I'm well into my first model from castings, a Stuart H10, and (fingers crossed) all seems to be going well.

However, and it may be because I'm a novice and not practiced at reading engineering drawing, I'm puzzled by one thing.

The brass crankshaft bearings are asymmetrical – the turned portion on one side where the flat part is machined away shown as projecting1/8" and on the other side of the bearing as projecting 5/32". I can't see from the drawing whether the longer projections face inwards toward the crank or outwards.

Perhaps they are intended to limit end-float on the crankshaft but it would be pretty large either way round. I think that these bearings would be the same for a 10V so the same question would arise.

While I'm here, any suggestions for a tool to machine the crank pin – it needs to be fairly narrow bur has to project from its holder to the depth of the crank webs (i.e. the crank offset plus a bit).

Thanks for any advice that you can offer.

Thanks Jason B:

I'd missed the relationship of the bearings to the centres of the bearing stud holes and, as you demonstrate, the wider projection will give a zero end float and just a little fitting. I'd based my misconception of a large end float on mounting the crankshaft but with the bearings not properly positioned axially. Beginner's mistake.

More question on tooling for machining the crank pin.- more newcomer's ignorance I'm afraid – so please bear with me.

I have an indexable parting tool, but only c.1/16" wide do you think it feasible to grind away the centre? More generally one would have to use something like a diamond slip or very small wheel to do this. My inserts are gold coloured so presumably coated (TIN?) I suppose the underlying carbide is fine without the coating, but are there unexpected negatives to removing it – I have wondered about his in respect of other inserts and giving a little sharpen with a diamond slip as I would with an HSS tool.

I do have a more (unused) substantial HSS parting tool which would be wide enough to bifurcate but this, squaring the end, and small roundings to provide the fillets would obviously require a regrind to return it to its original function.

Sorry to extend my original question, but now seems the time to ask.

Thanks again JasonB.
Not sure of the exact vintage of my 10H, but I got it on Ebay and had plainly been living in someone's attic for a while. It's old enough to have the cast crankshaft.
If needs be I'll finish the crankpin with emery, though pride and the challenge say that I should try to machine it to a finish. I'm wondering whether, as an alternative to emery I might lap it: a simple lap should be easy enough to make, or using the big end (which can be progressively tightened up as it is split) hence lapping the two together. I think that I can take the bulk off the inner faces of the crank webs and the pin with my heftier HSS parting tool and the try various strategems for finishing it while still over-size to see what woks best (this worked well with the rest of the crankshaft).