Online source for slide rules & surplus electronics?

Hi all
I'm looking for an reliable online source for slide rules in the US. Note
that I don't need antiques nor collectables, but a slide I can learn with
and use daily in the shop.
Also wanting to buy large surplus diodes (for future DC welder
construction). Someone posted an url (a dependable supplier?) but I cant
remember it.
Any help thanked in advance.
Reply to
mongke
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||Hi all || || I'm looking for an reliable online source for slide rules in the US. Note ||that I don't need antiques nor collectables, but a slide I can learn with ||and use daily in the shop. || Also wanting to buy large surplus diodes (for future DC welder ||construction). Someone posted an url (a dependable supplier?) but I cant ||remember it. ||
Coworker bought this one
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A very nice rule. Probably pretty expensive when new. Still new, $6.99 Texas Parts Guy
Reply to
Rex B
MECI has 150 and 300 amp diodes and I've had good luck with them in the past:
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I've also bought suplus electronics from Marlin P. Jones & Associates at:
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I don't know of a slide rule supplier but I'd start with eBay. And there's always this one:
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:-)
Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com
"Even if you are on the right track, you'll get run over if you just sit there." - Will Rogers (1879-1935).
Reply to
Keith Marshall
Thanks I'll give them a try.
Hmmm. Tough thing dragging the 'puter down to the shop and have it perform amidst sparks and chunks of flying metal ;-)
Reply to
mongke
Hit the garage sales, that's where I've picked up the ones I have. (About twenty of them now, still looking for something besides aluminum Picketts.) Cost me about a buck each, and that includes some I don't even pretend to know what all the scales are for. Also includes a 20" K&E.
Reply to
Lennie the Lurker
You don't *want* collectibles, but I don't think that anybody still makes the things, so any you find *will* be a collectible, and you'll have to look in such a place.
These days, you would do best to go to yard sales, antique dealers, and eBay to find them. I got my first ones from Sears (rather poor ones, but enough to learn on, and I was a kid then.
Later, I got a pocket sized (5") all metal one from Pickett -- bought from a local office supplies store.
My first *good* 10" one was from Lafayette Radio (now long out of business). That was around 1960 -- and the quality of the slide rule was excellent, though most Japanese tools and equipment was rather poor quality at that time.
After that, I picked up several used K&E ones (including one barely used from a summer hire who changed to business after a summer of actually *working*. :-)
My best two are a 20" K&E, and a Russian circular slide rule in a pocket-watch case. (The K&E is the more accurate, of course -- but the Russian one is fun.)
Now -- if you are planning to use this in the shop, I should perhaps point out some limitations:
1) A slide rule can't add. It multiplies, divides, squares and square roots, logs, trig functions, and exponentials, but not any good for adding.
2) A slide rule is of limited accuracy. For the most part, you should not expect to get more than three significant figures out of it -- though this varies somewhat with where on the scale you wind up, as things are spread way out at the low end of the scale, and scrunched up at the high end. If you are working in inches, say 1.25", you won't be able to calculate anything to 0.001" (where you are machining).
If you want more significant figures, you need a longer scale. 20" is not enough for machine shop work. Big circular slide rules squeeze a bit more scale length in a given maximum dimension, but still is not adequate. A big cylindrical slide rule might work -- but it would be awkward to use.
3) *You* have to keep track of where the decimal point goes. Now this is very good practice for a sanity check on the results of an electronic calculator, but can really trip you up until you are used to it.
Frankly, for shop use, I would consider an abacus or a soroban (the Japanese version, with significant differences) to be more useful, as you can put the decimal where you want it, and keep several significant figures of accuracy. (Think of the slide rule as an analog calculator, and the abacus or soroban as a digital one.
The slide rule was *great* in circuit design, as the components were usually not made to a precision as great as the slipstick could deliver. I would never consider it to be the best choice for machining.
And these days -- *I*, at least, need my glasses and good light to read one. :-)
Also -- in today's world, I would suggest a good scientific pocket calculator -- kept in a Ziploc baggie to keep swarf and coolant out of the thing, but to allow you to see and use the buttons and the display through the clear back of the baggie.
I'm afraid that I don't remember it either.
Good luck, DoN.
P.S. I also almost got arrested because of one. I was wearing it on my belt, and a policeman thought that it was a knife. :-)
Reply to
DoN. Nichols
Bummer. BTW, I seem to remember reading somewhere that at chip level (digital computers) division & multiplication are easy to implement, contrary to addition & substraction.
Mmm. Had no idea. What they did use in the machine shops of old?
LOL. I keep a Leatherman Wave and a Maglite in my belt. I often get the suspicious look from security people
Reply to
mongke
Although, at it's heart, it *is* an analog computer that does add and subtract. The trick is, the scales convert the operands into logarithms - so the addition and subtration thus performed turns into multiplying and dividing, etc.
Jim
================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================
Reply to
jim rozen
Hmm ... addition is quite easy at the chip level. For each bit, there are two duplicate interconnected circuits called "half-adders" (which can also be used for other things by themselves). Subtraction involves inverting all the bits of the subtrahend, and *adding* it to the other (with perhaps some fiddling to deal with the carry bit). Again, pretty simple to do in hardware.
The software implementation of multiply involves a lot of shifts and adds, and needs an accumulator twice the width of the two operands.
Hardware multipliers were available, (from people like TRW), but they tended to be big and hot chips (for their day). A 16x16 multiply chip was mounted in a 64-pin package -- the same size as the entire Motorola 68000 CPU.
[ ... ]
I suspect that pencil and paper was used mostly in machine shops in the US.
As suggested before, an abacus (or equivalent) would be likely in oriental countries.
There were some excellent mechanical calculators, such as the one by Frieden, but they were very expensive, and probably all of the gears in them did not deal well with the swarf to be found in machine shops, so if they had one, it would be in the office -- and a machinist would be more likely to use pencil and paper than to make a trip to the office. ;-)
Enjoy, DoN.
Reply to
DoN. Nichols
If you want a slide rule to just be able to add, just use two metric rulers side by side to do that.
Bill K7NOM
Reply to
Bill Janssen
You're right. I remembered it wrong. Thus, division is implemented as a series of substractions.
Reply to
mongke
[ ... ]
Subtractions and shifts to align the bits, so it doesn't take too many subtractions. (You *could* do it by simply subtracting the one from the other, and counting how many times it takes before the result goes negative -- then add one back and return the rest as a remainder.
Enjoy, DoN.
Reply to
DoN. Nichols
I have a few used 300 amp diodes left, see the electronic parts for sale page on my web site,
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maybe these will do your trick - I can ship a bunch in a flat rate envelope to keep postage down.
Reply to
william_b_noble

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