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.

Armstrong RML Cannon Trunnions – 2

Silver soldering the trunnions into the barrel and the squared blocks did not go well.

For a start, I did not know the composition of the steel of the barrel.  The trunnions were/are silver steel, and the blocks were mild steel.  So it is possible that I did not use the best flux.

And the barrel is quite hefty, so I knew that it would require a lot of heat to get it to temperature, and to keep it at soldering temperature.  So I used a large oxy-propane torch, and heated it to dull red heat.

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The steel pieces fluxed and wired together, ready for heating

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It was a cool day, but the heat output from the red hot barrel was ferocious.

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Soldered, but one side was not good, and a hammer blow dislodged it.  Damn.

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The good side, partially machined.

I dithered about how to deal with the faulty side.  I was not enthusiastic about re-soldering it, expecting that the good side would fall apart.

So I cleaned up the pieces, and used high strength, high temperature, Loctite 620, to join the pieces.  The machining will test the strength of the joins, so I will give it the full 24 hours before testing it.  This is the “reject” barrel.

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Still pondering how to join the trunnions of the “good” barrel (front).  I will discuss it with my colleagues tomorrow when we have a Model Engineering Society meeting on “Zoom” video link.  The 3D printed barrel at back is a handy “how it should look” example.

 

 

 

Armstrong RML Cannon Trunnions 1.

cannon from above front

The 80lb Armstrong RML cannon trunnions were probably heat shrunk into the sides of the barrel.  The squared off barrel sides would have been part of the original wound and welded steel rods, and machined to shape before the trunnions were inserted.

The hole above the trunnion is to hold one of the 4 sights.

For the 1:10 model I considered various construction methods. This is what I decided…

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The 20mm diameter trunnion is fitted into a milled steel block, and the 2 pieces on each side are then silver soldered into prepared recesses in the barrel.

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The the barrel is mounted in the CNC rotary table and tailstock.  15mm deep holes are drilled into the barrel….

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and widened to 20mm diameter (drilled then milled)……  (for cutting fluid I use a mixture of olive oil and kerosene.  It produces a lot of evaporated fluid but is very effective at keeping the job cool).

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….then complete the recess.   The bottom of the recess is 8mm clear of the bore.

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Next step is to make the blocks, the trunnions, and silver solder them all together.  Not entirely authentic, but compromises are required when scaling down.   Still on the reject barrel, as a trial run.

Rifling the Model Armstrong RML

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The HSS cutter is mounted in a tight 3mm wide slot in 16mm silver steel.  The 4 mm cap screw pushes the cutter up by 0.2mm per full turn of the screw.

The following video shows an air cut of the rifling cutter in the CNC rotary table on the CNC mill table.   Then some actual cuts in a 1:10 scale cannon barrel.  This barrel was a reject, and was used to practice the rifling cuts.

You can click on the arrow in the box below, or see the video full screen in YouTube.

 

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.

 

Bronze Casting 3. Equipment.

I have been unwell for 1-2 weeks with a respiratory disease.  I twice requested Covid-19 testing, but was declined because I fell outside the guidelines.  At the same time my wife fell ill with similar symptoms, but her situation rapidly worsened with severe asthma, and she required a hospital admission.  She was given the Covid test, but it was negative, and it turned out that she has a different virus named RSV (respiratory syncytial virus) which causes croup in infants.  So it seems likely that I have the same virus.

The  problem is that we are coughing constantly, and sleep is very interrupted.  And we need to continue self isolation just to avoid coughing near other people.  I feel some empathy for infants with croup.

So not much happening in the workshop.

But I have been accumulating various bits and pieces  that will be used for bronze casting pieces for the Armstrong cannon project.

First, the metal melting furnace.  10amps, 240v, 2600w, 1200ºc.  Graphite crucible.

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This should melt alu, copper, bronze, but not steel.  Is there a town named “Italy” in China?AUD$405

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And some quite reasonable gloves.

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A second furnace is needed to prepare the mould.  This was a quite old pottery furnace, used by a lady for ceramic painting.  Purchased by me second hand, (AUD$700) and knowing that some repair work would be required.

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It is a good size, and heating coils are intact and well seated.  I do not know if the thermocouple works so I have ordered a spare.

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The firebricks are in excellent, almost unused, condition.

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It is using the rated 2600w.

