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Tag: model cannon

Model Ship’s Cannon

I spotted this model cannon at the Townsville Maritime Museum, Townsville, Queensland, Australia.  The barrel is cast and bored.  Nicely detailed, particularly the barrel decorations.  My understanding is that such exuberant decorations on the original cannons would have been very costly, and not used on naval ships.  But they were sometimes commissioned by pirates who were spending their ill gotten gains.

The staff very kindly allowed me to reposition it for the photographs, and I am very happy to give the museum a thumbs up for some most interesting displays.

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Turkish Bombard – the barrel mouth

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Except for a name plate I have finshed the bombard.  The floral design at 12, 4 and 8 is not as clear as I wished, and the Arabic script at 2, 6 and 10 is even worse.  But it is cut in wood, and it is a first effort at such work, and it is not easily seen in a model only 106mm 4.2″ diameter, so I am reasonably satisfied.

Also, this was always a prototype, in wood, and I have not totally dismissed the idea of making it in cast iron or brass.  In metal I am sure that the detail work would be a lot finer.

Turkish Bombard. The Barrel Script

Well, I bought a pair of NSK bearings for the Z axis of my CNC mill, and removed the old ones and inserted the new ones.  Cost $AUD 200.  Plus 2 or 3 half  days of  dirty heavy work.    And the problem persisted!!@!@

OK.  Time to get an expert opinion.  Here comes the cavalry.  Thank goodness for my expert friend Stuart T.

Very puzzling.  Even for Stuart.  There was some unwanted movement in the Z axis (about 2mm), despite being apparently properly installed.  Not a problem with the ballscrew or ballnut.  Even Stuart was puzzled.

“have you got any left over bits and pieces?  Is it all installed the way it was before?”

To cut the story short, we installed a thicker washer below the locknuts, and it seemed the problem was fixed.  Or was it?

Today I did another test run of the bombard mouth Arabic script.  Worked fine.  OK.  Time to finish the bombard.

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Here is the finished result, ready for painting.  I have used a 20 degree engraving carbide bit with a 0.2mm flat end.  There is some loss of fine detail but it is I think, adequate.  When it is painted, the filling putty above the pin screws (the white circles) will be invisible.  The engraving took a total of about 60 minutes, at 500mm/minute, 15,000 rpm.

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The setup.   A large angle plate clamped to the table.  The work clamped to the angle plate.

The translation of the Arabic script is “Help O God the Sultan Mehmet Khan son of Murad. The work of Munir Ali in the month of Rejeb. In the year 868.”

More Scale Stuff

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There is the 1464 Turkish bombard (black), 17 tons, 307kg granite ball;  the 1779 long naval gun off USS Constitution or HMS Victory 24lb balls; and a 32lb carronade.  All 1:10 scale.  Interesting to see them together on my kitchen table?

Model Ottoman Bombard – Painting

I would have preferred that the title of this blog was “Finishing the Ottoman Bombard”, but I am still waiting for the vectors of the barrel mouth decorations and Arabic (?) writing, and the touch hole.

But I have at least painted the bombard, and the pictures follow.  You will notice that I have not attempted to reproduce the bronze or copper colours of the orginal in Fort Nelson.  Partly because I doubted my ability to make painting such variegated patterns realistic, and partly because the cannon would not have looked like that in its heyday of 1464.  It would probably have been either black, like most SBML cannons (smooth bore muzzle loading), or possibly gaudy golds and reds and blues like other medieval items.  So I painted it black.  I like it.  If I get evidence that it should be more colourful I can change it later.

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First coat – Primer.  Hmmm… interesting colour.

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Next coat – matt black brushed on, to fill the hairline wood cracks.  Incidentally, the (dirty) parquetry floor is also made from the red gum house stumps from which the cannon is made.

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final two coats –  matt black, from a spray can. 

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So there it is, finished except for the barrel mouth engraving, and the touch hole.  Now what to do with it…   SWMBO says it might be useful as an umbrella stand.

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The breech.  25mm diameter explosion chamber.  1:10 scale

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The barrel, 63mm bore.

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Assembled.  The model is 520mm long.

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It does need some decoration

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Ottoman Bombard Photo to Vector

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This is the low res photo from Fort Nelson.  High res photo on its way.

In the meantime, I have contracted with a US firm to convert the picture to vectors.  More $US.  ($US50 to be exact).

I am not sure that this is going to work.  But I will report to you.

I do wonder what that the Arabic/Turkish writing means.  Does anyone know?  I am pretty sure  that it is not complimentary to Christians/Westerners/Non Muslims.  Maybe it is just an instruction not to look before the touch hole is touched.  Or “do not stand here”.

