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.


--

Regards,


Mongke

On Tue, 20 Jul 2004 11:58:00 -0500, "mongke"
wrote:

||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 http://www.stupid.com/stat/SLID.html

A very nice rule. Probably pretty expensive when new.
Still new, $6.99
Texas Parts Guy

MECI has 150 and 300 amp diodes and I've had good luck with them in the
past:

http://www.meci.com

I've also bought suplus electronics from Marlin P. Jones & Associates at:

http://www.mpja.com

I don't know of a slide rule supplier but I'd start with eBay. And there's
always this one:

http://www.taswegian.com/SRTP/javaslide/javaslide.html

:-)

Best Regards,
Keith Marshall


"Even if you are on the right track, you'll
get run over if you just sit there."
- Will Rogers (1879-1935).


"mongke" wrote in message
...
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.


--

Regards,


Mongke

On Tue, 20 Jul 2004 20:19:40 +0000, Keith Marshall wrote:




MECI has 150 and 300 amp diodes and I've had good luck with them in the
past:

http://www.meci.com

I've also bought suplus electronics from Marlin P. Jones & Associates at:

http://www.mpja.com


Thanks I'll give them a try.


I don't know of a slide rule supplier but I'd start with eBay. And
there's always this one:

http://www.taswegian.com/SRTP/javaslide/javaslide.html

:-)


Hmmm. Tough thing dragging the 'puter down to the shop and have it perform
amidst sparks and chunks of flying metal ;-)




--

Regards,


Mongke



--

Regards,


Mongke

"mongke" wrote in message ...
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.

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.

In article , mongke wrote:
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.

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.

Also wanting to buy large surplus diodes (for future DC welder
construction). Someone posted an url (a dependable supplier?) but I cant
remember it.

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. :-)
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On Wed, 21 Jul 2004 00:51:53 +0000, DoN. Nichols wrote:


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.

Bummer. BTW, I seem to remember reading somewhere that at chip level
(digital computers) division & multiplication are easy to implement,
contrary to addition & substraction.

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.

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.

Mmm. Had no idea. What they did use in the machine shops of old?



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. :-)

LOL. I keep a Leatherman Wave and a Maglite in my belt. I often get the
suspicious look from security people
--

Regards,


Mongke

In article , DoN. Nichols says...

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.

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
==================================================

In article , mongke wrote:
On Wed, 21 Jul 2004 00:51:53 +0000, DoN. Nichols wrote:


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.

Bummer. BTW, I seem to remember reading somewhere that at chip level
(digital computers) division & multiplication are easy to implement,
contrary to addition & substraction.

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.

2) A slide rule is of limited accuracy. For the most part, you

[ ... ]

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.

Mmm. Had no idea. What they did use in the machine shops of old?

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.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

jim rozen wrote:

In article , DoN. Nichols says...



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.



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
================================================= =



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

On Wed, 21 Jul 2004 16:38:43 +0000, DoN. Nichols wrote:


Bummer. BTW, I seem to remember reading somewhere that at chip level
(digital computers) division & multiplication are easy to implement,
contrary to addition & substraction.

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.


You're right. I remembered it wrong. Thus, division is implemented as a
series of substractions.



--

Regards,


Mongke

In article , mongke wrote:
On Wed, 21 Jul 2004 16:38:43 +0000, DoN. Nichols wrote:


Bummer. BTW, I seem to remember reading somewhere that at chip level
(digital computers) division & multiplication are easy to implement,
contrary to addition & substraction.

[ ... ]

You're right. I remembered it wrong. Thus, division is implemented as a
series of substractions.

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.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

I have a few used 300 amp diodes left, see the electronic parts for sale
page on my web site, www.home.labridge.com/~wnoble

maybe these will do your trick - I can ship a bunch in a flat rate envelope
to keep postage down.
"mongke" wrote in message
...
On Tue, 20 Jul 2004 20:19:40 +0000, Keith Marshall wrote:




MECI has 150 and 300 amp diodes and I've had good luck with them in the
past: