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Posted: Wed Apr 06, 2011 6:32 pm
by Robert E Morey
Stephen,
Mucho gusto modifications to the gun. She looks a lot tougher now -able to deal some serious punishment. Fantastic work in all regards. I too am interested to see how you solve the rifling challenge. The 75mm looks great on the P3 chassis.
Best regards,
Bob

Recoil

Posted: Wed Apr 06, 2011 10:22 pm
by Stephen White
More work on the recoil system.

Chosen to go down the pneumatic route, having considered servo operated cams etc. This is a Robarts Air System designed for flying models. There is a limited choice of air cylinders but fortunately one was available with the right travel. I suspect that you could adjust the travel using some packing glands. This cylinder is fine for the small barrel of the L24 but wouldn't be man enough for the bigger guns.

This is a bench test of the system:

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I introduced a universal joint to reduce the chance of friction from a slightly off bore setup and had to machine a fitting for the barrel end with a hole to allow flash and smoke if I choose to fit them later:

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A test in the turret:

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And the outside effect:

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I'll post a short video soon. Next work is to make a mounting plate for the servo and air valve. Then to synchronise the recoil with the sound. Help!

Regards

Stephen

Posted: Wed Apr 06, 2011 11:26 pm
by Steven Day
That's one very nice tank you're building and I love your recoil system. I can't wait to see the video.

I noticed you have a hole drilled through the side, is this for a firing / smoke mechanism?

Steve

Recoil take two

Posted: Sat Apr 09, 2011 7:06 pm
by Stephen White
Completed the installation of the recoil system. Firstly, this bracket was made up to install the servo and adjustable air valve:

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The benefit of a pneumatic system over a straight servo operated system is the flexibility to place the servo anywhere. With a turret as tight as the Pz III, I didn't think there was room for a servo operated system. Here is the general layout:

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And here, the system in operation:

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Regards

Stephen

Posted: Sat Apr 09, 2011 7:30 pm
by Stephen White
Sorry Steve, I didn't answer your question. Yes, the hole in the barrel fitting is to give access to the barrel bore in anticipation that someone with more skill and knowledge than me will crack how to introduce smoke with gun firing. I think smoke would be really effective in simulating gun firing whereas muzzle flash is really more appropriate for MG firing. A tank main armament is designed to suppress flash both with the type of propellant charge and the design of the gun. So a good blast of smoke down the barrel would do it for me.

Regards

Stephen

Posted: Sun Apr 10, 2011 12:28 am
by Tim Bowman
Very nice.

I am really liking that L24 gun. Nice job on the recoil mechanism.

Bets regards
Tim

AIR RECOIL

Posted: Sun Apr 10, 2011 1:10 pm
by phil fitzpatrick
Hi Stephen
I am very impressed with your Panzer Recoil system brilliant.
I have been regularly following your Panzer Build and Tim's Tiger
Both amasing details and skills to learn from.
I've just finished my Comet recoil today with Halogen flash,servo
and timers to interlock with the sound.
I had my gun connection bored out as much as I could for the
Gun smoke.
Before fitting the Halogen flash with its cables I experimented
with Armortek's standard smouker up an empty barrel and it wasnt
too bad,but I think with Armorteks upgraded fan or Richies with
the fan turned right up it would be even better.
I have left a spare contacts on one delay off timer and a seperate
relay to turn on the elements to cook up a pot of smoke,which
would then be fired up the barrell in time with the recoil,flash and
sounds but held on for a bit.
The only snag is it works better up an empty Gun barrel like
the full sizel Gun.
So it may be a "Bridge too far" for my Comet unless the upgraded
smokers can power it out of a narrow tube,and still come out
realistic.
Cheers
Phil

Smoke

Posted: Sun Apr 10, 2011 9:00 pm
by Stephen White
Thanks for the coments Phil - I've been following your work with a lot of interest. I'm impressed you cracked how to get the timing sorted so that sound, flash and so on happen in the right sequence. I'm not good enough with electronics to do that without some guidance and for the moment I've got the recoil on Switch 7 and sound on the rotary encoder.

I really think smoke is worth persisting with but only if we could get a good blast out of the muzzle. We'll crack it in the end.

Best regards

Stephen

Barrel Rifling

Posted: Sun Apr 10, 2011 9:16 pm
by Stephen White
Well, couldn't put off doing the rifling any longer.

First move was to select some .032" brass sheet and mill the lands. The L24 rifling was at 020 degrees to the barrel axis. I broke two small milling cutters before resorting to a small centre drill which worked fine as an end mill and even produced the chamfered edge to the rifling of the real thing:

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I turned a mandrel at muzzle diameter less two lots of .032" on which to do the final rolling and soldering. The brass was annealed ready for rolling on the small rolling press:

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The tube was then held in the vice to allow the seam to be silver soldered:

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Final tube ready to insert in the barrel:

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And the finished effect:

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It's a relief that the method worked.

Best regards

Stephen

Posted: Sun Apr 10, 2011 9:26 pm
by leesellars
Hello Stephen

I love the rifleing well done

Lee

Rifling

Posted: Sun Apr 10, 2011 9:31 pm
by phil fitzpatrick
Excellent work on the rifling detail Stephen and the photo's
show off the thought and effort that went into making that part of
your gun.
Its crying out for some rounds to be sent down it now :lol:
Cheers
Phil

Posted: Sun Apr 10, 2011 9:33 pm
by simon_manning
very nice stephen and just what i wanted to know, lovely job! regards simon manning.

Posted: Sun Apr 10, 2011 9:39 pm
by Paul Morris
Fantastic :D what a great job you have done, now I know how to try to go about it doing myself for the Jagdtiger project very neat set of rolls to form the tube can I ask where you got them from?
Well done again top job.
Cheers Paul :wink:

Posted: Sun Apr 10, 2011 11:10 pm
by Adrian Harris
Superb detail Stephen - it really looks the part :D

Adrian.

Roll Press

Posted: Mon Apr 11, 2011 9:56 am
by Stephen White
Paul

Axminster Tools stock them here:

http://www.axminster.co.uk/sieg-miniatu ... rod815796/

I think the price is exhorbitant and I managed to find mine second hand on that other web site. I did invest in a Sieg Miniature Shear Brake and if you're doing any serious sheet metal work, it's a real godsend for accurate cutting and bending:

http://www.axminster.co.uk/sieg-miniatu ... rod815792/

Best regards

Stephen