How to unstick center disk of round slide rule?

Silicone oil, usually good with plastics and enameled aluminum, or a dry lube based on hexagonal boron nitride (this is sold as a white powder "lock lube" in most hardware stores). The solid is a bit less messy if you have difficulty controlling the delivered quantity.

Yes, silicon oil typically does not attack most polymers.

That was the main reason I suggested the lemon oil based stuff, which is also pretty benign in this regard.

Thanks for the hint. I'll try, but first I'll ask a guy who seems to be a slide rule enthusiast:

Aha, still made, who'd a thought ... thanks!

But you easily end up with one that has the same issues. Those things don't seem to like California temperatures.

Yes, looked like hard plastic, maybe melamin-based. Riding on aluminim. Both scratched :-(

Maybe I'll have to find some PTFE tape like Dave suggested. Can be thicker though because there's lots of clearance.

Ah, another trick. Thanks, didn't know about the oil. Washing did not work, didn't do a thing.

Well, I'd really like to revive it :-)

It still works but I don't want to keep forcing the center wheel since it'll probably rub off the lettering over time. Unless I always use

Here's my round one, found behind books on the shelf...

But my K+E "Slip Stick", found similarly...

didn't fare so well. In it's standard green leather case, unopened for I'd guess at least 35 years,... the thin metal holding the graticules has literally turned to dust :-( ...Jim Thompson

That's a real antique. Amazing that the manufacturer wishes to remain incognito.

If you are willing to drill out and re-install rivets it looks like this one could be salvaged. My small slip-stick has another problem, the melamine overlay or whatever material it is starts coming unglued from the wood. Have to fix it before it falls off completely.

The slide-rule that held up best is the Aristo Scholar 0903VS. Good old Teutonian quality. Only the top of the cloth-clad cover got lost, probably during our last move.

I think I bought it in 1960 at the Harvard Coop

I was puzzling over that as well. But, IIRC, it's by Post.

Yep. I was looking at it here. I wonder if the slider mechanism, as I recall its better days, something like spring steel, is still available?

I can't really see any use for them now, if you have a good calculator (*). I think I'll make a shadow box for my "antiques" ;-)

(*) I have TI-60X and TI-83, use mostly the 60X. Why trouble yourself even with those when you have a simulator that can solve the most difficult of non-linear differential equations, over temperature, in seconds ?:-) ...Jim Thompson

I bet not. You'd have to have that made somewhere. Or kludge something and call it the Thompson edition.

Can be a problem, like when you are in a tight space in production, trying to figure out why some camera automation routine doesn't home in. That's when I really like the li'l HP11C.

It's a Gilson "midget" 4-inch, by the look of it. These, and their

A Gilson Midget was my very first slide rule, back in 8th grade chemistry class (1968 or so, I think). A very nice little design, roughly equivalent in precision to a 10" linear rule, and at least as easy to use as a linear rule.

Mine was stolen out of my high-school locker some years later, and I really regretted the loss. Finally bought a replacement via eBay a few years ago, and this got me started on collecting slide rules... I have a couple of dozen now, of various types and conditions.

The old Nestler advice was silicone oil, but for slide rules on plastic base (not wooden).

Gun stores carry a spray lubricant that leaves a dry teflon powder. Pretty slick! John Ferrell W8CCW

Food grade dry "mold release" agent. Comes in spray cans. Bearing lube in squeeze tubes, etc.

Chalk dust tightens it--use graphite.

Cheers

Phil Hobbs

Yeah sure... all those gray smears on the white backdrop of the ruled faces would surely be desirable.

... both literally and metaphorically :-)

I've used dry-Teflon lubricants on slide rules, with good results so far. I've tried two types:

- micro-fine dry powdered Teflon. Bought this from a piano- servicing-supplies company, of all places - a bit of this is brushed on the hammer mechanisms to prevent squeaking. It can be applied to a slide rule's sliding parts with a fine brush. This works nicely on both plastic and wood rules (although I've read that bamboo rules shouldn't need added lubrication if the wood surfaces are clean - bamboo is somewhat self-lubricating).

- Miller-Stephenson PFTE release agent / dry lubricant. This is a very finely divided PFTE Teflon, suspended in a fast-evaporating solvent carrier... I wipe it on with a Q-tip. The Miller-Stephenson liquid seems to work really well as a lubricant for the Pickett metal slide rules, including the old models such as the Model 2 and Model 1000 which are made of magnesium (tends to oxidize and corrode over time). A few years ago I bought a Model 2 at a local flea market which was completely stuck... corrosion had frozen the slide in place and it wouldn't moved. I disassembled the whole thing, soaked it in soapy water, carefully scrubbed off the corrosion, lubricated the sliding surfaces with the M-S stuff, and reassembled it... and it now works perfectly, just as smoothly as if when brand new.