Making The Faux Barrel.
In a fit of design exuberance, I designed an elliptical barrel – which is a PITB to make but looks nice.
The slot down the side clears the steamchest and valvegear, the two holes in the underside are for the cylinder mounts to go through.
At this stage, I had forgotten the exhaust hole in the top side and added it later.
I had a piece of Namibian “Kameeldoring” = Camelthorn: used for making barbeque fires (makes great coals).
However it has a very attractive crown grain and red colour – it is also very dense and as hard as a whore’s heart. It sinks in water – its bone dry density is 1.06g/cc (I measured it).
Turns out it machines nicely as well.
Top Left: Block up and machine interior, drill dowel holes for assembly alignment – the Ø2 dowels are cut from bicycle spokes.
Top Right: Glue together. Make sure it fits your cylinder assembly before this step.
Bottom Left: Mounting blocks machined from MDF to mount it accurately on an M14 threaded rod mandrel in a collet chuck. Hole is a tight fit on the bar – it is not threaded.
I used the (non-preferred) M14 as it is the largest thread that will fit through my MT2 rotary table.
In the end it didn’t need to go all the way through and I could just as easily used M16 or M20
Top Left: Assembled (but not tightened) to collet – note turned down nut at rear.
Top Right: Collet tightened onto M14 rod and locknut tightened.
Bottom Left: Rough turning to Ø54.5 = 0.5 over finished major diameter of ellipse.
Remove from lathe to Rotary Table – which has an ER42 adaptor flange – makes moving between turning and milling operations nice and easy.
Top Left: Setting the job level at zero degrees on the RT – I didn’t want to use the RT to level and end up with some arbitrary numbers.
Top Right – The flange “floats” slightly and can be clocked dead true – in this case clocking wood with a micrometer clock might just be considered “anal”.
Bottom Left: Co-ordinate milling the ellipse with a R6 cutter – in retrospect a flat face or side of the cutter would have been better – I have provided co-ordinates in the drawing for either option.
(Above photo) Bottom Right: Rough machining completed.
Note the “Near Miss” indications – the mounting MDF block gave me a visible warning that I’d made a mistake. With hindsight it would have been just as well to attach a printed self adhesive label of the outline onto the MDF to act as a guide. Since the OD is only cosmetic you could use this form of “marking out” to eyeball the cuts.
Again the drawing has co-ordinates for using the corner of a milling cutter to produce fake “joints” approximating equal 8mm “planks” all round. Since the outside is still “rough” cutting the grooves is an act of faith in the data.
Back to the lathe for a quick linish to remove all the high points – and my faith in my co-ordinates was justified.
Barrel Assembled To Cylinder - unfinished and without hoops.
Not bad for a piece of firewood.
Next machining the hoops.
Regards, Ken
