Rifled Cannon Liners (Sleeves) in 1.000" Bore size Coming Soon...........

[Victor3]

   
     

 Will you be able to offer minor turning of the blank's OD, to blend the area left by the 4" long register you machine at the muzzle? I have an idea to maybe use the blank as is.   

 
      Yes, we can; email us a sketch.  Ah, function over form; we have done this many times and we still have those cannons too.  Some are surprisingly accurate! 
 
 Tracy
 

 Thanks, Tracy. I'll send a sketch when you get close to production. 

   

With the cannon empty, we went through all the motions of loading, setting the tube position on the elevation screw and removing the scope and what we found was the tube DID NOT reliably go back to the same elevation each time.  There was not enough weight on the breech end (preponderance).  Recoil DOES NOT translate 6:1 with the original gun either.  With these scale guns recoil is violent! However, scale service powder charges are the most accurate, so you must tame recoil by building nearly perfect braking devices and once in a while augmenting these historical brakes (counterhurters) by other means which are completely hidden from view.  To correct vertical stringing, we merely changed the drawing and put 12 pounds of preponderance on the tube which weighs 100 Lbs.  This fixed the problem and the tube settles nicely now and is repeatable, shrinking the group size to 2.5". 

 On my 1st scratch-built cannon (1" smooth bore) I added a couple of features that improved accuracy. One was a 2nd screw in front, to lock the elevation set by the rear screw. This prevents the barrel from pivoting at the trunnions when the gun is fired...
 

 
 Some added weight via two 1/2" steel plates (one inside under the bbl and one under the carriage) keeps the gun from jumping off the ground...
 

 
 It's not quite as elegant nor accurate as a Seacoast Artillery model.    I've learnt me a few things since building this one ~17 years ago though, mostly from this very forum.
 
 When I get my hooks into a 1" Seacoast Super Special Spiral bbl, I'm gonna build me my dream cannon. It will be ugly, but accurate. 

[jamesfrom180]

I think even a crudely finished barrel from SeaCoast would never deserve the moniker of ugly!!!!  I voted for a 1.75" bore with the intent of making a Parrott styled piece. Now the thought of the James Rifle is very enticing.

[PaulB]

I think even a crudely finished barrel from SeaCoast would never deserve the moniker of ugly!!!!  I voted for a 1.75" bore with the intent of making a Parrott styled piece. Now the thought of the James Rifle is very enticing.

I see from the dimensions you posted that scaling it to the bore wouldn't satisfy the 1 caliber rule. As I have just conpleted a #2 field carraige that I would like to replace the barrel on I would be scaling it up slightly, not down. I'm probably one of the few that like the type 2 James rifle better.
Paul

[seacoastartillery]

 

 
  On my 1st scratch-built cannon (1" smooth bore) I added a couple of features that improved accuracy. One was a 2nd screw in front, to lock the elevation set by the rear screw. This prevents the barrel from pivoting at the trunnions when the gun is fired...
 
 
 
  Some added weight via two 1/2" steel plates (one inside under the bbl and one under the carriage) keeps the gun from jumping off the ground...
 
 
 
  It's not quite as elegant nor accurate as a Seacoast Artillery model. I've learnt me a few things since building this one ~17 years ago though, mostly from this very forum.
 
  When I get my hooks into a 1" Seacoast Super Special Spiral bbl, I'm gonna build me my dream cannon. It will be ugly, but accurate.
 

 
      Victor,   I like your idea of a screw up front.  With these big, (compared to a skinny modern rifle barrel), cannon tubes, you don't really have to worry about nodes of vibration usually, but the steadiness of the tube is very important as we learned.  Your cannon is improved by the 1/2" plate additions too.  I made one which was a stand-off scale gun, but looked pretty good, but bucked like the nastiest bronco a cowboy ever rode.  I had all kinds of ideas to hide weight, lead shot, lead sinkers, poured lead in bored holes, but I finally added steel plates to the very bottom.  It worked!
 
      We will try very hard to make each and every tube a "Seacoast Super Special Spiral bbl", and while sub 3" groups of 5 at 100 yards are guaranteed,  we expect to see quite a few shoot 1" to 2" groups.  It does take patience and perseverance, however, as many experiments are sometimes necessary to achieve the best accuracy. Load development is not always easy, but, in our experience, is always worthwhile.
 
