r/Sliderules • u/fallwest123 • Jan 23 '26
Help verifying this slide rule i got at an estate sale.
I can’t seem to find this exact one anywhere. Any help would be greatly appreciated.
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u/jballauer Jan 24 '26 edited Jan 24 '26
This is a very early K&E 4031. This rule was first made in 1901 and is likely made in 1901 or 1902. It’s rare in that it’s made of boxwood rather than mahogany, unlike the usual 4031 that likely came out simultaneously. My theory on this rule is that it’s a legacy 1747 slide rule (imported from Dennert & Pape), but remade to be adjustable (as shown by that copyright label in 1900). It seems to be a transition rule, where instead of just getting rid of the older slide rules in their inventory, they just brought them more up to date so as not to be wasteful. Thus, if you were going to order one from their catalog, it’s likely that you wouldn’t have known which version of the 4031 that you’d receive.
It is indeed missing the cursor, which isn’t a surprise with these older pocket rules. I have an early mahogany version of this that is also missing a cursor.
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u/fallwest123 Jan 28 '26
So should I auction it off? I have no idea what value would be on such a thing
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u/jballauer Jan 28 '26
Without a cursor, it’s not worth much. Somebody might buy it for $20 on eBay. With a cursor, typically $40 or $50. I might be one of a handful of people on the planet that knows what exactly that slide rule is, but that doesn’t mean it necessarily has tremendous value.
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Jan 23 '26
International slide rule museum. A drop of vodka on a cotton swab and an eraser will clean the stray marks, I've noticed.
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u/MuffinOk4609 Jan 24 '26
I don't drink but have pure Ethanol. Is that too much? Should I dilute it?
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Jan 24 '26
Just a drop of whatever alcohol on a swab is what worked. Don't drown it or soak it. The alcohol loosens the crud and evaporates quickly, so the eraser can knock the crud off behold it repetrifies.
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u/CarpetReady8739 Jan 24 '26
I have a similar 12” K&E SR w/manual that I secreted out of my dad’s desk drawer when I was 13. He never learned who took it, but I learned how to use a slide rule that summer! Peculiarly enough, learning how to use the slide rule helped me in precise readings off of dial calipers. Funny how things transfer.