Author Topic: Modifying a full scale 2.9 Parrott rifle (Read 1676 times)

travis_towle · « **on:** February 17, 2010, 06:45:23 PM »

I am looking into buying a full scale 2.9" Parrott Rifle (3" Bore)(1/2" Liner) from Hern Iron Works – and I was wondering if anyone has ever taken the “CAST” iron reinforcing band and had it spun off on a metal lathe, and then put a wrought iron reinforcing band and overlaid it on the breech using the process that Parrott patented.

I am a stickler for getting things as close to original as I can, and thought this would really bring the cannon up a notch. I also thought this would be a fun project o try and would make it even more original looking.

Any thoughts or ideas?

Travis
Topeka, Kansas

Double D · « **Reply #1 on:** February 17, 2010, 08:00:17 PM »

Doesn't make a lick of sense to me.

BoomLover · « **Reply #2 on:** February 17, 2010, 08:05:42 PM »

That said, welcome to the forum, if you haven't been yet. The guys here have years of knowledge, and I'm sure you will hear from several on this topic. BoomLover

travis_towle · « **Reply #3 on:** February 17, 2010, 08:54:18 PM »

Thanks for the welcome “again” lol I have been coming here since September 30, 2007 – I just always read and never post. I originally came back then in 2007 because I was looking into the full scale Mountain Howitzer – fun project, but I want something bigger now.

I like this parrott rifle design and can not afford the bronze cannon barrels – so in my research I found that the parrott was the only cast iron 10# cannon/gun used in the US Civil War, with the exception of the steel band they put on the back of it. So I want to just make the gun as close to original – with a steel band – not for any other reason but to make it as close to an original as I can, and I kind of like the idea or challenge of trying to do what parrott did back then as found in his patent.

Silly I know, but I wondered if anyone else has done this, or knows something I do NOT know like “danger or beware”…

The only other hurtle I need to find a way around is the rifling of the full scale liner – NSSA says they have to be rifled now since it had it originally. I was hoping I could find a company that would rifle it for me – or even a way I can do it on my own which would be even better.

Travis
Topeka, Kansas

KABAR2 · « **Reply #4 on:** February 18, 2010, 01:07:50 AM »

The problems you can and may run into with shrinking the band on the breech are as follows,

compressing the cast iron and causing stress cracks that over time may fail.

compressing steel liner in breech area..... if you don't think this could happen read up on the construction

Ellsworth Gun when they shrunk the trunnion on they compressed the bore and had to ream it out,

http://www.nwtskirmisher.com/useful-extra4.shtml

and you could always build a rifling machine....

How to Build a Rifling Machine.......A to Z
http://www.gboreloaded.com/forums/index.php/topic,108012.0.html

GGaskill · « **Reply #5 on:** February 18, 2010, 05:58:26 AM »

Besides the obvious problems such as a lathe big enough to turn off the cast reinforcing band, the original Parrott band was a forged bar that was wrapped around the cast barrel. While it would be relatively easy to turn a new band from round bar, forging a straight bar into the cylindrical reinforce would be a real project. Wouldn't be cheap. Would be hard to find someone with the experience to guarantee a good outcome.

It is my opinion that it would be better to make an all steel one instead of using cast iron.

Terry C. · « **Reply #6 on:** February 18, 2010, 03:25:55 PM »

Something you should bear in mind is that the original Parrott was not perfect.

Granted it was head and shoulders above other iron field guns of the time, but shooting iron artillery was a risky occupation in general. Iron guns were prone to bursting without warning.

And the Parrott was not immune, they were certainly not indestructible.

So what your suggesting, as I see it, is to take a safe replica and compromise it in the name of authenticity.

Just my opinion.

gary michie · « **Reply #7 on:** February 18, 2010, 03:56:37 PM »

Hi;

I have to agree.
Owning a Steel parrott (because wcwa will not allow cast iron on the field) I have though about rifling my bore but the parrott pattern looks as if you would have to remove a lot of metal and I've keep talking me out of it. Hern (I've been there mant times and Jole is a member of our company) does make a nice Parrott and with a big lathe will clean up very nicely.
gary

guardsgunner · « **Reply #8 on:** February 19, 2010, 09:30:24 AM »

I would have to agree with KABAR2, as far a heat shrinking on a new band. Without good temp control you cannot tell exactly how much shrinkage you will have and materials also make a differnce. If you cleaned up the casting and paint it with the proper paint,you would never be able to tell it wasn't cast in place.
Spend the money saved and build the rifling machined. The A to Z rifling machine is good but you will want to modify with a drive unit.

Bob

rampa room artillery · « **Reply #9 on:** February 19, 2010, 11:03:47 AM »

hern will cast a rifled liner in their mold but they do not take responiblity but if you get a good liner it is 5/8 to 3/4 depending on who you got it from, and will do fine in the casting most large machine shops can turn the band off, and then heat slide a new steel band on, it will be plenty strong.

rick bryan
N-SSA

guardsgunner · « **Reply #10 on:** February 19, 2010, 11:19:20 AM »

But what is the gain for the expense and time/work involved ?

