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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: ironwood

More Naval Cannon

Some temporary bolts inserted until I get around to making the permanent brass fixtures.  And the quoin and bed finished.  And the wheel halves joined with brass pins.

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The quoin is the wedge which is used to set the elevation of the barrel.  It has a dovetail connection to the bed underneath.    The brass pins which connect the wheel halves are also seen here.

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The dovetail groove was smaller than any commercially available router cutter.  That top opening is only 3mm (1/8″) across.  After considering options I elected to cut the bed in half and then machine a 60 degree groove into each half, then superglue the halves together.   The tongue in the quoin was similarly machined, but in one piece.   That handle hole in the quoin is not centered, despite careful positioning.  The wood grain must have pushed the drill bit laterally.  I will use an end mill to get a bigger, centered hole and glue in a patch.

 

The barrel is 300mm-12″ long.  It has straight sections, a taper section and several curved sections.  Plus several types of bands called astrogals.  It would be ideally suited to turning on a CNC lathe, but is much too long for my Boxford.  So I am asking around, to locate a larger CNC lathe for hire/loan.  If all else fails I will use my manual lathe, but I expect that the finish would be better on a CNC.

I will drill the bore first, and after considering the options, will use the Jerry Howell recommended method, which is to use a D-bit.

24 Pounder Naval Cannon

A half day in the workshop today, and the naval cannon carriage is taking shape.

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The pieces at this stage, just push together.  A few more bits of ironwood to be machined, then for the fun time… machining the cannon barrel.

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Ironwood cannon carriage, sitting on an ironwood kitchen table.  SWMBO is impressed! “it is looking interesting!”  Wait until she sees the brass bling.

DESERT IRONWOOD

Some decades ago I made a table for our kitchen.  (cannot find  photo just now, will add one later)

I bought the wood from a wood recycler.  He removed trees from Melbourne suburban gardens, then cut them into slabs and air dried them.

I recall that I paid about $AUD 1000 for the 6-8 planks.  They were about 40mm thick and 300mm wide and about 2.5m long.  They were so heavy that I could barely lift them.

I have since learned that they weigh 1.1 to 1.4 tonnes per cubic metre, which is at the high limit of wood densities.

The tree must have been 400mm diameter, because some slabs still had the bark attached to both sides.

The wood has a beautiful dark brown colour, with almost white sapwood solidly attached. It is unbelievably hard, and I struggled to machine it with my thicknesser/buzzer.  Also, it was the most reactive wood I have ever worked.  When planed or thicknessed it would bend and react totally unpredictably.   My 40-45mm thick planks ended up 25-28mm thick and even then they were not totally flat.

But SWMBO liked the table, and it still is the main meal table in out house.  One of my daughters requested a similar table, which I made from Gippsland Blue gum, another spectacular dense hard Australian wood.

The ironwood has survived kids dancing on it, steam engine demonstrations, being used as a work bench, not to mention many meals with never a table cloth.   And the wood itself is unmarked!  The polish has disappeared in places, but the wood itself seems impervious to damage.

To get to the point of this post, I am currently making a 1779, 24 pounder, 1:10 scale naval cannon.  Jerry Howell design.  About 300mm (one foot) long.

When I was looking in my shed I considered various woods for the carriage-base.  I considered some black walnut, which was recommended, but it seemed a bit light in weight and colour.  I considered some Australian redgum, which polishes beautifully, and is dense and tough, but it is a bit too red.  Some African Odum looked possible, but the figuring is a bit plain.  Then I found some ironwood offcuts from the table job, and the decision was made.  Ironwood it is.

So here are the initial photos of the carriage parts.  They were machined on my metalworking mill, using HSS cutters.   I CNC’d where possible.

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Ironwood after conventional thicknessing.  Tearouts are a problem.

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Ironwood after surfacing with a 1″ endmill.  Here I am CNCing the profile of the carriage.  3000rpm, 500mm/minute.

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After milling, I am tempted to just oil the surface.  The edges are sharp, like milled metal.

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CNCing the wheels.

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A little deburring or with wood is it called defuzzing? required

Watch this space for progress on the cannon.

There are some technical challenges, including deep boring 14mm diameter 275mm deep, making a tiny dovetail in the ironwood,  and turning the barrel from 50mm diameter brass.

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