Lets say I wanted to make homemade wooden C-clamps. Is there any advantage to using a better grade of ACME thread than single start RH 2G? Will 3G or 4G buy me anything? What about multiple starts or 2C, 3C and 4C?
Is there any advantage to using a better grade of ACME thread than single start RH 2G? Will 3G or 4G buy me anything?
To answer the question as asked, no. But you're overthinking this, you don't even need to use Acme threads.
Plenty of people have made clamps of various types made using standard bolts or threaded rod. It is slower and they are not as strong*, but they give a long service life all the same (years or better).
An early reference to DIY clamps using standard threaded rod is this from 1960:
Source: Popular Science, June 1960
And some more modern ones:
By all means use Acme thread if you want, it makes for a clamp that works much faster which over time you could find a boon. But if you don't think that'll be a big issue for you and you want to save a bit of money it's fine to use standard threaded rod instead.
*If you need a good reason not to stress the strength of the threads for wooden C-clamps is that the force the threading is capable of exerting can easily exceed the strength of the clamp itself. Metal C-clamps can break in use when overtightened, so this is a real concern with the wooden variety.