PS.  Note added 17 Oct 2016.    The translation is   “Help O God the Sultan Mehmet Khan son of Murad.  The work of Munir Ali in the month of Rejeb.  In the year 868.”

868 = 1464 ce.

 

TURKISH BOMBARD – the real thing

I have found this video to be particularly useful in my modelling of the Ottoman bombard. The subject of this video is the gun that the Turkish sultan gifted to Queen Victoria when the Brits and the Turks were allies.  It might be one of the guns which fired on the British fleet in 1807, when it (the gun) was 343 years old!

Notice the colour.  It is aged bronze.  I am thinking about how to reproduce that colour on my model.

 

Length of the assembled gun 5.2m (17′)

Bore 635mm

Breech weight 8942kg

Barrel weight 8128kg

Average weight of shot 307kg

the model is at a scale of 1:10.  photos soon.  being painted.

 

Modelling A Turkish Bombard- The Pins

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There are 16 pins at each end of each section of the cannon.

These were certainly used as leverage points, for very strong men with large levers to rotate the 8-9  tonne segments against each other to engage and tighten the screw.

I cannot see how the pins would have been cast with the breech and barrel.  For my model I decided to make separate pins and fit them into the gap between the big rings, then insert a grub screw through both rings and the pin.  The holes are then filled.

I wonder if a similar method was used in 1464.  I would love to have a close look at the original cannon to figure this out.  From the photographs, I can see no evidence of later insertion of pins, but neither can I see how it would have been done any other way.

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Drilling the holes for the grub screws

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In order to continue with red gum, I made my own pins.  This is the setup.  The blank is held approximately centre in a 4 jaw….

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…and the pins are turned, centre drilled, drilled, cut to length,  and tapped M4.  64 altogether.

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The M4 x 25mm grubscrew is screwed into the pin.  The wood join is super glued.  Also, I am attempting to patch the worst of the thread tearouts.

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Using a battery screwdriver to insert the grub screws.  The pins protrude above the ring surface for a reason..

 

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Sanding the pins flush with the rings.  Check the photo of the original 1464 model.  There is also some wood filler in other splits.  Not surprising after holding up a house for 70 years.

The holes are now filled with wood filler, and will be sanded flush.  They should be invisible after painting.

Next the painting, the stands, and some cannon balls.  How to reproduce that aged copper colour…

 

Modelling a Turkish Bombard -4 Decoration

The decoration around the barrel is formed by a repeating pattern, which when milled, very cleverly forms 2 identical patterns.  One is excavated and one is the original barrel surface.  You will see what I mean if you look at the pictures in the earlier blog, and the video below.

It took me an evening of experimenting on the computer to work out the system and draw it.

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Then I measured the diameters of the 2 gun components, calculated the circumference, (OK it is not rocket science.   3.142 times diameter), then working out the number of identical shapes which would fit around the 2 different diameters, at the same size and spacing.   Amazingly, it took 18 shapes to fit almost exactly around the barrel, and 16 of identical size almost exactly around the breech.  the angular spacing was 20 degrees and 22.5 degrees.

Then the shape was imported into V-Carve Pro, and G codes were generated.

My CNC mill does not have a 4th axis, so I used a dividing head to move the workpiece at the precise angles.  See the setup in the video.  That meant that the pattern was engraved into 16 and 18 flat surfaces, rather than a continuous cylinder as on the original.

It worked very well.  There were minor compromises due to the shapes being milled with a fine end mill but when you look at the pics I hope that you will agree that it is effective.

I calculated that the milling had to be at a maximum depth of 2mm in order to cope with the curvature, but if I do it again,  I would reduce the depth by 25%.

The first part of the video is a shot of CNC drilling.  Then the CNC routing of the repeating patterns.  Each angular setting of the pattern took 4 minutes to complete.  136 minutes altogether.  In reality, it took a whole day, most of which was spent doing the setups.

 

 

Bombard Model. Turning the Breech

 

So if you watched the video, you can see that I have a problem with the big thread between the breech and the barrel, at least in the wooden prototype.  It might work better in brass or gunmetal.

The thread has a pitch of 6mm and a diameter of 60mm.   It is big.

