The connection rods were a nice between-centers turning job, and then a selection of milling set ups.
Rather than write a lot, I will put some pictures below – the main thing to note was that almost all of the milling and boring was done with the partially machined big-ends attached to the partially complete rod – in order to ensure a good level of concentricity….
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- Facing the top of the big-end on the shaper, using “stop-pins” to hold it (and idea from a 1900 text book
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- …an even better view. Stop-pins hold the job down and central. and the shaper does not produce significant lifting forces. so all that is needed are the pins and a stop plate on the end of the table
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- Cutting flat face to lock big-end bolts
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- Cutting flat face to lock big-end bolts
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- Boring big and little ends at same setting to ensure concentricity. The DRO is used to find the mid-line of the castings – no marking out at all!
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- By bolting the rod/end to an angle plate ensures that the rod winds up square to the bores.
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- Using the DRO… first place cutter on the bed and zero display…
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- then raise cutter to provide exact width of little end bearing housing
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- Cutting the fork. Rotate thru 90-degrees, and use a vice to ensure that the rod in perpendicular – cut slot to width, and then use boring head to provide a clean foot to the slot.
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Subsequent analysis showed that the big ends and piston rod bearings were not entirely true. So while replacing the crank at the end of the 2018 season I re-machined these bearings as described here to get then true… https://sy-befur.co.uk/2019/02/19/steamboat-crankshafts-lessons-manufacture-pt2/