Rifling simulation and scopes

Forum for Armortek Owners to Meet, chat and share knowledge. You are advised to check 'official advice' before carrying out any modifications.
Post Reply
Jerry Carducci
Posts: 20
Joined: Sun Apr 05, 2020 7:38 pm
Contact:

Rifling simulation and scopes

Post by Jerry Carducci » Sat Jul 04, 2020 4:12 pm

Hello all. Two questions
  • What is the current thinking/ solution for simulating rifling in a main gun barrel; I've heard of various inserts- 3D printed or rolled metal
  • Is there a supplier for AFV optical equipment or is each up their own design? I've simulated these in smaller scale but here more detail in needed
I read a thread where a fellow approached a gun maker ostensibly to cut actual grooves in a barrel but it was deemed impractical, Why? It would seem
a short plug broach could be made, likely more than one to cut shallow (very shallow) grooves for a short length of the barrel. Using a PaK 75 as an example having 32 grooves and a progressive twist (I believe anyone could be forgiven the progressive part in a model!). I don't have the exact groove depth of the original to hand but a few thousandths of an inch for a model should be sufficient.

Thoughts?

Be well.

Jerry Carducci
http://tanks.linite.com/ - RC tanks: stay home, build a tank and save a life!

User avatar
Robert E Morey
Posts: 1767
Joined: Wed Jul 18, 2007 12:59 am
Location: Seattle, WA USA
Been Liked: 144 times

Re: Rifling simulation and scopes

Post by Robert E Morey » Sat Jul 04, 2020 7:17 pm

Hi Jerry
I think the 3D printed rifling insert is most practical. The ease of modeling the insert and printing the insert with high accuracy are the two biggest factors. The inexpensive resin printers available now can do just that. If you don't get your first design just right - its easy to tweak the model and print another.

But some folks don't like plastic parts on metal models, so other methods could be explored. Could you rifle the barrel - sure if you have the equipment and know how. Could you make a tank barrel from a large bore rifle barrel - probably, may not be scale and involves a lot of machining. The late Mike Stannard and perhaps others experimented with flat photo-etched rifling inserts that were then rolled and glued in the barrel. This option does solve the metal material question but creates new challenges -getting a flat sheet round and to the correct size. All possible with fiddling. Perhaps if you must have metal part - creating a rifled plug insert (instead of the entire barrel) would be another possibility.

I suppose it depends on how accurate you want it to be and what purpose it would serve once complete. The 3D printed part will look just like the real thing once painted and weathered, so in the end that is the most practical for me. For my needs there is no need for a fully rifled barrel that no one would really see.

There are several members which have used FPV for steering tanks - I don't know if that answers your "optics" question.

Best regards,
Bob

User avatar
Stephen White
Site Admin
Posts: 2623
Joined: Sat Oct 11, 2008 7:05 pm
Location: Dorset
Has liked: 377 times
Been Liked: 935 times

Re: Rifling simulation and scopes

Post by Stephen White » Sat Jul 04, 2020 8:34 pm

This is where Mike Stannard got the idea for barrel rifling.

http://www.armortek.co.uk/Forum3b/viewt ... &start=450

I milled the lands but I think now I would use photo etch.

I also bored out the kit muzzle to accommodate the thickness of the insert material, giving an accurate calibre weapon.

Jerry Carducci
Posts: 20
Joined: Sun Apr 05, 2020 7:38 pm
Contact:

Re: Rifling simulation and scopes

Post by Jerry Carducci » Sat Jul 04, 2020 8:51 pm

Thanks for the insight into simulating rifling grooves. A rifle barrel wouldn't do to simulate a large bore as just the groove count alone
wouldn't be close.

Apologies for the lack of clarity surrounding the optics question. By optics I meant episcopes/ periscopes, vision ports and other optical
glass items used in a tank.

Jerry
http://tanks.linite.com/ - RC tanks: stay home, build a tank and save a life!

User avatar
Adrian Harris
Posts: 3999
Joined: Thu Jul 12, 2007 10:46 pm
Location: Berkshire (UK)
Has liked: 310 times
Been Liked: 425 times

Re: Rifling simulation and scopes

Post by Adrian Harris » Sat Jul 04, 2020 10:08 pm

Various people have made resin optics for cupolas etc, but I believe it was only Mike Stannard (FOA) who made optically reflective prisms in this scale.

Adrian.
Contact me at sales@armortekaddict.uk for details of my smoker fan control module and other electronic gadgetry

Robert Reid
Posts: 476
Joined: Mon Oct 09, 2017 9:49 pm
Has liked: 71 times
Been Liked: 318 times

Re: Rifling simulation and scopes

Post by Robert Reid » Sun Jul 05, 2020 1:44 am

Jerry Carducci wrote:
Sat Jul 04, 2020 4:12 pm
  • Is there a supplier for AFV optical equipment or is each up their own design? I've simulated these in smaller scale but here more detail in needed
Jerry Carducci
viewtopic.php?f=50&t=7752&hilit=mirbat&start=30

I did my own optics, simulating the lenses with German Silver highly-polished and clear epoxy.

Cheers,

RPR

Jerry Carducci
Posts: 20
Joined: Sun Apr 05, 2020 7:38 pm
Contact:

Re: Rifling simulation and scopes

Post by Jerry Carducci » Mon Jul 06, 2020 4:19 pm

Robert Reid wrote:
Sun Jul 05, 2020 1:44 am
Jerry Carducci wrote:
Sat Jul 04, 2020 4:12 pm
  • Is there a supplier for AFV optical equipment or is each up their own design? I've simulated these in smaller scale but here more detail in needed
Jerry Carducci
viewtopic.php?f=50&t=7752&hilit=mirbat&start=30

I did my own optics, simulating the lenses with German Silver highly-polished and clear epoxy.

