Stuart Twin Victoria (Princess Royal) Mill Engine

[JasonB]

On JasonB Said:

Going back to the handwheel suggestion. Put your alignment pin in the flywheel that is in the chuck, slip on the previously turned one and touch the tool on the rim and zero the handwheel. Now you know the setting to turn the second handwheel to.

It’s times like these that my 300mm digi calliper comes out of the draw.

Yes, another option. I’d already forgotten about the spigot.

[Dr_GMJNParticipant @dr_gmjn]

OK, so I’ve used three measuring methods – just out of interest to see the relative accuracies:

1) A strip of card wrapped around the smaller wheel, and its length (circumference) measured with a tape measure, then wrapped around the larger wheel and the difference measured with verniers:

2) Measuring the chord length and its offest from the circumference using verniers:

3) Height gauge:

 

Assuming the height gauge is the datum (as the most accurate method) Anyone fancy a bank holiday guess at the maximum and minimum deviation from this – on radius, in terms of thou – between the chord and tape methods?

I’m going to use Jason’s spigot method as a double-check on the height gauge readings, and hopefully get it done this afternoon.

Thanks all.

 

[JasonBModerator @jasonb]

I thought you wanted to do the measuring with the second one still in the lathe, if so height gauge method may be tricky.

 

If off the lathe then stand the two side by side and measure the height difference with depth gauge or the back of your callipers.

But as you have a height gauge then just clamp a flat plate to the bottom and you effectively have a vernier calliper.

[Dr_GMJNParticipant @dr_gmjn]

I did want to keep it on the lathe, but as mentioned I then thought that I really want to bore the hub and face the mating parts of the rim/hub in one setup, to reduce the chance of them being out of true. I’d machined the outer face first (as per the article method I think), which I suppose was a mistake.

So with both wheels off the lathe, I’ve now just measured them directly with the height gauge, and will take off the measured difference once the second wheel has been re-set.

I tried the other two methods out of interest to see how accurate (or inaccurate) they would have been.

 

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