The 'heart' of Elmers vertical open column engine is nearing completion. Note the addition of bolt-on inlet and exhaust manifolds and additional bolts on steam chest cover.
This stage is concerned with the fabrication of the steam chest and air control valve. Built according to plan (enlarged by 50% from Elmer’s original). The only deviations relate to added detail in the form of six, in place of four, hold down bolts on the steam chest. The two additional bolts are dummies simply attached to the cover but, in my view, improves the overall appearance. The other modification is the addition of inlet and exhaust manifolds which again add a little authentic detail.
A further point worth commenting on is the fabrication of the valve rod which was made in two pieces – rod and attachment clevis. Easier to produce in two pieces and also provides some adjustment should this be required during the final setting up.
Now that the ‘heart’ of the engine has been completed the remaining work concerns the fabrication of the running gear – linkages, crank and flywheel. Doesn’t sound too much but will inevitably take longer than I think. Domestic issues will mean there will be a break of several days before production re-commences.
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- A brass blank is carefully set up in the independant 4 jaw chuck with the aid of the DTI (dial test indicator). This is a procedure that does become a little easier with practice.
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- The end sections of the steam chest are turned down to size. A central hole is then drilled for the valve rod and the entry end drilled and tapped for the gland nut.
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- After marking out the cut-away area for the steam chest four corner holes are drilled just within the scribed lines. Clearance holes for the hold down bolts are also drilled at this stage.
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- Working in a clockwise direction to avoid climb milling the bulk of the material is removed and light final cuts are taken up to the scribed line.
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- A suitable piece of brass flat was flycut down to the required thickness for the valve plate. A mirror finish on this piece is highly desirable.
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- A good level of precision should be aimed for when drilling the air (steam) holes on the valve plate. The plate will be cut from the main piece of stock when machining is completed.
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- I like the appearance of inlet and exhaust manifolds and these are turned from round stock.
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- Manifold clearance bolt holes are drilled then surplus material is removed using an end mill cutter.
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- The valve rod was made in two pieces (clevis and rod) for ease of construction and is shown here with valve attached.
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- Shaping the underside of the valve with a 2mm slot drill. I made three before I was satisfied – hopefully my care will be rewarded !
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- Assembly of the steam chest and valve components. PTFE gaskets are fitted to all joint surfaces. Note four hold down bolts – the other two are dummies fixed to the cover only.
