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Michael
3rd Apr '11, 02:10
So I made this in turbocad the other day, it's the brass casing (minus the bullet) of a 7.62 x 51 NATO round, a full sized rifle cartridge.

http://www.mechanicaldesignforum.com/forum/images/miscellaneous/Michael.jpg

xmechanic
4th Apr '11, 00:43
And your point is?

Michael
4th Apr '11, 01:09
Well no point, this is the forum where we show stuff made in CAD, and this is what I made...

MetalDesigner
4th Apr '11, 02:48
The casing drawing looks very nice. Don't worry about others on this forum acting superior or arrogant ... sometimes people forget that no one is born with this knowledge and we all had to start somewhere. Keep drawing things and submitting them. The best practice is to find normal things that have unusual shapes and draw them. The Rifle Shell Casing was a good idea... maybe work on drawing the parts in the rifle action assembly next.

maniacal_engineer
4th Apr '11, 22:14
Cool model. I seem to remember hearing that the walls are not constant thickness. So what would be a good way to model that? I don;'t think there is a variable thickness shell option. is there a variable offset entities option?

Michael
4th Apr '11, 22:59
You would do a solid subtract; make a shape of the 'inside', place it appropriatley inside the casing, then subtract the inside shape. I couldn't find dimensions concerning the inside, so I just left it solid. And thanks for the compliment.

Strambo
5th Apr '11, 06:51
Looks like a good shell casing to me; one of my favorites, in fact. I have a good .308 target rifle that shoots basically the same cartridge.

For the variable thickness: I would probably model this as a revolved solid, and just set the thickness in the sketch explicitely.

Upward and onward...

Michael
30th Aug '11, 20:27
Thanks for the compliment; I find in Turbocad doing either the subtraction or revolving works equally well, and taking same amount of time for each method. Thanks guys for the compliments :)

mrroy76
8th Apr '12, 11:27
Hi, i see this is an fairly old thread, but my suggestion to do this model if you know the thickness is to draw the cartridge profile, both inside and outside profile. Make this a closed sketch. And revolve it around the center axis. Voila and you have a correct cartridge :)

Strambo: You are right about the 308. Will just explain the difference. 7.62x51 is the military description of this bullets. And 308 are the civillian description. Exactly the same measurments of these two. The reason iknow these is because i worked for several years in the Norwegian infantery and have been shooting civilian competitions with 308.

Norwegian armed forces used 7.62x51 nato on their Heckler kock G3 or AG3 as we named it. But a few years ago they switched to 5,56 x 45 NATO that are pretty mutch like 223 . But my knowledge of this cartridge is very little.