Gillmor Ordnance - Bronze Foundry Pieces

[gunsonwheels]

Has anyone out there in netherland bought any of Bob Gillmor's product?

http://www.gillmorordnance.com/Pictures.htm

http://wn.com/Casting_Bronze_Cannons

[Double D]

Looks like a pretty new website. 

Would like to know more about their process.

I don't know much about metal casting but I do see some stuff in the pictures they post that is contrary to the science of casting cannons that has been explored here before---horizontal sand cast instead of  vertical.

I don't see any thing on bores or the use liners.  This may be because the website is just going up and they haven't posted the info yet.  Let us know.

[dan610324]

I can just agree with you dd , safety is always number one
rough sand castings aint fun to deal with either
AND NO DOLPHINS 

[KABAR2]

This site has been around for a few years I have seen it before,
it has not changed since the last time I saw it, I have sent them
an email on priceing on their swivel cannon and 3 pounder.

[gunsonwheels]

Here's another link to a five part series done by a local news program.  With audio up you hear "spade drilled" for the bores and other details.  I e-mailed him and asked if he knows what they are achieving for bore/OD concentricity at the breech end.  In the video by Springfield you do see thay are casting vertically w/breech end down and I think he mentions that.  He quoted me $3200 for the 3#'er.


http://www.youtube.com/watch?v=h7mTASaTN0c

DD
I just got off the phone with Bob Gillmor and he said okay for you to contact him about becoming a sponsor:  419-355-6977

[Double D]

I would want to know more before about his process before I asked him to step up as a sponsor.

Are his barrels lined and do they meet that safety standards. 

[seacoastartillery]

     I wasn't aware that cast bronze tubes needed any liners.  I thought that bronze was tough enough and strong enough to stand on it's own.  The only one I have seen lined is the Confederate Mountain Gun with an inserted rifled liner.  A caveat to these observations is that we don't look for these field artillery items, so they might be quite common.  We need to hear from someone much more familiar with competitive shooting and how those rules apply to bronze guns.

T&M

P.S.  I must say that I was pleasantly surprised to see that Cannonmn chose Gary's Bronze Cannons with Seacoast assistance as his #3 movie on the bronze pouring movie list.  The mostly amateur camerawork is mine, but this was only 3 or 4 weeks after we bought that new camera and I was still searching for the correct buttons.  Gary and Mike did great without lighting their pants on fire.  The first bronze cannon, a small smee (pronounced 'shmee') mortar came out fine.

[gunsonwheels]

When I told him I had these two 40mm tubes around here he said welds trunnions to tubes along with a breech plug and then welds a rod to the plug extending toward the rear... and then uses that as a core to cast an aluminum barrel around (the rod allows him to keep things well centered).  He said he is selling to folks doing boat/ship re-enactments etc. and they like that solution for keeping the weights down and for land lubbers they like the higher recoil from the reduced mass/weight.  I didn't/haven't heard anything about liners in the bronze tubes.  Agree with seacoast... I think I remember there were a few original 6 pounders shooting competitively in NSSA..? ? ?  As seen in his pics he does build a full scale six pounder for around $12K.   

[Double D]

I think the issue is up for debate.

They are or were not reading it that way.  They are reading it as all barrels failing inspection must be lined.  Cast iron reproductions "fail" if they are not lined.  Reproduction barrels made entirely of steel for example do not need to be lined as that would be redundant.  There are or were unlined reproduction bronze barrels that were approved.  I have been out of that organization for a year now and I am not up on their current interpretation only what it was before I left.

We have long debated the vagaries of the N/SSA rules and Norm points out one of these vagaries above having to do with lining bronze barrels. 

The new American Civil War Skirmish Association seems to address some of the vagaries that we have discussed at length.  http://www.acwsa.org/ACWSA_Misc_Files/ACWSA_Artillery_Rules.pdf.  They clearly state reproduction bronze guns must be lined, unlike the  N-SSA rules which imply reproduction bronze barrels need a liner but as practice don't require them.