 
 
 

 I think even a crudely finished barrel from SeaCoast would never deserve the moniker of ugly!!!! I voted for a 1.75" bore with the intent of making a Parrott styled piece. Now the thought of the James Rifle is very enticing.
 

 
      James,   We don't think you have seen this one which is the first successful Brooke 1.167" bore dia. tube.  Talk about uuugly!  This is it.  We were so happy with this one's accuracy, that we left it as is to this day.  This 4150 steel tube was rifled one day and at the range the next and we shot into the teeth of a 20-25 mph wind from 12 o'clock.  The tube gave us a wonderful 1.111" 4 shot group at 100 yards.  A week kater it was the first tube to launch an experimental penetrator round against a stout piece of 1" thick boiler plate.  When the dust settled there was a hole clean through.  A large plug of plate steel was found behind the plate in the dirt.       Paul, we find the Type 2 James Rifle very attractive too.  I saw one in action at Westerlo, New York at an AAA match in the late 1990s.  That gleaming bronze rifle shot very well too.  I'm quite sure they called a 14 Pdr.  It had a 3.80" diameter bore.  It's a good looking piece!     Tracy
 
 The ugly cannon that worked very well.  Super accurate and very hard hitting.  S-7 tool steel penetrator with a 12L14 expanding steel sabot.  1550 grains of FFFg black powder did the job.  Placed it in a 2 foot deep pit for safety.  Long fuse.  We never run.
 
 
 
 
 Dig deep for safety!
 
 
 
 
 Plate pushed back into hard packed prairie soil.  Something was pushed through and out the back!
 
 
 
 
 
 We heat treated the S-7 to about 55 to 58 on the Rockwell C scale.  Should have been 51 to 53 Rc.  It cracked and splintered.
 
 
 
 
 
 A fragment of the bolt stayed behind welded to the hole in the plate.  Mike used it and 5 quarts of 30 weight oil as a shield when developing loads for his Carcano WWII rifle.  Flat primer city!!!!!
 
 

[jamesfrom180]

LOL Ugly no I'm more a function over form guy.  I would not consider a beautifully machined instrument of hole making ugly if it makes a hole. One question your penetrator seems to have some carbonization in the fracture am I seeing it correctly that that is what the dark colorization is? Did it fracture in the bore? The "white" metal at the tip would then be sheered by the force of impact. 

PaulB, Very good point I quickly breezed through those numbers and didn't even use any critical looks at it.  Any time a dimension is changed on a design it should pass through the checks.  To satisfy that point I would select a 1" bore or select a scaling factor that would provide the 3 times rule.  I would note that the original design does not satify the stated "rule of thumb".  The dimensions I gave also does not state the diameter at the chamber of the piece.  The Base Ring is actually larger than the point over the powder chamber. 

In any design I would be copying I would pas it through some simple test.  Does it conform to known working designs?  The James rifle was built in moderate quantities.  Performance should be researched, how many of these things blew apart?  Next would be does it conform to any know standards.  It is accepted that modern materials have more consistent qualities, some are even of higher standards.  The design I was taking these numbers from was even bronze not known modern steel.  I would argue that a steel barrel would be stronger than a similar bronze barrel.  That said I still would not want a safer unsafe design.   

Not to run too far afield with this thread I think the selection of cannon blanks would be very dependent upon what you could make from them. 

[seacoastartillery]

 LOL Ugly no I'm more a function over form guy.  I would not consider a beautifully machined instrument of hole making ugly if it makes a hole. One question your penetrator seems to have some carbonization in the fracture am I seeing it correctly that that is what the dark colorization is? Did it fracture in the bore? The "white" metal at the tip would then be sheered by the force of impact. 

 
 
     James,  the penetrator does have some carbonization or soot on the fractured surfaces.  You'll be more aware of how that happened if I mention that the muzzle was only 2 feet from the plate.  The volumes of hot, blow-by gasses and soot shot onto the surface of the plate before the bolt hit it, but, more importantly, about 3/4 of the gasses and soot followed the penetrator into the plate and continued to pour into the hole after the bolt fractured, hence the fresh fractured surfaces were covered with those particulates and blackened.  We are quite sure of this, because a thorough inspection of the bore revealed no damage.  The white metal, we believe, was caused by the wedging action of that part of the bolt, which is quite thin at the top like a chisel.  You see, the other side which was part of the bolt's O.D. should certainly be black with soot, but it's not. This chisel piece was jammed into the plate metal and helped separate it from the plate in an irregular oval shaped plug.  The cavity in the plate behind the penetrator was highly pressurized until the plate material was driven out and most of the driving gasses and soot spilled out over the plate and onto the surrounding soil.  You can see this smut on the light brown soil of the pit.  That's our informed opinion at least.
 
