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Assembly Problems

Started by Dave_P, Feb 28 2022 17:34

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I have acquired a part finished Loco (Bond 4-6-0 mixed traffic) for which I have a number of blue prints although most of the machining is complete.
Where I have got stuck is fitting the connecting rods and wheel coupling rods.
The Bonds BS307  "Pacific" coupling Rods fit the crank pins fine but the connecting rods insist on clipping the crank pin on the leading wheel. The crankpin only protrudes about 0.010" from the coupling rod but as there are only about 3 threads I'm reluctant to shorten it any more.
Is it normal to have a shim on the centre crank pin between the coupling rod and the connecting rod? What sort of clearence should I aim for at the leading wheel crank pin?
Is there another surviving one of these locos in captivity?


Do the drawings you have cover the coupling/connecting rods, crank pins etc Dave?

If so, I'd check the dimension of these parts against them and also perhaps the wheel thickness/boss depth etc. The coupling rod position (distance from frames etc) if defined by the cylinder placement, so a slight mismatch there may also cause lack of clearance elsewhere.

If you do not have a complete set of drawings, then the N25GA should have scans of most of the 'standard' Bonds design sheets, as all the engines shared a lot of common parts.



Nothing's ever Easy - At least the first time around.


I am sure David White (address in the membership list but he's in the Coventry area) must have one or more of these.  Sometimes its easier to see and handle another example.