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.

Reversing Gears and Handwheel

Another 2 days in the workshop.  Heaven.

I had made a worm drive and gear using an M14 x 2 tap, but it did not look the part, despite being functional.   The problem was that the threads were sharp triangular and they did not look correct.

So I made a worm drive and gear using Acme specifications.  The teeth have a chunkier squarish look.  More authentic.

I ground a lathe cutter and used it to make the worm drive in gunmetal, and another identical thread in 14mm silver steel (drill rod).   The steel thread had cutting edges formed, and when finished it was hardened by heating red hot and quenching.  After hardening, a file would not mark it.  I did not bother to anneal it, since it would be used only to cut cut brass or gunmetal.  The hardened tool was used to make a gear in gunmetal.  Unfortunately I did not take pictures of those steps.

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Showing the handwheel, worm drive and gear.  the shaft is mounted in gunmetal bearings which are bolted to the columns with BA8 bolts.    The thread is Acme. 2mm pitch.  The handwheel will control forward-reverse of the triple expansion steam engine.

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In order to determine the position of the bearing bolt holes for the worm drive, I used SuperGlue to tempararily join the worm and gear.  

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When the position of the bearings was determined, the holes were drilled 1.8mm and tapped.  the taps were BA8, about 2mm diameter.  The engine is held vertically on the milling table, being cramped to a large angle plate.  The holes were drilled accurately on the mill.  The threads were made using a tapping head made by me from plans published in “Model Engineer” by Mogens Kilde.   The double parallelogram of the tapping tool keeps the tap vertical.  The tap did not break.

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Close up photo of tapping the BA8 threads.  Showing the bearing, shaft, worm drive and gear.  Note the Acme thread.  The bearing is Super Glued into position to facilitate the drilling and tapping procedure.  The Super Glue will be removed later.

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The final step for today was to make the handwheel.  It is 1.5″ diameter.  The rim is 1/8″ brass and the spokes are 1/16″ brass.  I made 4 of these, with each being better than the last.  I softened the 1/8th brass before winding it around a 32mm pipe to form the rim.  The join in the rim was silver soldered.  Then the rim and the hub were drilled using a tilting indexing head on the mill.  I soft soldered the spokes on intital handwheels, but the final (and best) examples were glued with Loctite.  Loctite allows a few minutes for adjustment of the spoke lengths, whereas there is only one go with the soldering.

It is looking interesting, Yes?  And there are 3 spare handwheels.  The rest of the reversing mechanism components were made several months ago.  Almost ready to install them.

Broken Tap Removal

In a previous post I admitted to breaking a BA7 tap in the Edwards air pump of the Triple Expansion Engine, and being unable to remove it.

The hole being threaded was one of 4 to be used to hold a water pump to the air pump. It was 2.5mm diameter (i.e. pretty tiny)

I tried to grasp with pliers the fragment still protruding but it then broke below the surface.

I tried to break up the embedded tap, using a HSS punch, with partial but inadequate success.

I briefly considered drilling a hole from the other end, and punching in the reverse direction, but that would really have compromised the pump.

So I decided that the three remaining bolts would have to be enough.

A night sleeping on the problem.

Next day, with a fresh determination, I decided to attack the problem again.

I had some used carbide milling cutters 2mm diameter, and I was prepared to sacrifice one or two of them.   So I carefully set up the Edwards pump in the milling machine.

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You can see the three good tapped holes.  The carbide milling cutter chomped away at the broken tap, and using gentle pressure, and ignoring the metallic screeches, the tap was broken up and most of the fragments came out.  I was prepared to sacrifice the milling bit, but it seems to have survived this insult.  The harder metal always wins.   It was probably fortunate that the tap was carbon steel and not HSS.

Somewhat surprisingly, the tapped hole was in reasonable condition, and it accepted a BA7 bolt, although I will not be aggressively tightening this one.

Triple Expansion Steam Engine -The water pump

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The triple will not be finished by Xmas.  No chance of getting into the workshop while we are looking after 2 grandchildren.  So the new aiming completion date is Jan 6, in time to run the triple on steam at the Geelong truck show.   If I don’t meet that deadline, the next access to steam will be the end of 2017.  I really do not want to wait that long.

So the next component to produce out of a chunk of gunmetal is the water pump.

