johnsmachines

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: Armstrong Cannon

Laser Cutting High Speed Steel

As previously detailed, the rifling cutters which were made from a broken Brobo blade were unsuitable because I had not taken into account the thinning of the blade due to hollow grinding.

So I bought some high speed steel in the form of woodworking thicknesser blades, which were 3mm thick.  Also, I redesigned the cutters to be a bit more robust, and take a 4mm pin instead of the previous 3mm pin, which looked a bit spindly.

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6 cutters from one thicknesser blade 225mm long, 3mm thick

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3.03mm thick.  Just right.

 

NBN. At Last!

And about the last.  The fibre optic network was commenced about 3 years ago, and I applied for a connection shortly after.

Despite living in the centre of Victoria’s second biggest city, my house was not connected to the National Broadband Network until today.

Until then I have coped with download speeds as low as 1mb/sec, and uploads as slow as 60kb/sec.  Do you wonder why I upload so few videos?

Today, the NBN was finally connected.  The download speed is a blistering 50mb/sec, and uploads 25mb/sec.  Wow!

Just to celebrate, I am posting some pictures.  Not much to report from the workshop, but I am accumulating some items in readiness for rifling the model cannon bore.

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This photograph would typically have taken 60-120 seconds to upload previously.  Today it took about 5 seconds!    As you can see it is a cold saw blade which has seen better days.  My bad, unfortunately.   But I saved the pieces,  because these blades are made of high quality tool steel.  I have had some parts laser cut .

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The laser cutter left the tabs intact so the tiny parts would not be lost.

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The 2.5mm thick part popped out with a bit of finger pressure.  Not much tidying up required here, but I will sharpen the cutting edge.  This will be the cutter for the rifling of the model cannon.

This is the first time I have had parts laser cut, and I am impressed by the accuracy and smoothness of the cut and the narrow kerf (0.2mm).    Oh, and the cost.  It was surprisingly inexpensive.  ($AUD26).

 

Repairing Failed 3D Prints

As a beginner, I have a fair percentage of unsatisfactory prints.

Print breaks free of plate.

Supports fall over.

Overhanging areas insufficiently supported.

Holes appearing due to wrong settings.

etc. etc. etc.

Most of the time I just bin the failure, change the settings or setup, and make another print. And wait another 2, 9, 12 or 24 hours……  Not a huge financial cost, but does involve waiting.  And I am not very good at that.

I used to grow olives and make olive oil.

Sometimes the bottles of oil were sealed with wax.  Melting point 85ºc.

After a failed print of 6 items today, due to inadequate supports of overhanging areas, I wondered if the holes and thin areas could be fixed with the bottle sealing wax.  After all, lost PLA casting is just a descendant of the lost wax method in the metal casting process.

So I found the left over remnants of the bottle sealing wax, and heated up a soldering iron.

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One of the failed prints.  This is a wheel trolley bracket for the model Armstrong cannon.  The moth eaten area was overhanging, and the support had fallen over.  The area was thinned and the holes were not properly formed.   If a brass or bronze casting was made from this, it would have been unusable.

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The 850g slab of bottle sealing wax, and soldering iron.  I do not know if this supplier is still available.  It was not expensive.

The soldering iron is heated, dipped into the wax, and the molten wax carefully dripped onto the deficient area of the print, gradually building it up.

The wax can then be shaped with the soldering iron, or a heated knife, or even a finger or thumb.  I also tried a blade shaver and sharp knife.  I think that my soldering iron, and finger were the best tools.

 

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The repaired area.  It looks unsightly, but of course the wax will all disappear during the casting process, along with the PLA.

I am probably reinventing the wheel with this idea.  Again.  But have not seen it used anywhere else.  So there it is.  I think that it will be useful to me.

PS>. 12 hours later.  I now realise that this is so old hat that I am embarrassed that I posted this.  Reinventing the wheel,… that’s me.

 

 

Bronze Casting. 1.

My model Armstrong cannon has some components which will be difficult to machine, and would involve silver soldering many tiny pieces.

For example, the steel brackets in which the wheels are supported, and the centre column.

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There are 4 trolleys like this.  Each one has 2 or 3  wheels.  It is a Z shaped profile with 3 gussets visible and 2 more inside.

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The centre column.  It could be fabricated.  

But being basically lazy and always looking for the easy way out, I have decided to investigate the possibility of casting these parts.  And some others.

