Creating sections from a mesh object STL

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Sirjaymond
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Joined: Sun Aug 14, 2022 11:50 pm

Creating sections from a mesh object STL

Post by Sirjaymond »

Hi all!

First post I know - but would love your help.

I make skateboards as a hobby and am building a new two-part mold for gluing and pressing veneer into shape. I am basing my build on the technique used here (http://www.diyskate.com/wood_mold.html), but am planning on using thinner planks, for greater resolution and accuracy.

I have designed a two part mold using this tool (https://sk8cad.com/), and have exported it as an STL file, attached.

What I'm trying to achieve is creating a set of cross sections down the length of the mold. These sections should be 19mm wide, centred symetrically from the centre line down the middle of the mold. The STL file itself uses inches as units of measurement, and the mold is 9.5 inches wide. I should end up with about 14 sections total.

I don't necessarily need to split the 3D model itself, all I really need is a set of printable cross-section outlines to glue to my planks and use as cutting guides.

I am new to CAD, but a quick learner. I've had a look at some TechDraw Section tutorials, but can't seem to get it to work.

Any guidance or tips would be greatly appreciated!

Thanks in advance.
Attachments
New dual mold.stl
(591.34 KiB) Downloaded 9 times
edwilliams16
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Re: Creating sections from a mesh object STL

Post by edwilliams16 »

Welcome. However, the stl file is really in bad shape.
Screen Shot 2022-08-14 at 5.19.57 PM.png
Screen Shot 2022-08-14 at 5.19.57 PM.png (74.31 KiB) Viewed 759 times
Even after this repair, I couldn't get two valid solids for the two halves of the mold. The file is ridiculously complicated for a simple shape. What's the purpose of the tiny pinholes, anyway?
Sirjaymond
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Joined: Sun Aug 14, 2022 11:50 pm

Re: Creating sections from a mesh object STL

Post by Sirjaymond »

Hi, thanks for taking a look!

I expect the pinholes you're talking about are the 8 holes penetrating through both molds. These are references for the truck mounting holes on the finished board.

I've removed these and some other un-needed features, which might make it simpler. See attached.

Thanks in advance
Attachments
Dual-mold-no-holes.stl
(323.03 KiB) Downloaded 10 times
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thomas-neemann
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Re: Creating sections from a mesh object STL

Post by thomas-neemann »

Sirjaymond wrote: Mon Aug 15, 2022 4:30 am .....
here is a suggestion, but I would create dxf files and use e.g. Print out to scale with librecad


https://www.youtube.com/watch?v=95N6k32iEmY

phpBB [video]
Gruß Dipl.-Ing. (FH) Thomas Neemann

https://www.youtube.com/@thomasneemann5 ... ry=freecad
Sirjaymond
Posts: 8
Joined: Sun Aug 14, 2022 11:50 pm

Re: Creating sections from a mesh object STL

Post by Sirjaymond »

It looks like you just created that video, did you? Thankyou!

The sections I need are actually down the length of the mold, not across the width, so 90 degrees from what's in the video.

I guess that's just a matter of changing the axis though?

Hopefully it's not too hard to translate the text in the app from german to English :D

Thanks very much, I'll see how I go.

Thanks again
Sirjaymond
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Re: Creating sections from a mesh object STL

Post by Sirjaymond »

I've tried to follow along with the video, but it doesn't seem to be working for me.

Is there anything you do in the way of mesh repair, or preparing the part beforehand?

I can successfully "create shape from mesh", but when I do so, it doesn't change to look like the one in your video.

Then when I use the same parameters as you on the crossSection tool, I end up with a single cross section in the middle, and only on the lower half of the mold.

Also, is there a way to determine the width of each section?

The documentation is not very clear on exactly what each parameter is doing...

Thanks again
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thomas-neemann
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Re: Creating sections from a mesh object STL

Post by thomas-neemann »

Sirjaymond wrote: Mon Aug 15, 2022 12:23 pm ...
which freecad version are you using? which operating system do you use?
Gruß Dipl.-Ing. (FH) Thomas Neemann

https://www.youtube.com/@thomasneemann5 ... ry=freecad
Sirjaymond
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Re: Creating sections from a mesh object STL

Post by Sirjaymond »

I figured it out!

When I imported the mesh, it defaulted to mm instead of inches. Once I scaled the mesh up x 25.4, it started working properly :)

I think I've got it from here.

Many thanks :)
Sirjaymond
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Re: Creating sections from a mesh object STL

Post by Sirjaymond »

So I'm now stuck trying to export the sections individually to PDF, or just something I can open in Inkscape.

Can anyone tell me what the window open is at 00:25 in the video? And what is the purpose of this step?

I've attached my work in progress...

Thanks very much to anyone with some tips :)

Cheers,
Attachments
Dual Mold no mesh.FCStd
(915.66 KiB) Downloaded 5 times
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thomas-neemann
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Re: Creating sections from a mesh object STL

Post by thomas-neemann »

Sirjaymond wrote: Mon Aug 15, 2022 11:24 pm ...
Can anyone tell me what the window open is at 00:25 in the video? And what is the purpose of this step?
...
it appears after ctrl-c. I forgot to turn on screenkey, sorry
Gruß Dipl.-Ing. (FH) Thomas Neemann

https://www.youtube.com/@thomasneemann5 ... ry=freecad
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