The Ship Model Forum

Drawing and printing of this famous 20 mm gun:

I will refer primarily to this model of the PT-109 torpedo boat and my video and photo documentation.

There are a plethora of different models..

https://modelingmadness.com/review/misc/v20mm.htm



















Sketches of the cannon design:





This excellent HD video serves me well for detail and proportion.














https://youtu.be/6yCxITYzW-0

I progress slowly towards the back of the barrel, the middle is complicated.

The extreme rear is easier to decipher. It should go faster. Then it will be the turn of the magazine and the foot.

A few small details to add on the gun itself and tomorrow I'll draw the sight and the magazine.

Beginning of the drawing of the anti-aircraft sight.

Is for fun and test of the program rendering fonctions. It�s not the final rendering of course.

Pascal:

Of course an interesting project of a famous Swiss designed gun which was installed don thousands of USN vessels during WWII. I am surprised that PT 109 might have used the model with the solid base and center shaft elevating crank as this one required another crew member to operate the crank. But again that was early in the war and they would use what was available. The various one's I did in 1:192 and 1:120 are so much more simple than this large version you are doing. I did find on line somewhere (will have deleted it by now) a maintenance manual showing all the parts in disassembly and with 3D illustration.

The bag for catching the expelled cartridge brass would not be an easy subject!

Thank you for sharing another 3D adventure:

Tom

Tks Tom.

It looks well documented though...

https://modelingmadness.com/review/misc/v20mm.htm

I use this manual:

https://www.forgottenweapons.com/wp-con ... manual.pdf

I draw and print this gun for my friend Stephane who scratchbuilt an Elco 80, but this star will have no historical reality, Stephane does this for fun and let his imagination guide him.

More here: https://www-laroyale--modelisme-net.tra ... r_pto=wapp







An another 1/72 project of Stephane, the HMS Rodney, (Don't look for historical reality either) :

Scratch:

More here:

https://www-laroyale--modelisme-net.tra ... r_pto=wapp

https://www-laroyale--modelisme-net.tra ... r_pto=wapp

Very nice! One of these days I intend to create a CAD model of this gun for the WWII Cleveland class cruisers.

The Historic Naval Ships Association has a color copy of OP-911 in the Documents/Ordnance Gunnery and Fire Control page:

http://archive.hnsa.org/doc/index.htm#guns

They also have OP-909 for the base/mount and OP-1439 for the twin 20mm assemblies.

If I recall correctly a few years back someone posted a 1:24 scratch build of a PT boat on this forum. It was a beautiful and fantastically detailed model!

Phil

Pascal:

I rather like your friends imagination! Often we can improve with our hindsight what could have been for instance a WWII ship. It's an interesting intellectual exploration. A warship is a series of compromisizes The hitch is the time to construct a warship suffers from a rapidly changing war scenario. Perhaps the magnificent Iowa's would have been better replaced as the new Kongo's by the Alaska's in greater numbers. The 16" 50 MK 7 never had an opponent. The Japanese giants equally never really had an opponent and were swarmed by gnats.

Cheers: Tom

DrPR wrote:Very nice! One of these days I intend to create a CAD model of this gun for the WWII Cleveland class cruisers.

The Historic Naval Ships Association has a color copy of OP-911 in the Documents/Ordnance Gunnery and Fire Control page:

http://archive.hnsa.org/doc/index.htm#guns

They also have OP-909 for the base/mount and OP-1439 for the twin 20mm assemblies.

If I recall correctly a few years back someone posted a 1:24 scratch build of a PT boat on this forum. It was a beautiful and fantastically detailed model!

Phil

Thanks Phil, very useful for me:

https://archive.hnsa.org/doc/gun20mount/index.htm







https://youtu.be/k6hEcuYXpGg


https://youtu.be/W7qExnBNWJk

Much of sophisticated military technology is outdated by the time it enters service due to the long planning and execution times ... a few pieces of basic technology on the other hand have survived in active service for decades - the German MG42 (now G3) and the Kalashnikov comes to mind, for instance.

https://youtu.be/HwgebSpFApI

So I have some small mistakes to erase on the barrel, when you see how it works mechanically, you understand better the role of some parts and their precise shapes.

The sight is not finished.

That's an incredible amount of detail already.

Puts the ones I made for my Liberty Ship to absolute shame (they're on Thingiverse if you look for "Oerlikon" or "NavyShooter".)

https://www.thingiverse.com/thing:5259571

I'm in awe of what you guys can do!

Tks!

Yesterday I slowly resumed 3D modeling after a good break to recharge the batteries.

I've started to work on the cannon, without any real plan, but thanks to the excellent video presentation of this cannon from "Forgotten Weapons", I think I'll come up with something acceptable and credible in a while.

https://www.youtube.com/watch?v=6yCxITYzW-0







Today's advances, the mount has been modified.

Yep, these videos are very useful, as the guy shows how these thingies work from a mechanical point of view and some could be also shown in 'action'.

The HNSA website is down...

https://archive.hnsa.org/doc/gun20mount/index.htm

I don't know how long it's been, boring...

Fortunately, I saved a lot of things several months ago.

Pascal,

Your 3D work on this is really nice - I'm sure you have lots of references to use in the meantime while HNSA is down.

Hank

Iceman 29 wrote:The HNSA website is down...

https://archive.hnsa.org/doc/gun20mount/index.htm

I don't know how long it's been, boring...

Fortunately, I saved a lot of things several months ago.

The San Francisco Maritime Park Association has a webpage that is basically a copy of the HNSA's document pages, so one can try looking there: https://maritime.org/doc/index.php

Even the URLs are essentially the same except for the domain, so for the 20mm it's: https://maritime.org/doc/gun20mount/index.php

Thank you, Hank, Timmy!

Today's progress.

I've started sketching the magazine, it's not an easy object to draw, especially without real plans.