The frame or chassis for Elmer’s Open Column engine was whisked away for a professional paint job at a nearby paint shop. It was powder coated in satin black to provide a good durable finish and care was taken to mask off threaded holes and ball race holders. It cost less and gave a much better finish than if I had done it myself with car spray enamels.
Whilst it was away I fabricated the eccentric strap and the two movement support arms. I became so immersed in machining that progress photographs were forgotten – sorry about that. My first attempt at making the eccentric strap was consigned to the scrap box but I was reasonably satisfied with my second effort.
Today I have made a start on the heart of the engine – the cylinder block. There is a big investment in both material and time so I am proceeding with extreme caution. Here is how this mornings workshop activity has proceeded.
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- Radiusing the arm ends using a simple jig set up on the milling machine.
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- Milling the arms as a matched pair ensures identical dimensions for both components.
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- After a quick polish the finished arms will be ready for assembly onto the engine chassis.
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- The tape measure provides an indication of the size of Elmer’s enlarged engine. Note that the chassis has been powder coated for a good durable finish.
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- The eccentric strap with added detailing provides the illusion of a split bearing.
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- The lump of brass for the cylinder block is brought effortlessly down to size in the bandsaw whilst I have my morning coffee. A temporary jig using an old machine vice was required.
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- After facing each end in the 4 jaw chuck the block is transferred to the mill for drilling and milling operations. My DRO system removes the need for marking out though I employ both methods as a belt and braces precaution.
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- As I am building 50% up on plan size I am increasing the number of steam chest holding down studs from four to six for appearances sake. Here I am starting the threads by hand to ensure correct vertical alignment.
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- The block is offset in the independant 4 jaw chuck using a dial test indicator (DTI) and the bore drilled in stages up to 10mm
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- I then switched to the boring bar to increase the bore up to 12mm to provide the necessary clearance to attack the hole with my new indexable internal lathe cutting tool.
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- I reckon that the indexable tool is more rigid than the boring bar and produces a more accurate and smooth finish throughout the length of the bore.
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- Before removing the cylinder block from the four jaw chuck the outer edge is turned to plan as it shares the same centre as the bore.