The one vague issue still remaining even in the ACWSA rules is the definition of minimum ANSI standard for extruded seamless steel tubing.  Is there a basic  minimum standard for all extruded seamless tubing, then increasing higher standards for different alloy?  That specific standard needs spelled out.   

I am inclined to consider the ACWSA standards clearer and thus more useful than N-SSA.

[GGaskill]

The main advantage of a steel liner in a bronze tube (from my perspective) it that the bore should have virtually unlimited life, unlike the typically 500 shot life of a bronze tube of the Civil War era.  The liner thickness usually used is not sufficient to carry the whole stress of firing full service loads without the bronze tube so the bronze is carrying part of the load (probably most of it), not just sitting there for decoration.

[KABAR2]

I think the main reason lining bronze tubes came about is unless you know
the pedigree of the cannon in question a steel liner removes all doubt,
by pedigree I mean who made it? was it cast vertical or horizontal?
cast solid or cored and then bored - on a finished cannon how can you tell?
as to the firing life of a bronze tube 500 rounds during the civil war with full
service loads and 500 rounds of a hobbyist shooting a bronze tube would
probably give different results as to it's service life.

I would have no problem shooting a bronze tube cast solid verticaly and bored
as an added precaution it could be x-rayed for defects.

[Max Caliber]

The Ordnance Manual of 1863 speaks of service life of cannon based on erosion of the vent, iron smooth bore guns had a service life of around 500 rounds, iron rifles had half of that. With replacement of vents, bronze guns could go on and on. On my first trip to Chickamauga NMP in 1961, I ran across a M1841 6-pdr that had hand engraved on it's chase, in large script, "Fired 1000 times 184?." It evidently went on to serve through the Civil War. I wonder if that gun is still there since some pieces are moved around from time to time.

[Cannoneer]

Max; your observation about bronze guns is right on target not only concerning our CW, but also through history. One of the most obvious examples that comes to mind is Spain, and some of the outmoded bronze muzzleloaders (some converted to rifles) that they actually still had in service during the Span-Am War. There are also original bronze Civil War guns that are currently still being used by skirmishers and reenactors, and I doubt that many of the owners know how many rounds have passed through those gun's bores.


I was in contact with Gillmor a few years ago, but didn't follow up with anything because he wasn't doing any lost wax casting, and he said himself that his sand castings were a little rough compared to the other process. I did hear him say in the local TV vid that he was now considering getting into the lost wax technique of casting.   

http://www.gboreloaded.com/forums/index.php?topic=178675.0

[gunsonwheels]

On Sons of Guns on Discovery channel they had an original Napoleon come in and which they x-rayed and then fired.  The x-ray revealed inclusions and porosity typical of bronze castings of that period.  One only has to look at the sites carrying the history of Colonial Williamsburg's efforts to cast a "bronze cannon" and witness the horrible surface porosity and inclusions  to understand what is likely below that porosity and that there can be, and are, extreme varities in casting(s).  Mr. Gillmor mentioned a competitor who was turning bronze barrels out of solid bronze "bar stock" and that his raw material cost was equivalent to Gilmor's cost of the finished product.  If the rules say all bronze tubes will be lined then what is my personal incentive to have bronze that is pure and void free?  For looks, I TIG the holes and call it good.  Personally, as a retired engineer, I would build and vote for good pure bronze and forget the liner requirement.  It makes me wonder if the rule's liner requirement for bronze doesn't actually encourage "garbage" showing up for competitions... just as long as they have a liner!

[Double D]

... Mr. Gillmor mentioned a competitor who was turning bronze barrels out of solid bronze "bar stock" and that his raw material cost was equivalent to Gilmor's cost of the finished product.  If the rules say all bronze tubes will be lined then what is my personal incentive to have bronze that is pure and void free?  For looks, I TIG the holes and call it good.  Personally, as a retired engineer, I would build and vote for good pure bronze and forget the liner requirement.  It makes me wonder if the rule's liner requirement for bronze doesn't actually encourage "garbage" showing up for competitions... just as long as they have a liner!

If  the  barrels were perfectly safe without a liner what is the rationalization/motivation for requirement for the liner?