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The electrics work, but most of the joins and fittings are rusty.  I will clean up the joins, and replace the fasteners.  I also intend to replace the power switch with a digital control.

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To make the mould I have chosen (on advice) a jewellers investment powder, normally used to mould rings and brooches with very fine detail.  It is not cheap (AUD$130), and must be handled carefully and not inhaled.

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The steel mould cylinder, and rubber end piece.

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Wax cylinders to be used as supports, sprues and vents.

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And finally, the vacuum unit, for removing air bubbles from the investment powder mix, (AUD$200)

A significant financial investment, and not finished yet.  And no guarantee of acceptable results.   I did obtain a quote from a professional caster, but it was even more expensive.  So, I will be giving bronze casting a trial soon.

 

 

Boxford TCL125 CNC Lathe, 3rd AXIS.

Below is a video which was recorded by my machining mentor friend, Stuart Tankard.  Stuart made a milling attachment for his Boxford CNC lathe, and he demonstrates it in the following video by making some lovely small valve control handles.

I followed in Stuart’s footsteps by making a similar attachment for my identical Boxford 125 CNC lathe, but I have not yet video’d it in action.  Not much point when Stuart’s video is so good.  I really like the absence of irrelevant, irritating music.  Just machining sounds.   Enjoy.   (if you want to see it full screen, copy the YouTube address from the settings icon).

Bronze Casting -2

When I looked closely at the rifling cutters which I had lasered out of a broken Brobo saw blade, I realised that I had boobooed.  I had measured the thickness of the blade at 2.5mm, which was actually a bit thinner than I wanted, but would have been acceptable. But when I measured the cutters, they were only 2.2mm thick.   Reason?  The saw blade had been hollow ground, and the blade inside the teeth was thinner.   Too thin, I decided.

So after some wailing and teeth gnashing I have ordered some 3mm thick tool steel in the form of planer blades, which I am pretty sure will not be hollow ground, and I will ask the laser cutter to cut me some more blades.  So waiting waiting.

And I am setting up the cannon barrel for rifling.  The CNC rotary table (stepper motor hidden behind) will be bolted to the CNC mill table.  The barrel is held in the jig which is held by the mill quill.  The cutter, (not seen in this photo) will be drawn out of the barrel by the mill X axis, while being rotated in the A axis by the rotary table.   That is the plan anyway.  But still waiting for bits to arrive so I can finish the cutting tool.

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The Armstrong cannon barrel held to the mill quill, and the rifling cutter will be held by the CNC rotary table.

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The rifling tool which I will not be using because the cutter is too narrow.  The cutting edge just peeping out of the slot will be dragged and twisted through the barrel bore.  The cap screw adjusts the degree of protrusion.

 

BRONZE CASTING

Meanwhile, I am accumulating various bits of gear to do some bronze casting.   An electric furnace with graphite crucible from China, Some jewellery investment material for the moulds, and a second hand pottery kiln for preparation of the moulds, and melting out the PLA 3D printed parts.   I will take some photos when it is all here.

And SWMBO has conscripted me to assemble and install some kitchen cupboards for a property which she is renovating.

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These are flat pack units.  Kaboodle.  Well designed and CNC cut and predrilled.  Not quite finished.  Waiting for the stone bench tops to be made and installed, and for appliances to be wired and plumbed.  Frankly I would prefer to be tidying up my workshop, but hopefully I am gaining some “Brownie Points”.

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.

rear trolley

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.

3D Printing Question

3D printing is really slow.  So slow, that the machine is left unattended to continue the print, overnight in many instances.  The print head is set at 205ºc and the table at 60ºc, and it does bother me that this hot machine is left unattended, unwatched.  I do not know if any fires have resulted, but fires are of some concern, particularly here in Oz.

A substantial component of the printing time is the hidden, internal structure of the object being printed, the “infill”.

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In this photo I set the infill at only 3%, but to compensate for that I increased the wall thickness.  The result was a nicely rigid article, but it was a 24 hour print.

My question.   At this point in the print job could I have paused the printing, and filled the cavities with a substance which set hard.  It would have to be done carefully of course, and keeping the level below the printing edge.  It would also have to be cool or cold, so the PLA did not melt or distort.  It would also need to be able to be poured, or injected.  Plaster of Paris comes to mind.  Car filler bog would be too viscous.

Any suggestions?

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.

Naval Gunnery. A Book Review.

