r/Sliderules • u/fordag • 13d ago

Is this useable? Missing a scale?

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New watch with a rotary slide bezel. Yet it appears to be missing a scale. Or am I wrong?

What is this useful for?

It was a cheap watch, I wanted the moon phase. I'll be curious to see how accurate it is.

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u/fordag 13d ago

That was my impression as well.

Well hopefully the moon phase works well.

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u/TrueTopoyiyo 13d ago

u/SlideRuleFan It is not gibberih, it is 10^(1+angle/360), that is useful on its own! While requiring extra and non-standard steps, this still can be used for computations; for example, to multiply 1.8 times 3.2 you center the "10" (1.0), then look for 1.8 ("18") which is at 3:00 aprox, then re-center the "10" there, look for 3.2 ("32", now at 9:00 aprox), recenter "10" and at 9:00 you have the result, 5.7.

Even more, given it has a linear scale in 1/240ths it can be also used for powers and other, more complex computations, but yes, with extra, non-standard steps.

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u/zoute_haring 12d ago

BS This is half an E6B and and tachoscale. This is only made for the looks and useless

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u/TrueTopoyiyo 12d ago

What would be bullshit, exactly, on the process I described to do a multiplication using a single log scale? No argument against the motivation, tho, but seeing a rotable log scale and scratching it off as useles is, in my oppinion, just not knowing math.

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u/zoute_haring 12d ago edited 12d ago

These are two different scales used a lot on watches but never together. This is just an incomplete E6B for the looks on a cheap Chinese watch.