[KABAR2]

   One only has to look at the sites carrying the history of Colonial Williamsburg's efforts to cast a "bronze cannon" and witness the horrible surface porosity and inclusions  to understand what is likely below that porosity and that there can be, and are, extreme varities in casting(s). 

I know people who work at CW and those who are trying to cast have little or no experiance casting
large amounts of bronze knowing something about things transpiring the porosity and inclusions were
due to not having their furnace hot enough to properly cast bronze, they built a larger furnace..... it sits with a solid chunk (300-400 pounds) of bronze in it from the last attempt to pour a cannon..... the team
working on this project have since been to england to study casting we will see if it took...

[gunsonwheels]

Ahh... at least half my kingdom for a chance to talk to Jan and Peter 

[Double D]

GoW after you answer this can you can tell us who Jam and Peter are?

If  the  barrels were perfectly safe without a liner what is the rationalization/motivation for requirement for the liner?

[gunsonwheels]

I'm sorry...

I was refering to Jan and Peter Verbruggen who pretty well invented/re-invented the bronze barrel casting process in England in the 1700's.  The Art of Gunfounding by Carel deBeers does a good job of covering the topic.  brass cannon and ex-limey, et.al.  are far more familiar with the book and history than I am.  But it does appear several folks (want-a-be brass founders) today are struggling to discover/re-discover what the Verbruggens apparently knew well.

If  the  barrels were perfectly safe without a liner what is the rationalization/motivation for requirement for the liner?

IF...  and it appears that at least can be a pretty big IF...  the bronze is clean or even reasonably clean I can only see two reasons for a liner: 1) Compliance with the ACWSA regulations and 2) Some idiot like me wants to sneek a rifled 40mm liner into the bore, stake it ( so the liner cannot rotate) and shoot the paint off 55 gallon drums at 500 yards...         that is soo much fun!!

[Double D]

So why would Organizations like N-SSA and ACWSA require liner in bronze guns? 

[rampa room artillery]

the requirement for liners in the n-ssa came about from poor quality  casting that were coming out during the 100th anniversery of the civil war.  whether it was cast bronze or iron.  the easy way to make sure everybody was safe was to make new cast gun have a liner.  but you can still have a cast bronze gun with out a liner as long as you submit the recipe of bronze the foundry used so that strength ability can be calculated.    as for sleavin originals i am against it.
   I shot next to a original 32 lb field howitzer two weeks ago firing 2 lbs of 1 f powder  he shot great and i was not afriad at all.  tho then he brought out one of only two original  heavy 12 lb rifled cannon. now that was a gun. again 2lbs 1 f powder.  what a bang.  liners in your gun.  all depends on the gun.  if you have not xrayed the gun. and want to shoot it. then line it.  is it a full scale bronze napoleon?  leave it alone and enjoy it.  oh and no i wont help you polish it.  lol 

 rick bryan


   

[gunsonwheels]

I too believe that is the answer...

They know what I am finding out... bronze guns, especially repros,  can be pretty crappy internally (like I said, if I get a porous and bubbly mess of a barrel casting, I can go over it with the TIG torch and make it look great... on the OUTSIDE... but it is (or can be) a bomb casing underneath).  So if I am a sponsoring organization and have to go find liability insurance to cover my events... darn right I am going to require liners.  The only other option would be for the sponsor to hire an NDT (Non-Destructive Testing) contractor to be at the meet,  out in the "south 40" with a lead encased Cobalt 60 pill, lots of film and a developing shack to assure me those UNLINED bronze pieces are safe and will not kill someone... especially if it might be me!

On the other hand, if I have machined my tube from solid bar stock and TIG'd on the trunnions, I would be inclined to stay home from shoots requiring me, with my high-integrity tube, to have a liner.  I'd go find some other rednecks to shoot against (and possibly let one of THEM kill me).  Maybe you can't win but by building garbage and lining it!!!!!!