 " The design I was taking these numbers from was even bronze not known modern steel.  I would argue that a steel barrel would be stronger than a similar bronze barrel.  That said I still would not want a safer unsafe design." 

      You will find that while most of the seacoast guns follow the 3:1 rule with ample cast iron to spare in some cases, most of the field artillery do not.  They are close, however and meet the spirit of that rule of thumb, if not the letter. Abundant today is a curious lack of common sense which keeps our decisions safe, less costly and on time.  Two things save your butt here:  one, your ability to make decisions regarding wall thickness in a logical, thoughtful manner.  If you want to follow the dimensions of a historical design in which the gun was made of cast iron or bronze, each material quite inferior in strength to a modern steel such as 1018, 1020 or 1026, you should not get all twitterpated if the historical design comes up .100" short.  It's steel, after all, not cotton candy!  Remember, if you get nervous, you can always order a larger diameter round and machine it slightly over traditional specs.
   
"Not to run too far afield with this thread I think the selection of cannon blanks would be very dependent upon what you could make from them."  

   We have drawings of all the popular field guns and seacoast guns and are well aware of how to determine scale dimensions, so you can be sure that we will include enough metal on the blank to allow for historical dimensions to be machined or more if the customer wishes.   

 Tracy

[PaulB]

Tracy, I agree completely.

Jamesfrom180, What I was suggesting is that it would be better to keep the barrel 1/2 scale and have a slightly subscale bore than to scale down the overall tube dimensions to match the
1.75".
Paul

[GGaskill]

If you want to follow the dimensions of a historical design in which the gun was made of cast iron or bronze, each material quite inferior in strength to a modern steel such as 1018, 1020 or 1026, you should not get all twitterpated if the historical design comes up .100" short.  It's steel, after all, not cotton candy!

While I completely agree with this, you should also keep in mind that the historical guns had a limited service life (bronze guns being removed from service after 500 rounds due to bore erosion, and cast iron guns typically bursting by 1500 rounds), so they were out of service before reaching fatigue limits.  Even with better materials, it will give longer service with less stressful loads.  As I recall from earlier posts, even modern artillery has a limited service life with full power loads, yet an almost unlimited life with lesser ones.

[jamesfrom180]

To All,

I hear my own thoughts being echoed here.  T&M, its good to know you will be offering this service based upon bore in a reasonable range of rounds. This allows alot more choices to the end user.  Select the size blank to meet your needs.  Rules of thumb are always viewed as suggestions by me.  Like I said researching the performance of certain designs would be a very smart idea.  Knowing the service life is a good start.  Knowing any historical failures is another.  I would like to point out that these blanks will have for the most part a much more demanding life than lets say the average cannon built on this site.  The rifled nature and the specialty projectiles being used will create higher pressures I am sure, than lets say a salute.  These are as close to modern artillery as we can get.  I personally would just feel better with a sub-scale bore. 

Tracy,
Thank you for the explanation.  In college I had a good friend that operated the Electron Scanning Microscope and he was always bringing fracture studies by to show off.  Reading grain size and orientations of fractures is an art. Right now I look up at my materials text and shutter.  Even for non-majors it was tough.  I surmised that you had tested the penetration at close range from the carbon on the target.  You and Mike always amaze me in your patience to explain your work.  Please do not take my asking questions as a criticism, it is my way of trying to understand in some small way the great amount of knowledge you possess. 

James

[seacoastartillery]

     We said this poll would last three weeks.  Three weeks have gone by and this poll is closed.  The results are as follows:
 
                                In First Place is the 1.7500" Bore Dia. Rifled Cannon Blank
 
      10 of the 23 total votes cast were for this size.  We will work to make sure that the golf ball size rifled cannon blank becomes a reality.  As we mentioned before, this will only be possible after we lengthen our lathe and rifling machine by about 3 feet. This will happen in  Jan. or Feb. as money and time permit.  Cannon Blank availability will occur approx. 3 months after that time allowing for order acceptance, obtaining new gundrills and reamers, constructing a new rifling head and new hook cutter and new sine bar and obtaining 1018 rounds of the proper size.   We will be able to cut 9 groove to 15 groove rifling of  .305" to .184" width of lands and grooves, making authentic scale 100 Pounder Parrotts to Type 1 James Rifles possible and many others too.    If you do not need authentic form rifling, then you can make any type of rifled cannon you want with our Rifled Cannon Blanks.
 