My plan at this time, is to make a brass male threaded section, and glue or screw it into the breech.  Then to make a steel tap using the same G code, and cut a thread into the wood of the barrel.  (p.s.  note 30 Sep…  I continued to experiment with feeds, speeds, and cutter shapes in the wood.  The final result was OK so I did not make  metal threads.  That will have to wait until I do this project entirely in gunmetal or brass…  maybe never)

Turkish Bombard 1:10 scale

Just for fun I will use my newly converted CNC lathe to make a 1:10 bombard.  The original was cast in 1464 and was thought to be a close copy of the bombards which Mehmet 2 (“the conqueror”) used to breach the walls of Constantinople in 1453.  There are several of these bombards still in existence, including one in UK, which was given to Queen Victoria by the then Turkish Sultan.

These bombards were last used, against the British, in 1807, when a British warship was holed with substantial loss of life.  Pretty amazing for a 340 year old weapon.

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5.2 meters long, 1.060 meter diameter. 16.8 tonnes.

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The large thread connected the halves.  Easier transportation, and casting.

 

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Is this Turkish or Arabic?

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Granite balls are 630mm diameter.

 

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A reconstruction of the walls of Constantinople, with moat.  Almost 1000 years old in 1453  

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And as they are today.  Massive.  High.

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Huge siege cannon used in the final assault and fall of Constantinople in 1453. Diorama in Askeri Museum, Istanbul, Turkey.  The bombards were probably dug in, to manage the massive recoil, and concentrate the aim at a particular wall section.  There is a wooden structure built around the cannon in the background of this modern picture.  As far as I know there are no surviving  wooden structures like this.  Nor have I come across any old pictures, but if anyone knows of any I would be very interested.  The bombards took about 3 hours to cool, cleanout and reload.  

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My model will be about 520mm long.  I would like to make it from bronze, or gunmetal as in the original.  Any mistakes will be costly.

So I have decided to make a prototype in wood.  That will test my drawing, the machining procedure, and the final appearance.  Not to mention how the CNC lathe will handle the task.

I will use a very dense, tight grained Australian hardwood (red gum).  The wood was salvaged when my house stumps were replaced with concrete.  Some was used to make parquetry, and the rest was put aside for possible future use.  Such as this.

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About to cut off the below ground section of a 70 year old house stump.

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A 5hp metal lathe with a tungsten bit chomps through the hard dry wood.

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I turned 6 lengths before I found 2 that were satisfactory.  The rest had sap holes or splits.

I have used Ezilathe to generate the G codes.

to be continued….

 

CARRONADE 1

It has been a while since I posted, but I have been busy.

Some of that has been in the workshop making a scale model carronade.

A carronade, in case you are wondering, was a muzzle loading cannon, made 1776-1852 in the Scottish town of Carron, by the Carron company.  And subsequently much copied elsewhere.

It is a cannon which is short, squat and ugly.

Weighs about 1/3 as much as an equivalent bore long gun, (see previous posts), requires only 3 men to operate (compared to 9-11 for a long gun), and can fire balls or other nasties at 3 times the rate as long guns.

2 carronades, 68 pounders,  were on the foredeck of Nelson’s “Victory”, and they caused huge damage  at Trafalgar.   Can you imagine loading a 68 pound cannon ball into the muzzle of a hot cannon?   Many actions proved the killing power of carronades, and the British Admiralty were so impressed that they replaced long guns with carronades on many of their ships.

The French, and Americans were less rapid to  access this new technology, although Napoleon, who was an artillery officer, was adamant that the French navy should have the carronades installed as quickly as possible.

The British equipped some of their ships almost exclusively with carronades, and at close quarters they were devastating and they won some notable victories.

Unfortunately, although they were devastating at close quarters, they did not have the accuracy or range of long guns beyond about 500 meters.

So in the war between the Brits and the Yanks in 1812, the Americans found that all they had to do to win at sea and on the Great Lakes, was for their frigates to remain beyond the carronade range, and shoot their long guns, with many victories, and great frustration of the Brits, who were not used to losing naval battles.

Carronades were commonly installed on merchant ships, privateers, pirate ships, and small naval vessels, due to their relatively light weight, and small gun crew. But the Royal Navy stopped using them from 1852, when breech loaders were the latest new technology being installed wherever possible.

I decided to make another 1:10 scale model cannon.  A 32 pounder carronade, the same scale as the previously blogged 24 pounder long gun, to put them side by side for comparison.

It is almost finished.  I will post some photos soon.  Look forward to squat and ugly.

 

 

Video of Making the Model Naval Cannon

Click on the arrow in the screen link below to connect to the YouTube video of the making of the 1779 model cannon.  Probably of interest only to machine aficionados, but it does feature some very pleasant music composed and played by Lis Viggers.

The labels appear too briefly, so use the pause button to read them.

The segment on boring the barrel is really boring. (really)

And a few editing errors appeared.  I typed cascobels when it should have read astragals.  Not prepared to delete, re-edit and re-upload given my very slow Internet connection.