So I have printed them in PLA filament, with a view to a “lost wax” type of casting process.  It will be “lost PLA” of course.  Maybe doing the casting myself.  But also checking the possibility of having it done professionally.

The PLA printed parts which will be melted and burned away in the casting process, have to be as well finished as possible.  So I have been experimenting with various settings in 3D printing.  One problem is that the molten plastic thread has to be supported.  Overhangs up to 45º or even 60º can self support.  And even horizontal overhangs can self support if the gap is not too big.

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But this gap, about 20mm, proved to be too big…

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The threads are partly bridging the gap…

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Horrible.  It is the underside, but even out of sight, it is unusable.

So, I am printing up some supported versions, even as I type this.  And I am going to look at some casting equipment which I might be able to borrow.  Apparently the gas furnace is very noisy, and it needs a home with no close neighbours.   List…. a furnace capable of melting bronze, a crucible, investment casting powder,  protective gloves, helmet or face mask, leather apron, tongs, slag ladle, a casting box.   There are many YouTube videos on the subject of lost PLA casting.    Watch this space.  But if the quote for professional casting from my printed molds is not too fierce, I will probably take that path.

Model Cannon Barrel. (T)rifling Thoughts.

My aim (as it were) in making this model cannon is to have a high visual quality exhibition piece.

It is a 1:10 scale model, 1866 Armstrong 80lb, rifled muzzle loader, blackpowder cannon.

One question which always arises is whether it will be actually fired.  My answer is that if it could be fired legally, it would be nice so I could make a video.  However, Australia has very strict gun control laws, (with which I totally agree), and I do not intend to flout those laws.  So this gun will not be capable of being fired.  It will have no touch hole.

To satisfy the visual appearance of a touch hole there will be a laser printed dot at the location.  Along with laser engraved Queen Victoria insignia, sight lines, etc.

But, it IS a rifled cannon, so I do intend to rifle the barrel.  And that needs to accomplished before the trunnions are fitted, and after the cascabel is fitted, so the orientation of the rifling is as per the original.

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The original rifling.  The 3 grooves are each 30mm wide, (clockwise or anticlockwise, not sure) and extend up to the edge of the powder chamber.  They are about 2 mm deep.  The powder chamber is slightly wider than the barrel bore, being continuous with the depth of the rifling grooves.  It is academic, because it will not be visible, but I will make it (the powder chamber, and the whole model) as accurately as I can, for my own satisfaction.  Fortunately the powder chamber is accessible to machining from the breech end, because the cascabel is screwed into position, and is removable.

Yesterday I started making the cascabel.  It was difficult.  The steel thread is lathe cut first, then the shape is lathe CNC’d.  Then there is milling the insides, and making a removable pinned rope retainer.  The third attempt was the most successful, but I am still not satisfied, and so there will be another one made today.   This is what I have so far…

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The turned barrel, threaded to accept the cascabel.  More work is required on the cascabel.

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The cascabel is mounted in an ER40 chuck.  It has been drilled and milled, and a removable insert is temporarily glued into place pending more machining.

 

Rifling.  Searching YouTube reveals multiple tools and setups from US sites.  Here are a few screen shots to show you some varieties.

From the sublime ….

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to the other extreme…

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No.  I will not be using a PVC pipe lash up.

The amateur designed and built machines are interesting….

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Sine bar on the right.

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Then there is the method of pressing a button cutter through the bore.  My bore is an odd size, so if I used this method I would need to make my own cutter.

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This one is a computer animation of a 19th century rifling machine, now a museum exhibit.   Can you see the barrel?   Armstrong probably used a much larger version of this type to rifle his cannons.

 

But I think that I will use none of these methods.  I have a CNC mill and a CNC rotary table.  Mach3 can control both of these machines simultaneously.   If I mount the cutter assembly in the rotary table, and the cannon barrel to the mill quill, I should be able to cut the rifling grooves.  Still working on this one.

Armstrong RML. Roughing Out the Barrel

Today was humid.  But I hardly noticed.  I was attacking a piece of 72mm diameter steel rod for the Armstrong 80lb model cannon barrel.   Enough of the plastic printed shit.  Now for the real material..

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It was a piece of an axle.  No idea of the exact material.  But it is magnetic, turned beautifully.  So not stainless.

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The roughed blank, and the plastic printed model.

Next problem was to produce the 16mm bore, through 285mm.