Naval Gunnery.  A Description.  by Captain H. Garbett.  R.N.  360 pages.

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Was originally published in 1897, and is a book which has been considered by academicians and scholars as being of great significance and value to literature.  As such, it has been reproduced by Alpha Editions in an inexpensive, facsimile, paper back edition.

I came across an article about rifled muzzle loading cannons which referenced the book, and led me to purchase it from the Book Depository for $AUD20.

It, the book, is fascinating.  1897 English, is beautiful to read, non ambiguous, and unusually, does not provoke the grammar Nazi in me.

And the book has answered my questions about cannon construction.  Not completely, mind you.  I still do not know how they managed blind rifling.  But most of the first 78 pages are about muzzle loaders, particularly Armstrong muzzle loaders.  With diagrams.

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One question which was answered was about the “recoil tube” located below the barrel of the Port Fairy 80 lb RML’s.  I wondered whether it was like a gas shock absorber.  The book explains that these long cylinders had a piston, and were filled with “Rangoon Oil”, (look it up.  It is in Wikipedia), and they were indeed designed to moderate the rate of recoil of the cannon.

Another fact about rifled cannons…   the rifling causes the projectile to emerge from the cannon slightly to the left or the right of the cannon axis, depending on whether the rifling is clockwise or anti-clockwise.

The book has chapters on breech loaders, naval mountings, quick firing guns, magazines, shell rooms, loading arrangements, sights, powder, cordite, projectiles fuzes, battleship development (up to 1897), battleship organisation and manning.

360 pages, 12 plates (black and white), 113 text illustrations.

If you have an interest in pre-dreadnought naval guns, this book is highly recommended.

 

Another Model Cannon Builder

One of my US readers has made a model rifled cannon, an Armstrong 110lb breech loader, 1:9 scale.  And it looks superb!  Best of all, he has made 2 videos of firing it.  I definitely recommend checking out the build and the firing in the link below.

I will substantially copy the rifling setup which Jeff used.  My sincere thanks to him for the information.

http://jefenry.com/main/110PounderArmstrong.php

Armstrong RML barrel

After 3D printing a plastic 1:10 barrel I decided to have a go at turning one in steel.  I had a length of steel 70mm diameter and 290mm long, which was just too short to turn the entire barrel, so I decided to make one of the breech reduction rings separately, when I make the cascabel.

I did not know what the steel grade was, but it was off a machine so I thought that there would be a good chance that it would be reasonable quality.

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The length of rod next to the printed barrel.

The turning was initially fairly routine.

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and I was really pleased with the finish which was appearing.

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Mountains of hot swarf.

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The roughed out barrel.  I used the 16mm drill bit to drill the bore from both ends, but there was still 50mm or so beyond the reach of the bit.  So I silver soldered the drill bit into a length of silver steel (drill rod).

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And quickly completed the drilled hole. 

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Then transferred the piece to the CNC lathe, and shaped the barrel exterior.

I experienced 2 problems with the CNC turning.  The tapered chase of the barrel, and the rounded fillets came out really well, but the straight sections of the breech developed chatter marks.  I was preparing to take a skim to remove the chatter marks when I bumped the manual CNC control, the cutter dug in, and I got a deep score in the breech.  And broke the carbide cutter.  I turned away the dig in, but it left the breech diameter 3.5mm undersize.

I have no more steel of that size, and it will be quite a while before I get an opportunity to buy some.  So I persisted with the slightly undersized barrel.  It will be 62mm diameter rather than the intended 65.5mm.   I still have not decided whether to scrap it and start again.  But if I can get some more suitable steel I will remake it.  I might even use the undersized barrel to make a 64lb Armstrong RML, which had a smaller diameter breech than the 80lb RML which I am making.

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I showed it to SWMBO.  “That is beautiful” she said, somewhat to my surprise, and being surprised by its 3.5kg weight. 

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Ah…  if only…

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.

 

 

3D Printing is FUN! (but still slow)

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My 3D printer.  Bought from Amazon on a special offer.  $AUD279.  Worked straight out of the box after minimal assembly, and using the supplied plastic filament (PLA).  You can see the large gear on the platten which I drew up using a CAD program.  I used the software (Cura) supplied by the printer manufacturer (Creality).   The printer is a Creality CR -10S.  The “S” refers to a “filament out” sensor which I have not yet installed.  I read some reviews of the printer before spending my money, and so far I am very happy with it.  You might notice some bracing bars which I bought separately on Ebay.  Not sure if they are necessary, but they might improve the print quality by reducing vibration in the printer.

