Castings problem remedial advice, please

[Cornish JackParticipant @cornishjack]

As previously promised, an update.

Ramon’s suggestion was initiated but quickly realised that it wasn’t quite the answer as the already bored standard was both tapered AND tilted!! The expanding mandrel would certainly have centred the top end but I had no way of centring the ‘feet’ end. Much thought ensued … result – cut two strips of steel model a/c wing joiner to exactly span the standards feet. These closely matched the feet width. These pieces were then carefully centred in the four jaw and a small centre drilled. Each standard was soft soldered to the plate as accurately as possible, with the centre hole outwards. The standard was then located by a sprung centre at the headstock end and the live centre at the t/s. The standard top end periphery was then machined to give a reference surface to match the top of the bore. This reference surface was then located by the fixed steady using the previous setup and the live centre was removed to allow machining of the top surface of the standard and reboring to oversize but slightly straighter. An oversize bar was machined to a size which fitted that bore and centred at both ends. The standards were then mounted on this bar, top in the four jaw, and the feet were machined to parallel the top (the plates had been de-soldered!!). The end result is still not perfect but an improvement on the previous state and should only require oversize crossheads … (fingers crossed)

Apologies for longwinded spiel but the process was similarly so!!

Rgds

Bill

[Ramon WilsonParticipant @ramonwilson3]

Whoever it was ‘pre-machined’ these castings for you Bill certainly set out to provide you with a firm challenge eh?

Still, it sounds like you have made a good start and have a basis from which to build.

 

Keep us posted on the progress

 

Regards – Ramon

[Author]

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