Silly resistor values

[Joerg]

If the cheap Chinese "crap" is just as good as what you prefer to build (e.g.,
the Chiense stuff has various 10% resistors whereas yours are all 5%), why
not?

Yeah, the attitude of some folks that stuff from China is always crap
has brought down whole companies. I will never understand it. After we
did a major cost reduction effort at an ultrasound company (without
compromising quality at all) one of our two main competitors threw in
the towel for our market. That was Hewlett-Packard, no less.

This reminds me of major ROFL episodes among the big three in Detroit
when the VW Beetle was presented. Nobody is laughing there anymore ...

Would it change your mind if you were a stockholder and could garner the
company couple a couple million bucks extra each year by going through the
designs and making sure nothing was specified any more tightly than it
actually had to be?

You can bet that Apple, who has everything built in China these days, to very
high specs, is keeping a close watch on exactly how much it costs to build an
iPhone, an iMac, etc... they want to keep their profit margins up!


I would welcome a contract manufacturer who mentioned that they had sources
for cheaper parts if looser tolerances were OK, and if I wanted to they'd be
happy to hook me up.

Oh yes! There is no purpose in having 1% or 5% pull-up resistors for
push-button inputs or digital lines. It's like wearing sun screen under
a swim suit. I have spec'd in as loose as 20%. Because it didn't matter.

The most coarse was -10% to -35% in hybrid production, meaning that we
simply skipped the laser trim step for many resistors that were
deposited on the alumina substrate. That shaved off some pennies. At
tens of thousands per year that kind of savings really matters and is
worth the several extra engineering hours that had to be put in (which
we did).

 

[Joerg]

No, but I remember some stuff like that, like:
"See the USA, in your Chevrolet"
"A silly millimeter longer" - Chesterfield 101's
"The seven-minute cigarette" - Pall Mall Gold 100's

And who could forget Burma Shave? ;-)

Best happened yesterday. Us walking three dogs, two neighbor dogs escape
and barge out. Situation gets under control, neighbor says he is sorry
and just watching one of the dogs for a friend. "Hey, we've never seen
that one. What breed is it?" ... "Ah, ahm, well, a Budweiser dog".

http://upload.wikimedia.org/wikipedia/en/2/23/Spuds_mackenzie.jpg

 

[krw]

Yeah, the attitude of some folks that stuff from China is always crap
has brought down whole companies. I will never understand it. After we
did a major cost reduction effort at an ultrasound company (without
compromising quality at all) one of our two main competitors threw in
the towel for our market. That was Hewlett-Packard, no less.

This reminds me of major ROFL episodes among the big three in Detroit
when the VW Beetle was presented. Nobody is laughing there anymore ...



Oh yes! There is no purpose in having 1% or 5% pull-up resistors for
push-button inputs or digital lines. It's like wearing sun screen under
a swim suit. I have spec'd in as loose as 20%. Because it didn't matter.

Sure there is. It reduces P/N count, saving inventory problems and
possibly a second (perhaps impossible) pass at the pick-n-place
machine.

The most coarse was -10% to -35% in hybrid production, meaning that we
simply skipped the laser trim step for many resistors that were
deposited on the alumina substrate. That shaved off some pennies. At
tens of thousands per year that kind of savings really matters and is
worth the several extra engineering hours that had to be put in (which
we did).

Different issues. Saving steps isn't the same as adding parts.

 

[krw]

No, but I remember some stuff like that, like:
"See the USA, in your Chevrolet"
"A silly millimeter longer" - Chesterfield 101's
"The seven-minute cigarette" - Pall Mall Gold 100's

And who could forget Burma Shave? ;-)

I rather liked IBM's.

 

[Joerg]

Sure there is. It reduces P/N count, saving inventory problems and
possibly a second (perhaps impossible) pass at the pick-n-place
machine.

Thou shalt not use a machine that's close to being tapped out in terms
of slots ;-)

But seriously, this problem was fixed with two measures:

a. All 100K resistors became 10%.

b. The contract mfg supplies stock and they've got no problem whatsoever
with inventory because they make tons of other stuff. Otherwise they
wouldn't have asked us.

Different issues. Saving steps isn't the same as adding parts.

No parts were added, they were changed in spec and ECO'd part numbers.

 

[krw]

Thou shalt not use a machine that's close to being tapped out in terms
of slots ;-)

In this economy, thou shalt use what thou has. Thou shalt not whine
for new toys. ;-)

But seriously, this problem was fixed with two measures:

a. All 100K resistors became 10%.

b. The contract mfg supplies stock and they've got no problem whatsoever
with inventory because they make tons of other stuff. Otherwise they
wouldn't have asked us.

We don't use contract manufacturers. Inventory control isn't free.
OTOH, if the owner was really interested in saving money, he'd insist
that IT link the purchasing/inventory database and the
engineering/production databases. As it is, I only have a hint at
what _some_ parts cost, and I've caught purchasing buying parts for
4-5x what they should be paying.