 
                                In second Place is the 1.0000" Bore  Dia. Rifled Cannon Blank
 
      7 of 23 votes were cast for this size.  Considering the cost differential between this size and the larger 1.75" size, we believe this will actually be the favorite when the final orders are received.  The cost of the 1.0000" size we be posted when several material and tool suppliers gives us their bids.
 
      Several other votes were spread around the other sizes.  We can make all of these with drills and reamers we already have in lengths out to 29", so if you want one of the other sizes, please let us know via a PM or email.
 
      PaulB and GGaskill,    We agree that it's better to have a slightly sub-scale bore rather than a proportionally larger one.  It helps with recoil abatement too.   Also, it helps to use powder charges which are the smallest which will afford superior accuracy.  In our experience with the 1.0000" guns, this is normally between 60% and 80% of scale service loads.     
 
      James,    We will be offering this service based on having a reasonable range of round sizes (O.D.) available.  In most cases this will be covered by two sizes or 4 sizes if you are considering both bore sizes.  However, we will special order a special size based on your needs as we cannot order enough weight of 1018 steel to qualify for any volume discount, so, other than more actual weight, your "special" will cost you no more than the regular proportional weight increase.  We feel better with slightly sub-scale bores too.  As far as knowledge goes, if we did not learn something completely new from this GBO forum almost every day, we would not bother to show up.  This is a very, very special place on the World Wide Web, a vast store house of BP Artillery knowledge and you all would do best to take notes as we do.  We have a huge Favorites file, backed up, the overwhelming bulk of which, is derived directly from links offered within our member's posts.
 
 
 Tracy

[Double D]

1.72"

A golf ball gun with proper windage would need a minimum bore of 1.723 inch.
The diameter of a golf ball is 1.68 inch. .  (1.68/39)x40=1.723
http://www.learnaboutgolf.com/beginner/balltypes.html

1.75 would have .035" windage.  1/40 windage for a golf ball is  .022"

[seacoastartillery]

    Double D.      1.72" is what we used for a bore size when making our scale GB mortars, but these were drilled undersize, then bored out, which has Nothing to do with making rifled tubes for scale artillery.  We will use a 1.75" bore dia. for the same reason that 90% of the golf ball cannons offered for sale here on GBO in the past have had this 1.75" dia. bore size. If you think like a manufacturer, you will design to produce whatever you are making for less to save your AND your customer's money and be more competitive by having a lower cost.  The 1.72" size requires odd size Gundrills, Reamers and inspection gages.  Odd sizes add 20% to 50% more cost which is unacceptable to us.

     As far as windage goes, this size bore and the standard steel target projectile will have .006" windage, .003" all around.  If you want accuracy, you will clean the bore for every shot.  Safer that way anyway!

Tracy

[Double D]

That makes sense of course. It is not however golf ball size but 1.75 

Anyone who sells 1.75 diameter for golf balls cannons  should make it very clear that their barrels are oversized.  Saying 1.75 is golf ball size is misleading.  1.72 is golf ball.  Just say it is 1.75 not golf ball.

Not really relevant in rifled bores since you are going to have custom make projectiles  anyway.

[gunsonwheels]

Been away for a while...
 
M&T
Great pics of the 1841 styled James barrel (Type I).  Are you still projecting that offering for 2013?
 
Having just started smooth-boring, I still do not see how windage applies to rifled tubes which are designed to shoot sealed breech, sabot-type projectiles (or as some do - upscaled mini-ball castings).  Seen a lot of rifle shooters lately (last 5-10 years) casting or swaging an undersized, inverse, portion of rifling onto the breech end of their projectiles.  The projo's not only fit snugly into the rifling but clock the projo as it is rammed down against the powder charge.  Accuracy is fierce all the way out to 1000 yards (on a calm day )
 
I just finished up my range impact area.  From the edge of the patio out my back door... 241 yards by a laser range finder.  Canal bank is 219.  Got to get some custom signage made up for road on the canal bank and we should be ready to shoot... Sure like living in Wyoming. 
 