 

And this is a link to another YouTube video with an excellent description of how these type of cannons were made originally.  Definitely worth watching.

Cannon Trunnions

I am unsure whether the trunnions are the semi circular holes in the carriage, or the cylindrical bits of the metal barrel which support the barrel.   I am going to assume that the trunnions are the part of the barrel.  (I checked.  The trunnions are the cylindrical parts of the barrel which support the barrel.)

So, today I made some trunnions and silver soldered them to the barrel.  In the full size original version they would have been part of the barrel casting.

But before that, I polished the barrel with a Scotchbrite type pad, impregnated with some polishing compound.  And it made the barrel sparkle!

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Then I attached the knob at the breech end, M4 threaded rod attachment.

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Looks OK, Yes?  This protrusion would also have been part of the cannon casting.  It was used to attach the huge ropes which limited the recoil movement when the cannon was fired.  

 

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Turned some brass for the trunnion.  It was later cut into two pieces.

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Drilled the holes with an endmill in the barrel for the trunnions.  Stopped short of the bore by 3mm.  Jerry Howell specified threaded trunnions, but I decided to silver solder them in place.

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This is my silver soldering forge, for this project. (actually a hearth).   The barrel is still a hefty lump of brass, and I predicted that a lot of heat would be required to raise it to a suitable temperature.  The base is steel, and the bricks are fire bricks.  I used oxyacetylene as my heat source.

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After the silver soldering.  Not quite so pretty now.  I waited an hour before I could handle the hot item.  Note that the spigot in the bore which was Loctited in place, has come out.  Eventually, I became impatient, and applied wet rags to speed up the cooling process.

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Then a soak in dilute sulphuric acid for 15-30 minutes, to remove the flux.

Turning a cannon barrel

Today the exterior surface of the model 1779 naval cannon barrel was turned.

The piece of brass material weighed 5.1kg, was 300mm long and 50.8mm diameter.

I had used Loctite to glue a spigott in the bore, to provide a center and a driving diameter which the small CNC lathe would accept.

Although the lathe was nominally 300m between centres, the toolpost would move only about 200mm.  So the turning had to be accomplished by turning the cannon mouth end first, and then reversing the workpiece to turn the breech end.

The CNC lathe, owned by Bob Julian,  is about 30 years old, and it came out of a school.  In the course of this  job, it seemed to progressively free up, making us suspect that this is possibly the first time it has ever been seriously used.

The lathe electronics had been replaced by Stuart Tankard to use Mach3.  The G codes were generated by Stuart’s program “Ezilathe”, which is available as a free download on “CNC Zone”.   It is an excellent CNC lathe program, and I thoroughly recommend it.

I will eventually post some videos of the turning progress, but my Oz internet connection is so slow, that for the moment I will post photos only.

I started by turning a piece of rubbishy pine as a test.

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That’s me, watching carefully.  Later we installed the swarf cover.

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The metal turning lathe does not miss a beat chomping through wood.  These are the roughing cuts.  F300mm/min, S800/min.

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The Mach3 picture of progress.

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The finished distal half of the cannon barrel in pine.  If I stuff up the brass version at least I can have a wooden barrel. 

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Roughing the barrel in brass.  1mm cuts, feed 100mm/min.  It took almost 50 minutes for this section, and about 15 minutes for the breech section.

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The barrel mouth.  No gouging resulting from the 22 degree HSS cutter.

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Finish was quite good.  Will require minimal polishing with ScotchBrite.

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The workpiece was reversed in the lathe, the Z zero carefully set, the X unchanged, and the breech end turned.

The starting weight was 5.1kg.  The end weight, including the spigott was 2.9kg.  So at least 2kg of brass swarf, most of which I swept up and saved for possible future use.

Next to machine the trunions and some silver soldering.

 

1779 Cannon Bling

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Rings for attachment of ropes & pulleys, nuts and bolts, wheel pins and ferules, all made of brass in my workshop.  Note the square nuts.  Since this is a scale model, the originals would have been 50 x 50mm(2″x2″).

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The round bits are flat head bolts which secure the rear axles.

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Making the rings.  2.4mm (3/32″) brass wire is annealed by heating red hot, then wound tightly around a 3mm bolt.  The resulting helix is slit to form individual rings.

 

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The rings are flattened and adjusted using heavy pliers, then silver soldered to the threaded rods.  The hole in the smallest ring is only 3mm diameter.

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I intend to allow the brass to tarnish and darken.  The bright new brass is, I think, a bit glitzy.

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