No parts were added, they were changed in spec and ECO'd part numbers.

Skipping a trim step <> adding a part number.

 

[Joerg]

[...]

But seriously, this problem was fixed with two measures:

a. All 100K resistors became 10%.

b. The contract mfg supplies stock and they've got no problem whatsoever
with inventory because they make tons of other stuff. Otherwise they
wouldn't have asked us.

We don't use contract manufacturers. Inventory control isn't free.
OTOH, if the owner was really interested in saving money, he'd insist
that IT link the purchasing/inventory database and the
engineering/production databases. ...

In larger companies that's linked. In the one where I took over a
division it wasn't at that time but we made darn sure this was done, and
soon.

... As it is, I only have a hint at
what _some_ parts cost, and I've caught purchasing buying parts for
4-5x what they should be paying.

Exactly that is one reason for using contract manufacturers. They never
pay 4-5x of what they should be paying. More like 0.8-0.9x because with
their qties they have so much more negotiating power.

Skipping a trim step <> adding a part number.

Got to streamline that process. At Endosonics we "electronicized" the
ECO process. No more walking a stack of papers to the next signing
person. You could have an urgent ECO signed off in under 15 minutes.
Anyhow, the first time I eased off resistor tolerances for a client it
saved them 5c/unit. Doesn't sound like much. I billed 0.25 hours for my
time for this task because that's all it took. Then they began to
produce around 50k units/year, looks like this product could make it to
the 20 year anniversary. For the cost savings to date you could buy a
nicely equipped Cadillac (the owner did ...). Unfortunately this product
has now survived the owner :-(

 

[Archimedes' Lever]

If the cheap Chinese "crap" is just as good as what you prefer to build (e.g.,
the Chiense stuff has various 10% resistors whereas yours are all 5%), why
not?

Sorry, but even between different makers of metal film 1% resistors,
there are differences in operation.

When you have 1mV ripple figure on a 4kV x-ray supply, changing a
resistor maker can change that figure in a bad way usually. If what you
sell is a sub 1mV PARD figure for that supply, and you have some lame
contract maker build 100 of them for you, unless he knows how to keep to
the BOM, you are going to get 100 different power supplies, and an
unhappy customer.

 

[Archimedes' Lever]

Would it change your mind if you were a stockholder and could garner the
company couple a couple million bucks extra each year by going through the
designs and making sure nothing was specified any more tightly than it
actually had to be?

If I were doing multiple M counts of a given build, *I* would economize
the design, not the contract builder. They are nothing more than
assemblers. My contract builds usually involve MY purchased parts. Were
I to do a turnkey build, I would specify in the quote request, everything
in the BOM that had to remain the same, right down to the maker, and
everything which can be his turnkey part. He would not, however, get to
reduce tolerances on a part. It is in no way up to the contract
assembler house to make any design change decisions based on his guesses
about the design or function of ANY given section of ANY given circuit
design.

 

[Archimedes' Lever]

You can bet that Apple, who has everything built in China these days, to very
high specs, is keeping a close watch on exactly how much it costs to build an
iPhone, an iMac, etc... they want to keep their profit margins up!

Bull. You can bet that the China builder is building the EXACT product
Apple specs out, and Apple buys the entire facility, and stocks it with
their part, and NOBODY is economizing the design of ANYTHING.

Did you honestly believe that Apple goes contract builder shopping in
China, and picks someone that is building other things as well? I do
not. I think they went over there and BOUGHT lock-stock-and-barrel
everything. They OWN contract builders in China.

The mere fact that they are building there instead of here now, is
enough margin gain alone. They do not need to piss around compromising
their design to save one penny over a million capacitors. It is far
cheaper to install the BOM, and save the admin fees of some dope spending
a years salary to save $10k.

You can bet that with the volumes that Aplle sells, they are already
getting all their electronic parts cheaper than you EVER did at ANY time
in your ENTIRE LIFE. So they are ALREADY economized out the yin yang at
the front end. There is no ass end economizing like that which you are
familiar with ever needed.

 

[AwlSome Auger]

No, but I remember some stuff like that, like:
"See the USA, in your Chevrolet"
"A silly millimeter longer" - Chesterfield 101's
"The seven-minute cigarette" - Pall Mall Gold 100's

And who could forget Burma Shave? ;-)

Cheers!
Rich

The White Tornado

Andy Rooney would love it!

 

[Joerg]

[...]

The mere fact that they are building there instead of here now, is
enough margin gain alone. They do not need to piss around compromising
their design to save one penny over a million capacitors.

The big savings are in the overall architecture, certainly -- I expect you've
read Joerg's stories where he's been able to replace, e.g., an entire DSP
(maybe $10?) with under a buck worth of discrete parts. That's significant.

Plus eliminated something like $150-200 worth of programmable digital
delay lines per system. Oh, was that sales rep pissed.

Heck, saving just ten cents on something you're building a million of per year
is enough to fully pay a U.S. engineer's salary.

