Designing a Surfboard Fin

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quick61
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Re: Designing a Surfboard Fin

Postby quick61 » Wed Jan 15, 2014 1:14 am

As best I can tell, something went wrong with the import, or somewhere with the conversion to the Bspline. Might even be in the .dat file... I pretty much replicated your scale, spacing and placement with my set of imports and it worked just like it should.

Here is the LE of the foil you have -
LE_1.png
LE_1.png (4.4 KiB) Viewed 1585 times
And here is the one I have -
LE_2.png
LE_2.png (4.43 KiB) Viewed 1585 times
You may want to take a look at that .dat file and see if something is off in it. I'll take a look at my file with my 0.13 windows version and see if the older FreeCAD importer is getting something wrong.

Back in a bit. I have to go fire up that old moldy XP box again :roll:

Mark

Ok, I'm back... ;) Not the importer, the n0012 foil looks just fine in the windows 0.13 stable version. It also converted over to a Bspline just fine, so it's looking like there is something not quite right with the .dat file. You can post it here by just adding a .zip to the end of the file name. No need to compress it, just rename and upload. I'll take a look if you don't see anything yourself.
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woodbuddha
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Re: Designing a Surfboard Fin

Postby woodbuddha » Wed Jan 15, 2014 3:29 am

Just had a closer look at the b-spline of the foils from my two DAT file and they doesn't look right. I have one DAT file sourced from Xfoil and another from the UIUC data base. Do you know a reliable repository for foils?

Here's the attached DAT file.

TK
Attachments
naca0012.zip
(2.93 KiB) Downloaded 54 times
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quick61
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Re: Designing a Surfboard Fin

Postby quick61 » Wed Jan 15, 2014 4:11 am

Well, that one looks right and UIUC has been my main go to for Airfoils, (though there are a few that aren't correct). The n0012 that I have been using is from there. Give it a try again just importing a single foil, take a look and then look after each step to see where it's going wrong. That does seem strange, as it's working just as it should here.

Mark
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woodbuddha
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Re: Designing a Surfboard Fin

Postby woodbuddha » Wed Jan 15, 2014 5:11 am

Downloaded a fresh n0012.dat file. Imported it using your macro. All looks OK at this point. Go through the steps of downgrading and up grading and get to DWire001. When I use the wire to b-spline conversion tool the resulting b-spline seems to have multiple lines. See the attached screen shots.
DWire001.gif
DWire001.gif (58.12 KiB) Viewed 1574 times
Wire to B-spline.gif
Wire to B-spline.gif (63.44 KiB) Viewed 1574 times
messy bspline lines.FCStd
(31.95 KiB) Downloaded 59 times
TK
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quick61
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Re: Designing a Surfboard Fin

Postby quick61 » Wed Jan 15, 2014 5:06 pm

I see that you upgraded to FreeCAD to 0.14 Rev 2370 W7 32 bit. Humm.. When I open that file, I get an error -

Code: Select all

Traceback (most recent call last):
  File "/usr/local/Mod/Draft/Draft.py", line 3892, in onChanged
    self.createGeometry(fp)
  File "/usr/local/Mod/Draft/Draft.py", line 3903, in createGeometry
    spline.interpolate(fp.Points, True)
<type 'exceptions.Exception'>: Standard_ConstructionError
That Bspline does not look right. If you don't have it enabled, go to View > Views and put a check mark on the Report view. does this error message above show up there? It seems that it is failing with the Dwire as I can not make a Bspline from it.

Maybe someone else can check this out? Is anyone else getting this error, or is it just me?

Mark
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bejant
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Re: Designing a Surfboard Fin

Postby bejant » Wed Jan 15, 2014 6:12 pm

No errors opening "messy bspline lines.FCStd" here on:
OS: Windows XP
Platform: 32-bit
Version: 0.14.2370 (Git)
Branch: master
Hash: a836759ebd91404954a778ff8885e152611576e1
Python version: 2.6.2
Qt version: 4.5.2
Coin version: 3.1.0
SoQt version: 1.4.1
OCC version: 6.5.1
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quick61
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Re: Designing a Surfboard Fin

Postby quick61 » Wed Jan 15, 2014 6:22 pm

bejant wrote:No errors opening "messy bspline lines.FCStd" here on:
OS: Windows XP
Platform: 32-bit
Version: 0.14.2370 (Git)
Branch: master
Hash: a836759ebd91404954a778ff8885e152611576e1
Python version: 2.6.2
Qt version: 4.5.2
Coin version: 3.1.0
SoQt version: 1.4.1
OCC version: 6.5.1
Thanks for taking a look at this bejant. I'm currently on Version: 0.14.3025 and there have been a few changes. :shock: Are you getting the Dwire looking Bspline? The Bspline shouldn't be coming out looking that way should it? Maybe some backwards compatibility was broken? (just as likely to be OCC as anything)

OS: Ubuntu 13.10
Platform: 64-bit
Version: 0.14.3025 (Git)
Branch: master
Hash: 15089556cda467b82bcf730fe473eeec4154542c
Python version: 2.7.5+
Qt version: 4.8.4
Coin version: 4.0.0a
SoQt version: 1.5.0
OCC version: 6.7.0
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woodbuddha
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Re: Designing a Surfboard Fin

Postby woodbuddha » Wed Jan 15, 2014 10:26 pm

I don't get that error message in the report view. This is what I get:

matplotlib not found, Plot module will be disabled
Teigha File Converter not found, DWG support will be disabled.
pycollada not found, collada support will be disabled.
Draft workbench activated
Found 1 face: extracting its wires
Found closed wires: making faces
Found 1 non-parametric objects: draftifying it

The strange thing is when I convert the DWire001 to a BSpline I don't get a message in the report view. All other actions (upgrade and downgrade) give me a message.

I installed 0.14 rev 2370 on a W7 64 bit machine and the BSpline still has multiple lines. I'll try installing on my Ubuntu machine and see if that makes a difference.
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bejant
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Re: Designing a Surfboard Fin

Postby bejant » Thu Jan 16, 2014 1:37 am

quick61 wrote:Are you getting the Dwire looking Bspline? The Bspline shouldn't be coming out looking that way should it?
Sorry but I don't know how the Bspline should appear. When I open the file the Bspline is set to Data -> closed = true, the solid is filled and the Bspline is continuous. Here it is with the Bspline selected:
20140115a.jpg
20140115a.jpg (12.22 KiB) Viewed 1539 times
It looks like this when Data tab -> Closed = False:
20140115b.jpg
20140115b.jpg (10.63 KiB) Viewed 1539 times
When I double-click on it to edit when closed = true it looks like this:
20140115c.jpg
20140115c.jpg (8.45 KiB) Viewed 1539 times
I'll put the last screen grab in the next post...
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bejant
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Re: Designing a Surfboard Fin

Postby bejant » Thu Jan 16, 2014 1:39 am

Double-click Bspline to edit when closed = false looks like this:
20140115d.jpg
20140115d.jpg (10.26 KiB) Viewed 1538 times
I'm not sure if this helps or not...