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None of my 5/8″ (15.87mm) or 16mm drill bits were long enough, so I drilled from both ends.  Still have a substantial chunk in the middle.  The cutting fluid is my own mixture of olive oil and kerosene.   I used to grow and make olive oil and I have quite a bit left over.

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The roughed barrel, ready for CNC finishing.  And a 16mm drill bit which I turned down to a 10mm shank, and a piece of 5/8″ drill rod/silver steel drilled to 10mm, which I will silver solder to the drill bit to make it adequately long to drill through the whole barrel tomorrow.

 

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The roughed barrel, and the 16mm drill bit ready for silver soldering.  Yeah.  It is a bit longer than necessary.

Turning cannon barrels is really satisfying.  Still considering how to manage the rifling.

BTW.  I am not feeling the love lately.  If you want these posts to continue, you need to hit the “like” button occasionally, or better still, make a comment.  If I continue to feel unappreciated I will just stop.

3D Printing a Cannon Barrel

There is quite a learning curve to 3D printing, and most of my prints so far have exhibited considerable room for improvement.  There are some helpful YouTube videos on the subject, but at my beginners level there is still a lot of trial and error.

I am still planning my next cannon model build, and printed some cannon barrels to improve my printing skills, and also to have a plastic model of the barrel to help decide about construction methods of the metal model.

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This is a 1:20 print, but was unsatisfactory because the cascable, and the rifling did not print.

The next prints took 22 hours (vertical orientation) and 24 hours (horizontal orientation) each.

Firstly the vertical orientation..

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It starts with a thin line which marks a little beyond the outside outline of the model to ensure that it is properly located on the printing plate.  Then a thin base to ensure adherence of the model to the printing plate, for the duration of the printing.  My plate is heated to 60ºc, which is not essential with the PLA filament which I am using.  I changed the filament colour for aesthetic reasons.

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Each layer of filament adds another 0.2mm of height.  The rectangular columns support the overhanging parts, and increase the overall support of the model during printing.

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The printing is finished after 22 hours.  I can already see some mistakes.  The barrel should be smoothly rounded, instead of faceted.

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After breaking off the supports.  Next to a bit of workshop rod  which I will use to make the actual cannon model.   Not quite long enough, but the rifled gun tube and cascabel will be made separately so the steel rod will be long enough for the rest of the cannon.

The next print was horizontal…

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I made the supports more densely placed to improve the support.  The cannon barrel is just appearing in the centre.

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I left the printer to continue overnight, and this is what I saw next morning.  Note the longitudinal placement of the plastic fibres.  Infill set at only 3%, which was adequate.  I increased the outside wall thickness to 5 layers, which was plenty thick enough.

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The finished horizontal print on its supports (front) and the vertical version (behind).   Apart from the facets, the appearance of the vertical version was better IMO.

Now I am ready to turn the barrel in steel.  I have obtained a facsimile book about naval artillery which was written in the late 19th century, it reveals that the Armstrong barrels were made in concentric pieces, and heat shrunk together.  I will adopt a similar method, making the cascabel and the central rifled tube separately from the breech sections.   Not decided whether to heat shrink them together, or silver solder, or Loctite. (ps. a week later.  Changed my mind.  Making the barrel from a single piece of steel)

The artillery book also answered my question about 64 -80 lb cannon and bore sizes.  When round shot was replaced by pointy cylindrical projectiles, the projectile weight could increase by increasing the length rather than the diameter of the projectile.  And some 64lb cannons were redesignated as 80 lb cannons, after modifications which did not necessarily alter the bore.  Unfortunately the book does not answer how the rifling was accomplished with a closed breech.

And I made another workshop tool.   This one is a lathe tool height gauge.

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I expect that the tough PLA will stand up to workshop treatment quite well.  It is light, very visible, will test upright and upside down tool bits, and will hang on a conveniently placed hook. Also, it is within 0.01mm of the required 38.05mm tool height.  A light rub of the base over fine emery paper will get the dimension right on.

 

 

Armstrong RML

Some images of what I am planning to be my next model build.  As mentioned in a recent post, I photographed and took lots of measurements of this Rifled Muzzle Loader at Port Fairy, and have been searching the web for more information.  It is said to be an 80 pounder, but the bore (6.3″) is more consistent with a 64 pounder.  Can anyone shed any light on the discrepancy?

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Yes, there will be some interesting machining challenges.

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Not looking forward to all of that riveting.  Considering options.