Right now I plan on buying one 1" Seacoast tube and at least one 1.75" James tube (1.75" hole in a 5.25" OD shaft).  Again I hope the latter is available by 2013
 
I bought a new printer and it has a scanner built in so I will post those Fa and Fg spec sheets (sieve pass/hold specs, densities and chemical composition) I have as soon as I get hooked up and learn how to do that.
 
GOW/George
 
 

[PaulB]

     We said this poll would last three weeks.  Three weeks have gone by and this poll is closed.  The results are as follows:
 
                                In First Place is the 1.7500" Bore Dia. Rifled Cannon Blank
 
      10 of the 23 total votes cast were for this size.  We will work to make sure that the golf ball size rifled cannon blank becomes a reality.  As we mentioned before, this will only be possible after we lengthen our lathe and rifling machine by about 3 feet. This will happen in  Jan. or Feb. as money and time permit.  Cannon Blank availability will occur approx. 3 months after that time allowing for order acceptance, obtaining new gundrills and reamers, constructing a new rifling head and new hook cutter and new sine bar and obtaining 1018 rounds of the proper size.   We will be able to cut 9 groove to 15 groove rifling of  .305" to .184" width of lands and grooves, making authentic scale 100 Pounder Parrotts to Type 1 James Rifles possible and many others too.    If you do not need authentic form rifling, then you can make any type of rifled cannon you want.....
Tracy

It won't be easy waiting a year but I'm sure it will be worth it.
One thing that concerns me is welding on the trunions w/o distorting the close toleranced bore. Any thoughts on that. Obviously it would be better to to do any welding and profiling first.

[GGaskill]

Having mentioned gain twist Parrott barrels early in this thread, I am now thinking more along the lines of a 1/3 scale 3"wrought iron rifle which had constant twist rifling.

[Double D]

Trunnions need to be welded.  Interference and loctite fit both can come loose.  Been there done that 30 years ago.  Weld your trunnions for safety sake.

When mine were welded they were TIG welded for it lower heat properties as wel as is finer bead.

[Double D]

 
Having just started smooth-boring, I still do not see how windage applies to rifled tubes which are designed to shoot sealed breech, sabot-type projectiles (or as some do - upscaled mini-ball castings).  Seen a lot of rifle shooters lately (last 5-10 years) casting or swaging an undersized, inverse, portion of rifling onto the breech end of their projectiles.  The projo's not only fit snugly into the rifling but clock the projo as it is rammed down against the powder charge.  Accuracy is fierce all the way out to 1000 yards (on a calm day )
   
 
GOW/George

The windage I am referring to is that applied to define smooth bore.  In this case 1.72 is correct 1/40 windage bore for a Golf ball. 1.75 is not, no matter the industry practice.  Definition only.  1.75 bore would call for a 1.7 projectile. 

As to the matter of windage in rifled bore.  If you are going to muzzle load a rifled bore, the projectiles dimensions must be smaller than the dimensions of the bore for the projectile to pass down and manually seat the projectile. The difference between bore measurements and projectile measurement is windage.  That is why you need some sort of skirt or driving band that gets upset into and engages the rifleing sealing the bore when the gun fires. 

If your projectile is the same dimensions- no windage as the bore it will require some sort of mechanical means to load and seat the projectile.

[gunsonwheels]

Sorry to those of you who want to rigidly stay on topic...
 
I certainly agree with DD about the windage... the 1/40th is, in my opinion bad enough... more would be even worse...
 
In the technique I was referring to, the shooter machined his mini-ball-style (hollow cavity in the base) mold with lube grooves and ends up with an as-cast OD of about .003" to .005" smaller than the land diamater of the rifled tube.  However he also leaves a skirt on the back of the slug about .005" larger than the groove diameter of the tube's rifling.  When he machined the barrel, he saved a small piece from the milsurp 40mm tube and had the bore of it hard chrome plated.  He stipulated we wanted about .004" to .006" of total plating thickness.  After casting his slugs (he uses wheel weight metal) he takes the cooled slug and using a press, he swages the skirt area of the slug through the chromed bore piece... hence he ends up with a slug whose body just clears the land diameter and it has a skirt that just clears (because of the plating on the bore of the swaging die) the exact profile of HIS rifling.  The hollow base and the interference of the skirt IN the rifling causes the charge to swell the slug's base on firing completing a gas-tight seal.   And then he proceeds to shoot so accurately and consistently he wins most matches he enters... many out to 1000 yards.  His slug is about 6" long... truly a bolt-type configuration.
 
