Steam tube & fittings size for Stuart S50 and similar

So Ive just completed my first steam engine project, a Stuart S50 and in the process of looking at boilers, but how do you determine the optimum size of steam tube in relation to both an adequate supply of steam vs a good scale size? Is there a good book out there that goes into this sort of thing? Also anything that describes what correct steam fittings to use and what layout? Ive already determined that I will need a displacement lubricator and some sort of steam valve or regulator between the boiler and engine (globe valve?) but what sizes are appropriate for this size of engine? Sorry if its a daft question but Im a beginner with steam.

I've used 1/8" OD on small engines. Chuffs along ok at that. You might want to go up a size for more high performance or larger engines. Put the steam shut off valve right at the boiler and run it just cracked open to control speed. This "wire draws" the steam through the small opening and helps to keep it dry, or at least drier than otherwise. Also safer to not have lengthy pipework under boiler pressure while valve is closed.

Thanks Hopper, I’ll do that. I assume the lubricator then needs to go near the steam chest or does it not matter so much? I’m going to have a go at making both the lubricator and the steam valve rather than buy them.

Stuarts have a chart with the pipe sizes for all their engines they give the 50 as 5/32" inlet and 3/16" outlet

Thanks for this Jason. Ive had a look but cant see it on their website. Can you tell me where I can find it?

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In the paper catalogue, at least the one I have has it, not sure if the current one does

Have look at Keith Appleton's YouTube. He has just bought some pipe, 4mm OD for inlet, 5mm for exhaust. Note you can buy 10M lengths from plumbing suppliers much cheaper than small lengths if you intend to use it in the future,