Not another sticky!

[BoomLover]

What exactly are you looking for, Ramrod? Are you looking for information that is constructive in this field, or are you trying to make a point regarding something else? If it's the first, we are all here to work together to help you. In the second, you have stirred the pot, so what do you wish to gain out of it? Thanks for sticking around and hopefully learning. We are happy to have Double D here as our "Dictator of Proper Barrel Construction", because the very best teacher is experience, and he and Cat have the most experience of just about everyone here. Not only that, if you had read further, you would have discovered they started this forum, against the odds, and it has become one of the best for information on the subject worldwide. Doug, if I'm stepping out of line, let me know, ok? BoomLover

[Ramrod]

I'm not looking for anything, just pointing out some hipocracy. If that's stirring the pot, then that's the pots fault. I've seen one of these guys crouching proudly next to their DOM mortar, then on a recent thread, tell someone else they are not safe. Even when used as a liner in a cast iron barrel by a well known foundry.

[Mike H.]

I've seen one of these guys crouching proudly next to their DOM mortar, then on a recent thread, tell someone else they are not safe. Even when used as a liner in a cast iron barrel by a well known foundry.

That might explain a little.  On here a "Dom" mortar, or cannon or anything else frequently means made by Dominick Carpenter. Many on here have Dom barrels.

[Cat Whisperer]

We all have skeletons in the closet!  (Don't ask)   

I think it would prove useful to proof test two identical tubes - one of 1018 and one of 1144SP.

[Cat Whisperer]

I'll start a thread (later tonight) on failures, failure analysis.

Note the fresh cracks here are clean (outside 1/2") the OLD cracks have darkened with age and corrosion.  That is to say there are cracks that were there for YEARS before the catestrophic event.

[Double D]

I'm not looking for anything, just pointing out some hipocracy. If that's stirring the pot, then that's the pots fault. I've seen one of these guys crouching proudly next to their DOM mortar, then on a recent thread, tell someone else they are not safe. Even when used as a liner in a cast iron barrel by a well known foundry.

Again by your own words, you demonstrate you are here for no other reason than to start an argument.   

You call it hypocrisy that I made  the cannons from 1144 and I now warn other to not use that type steel.  You purposely ignore the fact that at the time the barrels were made 1144 was accepted as a gun-barrel steel and was widely used in the gun-barrel manufacturing industry.  If you were knowledgeable on this steel you would know that the failures reported were limited to a specific run of the steel  used in smokeless power rifle a barrels.  There were hundreds if not thousand of barrels made from this steel.  There was no recall of the barrels and they are still out there in use.

You further choose to ignore the fact that my reporting of my use 1144 is posted to serve as warning.  You yourself have not expressed a knowledgeable concern about steel types.  You just make a blanket unsupported statement say we don't need to follow safety guidelines.

Your words further demonstrate you are lacking in knowledge and only looking for an argument by failing know the difference between Dom Carpenter and DOM extruded steel. 

The purpose of your comments here do not appear to be to generate discussion on an interesting and important subject.  By the words you choose to use your sole purpose here seem to be to start a flame war and nothing else. 

[subdjoe]

Some years ago 1144 in particular La Salle Ebony Stress-proof was touted as the new miracle gun barrel steel...So I bought some and built two Parrot smooth bores on them.  Beautiful to machine, easy to bore. nice stuff to work with.  The came the reports of barrel failures and  Stress proof became "reviled" in gun work. 

I still have the one of the parrot barrels and I have never been able to track down the other.  The one I have sits over in the corner where it will sit until I get a liner for it.

So there is a potential pipe bomb out there, built by your own hands. Is this why you spend so much time here as the dictator of proper barrel construction? Guilty conscience? 

I think he was citing that as an example that even when There are many people out there that know for a fact that 1/2 inch thick steel walls with a properly constructed breech plug will withstand any reasonable charge of cannon grade powder, that isn't always so.   

[Double D]

Some years ago 1144 in particular La Salle Ebony Stress-proof was touted as the new miracle gun barrel steel...So I bought some and built two Parrot smooth bores on them.  Beautiful to machine, easy to bore. nice stuff to work with.  The came the reports of barrel failures and  Stress proof became "reviled" in gun work. 

I still have the one of the parrot barrels and I have never been able to track down the other.  The one I have sits over in the corner where it will sit until I get a liner for it.

So there is a potential pipe bomb out there, built by your own hands. Is this why you spend so much time here as the dictator of proper barrel construction? Guilty conscience? 

I think he was citing that as an example that even when There are many people out there that know for a fact that 1/2 inch thick steel walls with a properly constructed breech plug will withstand any reasonable charge of cannon grade powder, that isn't always so.   

No he is not, he is flaming and trolling.  This a pattern of flame posts he has dropped all over our board the past few days.

[subdjoe]

Some years ago 1144 in particular La Salle Ebony Stress-proof was touted as the new miracle gun barrel steel...So I bought some and built two Parrot smooth bores on them.  Beautiful to machine, easy to bore. nice stuff to work with.  The came the reports of barrel failures and  Stress proof became "reviled" in gun work. 