I guess to get back on topic:
 
M&T,
 
What are the chances of getting a couple extra inches of rifled bore with these tubes??  Until I see something better I would like to have enough excess rifled bore to copy this guy's technique... verbatim.
 
GOW/George
 
 

[Double D]

In the technique I was referring to, the shooter machined his mini-ball-style (hollow cavity in the base) mold with lube grooves and ends up with an as-cast OD of about .003" to .005" smaller than the land diamater of the rifled tube.   
GOW/George

That .003-.005 is the windage

[seacoastartillery]

 

 
 As to the matter of windage in rifled bore.  The difference between bore measurements and projectile measurement is windage. 
 
 
 If your projectile is the same dimensions- no windage as the bore it will require some sort of mechanical means to load and seat the projectile.                   

 
      Double D.'s last statement quoted above probably doesn't seem remarkable to most of you, but to Mike and I, it was a real eye opener.  Here's why:  Working in the aerospace industry for several companies for about 12 years, we learned that the condition he was describing is called a "line-to-line" fit.  The machinists absolutely loved to see that callout on a drawing delivered to the machine shop.  It gave them an opportunity to prove to the newbie engineer who specified that unofficial class of fit, that he needed to learn more about how "fits" should be specified.  The engineering intent, of course, was for an extremely close, no rattle, push-fit.  What you got was an interference fit which could NOT be accomplished by hand. 
 
      The last part of DD's sentence, however, gives a very good clue as to what sort of equipment would be necessary to actually fit a steel tube and steel cylinder together if the I.D. of the tube and the O.D. of the cylinder were each specified to be exactly the same size.  The "mechanical means" to load and seat a projectile of 1.7500" O.D. into a thick walled tube with an I.D. of 1.7500" would be a hydraulic ram of at least 10 tons capacity.
 
      As for DD's first statement,  even though the amount of windage may be small, he has defined rifled bore windage correctly.  It is incorrect to say that windage disappears after the skirt or sabot or driving band has expanded to engage the rifling and seal off the propellant gasses.  Approximately 98% of the entire projectile still has the same amount of windage that it had BEFORE the powder charge was set off.
 
 
 
 
 

 Well If the trunnion are threaded and ample collant is applied to the turning od fore the profile it should remain true the trunnios below are tapped 5/8 -18 and then if one wanted they could be loctite'd in how ever i had never had any come loose but they wern't as large as the 1.750 bore just 1" bore
 
 
     Classic cannons and PaulB,  we cannot in good faith make any comment about methods of welding and what type to use on your carefully rifled and shaped tube when installing the trunnions.  We are quite sure that welding is the best and safest way to secure trunnions, but we have no personal knowledge or experience to know which type is best and the least likely to cause distortion.  We have several experienced welders on this board. Maybe they will share their thoughts on this related topic.
 
      Classic cannons,    The recoil of a cannon with a 1.75" bore  could be very substantial and could send a scale oak carriage back 3 or 4 feet.  The trunnion or rimbase attachment point is an area which is stressed severely during recoil, hence the suspicion about any type of attachment other than welding. 
 
 
 

 Having mentioned gain twist Parrott barrels early in this thread, I am now thinking more along the lines of a 1/3 scale 3"wrought iron rifle which had constant twist rifling.   

 
      George,    Since this rifling is 7 x 7 straight, and having equal width grooves and lands of .2244", we see no particular problem with making this rifled cannon blank.  Not having a drawing of this one yet, we don't know what a dia. of round will be necessary for a 1/3 scale Ordnance Rifle.  How will you be profiling the exterior of this tube?
 
 
 

Been away for a while...
 
 M&T
 
 Great pics of the 1841 styled James barrel (Type I).  Are you still projecting that offering for 2013?    Yes, we do, a 15 groove tack driver.
 