Artilleryman · « **Reply #11 on:** February 19, 2010, 11:35:54 AM »

If you have a proper liner, and proper ammunition, the gun is strong enough. If I was going to put in a rifled liner, I would have the barrel cast solid, bored and lined. Check with the Paulson Brothers.

daninwyoming · « **Reply #12 on:** March 15, 2010, 09:56:50 PM »

The process you are asking about is shown in a series of pictures on hatchergun.com under the subheading "black powder cannons". There is a lot of precision machining involved and the distortion can be handled by keeping the tolerances very "tight". The outside reinforcing band can compress the bore of the tube if placed on too tight. This is an advantage in one way. It puts compressive stresses on the liner and casting to reinforce it, similar to the way pretensioned cables in concrete add tensile strength to concrete beams. I don't believe the shrinking liner would cause cracking in the cast if installed properly. The reinforce is compressing the inner layers and they are very strong in compression. The tension forces could be a problem on the boundarys of the reinforce. I agree with DD. I would not try to do the original Parrott method of hammer banding.

KABAR2 · « **Reply #13 on:** March 16, 2010, 01:26:45 AM »

Quote from: daninwyoming on March 15, 2010, 09:56:50 PM

The process you are asking about is shown in a series of pictures on hatchergun.com under the subheading "black powder cannons". There is a lot of precision machining involved and the distortion can be handled by keeping the tolerances very "tight". The outside reinforcing band can compress the bore of the tube if placed on too tight. This is an advantage in one way. It puts compressive stresses on the liner and casting to reinforce it, similar to the way pretensioned cables in concrete add tensile strength to concrete beams. I don't believe the shrinking liner would cause cracking in the cast if installed properly. The reinforce is compressing the inner layers and they are very strong in compression. The tension forces could be a problem on the boundarys of the reinforce. I agree with DD. I would not try to do the original Parrott method of hammer banding.

What I would like to know is how do you know if it was installed properly this is not something a shop does every day, especially with cast iron,
this is not something you want to guess at and I believe the learing curve in doing it could be costly, it the band is too tight how would you know
if there are stress fractures under it? The gun as cast will hold up to the pressures and work fine mucking about banding it may end up giving you
something that has no greater performance and keep one guessing if it will come apart on next shot. as to compressive stresses on the liner if you
compress it and a ball gets stuck in the breech you have a problem....... and comparing this to concrete beams is apples and oranges....... concrete
beams are made to take a certain load usually from one direction and with known parameters, here we are talking a cylinder which has forces acting
on it from within and the pressures are more fluid than the stress on concrete and vary depending on the powder used and quantity used & projectile weight
etc. If one wants to go through the expense of experimenting go for it but realize in the end you are not going to get a better cannon......

Double D · « **Reply #14 on:** March 16, 2010, 05:42:55 AM »

Quote from: daninwyoming on March 15, 2010, 09:56:50 PM

The process you are asking about is shown in a series of pictures on hatchergun.com under the subheading "black powder cannons". There is a lot of precision machining involved and the distortion can be handled by keeping the tolerances very "tight". The outside reinforcing band can compress the bore of the tube if placed on too tight. This is an advantage in one way. It puts compressive stresses on the liner and casting to reinforce it, similar to the way pretensioned cables in concrete add tensile strength to concrete beams. I don't believe the shrinking liner would cause cracking in the cast if installed properly. The reinforce is compressing the inner layers and they are very strong in compression. The tension forces could be a problem on the boundarys of the reinforce. I agree with DD. I would not try to do the original Parrott method of hammer banding.

Hatcher Guns-Blackpowder cannon

Frank46 · « **Reply #15 on:** March 16, 2010, 06:53:02 PM »

I'm certainly no expert. But have you given thought to the different thermal expansion rates of the two different metals on your project?. The steel band and the cast iron of the bbl. You possibly could set up stresses in the cast iron barrel and the steel band as two disimilar metals. Like I said no expert. Just curious. Frank

GGaskill · « **Reply #16 on:** March 16, 2010, 07:51:12 PM »

The whole idea of the reinforcing band is to put the cast iron in compression before the shot so that some of the force of the propellant is used overcoming it, thereby lower the tensile force the cast iron has to resist. At the same time, the wrought iron band is stressed in tension which it can resist better than the cast iron.

The usual shrink fit dimensions are .001" plus .001" per inch of diameter, so the wrought iron band would have a hole .010" smaller than the 9" cast iron part of the barrel, at least for a 3" Parrott. The thermal expansion rate of iron and steel is about 6 millionths of an inch per inch per °F, so the band would have to be heated about 200°F above ambient to expand the hole .010". My guess is it would be heated about 400°F above ambient so that it slipped on with no trouble.