I still have the one of the parrot barrels and I have never been able to track down the other.  The one I have sits over in the corner where it will sit until I get a liner for it.

So there is a potential pipe bomb out there, built by your own hands. Is this why you spend so much time here as the dictator of proper barrel construction? Guilty conscience? 

I think he was citing that as an example that even when There are many people out there that know for a fact that 1/2 inch thick steel walls with a properly constructed breech plug will withstand any reasonable charge of cannon grade powder, that isn't always so.   

No he is not, he is flaming and trolling.  This a pattern of flame posts he has dropped all over our board the past few days.

Double D, my comment was that you gave that as an example that what Ramrod said ain't always so. 

I agree, though, that his purpose here is to flame and cause problems.

[Double D]

Yeah I see what your getting at....

[T Brooks]

Hello Everyone

As someone new to cannon building I would find it useful if there was a sticky or FAQ on some of the construction details.  I did read the safe loads and construction thread before I built my first barrel (machined from solid).  When it came to designing my second I did find it difficult to get any detailed info on a breach plug until it was highlighted to me in my discussion thread.  Perhaps I just glossed over the relevant page.

The construction page may simply need a post that states that a slip fit breach plug is not acceptable and that  an interference fit plug that is welded is required.

When I went back over the sticky and went through the links I did find the info but still think it is not well detailed.  It would be great if there was some info on how much of a shrink fit is required before welding.

Before I go any further with my howitzer plan I am going through the stress calculations and end blow out formulas.  I am going to assume 100,000psi at the moment of ignition and assume 20,000psi once the gasses are into the expansion part of the larger bore.

Cheers
Tarquin

 

[BoomLover]

T Brooks posed a good question, I'm pretty sure someone has an answer, maybe George?

[GGaskill]

I am guessing you are asking about the "how much shrink fit" question.  I don't have the shrink fit tables in front of me and they can be complicated to interpret for someone not experienced in their use.  Normally, I use the following to calculate the amount of overlap in a shrink fit:

.001" + .001" per inch of diameter.  That is, all joints no matter how large or small would be .001" overlap in size plus .001" per inch of diameter.  An example: 

I am making a Parrott style cannon barrel from 5.5" seamless tubing and I want to shrink or force fit the reinforcement on the barrel.  We are talking about small differences so the surfaces will need to be machined to get close to true roundness since seamless tubing in the raw is not perfectly round.  So say we clean up the tube diameter at 5.450"; then the hole in the reinforce needs to be .001" + (5.45 x .001") less in diameter than the tube.  That works out to be .001" + .00545" = .00645" or .0065" smaller, 5.450 - .0065 = 5.4435".

Obviously with smaller parts, the difference will be less and with larger parts the difference will be more.  And most likely the force required to push the parts together will get higher as the difference in diameter gets higher.  With small parts, you can heat the smaller diameter to expand it and freeze the larger diameter to shrink it.  Both processes become less effective as the parts get larger as it becomes difficult to control external heat sources and sinks. 

Back in the early days of the forum, a woman up in Canada made a bronze howitzer with a steel liner (see this thread) and she ended up needing 65 tons to force the liner into the bronze 22".

[Victor3]

  And most likely the force required to push the parts together will get higher as the difference in diameter gets higher.  With small parts, you can heat the smaller diameter to expand it and freeze the larger diameter to shrink it.  Both processes become less effective as the parts get larger as it becomes difficult to control external heat sources and sinks. 

 Huh?
 
 If machined, heated/cooled and timed (as in, drop that sucker in there like right now!) correctly, there will be no force required to put together a shrink-fit assy, regardless of the size of the parts.

[T Brooks]

Thanks GG

That is exactly the kind info I was looking for.  I am sure that others would find that info (even if it just a starting point) useful in a sticky.

I found an online calculator that gives the insertion force for a given set of initial conditions.  Would it be fair to assume that the insertion force would be the same as the force the burning powder would need to create to blow the plug out?

Given what you have said about heating/cooling problems with large parts would you suggest doing it at room temp or still continue with heat/cold and assume that large forces will still be required albeit less than at room temp?

Cheers
Tarquin

[GGaskill]

Would it be fair to assume that the insertion force would be the same as the force the burning powder would need to create to blow the plug out?

That would sound reasonable to me.  However, I would TIG weld the plug into the back of the tube for the primary retaining strength.  The shrink fit from my perspective is primarily to maximize the seal between tube and plug.  Also, I would put a radius in the plug so the pressure would tend to expand the plug against the sides of the tube and further maximize the seal.

I would design the plug so that at least one bore diameter is contained within the tube so it can't bend from the pressure.

[Cat Whisperer]

At work we press fit (interferrence fit) parts of motors together.  In some applications we use adhesives that set up in a few seconds.  But for the first part before it's set up, the adhesive acts as a lubricant - easing the insertion - and then it sets up.  Press fit and adhesive - belts and suspenders to ensure things stay together.

[T Brooks]

Hi GG

Exactly what I was thinking - just not saying.  My thoughts were that the weld would be sized to take the foreseeable shear loads created by the pressure and area, and the insertion force would give extra safety factor for the failure mode of blowing the end out as well as sealing the mating faces.

Cheers
T