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These gears and shafts were printed.  They were used to check the sizes of parts for my next model cannon build.  I used a program called “Gearotic” to plan the gear module, teeth numbers, distance between centres etc.  Gearotic is also great fun.

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The printed gear and pinion quadrant on a background of a photo of the real cannon.  On my model the gear and pinion will be made of steel or brass, machined from bar stock.

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Another part sitting on a photo of the original.  This demonstrated that I had got the corner chamfer a bit wrong.  Much better to discover the fault at this stage! 

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A half size print of the barrel.  This was just for fun.  The final part will be ~300mm long, and will be machined from steel.  This print took almost 4 hours.

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A print of the centre column which the cannon chassis sits on and traverses around.  It is ~60mm tall.  It will be tricky to machine from solid bar.  Could be fabricated in pieces and silver soldered together, but I am considering using the printed part to make a mould and cast the part in brass or bronze……   The original cannon column has an 5-600mm extension into the concrete base which my model will not need.

So far all of these prints have been made from PLA filament, which I read is easy to use, tough, rather brittle, and has a low melting point.  It is also inexpensive (about $20-25 for 1 kg).  I am still on the supplied small roll which came with the printer.  Future prints will be in colour!

The weather is a bit cooler today, so I might get back into the workshop and make some metal swarf.

 

 

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?

 

3D Printing is SLOW

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Crealty CR-10s 3D printer.  The machinists parallels were my solution to ensuring that the horizontal arm is parallel to the base frame.

So, I took delivery of the 14kg box, and spent a couple of hours assembling the printer.  It was partly assembled, as delivered, and if I had known what I was doing the final assembly would have been done in a fraction of the time.  The assembly instructions were adequate.  The wiring connections were well labelled.  The wiring connectors were delicate, and I took care not to bend or break them.

The vertical frame bolts to the base frame, and it is surprisingly rigid.  There are 2 Z axis stepper motors, and when not powered up, they can be individually turned.  It occurred to me that the horizontal arm which the Z axis motors raise and lower should be exactly parallel to the base, so I placed the machinist’s parallels as shown in the above photo and screwed the horizontal arm down onto the parallels to set the horizontal position.  I assume that the Z steppers will move the arm equally. (Hmm… I will check that assumption later.)

Next day, I downloaded the operating software.  An older version was supplied with the machine, and the newer version would not work on my old XP Pro Windows computer, so I used the old version.

I spent some time manually levelling the bed, then ran the automatic bed levelling software.

The printed operating instructions are very basic.  An Internet connection is assumed, and I did not have one available, so my first printed object was with default settings and the supplied white filament.

Somewhat to my surprise, it worked.

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The platten is aluminium.  A glass plate was also supplied, so I used that on top of the aluminium.

The filename was “dog”.  I had no idea whether “dog” was a 3D dog, a picture, or whatever.  Neither did I have any idea of its size.  After an hour, I had printed a disk about 125mm diameter and 1.1mm thick.  Then the disk came off the platten, so I aborted the print.

Today, after getting some advice from Stuart T regarding print adhesion I removed the glass platten cover and applied some special adhesive 3D printer cover.  It is called “3M double coated tissue tape 9080A”.  Then I printed 2 more items.  Neither broke free.  in fact they were difficult to remove at the conclusion of the prints.

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This tiny Tyranosaurus was printed from a 3D file which I found on my computer.  It printed in about 20 minutes.  Default settings again.  The supports were too big for the object, and when I broke them free I also broke off the T Rex arms.  Some settings for supports need to be changed.

The next print was a tool which I planned for the 3D printer…..

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The item is a speed handle for a milling vise.  It is 80mm diameter with some grippy indentations on the circumference.  The tricky feature to make is the hex hole, to fit a 19mm hex shaft.  This is the 3D drawing, imported into the Creality software, so the G code can be generated.

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First layers.  Each layer is 0.2mm thick

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The internal framework is a bit lighter than I wanted.  I thought that I had chosen 90% density.  (ps.  a couple of weeks later.  The speed handle seems to be standing up to the usual rough treatment in my workshop, despite my misgivings about its lightness.)

 

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The speed handle on the vise.  Nice fit.  The print took over 2 hours.

Not perfect, but too bad at all.

 

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