • The quality render of the part.  Same issue as the hidden line render.   No curve, just a kink.
  • The wireframe with the part selected.  The magenta selection highlight also shows the kink in addition to the wireframe part.

I'd really appreciate any help that can be given to make the hidden line and quality render show the curved shape of the part that the wireframe does.   I will need to provide an annotated hidden line picture of the fuselage to VR engineering in order to get a quote, and having some parts not be properly represented will not be good.

Thanks in advance for the help.

Jim
« Last Edit: July 12, 2017, 02:53:43 PM by jimhorner »

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* July 12, 2017, 04:25:11 PM
#1
Go to Options>ACIS and enable the settings shown in the attached screenshot. You might have to delete the part and then Undo the deletion in order to see the improvement. This setup is likely to slow down the performance, so you may want to live with the crappy rendering until you really need it to look good.

Henry H

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* July 12, 2017, 05:56:29 PM
#2
Go to Options>ACIS and enable the settings shown in the attached screenshot. You might have to delete the part and then Undo the deletion in order to see the improvement. This setup is likely to slow down the performance, so you may want to live with the crappy rendering until you really need it to look good.

Henry H

Perfect!   Thank you.  The problem was driving me crazy.  This fixed it.


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* July 13, 2017, 11:18:26 AM
#3
Go to Options>ACIS and enable the settings shown in the attached screenshot. You might have to delete the part and then Undo the deletion in order to see the improvement. This setup is likely to slow down the performance, so you may want to live with the crappy rendering until you really need it to look good.

Henry H

Perfect!   Thank you.  The problem was driving me crazy.  This fixed it.

Glad to help. Good luck with the project. No doubt you're aware that welded joints can be susceptible to fatigue failure.

Henry H

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* July 13, 2017, 12:53:02 PM
#4

Glad to help. Good luck with the project. No doubt you're aware that welded joints can be susceptible to fatigue failure.

Henry H

Thanks.  I knew if I posted my question here, I'd get some help.

Regarding the weld joints,  this technique of construction has been around for a long time in the aviation industry.   As long as my welding skills are up to snuff (not yet, but I'll be doing lots of practice before doing it for real on the plane),  I'm not too worried.   My current, factory built airplane, a 1989 Bellanca Super Viking, is constructed in pretty much the same way as the Triplane will be with wood wings and a fabric covered steel tube fuselage and empennage.  It has retractable gear, a 300HP engine, and cruises at 200mph.   There are plenty of planes -- Piper J-3 Cubs, Aeronca Champs, Citabrias, numerous homebuilts, etc. -- which use this technique of construction, some of which had their first flights in the 30's and 40's,  and which are still flying today.   Just a few weeks ago, I was doing some aerobatics in a Super Decathlon built using this technique, and I had no qualms about pulling 5-6 G's. 

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