[Solved] Need help modelling a rifled barrel

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nobeltnium
Posts: 16
Joined: Fri May 26, 2023 7:24 am

[Solved] Need help modelling a rifled barrel

Post by nobeltnium »

I found similar thread on our forum but it was from over 10 years ago: viewtopic.php?t=3252&sid=4df0a4af1433a9 ... 7e4c53f2f8
I think it's appropriate to make a new one
FYI: I'm using FreeCAD 0.20.1

I want to model a rifled barrel. With 4 land and 4 grooves. It should looks something like this from the front
Image
This picture below just to show how it would look in real life. Don't mind the number of land and groove on this one. I only need 4
Image

I'm thinking of create a pad from sketch. Then somehow induce twist to the whole thing. But i don't know how. This is as far as i can get
Image
Image

UPDATE:
For any user trying to find a way to model rifled barrel like me. I suggest to go with the Subtractive Helix method.
The example file below model a 45 ACP barrel section. Groves were made using SubtractiveHelix and PolarPattern
rifling_example.FCStd
(104.24 KiB) Downloaded 9 times
Last edited by nobeltnium on Wed May 31, 2023 6:35 pm, edited 2 times in total.
Nobeltnium
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NewJoker
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Re: Need help modelling a rifled barrel

Post by NewJoker »

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Shalmeneser
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Re: Need help modelling a rifled barrel

Post by Shalmeneser »

:idea:
(problem when different sketches are on the same plane : PartDesign_AdditiveHelix is not always a friend)
Attachments
Annotation 2023-05-30 113047.jpg
Annotation 2023-05-30 113047.jpg (22.45 KiB) Viewed 805 times
Barrel_SHALM.FCStd
(152.24 KiB) Downloaded 8 times
nobeltnium
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Re: Need help modelling a rifled barrel

Post by nobeltnium »

: PartDesign_AdditiveHelix is not always a friend
May i ask why? What happen if multiple sketches are on the same plane?
Nobeltnium
drmacro
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Re: Need help modelling a rifled barrel

Post by drmacro »

nobeltnium wrote: Tue May 30, 2023 10:03 am
: PartDesign_AdditiveHelix is not always a friend
May i ask why? What happen if multiple sketches are on the same plane?
It can cause what's referred to a coplaner failures. It is hard to describe, but when you see missing faces or faces that seem to poke out in odd directions from expected model shapes. Once you've seen it happen, it's easy to recognize.
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
frcaduser
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Re: Need help modelling a rifled barrel

Post by frcaduser »

Hello,

reference the attached sketch ... adjust to your dimensions.

frcaduser
Attachments
barrelCrossSection.FCStd
(22.88 KiB) Downloaded 9 times
nobeltnium
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Re: Need help modelling a rifled barrel

Post by nobeltnium »

Hi frcaduser
Not sure if i'm missing something here. I opened your file and don't see any twist rating on you rifling (it need to be twisted, that's why i asked)

Regards.
Nobeltnium
frcaduser
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Re: Need help modelling a rifled barrel

Post by frcaduser »

nobeltnium wrote: Tue May 30, 2023 12:36 pm Hi frcaduser
Not sure if i'm missing something here. I opened your file and don't see any twist rating on you rifling (it need to be twisted, that's why i asked)

Regards.
I corrected the cross-sectional design. You can follow Shalmeneser's post/project for adding the internal helix at your end.

frcaduser
Last edited by frcaduser on Tue May 30, 2023 5:48 pm, edited 3 times in total.
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papyblaise
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Re: Need help modelling a rifled barrel

Post by papyblaise »

I took several minutes to understand that he persists in helixing in Y, you have to force him in Z
Attachments
barrel.FCStd
(334.76 KiB) Downloaded 11 times
barrel.JPG
barrel.JPG (26.85 KiB) Viewed 599 times
nobeltnium
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Re: Need help modelling a rifled barrel

Post by nobeltnium »

Wow that's super papyblaise! I really haven't think of that
I was able to reproduce drmarcro method on my model and it works great. But helixing the sketch made things super simple and less work :o

I also notice that with drmacro method, once i introduce the Polar Pattern fundtion it takes a big toll on my machine. Everytime i open/close a sketch or changing the twist rate, FreeCAD will hang for 30-40 seconds even though htop and task manager show little CPU and HDD usage. My rig isn't wimpy either, she has a i5-9400 with 64GB of RAM with FreeCAD using only 2GB. Not sure if this is something every one encounter or there's something wrong on my end.

Nobeltnium.
Nobeltnium
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