Cheers,

RPR
Interesting approach to the simulation of optics, thanks for that. Marvelous work on the 25 pounder.

In terms of simulating rifling with some type of insert what length seems to work best? That is, how far back
from the muzzle does the insert need to extend to have a good appearance? I seem to recall Per mentioning
something about a rolled photo etch piece he experimented with.


Jerry
http://tanks.linite.com/ - RC tanks: stay home, build a tank and save a life!

User avatar
Adrian Harris
Posts: 3999
Joined: Thu Jul 12, 2007 10:46 pm
Location: Berkshire (UK)
Has liked: 310 times
Been Liked: 425 times

Re: Rifling simulation and scopes

Post by Adrian Harris » Mon Jul 06, 2020 5:29 pm

The ones Vince designed for the Chieftain are 25mm long and 20mm in diameter.

I haven't seen one painted black but I would imagine any longer and the grooves would be invisible.

The bigger the bore, the longer the plug would need to be. A muzzle brake makes the rifling all but invisible, except through the side vents.

Although machined and rolled metal sheet means you are not adding plastic to the kit, I do think the grooves can cause the metal to deform as it is rolled, leading to a plug which is no longer nicely cylindrical.

Adrian.
Contact me at sales@armortekaddict.uk for details of my smoker fan control module and other electronic gadgetry

Christoffer Ahlfors
Posts: 463
Joined: Sun Feb 14, 2010 5:19 pm
Location: Stockholm, Sweden
Has liked: 302 times
Been Liked: 105 times

Re: Rifling simulation and scopes

Post by Christoffer Ahlfors » Sat Jul 11, 2020 11:33 pm

Jerry Carducci wrote:
Mon Jul 06, 2020 4:19 pm
In terms of simulating rifling with some type of insert what length seems to work best? That is, how far back
from the muzzle does the insert need to extend to have a good appearance? I seem to recall Per mentioning
something about a rolled photo etch piece he experimented with.

Jerry
Hello Jerry!
This is the insert Per Sonnervik made for his hunting tiger. It's made of copper and as far as I know, Mike Stannard used nickel silver. Presumably then, Per "rolled his own" so to speak, but I am pretty sure that Stephen's idea is what spawned this.

In terms of getting it properly cylindrical, this is how it came out. He used a roller similar to that in Stephen's article and fitted it to the plug in this picture:
IMG_6456_RESIZE.JPG
It has a slip fit in the barrel:
IMG_6457_RESIZE.JPG
The length of this insert is 37mm.

Hope this helps!
:D
Klotzen, nicht kleckern (Guderian on panzer tactics, but the way I interpret it - it applies to a great many things in life)

Christoffer Ahlfors
Posts: 463
Joined: Sun Feb 14, 2010 5:19 pm
Location: Stockholm, Sweden
Has liked: 302 times
Been Liked: 105 times

Re: Rifling simulation and scopes

Post by Christoffer Ahlfors » Sat Jul 11, 2020 11:36 pm

I see now that the boys need to clean the barrel out properly. Amazing how revealing a photo is! :shock:
Klotzen, nicht kleckern (Guderian on panzer tactics, but the way I interpret it - it applies to a great many things in life)

Jerry Carducci
Posts: 20
Joined: Sun Apr 05, 2020 7:38 pm
Contact:

Re: Rifling simulation and scopes

Post by Jerry Carducci » Sun Jul 12, 2020 11:39 pm

I must look back on my email from Per. I do recall when he told me about that insert. I though at the time it was a clever solution. I also had a reference to the 128mm PaK that described the rate of twist and number of grooves however I can't locate it presently. This is good information as I'm on the list to receive a Jagdtiger kit!

Jerry
http://tanks.linite.com/ - RC tanks: stay home, build a tank and save a life!

User avatar
Adrian Harris
Posts: 3999
Joined: Thu Jul 12, 2007 10:46 pm
Location: Berkshire (UK)
Has liked: 310 times
Been Liked: 425 times

Re: Rifling simulation and scopes

Post by Adrian Harris » Mon Jul 13, 2020 10:15 pm

Armortek have supplied details of the JT barrel so plans are afoot for a 3D printed plug.

The Andrew Dewey book has all of the details apart from the rate of rotation, so if you did find that reference it would be most helpful.

Adrian.
Contact me at sales@armortekaddict.uk for details of my smoker fan control module and other electronic gadgetry

Robert Reid
Posts: 476
Joined: Mon Oct 09, 2017 9:49 pm
Has liked: 71 times
Been Liked: 318 times

Re: Rifling simulation and scopes

Post by Robert Reid » Tue Jul 14, 2020 12:05 am

Rate of rotation for most artillery (large bore guns) is 1:15 - 1:20 calibers....

So if you have a 100 mm gun, you are looking at a twist rate of 1 turn in 1500 MM to 1 turn in 2000 mm.

Tends to be a slower twist rate with larger bores. So if you are trying to do a large-bore 128mm PAK-type Maus cannon, you are probably looking at a twist rate if one turn in about 2.5 meters.

This is a guideline.... But as I collect, restore and shoot large (live) artillery (including making my own shells)... I can say this guideline pretty much applies. Of course, these days, smooth bores and fin-stabilized sabots are sort of the rule. But in the good 'ol days, this formula gave a general guideline.

As for count of lands/grooves... someone needs to visit the Tank Museum or Aberdeen MD and start counting!

Hope this helps!

Cheers,

RPR

Post Reply