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There are two cylinders in the water pump.  The gunmetal castings appear to be good quality.

Most of the machining will be done on the mill.  But I need a datum surface, and have decided that the attachment plate is the most appropriate.

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I do not need the small cylindrical protruberance, but that chunk of gunmetal might be handy for something else (eg as a bushing), so I parted it off and saved it.  Lovely parting tool is from Eccentric Engineering.

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Then turned a flat surface.  On the mill I machined it to a rectangle.   Diamond tool is also from Eccentric Engineering.

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The two water pump cylinders are bolted to the air pump.  BA7.  A broken tap is entombed in the air pump forever.

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When I get back into the workshop I will machine the rest of the pump parts.

MAKING SMALL SPLIT BEARINGS FOR THE TRIPLE EXPANSION STEAM ENGINE

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The bearings in the drag link are not split, because they can be slid onto the shaft.  But if there are obstructions to sliding, (such as big ends on a crankshaft), the bearings must be split, and assembled when in position on the shaft.  The bore in the intact bearings in the photo is 4mm.  The split bearings have a 5mm bore.  They are all bronze, but the split bearings have been heated then dipped in sulphuric acid so the colour has changed.

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The first step in making split bearings is to machine 2 strips of metal, of identical dimensions.

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Next the strips are soldered together.

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The bearing holes are drilled and reamed exactly to finished size.

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The strip of soldered metals is attached to a sacrificial base plate and the outside of the bearings are machined to final size and shape.

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Holes are drilled to take the bolts which will eventually hold the halves of the bearings together.  (1.6mm holes in this case).  The bearings are then heated to melt the solder and separate the halves of the bearings.  Sulphuric acid was used to remove the carbonised crap left on the surface of the bronze by the heating torch.

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The bosses around the holes was an extra machining step.

Drag

Not what you thought.

Today I made the rest of the drag links for the triple expansion steam engine, and just for fun I made one spare.

I ran out of BA10 nuts.  Ordered more.  1.6mm thread, 3mm overall diameter, 200 of them weighs nothing.  But if I drop one, that is another 25 cents down the drain, because individually they are invisible.

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Drag Links for Reversing Mechanism on Triple Expansion Steam Engine

A bit more progress today.

I spent the whole day making these drag links, and I was pretty happy with the result.

Then I realised that I need 6, and I had made only 3.  (well there are 3 cylinders you see).

So you know what I will be doing tomorrow….

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The drag links are the 3 items with the bearings at the ends, and the connecting rods.  Those rods are 1.6mm diameter (1/16″ inch), and the nuts are BA 10

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I dropped 2 of the nuts.  Gone forever.

The final 20% takes 80% of the time

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The weighshaft, supported on its brackets.  It will be pinned with taper pins to the shaft.  Also finished the reversing lever and reversing arm.  The reversing arm has gunmetal bushes.  About 2 x 8 hour days in the workshop to make these bits.  Just as well it is a fun hobby.

Triple Expansion Steam Engine resumes

Busy at this time of the year.

Making some wooden toys for the grandchildren for Xmas.

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Not sure whether these are ducks or chooks.  My talented wife brings them to life with colours.  When pushed by 1-2 year olds they waddle with an entertaining flap flap walk.  

Preparing the surgery building for sale.  Removing and storing 34+ years of medical records, moving furniture, arranging repairs and painting etc etc.  Feels strange to be no longer a registered medical practitioner, but I know that it was the correct decision to retire.  It has taken 2 years to totally burn the bridges by dropping my medical registration, and selling the surgery etc.

Model Engineering Club annual exhibition.

 

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This model quartz crusher at the exhibition was driven by a hit and miss engine.

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Another superb engine at our exhibition.

Plus ongoing military history book reading and reviews.

Slashing long grass, to reduce the summer fire risk.

Assembling and installing a kitchen into a rental property.

So it was a treat to get some time in the workshop today.  I had previously made the layshaft brackets for the triple expansion steam engine, so I spent a happy few hours setting up an angle jig on the milling machine to drill and tap holes to attach the brackets.

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This is the setup.  An adjustable angle plate was bolted to the milling table, and the angle was set so the columns were horizontal.  The layshaft brackets were Super glued to the columns with the shaft in place after filing to get the brackets quite level.  The holes were spotted through, then drilled (1.6mm) and tapped (2mm).