 
 Having just started smooth-boring, I still do not see how windage applies to rifled tubes which are designed to shoot sealed breech, sabot-type projectiles (or as some do - upscaled mini-ball castings).  Seen a lot of rifle shooters lately (last 5-10 years) casting or swaging an undersized, inverse, portion of rifling onto the breech end of their projectiles.  The projo's not only fit snugly into the rifling but clock the projo as it is rammed down against the powder charge.  Accuracy is fierce all the way out to 1000 yards (on a calm day)
 
 Windage still exists on 98% of projectile; see first response.   Without some windage, you would have a bomb, not a projectile shooting cannon.  We saw some of those type projos you describe at the Casper, WY shoots in previous years.  The close fitting cast rifling is on only the breech end of those projos, but the forward 3/4 rides on the bore and does have windage.
 
 Right now I plan on buying one 1" Seacoast tube and at least one 1.75" James tube (1.75" hole in a 5.25" OD shaft).  Again I hope the latter is available by 2013.
 
 GOW/George       

 
      Sounds good to us, GOW.  Hopefully the 1.0000" bore tubes will be available for sale by Oct. of this year.  Remember they will be 29" inches long max before cutting 1.5" of the muzzle off.  We studied this practice once more and decided 2.0" was too much and unnecessary.  1.5" will achieve the purpose and save the customer 1/2 inch more of useable bore length.
 
 Tracy and Mike

[GGaskill]

How will you be profiling the exterior of this tube?

While I would love to do it on a CNC lathe, it is probably going to be done HNC (human numerical control) with lots of small increments and some lathe filing to blend to a smooth curve.  Curves require patience.

[Cannon Cocker]

Gunsonwheels,  You got any photos of this 40mm projectile.  We all like projectile pics.  Especially ones that work well.

[Double D]

My recommendations are often based on personal experience especially experience at the school of hard knocks.

Trunnion welding.



My Cairo gun is built with 4140.  The trunnions has threaded studs that screw in to the barrel.  The trunnion was machined so when the rim bases were  screwed in they were interference fit.  They had to be screwed in with a barrel wrench.    Several years after the gun was built I attend a shot near Redding, CA.  Since I had never shot there before my gun had to be safety inspected.  The safety inspecter- Doug Titus noticed the trunnions were not welded.  When the barrel was pulled out of the carriage (first time since the gun had been built) both trunnions were found to be loose, and one was bent. One could be fully unscrewed and removed by hand the other would only partially unscrew--I think that was the bent one. 

Titus and I also did some test with screwed and pressed in trunnions.  We used a hand sledge and we were able to knock them out and break the screw studs one or two blows.    Doug Titus was no aircraft engineer and just a millwright in a Lumber mill.  In the year I was in the area I learned  tremendous amout about machining from him.

Windage

Another thing learn at the School of hard knocks was the theory, Tracy refers to as line to line fit.  In college, I just knew and was sure a 1 inch pin gauge would fit in a 1 inch ring gauge.  I was so sure the instructor invited me to the front of the class and demonstrate the application....stuff like that sticks with you.

[Victor3]

Well If the trunnion are threaded and ample collant is applied to the turning od fore the profile it should remain true the trunnios below are tapped 5/8 -18 and then if one wanted they could be loctite'd in how ever i had never had any come loose but they wern't as large as the 1.750 bore just 1" bore

 That's very close (I used 5/8-11 with Loctite) to how I did the trunnions on my 1" cannon in the post above. ~100 shots down the tube and no issues. 

[gunsonwheels]

I have a slug of "Curly"'s from over in Ashton, Idaho riding around in my truck that is much shorter with less engagement as the one I like best.  I'll post a couple pics of it as soon as I track down my camera...
 
M&T are obviously talking about the same guy I am at the Casper, WY shoot from Nebraska (Omaha area) shooting a 2/3 scale parrott circa 1860 10 pounder gun built up on a 40mm milsurp tube.  I was suprised he used wheel weight metal as I was never able to get it to upset/swell the skirt but I never had tried having that short section at the rear end opposite the cavity fully engaging the rifing except for the few thousandths of "windage"  I mentioned.  His accuracy is such he either wins or places second against the three inchers because of the wind.
 
Having shot a 40mm for a few years I can say I get as much esthetic feedback as any of the full-scalers do and I did it for much less cost and a whole lot less mass to pack around.  And it was a fiercly accurate piece.  The idea of a 1.75" James tube would give everything I've ever wanted over my 45 years envolvement in CW ordnance.
 
Pic later for Cannon Cocker...
 