If the maker wanted more compression, he would make the hole smaller, raise the heat hotter.

RocklockI · « **Reply #17 on:** March 16, 2010, 10:19:04 PM »

George , I believe it is the 'coeffciant of thermal expansion' and not the thermal expansion you mentioned .

I could be wrong but that is what I was taught .

Sorry couldnt resist

Gary

KABAR2 · « **Reply #18 on:** March 17, 2010, 01:34:58 AM »

The Hatcher gun site is interesting.... through out the build they are using steel,
and are using 19th century methods of building up a tube, the gun produced should be much stronger
than those produced from cast iron and Wrought iron the banding and compression on the steel will
be different than that done on the cast iron, it appears builder of this cannon looks like they have done it before,
my main concern is someone taking a cast cannon to a local machine shop and having the banding done
too many variables - one being experience, one of the members here when shrinking on the trunnion shrank
the bore and had to ream it out this was a breech loader.... now apply the shrinkage to the breech of a muzzle loader
it's a long way down to the breech to have to be reaming......and on a rifled gun to boot.

GGaskill · « **Reply #19 on:** March 17, 2010, 04:56:47 PM »

I believe it is the 'coefficient of thermal expansion' and not the thermal expansion you mentioned.

OK, that is the formal name, thermal expansion rate seemed close enough.

daninwyoming · « **Reply #20 on:** March 17, 2010, 08:12:33 PM »

The physical principle that applies to expansion or contraction of materials as they are heated or cooled is called thermal expansion. I do know of any material that doesn't expand when heated. If any knows of one I would like to know what the material is. The number that applies to this physical trait is called "the coefficient of expansion". Sometimes it is also called "the coefficient of linear expansion". I don't know how linear the number becomes when approaching the outer limits. Is the number the same at 300 degrees below if using liquid nitrogen to shrink the material. Or at the high end at 400+ degrees to expand the material. GGaskill was right on with his analysis. We use the numbers in his post and they work very well (0.0000067 inches/inch/ degree Fahrenheit). We do not like to go above 400 degrees fahrenheit to prevent taking the "temper" out of the steel. The lathe we used to machine the reinforce cuts a slight taper so we backed off the 0.001 inch/inch of bore figure. We put a shoulder half way down the bore to locate the reinforce when hot. We bored the reinforce from both ends to minimize the affect of the taper. The reinforced sleeve slides right on and in 30 seconds is part of the assembly. (Can not be moved).

daninwyoming · « **Reply #21 on:** March 17, 2010, 08:45:31 PM »

Before doing anything to your Parrott rifle, I would suggest studying the most famous Parrott rifle called the "Swamp Angel". Try a google search for "Swamp Angel". The reinforce didn't break, but "all hell broke loose" and it landed on the revetment.

seacoastartillery · « **Reply #22 on:** March 18, 2010, 05:15:01 AM »

   Gentlemen, This is just a little more info on why it is imperative to have your ducks-in-a-row BEFORE you use the technique of heat-expansion and shrink fitting. These items are referenced from our actual experiences while building the Mallet's Mortar Jr. in 2007. The entire thread, if you have any interest, can be found at: http://www.gboreloaded.com/forums/index.php/topic,125169.0.html

The illustrative portion is here:


   "We spent some long hours in the shop finishing this junior size Mallet's mortar, but other than learning a few new (BAD) words from the "Old Salt" as he was machining the base plate, retaining ring and trunnion out of a solid block of 1018 steel, everything went quite well. After heating the base at 400 deg. F. in the oven for a full hour to provide easy assembly of the tube into the expanded retaining ring of the base, Mike slid the two parts together a full 30 deg. out of cync! After 2 or 3 seconds he realized this and yanked the ring around to the correct alignment just in time! At this point, I heard more of those words my mom forbade me ever to say.

The base, retaining ring and trunnion structure is all one piece of 1018 steel, carefully carved out with a variety of tools on our Bridgeport Mill. Quite a bit of filing was needed in hard to reach areas as well."

Regards,

Tracy and Mike

The tube which fit inside the thermally expanded Base Retaining Ring.

The machined Base Ring which was heated to 400 deg F. in the kitchen oven. The 2.5" ring was expanded by .0057" which was plenty, but not having too much material around the ring, it cooled quickly and quick action was required by Mike to save it!!

carronader · « **Reply #23 on:** March 18, 2010, 07:58:02 AM »

heeeeeeeeeeeeeeeey Muskrat...I'm impressed.

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Re: Modifying a full scale 2.9 Parrott rifle
« Reply #17 on: Yesterday at 02:19:04 AM »

Reply with quoteQuote
George , I believe it is the 'coeffciant of thermal expansion' and not the thermal expansion you mentioned .

I could be wrong but that is what I was taught .

Sorry couldnt resist Grin Wink Cheesy Grin

Gary