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machines which I have made, am making, or intend to make, and some other stuff. If you find this site interesting, please leave a comment.

Tag: Fall of Constantinople

Fort Nelson. The Ottoman Bombard revisited.

Just to refresh your memory, if you are a long term reader of johnsmachines.com, this is the model of the Ottoman Bombard which I made several years ago …

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…but it is not finished.  I could not find a picture or drawing of the touch hole anywhere.  Requests to the museum drew no response.

Plus, I had some questions about how the square holes were made.  These were designed for levers to be inserted so the cannon segments could be screwed together.  But were the round pegs cast with the barrel and breech, or were they somehow added later?

Also, I wanted to take a close look at the huge V threads to see if I could work out how they made them.

And frankly, I just wanted to touch it.

It is currently on display at The Fort Nelson Royal Armories Museum near Portsmouth UK.  And I visited it today.  I allowed an hour to inspect the bombard and have a quick look around the rest.  4 hours later I staggered out.  This museum is another fantastic place to visit.  I will do a more complete report in another post. For the moment I will deal with the bombard.

Firstly the touch hole.  Save these photos.  They do not appear anywhere else!

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Not much design finesse there!  The wide opening becomes narrower about 25mm in (just visible).

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Next, the bombard as it was today..and I touched it!

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It is 17′ (5.2m) long, weighs 16.8 tons (17000kg).  It was made in 1465 by Munir Ali, as a copy of the bombards made by Orban, a Christian (Hungarian? German?) for Mehmet 2, the conqueror, who took Constantinople in 1453 on 29 May, (today in Oz).  Orban’s biggest bombard, named Basilica reportedly was 27′ (8.2m) long!

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That’s my hand underneath the “pins”.  Actually levering braces, cast integrally with the breech and barrel.  You can see dents, probably made by the levers.  In doing this I realised that the “pins” are not cylindrical, they are half a cylinder (split lengthwise).  The half cylinders allowed clay or something similar to be placed around the mold, under the half cylinders, and for the gaps between the half cylinders to be filled with clay pieces, to be broken out after the cannon casting.

And the huge threads…

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Well, I am no closer to understanding how these were made.  They are rough and irregular.  I would guess that they were carved in wood, then a clay mold made from the wooden model and baked, then the clay shape used in the final casting, and broken out afterwards.  Any other ideas?

I really enjoyed this visit.  If I have any WordPress storage remaining I will post some photos of some of theother artillery pieces later.

When I finally run out of space, I am afraid that will be the end of my posts.  Thankyou all for following.  It has been great fun posting, and answering comments.

Just in case this is the last post, I have to post these pics of the WW1 British rail gun.  It is truly awesome.

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Cannon caliber 18″.  The Yamato (Japanese WW2 battleship) had 9 guns of this caliber.

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The breech OD  is at least 5′- 6′

 

THROAT CUTTER WALL SMASHER

Some pics which we snapped a few years ago of a large bombard, sitting outside the wall of the “Throatcutter” castle (RumeliHisari), a few miles from Istanbul-Constantinople, overlooking the Bosphorus.  This castle was built by the Turks in order to control the Bosphorus waterway, just before they besieged Constantinople in 1453.

The cannon was clearly placed in this current position just for display.

Could this have been the one which breached the Theodosian walls in 1453?  It seems to be an  appropriate size and style.

 

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That’s a younger me.  No name plate  about the cannon.

 

 

 

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The bore is about 600mm.  The narrow part near the breach is the powder explosion chamber, with an enormously thick wall.  The original cannon was recorded as requiring 60 oxen and 400 men to drag it from its casting place.  And a gun crew of 200 men.  Cast in one piece.  (later note:  not sure about cast in one piece.  I will be in Istanbul soon.  I will try to determine construction.)

This could well be the original Orban cannon.

Updated Notes :

The Orban cannon was recorded 8.2 metres (27 feet) long, so the one in the photos cannot be it, unless the recorded figures are exaggerated.  Orban did cast additional smaller cannons for Mehmet 2 for the seige.

The biggest Orban cannon at the seige was named “Basilica”.  It fired  stone balls weighing 272kg (600lbs) over 1.6km (1 mile).   Reload took 3 hours.  The stone balls were in short supply.  Not surprising, considering the labour which must have been involved in making them.

Orban is thought to have been Hungarian or possibly German.

 

Lathe Conversion to CNC -2 and Wall Smashers

After removing most of the lathe gear which will not be required after the CNC conversion, the lathe is looking a bit naked.

The carriage apron, the lead screw, the back gears, the drive rod and control rods have all been removed.  Also the cross slide screw and handle.  The cross slide itself is temporarily removed, but available for measuring for fitting a ball screw.

I have now made accurate measurements and drawings of the lathe bed and carriage, in order to choose ball screws and nuts for the lead screw and cross slide.

The lead ball screw is easy.  There is plenty of room and machined surfaces for attachment.  I see no particular problems there.  Just time, careful machining and expense.  Chinese or Euro-American?  As usual, there is a big price difference and maybe not such a big quality difference as previously.   Looking at 25 or 32mm diameter, with 550-600mm of thread.

The cross slide ball screw is another matter.  The current cross slide square thread screw is 14mm diameter, and I would like to use a ball screw about the same size.  The problem is that a ball screw nut is considerably bulkier than the existing square thread nut, so some machining of the cross slide will be required to make space.  The cross slide dimensions are already fairly tight, to maximise the swing over the carriage.  I do not want to weaken the cross slide too much.  So it is all a bit tricky.  Time to consider options. And to get another opinion.

No lathe pics, so here are some of Turkish wall smashers.

 

Turkish cannon

This one was given to Queen Victoria by the Turkish sultan.  It was made about a decade after the fall of Constantinople.  It was cast in 2 halves.  There is a giant thread connecting the halves.  I imagine that the strange square holes are to allow levers to be inserted for the screwing by many strong men.  No double entendre  intended.

 

Turkish wall smasher

 

 

Turkish cannon and ball

This one could have been used to make the breach in the wall at the fall of Constantinople 1453.  That stone ball is 600mm diameter.  With no trunnions or other supporting mechanism the barrel was probably dug into the ground for support.  That would allow repeated shots at exactly the same point in the walls.  8-11 shots per day.  It was made for the invading Turks by Orban, a christian who had previously offered his services to the defending Byzantines.  The Byzantines whose empire by this time had been reduced to a tiny fraction plus the city itself, could not afford his services.  The rest is history.

 

 

 

 

 

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