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Most of the photos were taken with a Panasonic Lumix camera, but some, like this one, were with my iphone, using an App named “My Measures” which accepts annotations and measurements.  The barrel “diameters” above are actually circumferences.  And the “19” is the plate thickness.

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The emblem on the barrel surface.  I am hoping to engrave this on the model, but there would be a lot of time cleaning up the image.

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A web search turned up this image, which will be easier to clean up for laser engraving on the model.

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And some basic diagrams of similar design

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The rifling grooves are 1″ wide.  3 of them.  How to make them?

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I asked about rifling grooves at a GSMEE meeting, and Rudi showed me how it is done.  He made these 2 rifling tools.   They are pushed through the bore to create the grooves.  The bottom tool was most succesful, because it has a pilot diameter.  But, the tools cannot be pulled backwards, so both ends of the bore must be open.  But what about the cascable end of the cannon.  It is not a breach loader.

Then the penny dropped…..I remembered seeing this diagram…

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The cascabel screws into the barrel.  That opening will allow me to broach the rifling.  I do not know how the rifling was made in 1866!  (does any reader have information on that point?)  Note also that these barrels were usually made with some concentric tubes of steel.  I expect that the model will be one piece of steel, with the trunnions silver soldered.

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And I have started drawing up the cannon, massaging the field measured dimensions (which were obtained with a builders’s tape measure)…

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And doing gear calculations for the gear train and rack.  Lots more detail to go into the drawing and plans.   And thinking about construction methods meanwhile.  Now who has a metal sintering 3D printer for loan?

 

?Next Project

I am home after a short holiday at Port Fairy, Victoria.  Port Fairy is on the “shipwreck coast” of Victoria, labelled for the number of ships which were wrecked in the 19th century.  Dozens and dozens of them, including the tragic “Loch Ard”.   Port Fairy was a sealing, whaling, fishing village in the 19th century, but now survives on tourism and dairy farming.  It was also the site of horrendous massacres of aboriginals.

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Port Fairy was part of the coastal defences against a possible Russian invasion in the late 19th century, when Britain was the enemy of Tsarist Russia.  Not that any invasion eventuated, or probably even contemplated by the Russians.  But no doubt they were pretty pissed off by the defeats in the Crimea, so an invasion of a weak but gold rich British colony was not not totally ridiculous.

So Port Fairy, and nearby Warnambool and Portland were fortified with decent shore based artillery.  The coast is incredibly rugged, with few landing places.

Today I saw some of the fortifications.  And my next project?….

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It is a muzzle loading, rifled bore, 80lb, black powder cannon (RML).  The associated machinery is in poor condition, but much of it is present, and its original form can be inferred.  Most of the external brass and bronze fittings such as sights and gauges have been removed, probably stolen.

The barrel itself is in good condition.  It is fired to entertain the tourists every Sunday at 1200, and on New Year Day at 1400.  Just a blank charge of course, about 1/8th of the charge which would have been used to fire a projectile.  I was fortunate enough to be present at the January 1 firing, and it was awesome!  Very loud.  A sharp “crack”, and gout of flame, and air shock wave.  Very impressive.   Rated as an 80lb cannon.  Far from the biggest ever RML, but still awesome.

And our model engineering society has a connection with the gun.  One of our GSMEE members used to prepare the demonstration charge, and conduct the weekly firing.  He operated a stone quarry, and was qualified to handle black powder and other explosives.  He tells a story of one firing which had a funny ending.  Someone else had prepared the charge, inserted it ready for firing, which was done.  Unfortunately he had neglected to remove the powder container, which was a “Milo” tin.  A few minutes after the firing, a very irate cop demanded to know who had fired the gun.  The Milo tin had landed on his patrol car which was about 100 meters away.

No (legal) charges were laid.

And another connection…   my son in law grew up in Port Fairy, and has fond memories of the town.

So I have taken many photographs of the gun and its carriage and machinery, and many measurements using a builder’s tape measure.  The overall length is 4 meters plus protruding barrel, and if I use the same scale as my previous 3 cannons, 1:10, it will be about 400-500mm long.  At this time I am preparing some drawings.  Thinking about materials.  Possibly steel.  With some bronze and brass for the fittings.   But I will finish the Southworth vertical steam pump first.

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Found this photo of a very similar gun which was mounted at Port Jackson, NSW.

 

Back home now, and watching the news about Australia’s climate change fires, politicians posturing, and the president who ordered a murder.  Absolutely appalled. “We got him”.   WTF.

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