[1swampthing]

I just picked up a full scale full bore mountain howitzer this last Friday that was cast by Bob Gilmore. The barrel does have some sand pitting on the outside but not bad with the area of the cascable being the worst. Overall I am pleased with the appearance even though it isn't perfect although I didn't pay the kind of price you would for something like a Steen. The only issue I have had so far was it was received with the trunion shoulders misshapen and not square. The barrel was sent back and Bob squared them up sufficient to fit on the absolutely beautiful carriage that I had built by Miller cannon and carriage co. Right now very few people would notice that the trunion shoulders are not perfect. I have not been real exacting so far but it would appear that all the inside and outside dimensions including powder chamber are correct or very close. I am going out of town tomorrow morning for two weeks and as soon as I get back I am going to take my barrel to a local NDT lab that claims they have examined a bronze cannon barrel in the past. They said that they would first do an ultrasonic test(I think it was) and then xray any areas that may be in any question of being solid. If the barrel is cast well then this will save on the number of xray shots needed and $. I will then get a written report of their findings. When I have this done I will try and post my results along with some pics.(need to have my wife help me figure how)

[gunsonwheels]

1swampthing,

Very, very much looking forward to your NDT results,  Thanks in advance.

GOW

[gunsonwheels]

1swampthing had his Gillmor barrel NDT surveyed a week ago last wednesday.  He reads the board often but seldom posts... maybe with some encouragement we could get him to share the results.

[Victor3]

... bronze guns, especially repros,  can be pretty crappy internally (like I said, if I get a porous and bubbly mess of a barrel casting, I can go over it with the TIG torch and make it look great... on the OUTSIDE... but it is (or can be) a bomb casing underneath).  So if I am a sponsoring organization and have to go find liability insurance to cover my events... darn right I am going to require liners. 

 I still maintain that the N-SSA's requirement for a liner in a cast gun is a dangerous false sense of security. Their stated liner dimensions along with fuzzy material and construction requirements allow a liner that cannot withstand normal BP pressures by itself. However, when stuffed into an unproven cast gun, said gun is blessed by them as safe. Incredible.

[Double D]

... bronze guns, especially repros,  can be pretty crappy internally (like I said, if I get a porous and bubbly mess of a barrel casting, I can go over it with the TIG torch and make it look great... on the OUTSIDE... but it is (or can be) a bomb casing underneath).  So if I am a sponsoring organization and have to go find liability insurance to cover my events... darn right I am going to require liners. 

 I still maintain that the N-SSA's requirement for a liner in a cast gun is a dangerous false sense of security. Their stated liner dimensions along with fuzzy material and construction requirements allow a liner that cannot withstand normal BP pressures by itself. However, when stuffed into an unproven cast gun, said gun is blessed by them as safe. Incredible.

Victor you arr back with that old argument.  Welcome back.  Can you support that statement with some references and and numbers?

[Victor3]

"That old argument" is still valid and was never successfully argued against here IMHO.

 References and numbers? I gave a pile of them last time we debated this.

[Double D]

"That old argument" is still valid and was never successfully argued against here IMHO.

 References and numbers? I gave a pile of them last time we debated this.

Do it again.

You said you were going to get Switlik pressure article and get back to us.  Did you get the article?

[GGaskill]

Can you support that statement with some references and and numbers?

Since I concur with Victor's position about a 3/8" liner giving little increase in safety, let's look at the numbers for a 6 pounder (bore of 3.62") since things only get worse as the bore diameter increases.

Using the thick wall side of my thin wall/thick wall Cylinder Stress Calculator, we find, assuming a chamber pressure of 20,000psi, the the material stress for an unsupported 3/8" liner of 3.62" bore is 107,472 psi, which is about 30,000 psi greater than the strength required (70,000 psi) by the sanctioning bodies.  Firing a tube under these conditions would most likely result in a burst, if not on the first shot, then soon thereafter.  However, we know that tubes that meet these requirements do not burst soon, maybe not ever although I doubt any of them have been fired more than 10,000 times.  So the bronze or cast iron shells must be carrying part of the load. 

My old engineering texts have sample problems of two-material structures like this and I am researching the derivation and will add it to this post once I find it.  Well, it's not in the Statics text; I will have to find the Strength of Materials text next.