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The layshaft bolted in position with M2 nuts and studs.  M2 is very similar to BA7, and a lot less expensive, and is stainless steel.  Way to go!

 

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.”

Turkish Bombard. The Arabic Script.

A little unfinished business on my model bombard is the Arabic script and floral decoration around the barrel mouth.

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XIX.164 / 19-00164 Detail of muzzle of a great bronze gun. Turkish, dated 1464 Royal Armouries Museum, Leeds LS10 1LT Transparency tr-1185 Imacon Flextight Precision II

This is what I have managed so far….

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It is a practice run in scrap wood.

Some of the detail has disappeared because I used a milling cutter with an end width of 0.5mm.  Next time I will add another step using a cutter with a sharp point, and a lot more of the fine detail will appear.

That pattern took a total of 80 minutes to CNC mill, with the feed rate set at 500 mm/min.

Unfortunately my CNC mill developed a problem with the Z axis, probably due to a worn out end bearing.  I am hoping that it is not the ball screw nut.  Now in the process of removing the bearing. A heavy, awkward, dirty job.

When the mill is working again I will mill the actual bombard model and post some pics.

Computer graphics is not my strong point.  To get the CNC mill to cut that pattern I did the following..

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  1. Enlarged the photo, outlined the tracery and the script, then traced the outline onto tracing paper.  That 550 year old pattern is worn and hard to define in many places.  Quite a bit of guess work.  Lucky that almost no-one can read ancient Arabic script these days.
  2. Scanned the tracing and loaded the scan into Corel Draw
  3. Used Corel Draw to smooth the curves, and make 3 copies in an array of the floral design
  4. Converted the drawing to bitmap file (bmp)
  5. Used V Carve Pro to convert the bmp file to vectors
  6. Used V Carve Pro to generate the CNC G codes
  7. CNC milled the scrap wood at 16000rpm, using a 3.2mm carbide cutter

After the triple

I am back onto the triple expansion steam engine, after putting it aside for most of 2016.  I am guessing that it is about 75% completed.  I have been struggling with this project due to poor plans, no instructions and some lack of skill and knowledge.

When I was well into the project, a colleague pointed out that detailed instructions existed in some articles published in 1985 (Model Engineer, Bertinat).  I obtained the articles, and subsequent progress has been greatly assisted, but unfortunately some errors had already crept into my work, and these have not been easily or completely rectified.

So now I am back into it.  And I would hope to have it finished and working by the end of the year.  Watch for pictures when there is something to show.

I am already thinking about what will follow the triple.  Maybe a Harrison 1 clock? (of “Longitude” fame.)  Looking for some plans.

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Or maybe some more artillery?  How about a working  model  trebuchet?  Now that does have some appeal.  There are some plans on the Net, but they look over simplistic.  I am thinking of a more historically accurate model.  The following picture is from an old French encyclopaedia.  But I might have to abandon my preferred scale of 1:10 because the original was about 12 meters long.  But on the other hand……

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It does have some interesting features.  The ratcheted windlass, the travelling pulley, the trigger mechanism (“pulling the pin”), and the projectile release mechanism (trying to avoid the projectile going up vertically).

 

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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- HELP!

Does anyone have a decent photograph of the writing on the muzzle?

I have repeatedly hunted through every picture which I can find on the net, but they are either taken at an angle, or too poor quality to be useable.

Does anyone have a photograph which I could beg buy or borrow?

I also need a photo of the touch hole.

I have contacted the Fort Nelson Armoury Museum, but not too surprisingly there was no response.

Is there someone in the Portsmouth UK area who could pop in and take some pics for me?

POSTSCRIPT:  October 5.   I have had 2 excellent and positive responses to my appeal.

First, reader Richard sent me a connection to a Turkish Dr/Professor, who has made a 1:25 model of the bombard using 3D printing.  (at least that is how I think he has done it.  My Turkish is non existent).  I am following this lead.

Secondly I have had a response from Fort Nelson Armoury, with a good photo of the barrel mouth, and a high res photo on the way, after payment of a significant, but not unreasonable fee.  Isn’t the Internet wonderful!!

 

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.