GOW   
 
 
 

[PaulB]

 
 
     Classic cannons and PaulB,  we cannot in good faith make any comment about methods of welding and what type to use on your carefully rifled and shaped tube when installing the trunnions.  We are quite sure that welding is the best and safest way to secure trunnions, but we have no personal knowledge or experience to know which type is best and the least likely to cause distortion.  We have several experienced welders on this board. Maybe they will share their thoughts on this related topi
 
 Tracy and Mike

That's exactly what I was hoping for. I've been a millwright longer than I care to admit so I've done a bit of welding. I washoping that those who have welded trunions before would share what technique worked for them. My sense is if you limit your weld to say 1" at a time per side and let it cool between welds you shouldn't get any warping.
Paul

[gunsonwheels]

I worked in a weld shop (the old Pittsburgh Des-Moines Steel) and they usually pre-heated to minimize distortion..??
 
I do have some formulae stashed around here somewhere which by using the mass of the projo, barrel and carriage you can feed them the charge mass and they will give the forces at the trunnions, at the axle tips to accelerate the wheels and resultant rearward velocity of the entire piece.  Got an "A" on the paper I submitted for a Machine Design class way back in the late 1960's.  The prof. was an ex-Thiokol guy and corrected me before the final version was turned in to add in 1/2 the mass of the powder charge to the mass of the projo to use for the accel, velocity and resultant force on the barrel of firing.  Once I got all the formulae in place and working I could change projo masses and powder charges and predict forces on the trunnion and resulting overall recoil velocity.
 
I too was building my first piece and needed to know what forces would be exerted on the trunnions AND just how strong/large the axle needed to be to keep from bending.  Handy stuff to know.  Truth is at the join of the rimbases to the barrel, a suprisingly very little real good effective weld is required and that is most critical at the front of the rimbases where the weld is put almost entirely in tension... think of what a 1" chain will hold (1" diameter equivalent weld) and it is many tons.  Back then we proofed everthing from a burm or bunker (or car) and it all worked quite well but broke the trailstock from trunnion-to-barrel misalignment and the resultant down-ward force on the elevation screw.  Knowing there would be some misalignment I intentionally aligned them a tad high knowing I'd have the screw to counter the forces instead of dipping the muzzle before the projo exited.
 
We used 1100 FPS (about the speed of sound) for the projo exit velocity and it yielded a 15 FPS recoil velocity of the whole gun.
 
GOW 

[PaulB]

I worked in a weld shop (the old Pittsburgh Des-Moines Steel) and they usually pre-heated to minimize distorsion.

GOW

A tool and die welder I spoke with told me the same thing. He said they preheated the stamping dies in an oven before welding. That's not practical for me but the concept makes sense, (the molten weld shrinks as it cools setting up stresses with the surrounding metal. By preheating the whole thing you reduce the temmperature difference and therefore reduce that stress.) I'm not sure preheating it with a torch would accomplish the same thing. I suspect post heating might also reduce stress and warping.
 Paul

[gunsonwheels]

I did some weld cladding on a on a milsurp 40mm and I pre-heated.  Being afraid of air hardening ( I had no idea of the alloy or the carbon content of the BOFORS steel) I went above 350 degrees F.  I built a set of rollers and jury rigged a gear-motor to act as a "weld positioner" (rotating the barrel as it was heated and welded).  I used a couple of propane weed burners (they are non-regulator burner heads that run off of the liquid propane's tank pressure  (about 70 PSI on a 70 degree day)).  I rigged up a couple stands to hold/position the burner heads so they played on the barrel.  TEMPIL makes temperature "crayons" in different temperature ratings which melt at the temperature they are specified to.
 
Used a 400 degree crayon, turned on the burners and positioner and waited until the marks melted... then MIG'd about 6" of clad length on the muzzle end.  Yeh... shut down the burners when I started welding... that heat input was more than enough to maintain the 350 preheat recommendation.  Try to "leather-up" as the parent metal burns when even close to it let alone touching it...
 
Weed burners (about $60 ea.) and a temp-stik and you have poor man's pre-heating.
 
And about your comment about post heat treating...
 
That muzzle end I cladded was NOT bored/drilled in the center of the round but off center by about .100".  I was afraid to turn it as any stresses would be higher on one side than the other as it was turned (due to the varying thickness of the clad) and would tend to warp the barrel.  So for $80 I had it stress relieved at a Denver area heat treat shop.  M&T may have even used them before..??  My biggest problem was getting it from northern Wyoming to there and back.
 
Good luck!
 
GOW/George