1/4 hour of my billed time (to ease some resistor tolerances to 10%)
bought the boss of a client savings worth a nice Cadillac over 15
production years. He took me to dinner in it, very nice ride

 

[Archimedes' Lever]

Sure, my point was that it's usually worthwhile to spend the time to consider
which parts can be substituted (or have their tolerances loosened)

Well, we ALL already knew that. The thing is that you don't go letting
your CM dictate such things to you.

 

[Joerg]

Well, we ALL already knew that. The thing is that you don't go letting
your CM dictate such things to you.

The talk was never about the contract manufacturer dictating anything.
They don't, or they lose the contract. What they did in my cases was
suggesting something to be changed. That is most welcome feedback. Then
it was up to my client who then left it up to me to figure out whether
that is technically feasible. Sometimes resulting in rather remarkable
cost savings.

Of course all this usually doesn't make much sense if you only produce
1000/year. But then you probably would not contract out anyhow.

 

[Archimedes' Lever]

Also that it's preferable to work with a CM who'll be sure to mention
all the tricks *they* know that *might* allow you to reduce the costs of your
design.

I am perfectly capable of doing a thorough "DFM" cycle. Cost reduction
on parts came long before that.

Perhaps not with today's young engineers, but I come from a time when
we knew more than any CM we ever contracted to build one of our designs.

That is certainly true where I am now, where every single part is
verified, and no changes are even allowed. Tempest certs are tough, even
for a simple USB device, for example.

All of our CMs build what we spec. Some of our kits have thousands of
dollars worth of parts left over that never get used, and go past their
usable service life for soldering before they could even get shoved back
through the system. The admin to examine it alone would cost thousands.

If I could have all the expired popcorn that is around here, I could
build several motherboards worth of assembly (like 50k + parts easily).
All perfect parts, aside from the exp date. Hand solder is fine though.
Primo parts. I wish I could have them all.

 

[Joerg]

I am perfectly capable of doing a thorough "DFM" cycle. Cost reduction
on parts came long before that.

Perhaps not with today's young engineers, but I come from a time when
we knew more than any CM we ever contracted to build one of our designs.

That is certainly true where I am now, where every single part is
verified, and no changes are even allowed. Tempest certs are tough, even
for a simple USB device, for example.

All of our CMs build what we spec. Some of our kits have thousands of
dollars worth of parts left over that never get used, and go past their
usable service life for soldering before they could even get shoved back
through the system. The admin to examine it alone would cost thousands.

Oh man ...

Is that cost finally ending up with the taxpayer? If you had such
left-overs in industry the responsible person would receive an
"invitation" to the CFO's office, the door would be closed and it would
get very loud in there.

This is one reason why I have steered companies away from the old
kitting process pretty much everywhere I worked. It's wasteful.

If I could have all the expired popcorn that is around here, I could
build several motherboards worth of assembly (like 50k + parts easily).
All perfect parts, aside from the exp date. Hand solder is fine though.
Primo parts. I wish I could have them all.

So what happens with all that. It's chucked?

 

[Rich Grise]

As engineers we have a responsibility to help assembly people make as few
mistakes as possible. This includes obvious stuff like clear (and correct)
labeling/assembly documentation, but also things like using polarized
connectors (unless you just don't have the budget for it), not putting two
mechanically-identical-but-electrically-vastly-different connectors side by
side (particularly if mis-plugging said connectors blows something up), etc.

I bit myself on this one once. I had drawn up a schematic for a module
that we used in development - a dual-port RAM that acted like a ROM in-
circuit.

Somebody told me that the assemblers could build from a schematic. Cool,
I says, I don't have to do it! Unfortunately, I had used the convention
of showing all the bypass caps on the bus, rather than at each chip with
all those damn wires; when I got the board, there were the bypasses, in
a nice neat row, right next to the power bus. It turned out not to be a
problem; it took her about 10 minutes to add a half a dozen caps, so it
was no big deal. I guess the moral is, be more specific.

Cheers!
Rich

 

[Archimedes' Lever]

This is one reason why I have steered companies away from the old
kitting process pretty much everywhere I worked. It's wasteful.

At our company, stupidity like yours is what is wasteful. a few
hundred, or even a few thousand left over discreet parts is no big deal
when the assemblies are several tens of thousands of dollars as a
finished product. A couple hundred bucks worth of attrition is not even
worth tallying up.

Handling them in such a way as to re-introduce them into the MRP system
would take long enough that many would be expired going in, and therefore
unusable.

Unlike you, we cannot utilize parts that are past their solderability
expiry dates, and ALL parts have them, whether you know it or not.

 

[Archimedes' Lever]

So what happens with all that. It's chucked?

Ten years from now, when there is no chance that any component could be
used to undermine the nation's security. Yes, even "dumb" components.

 

[Archimedes' Lever]

Is that cost finally ending up with the taxpayer?

That "cost" as you call it is a savings to the taxpayer. When the parts
ALL have to be ordered to the job, and expiration dates creep up, the
cost to retain tailings on kits and re-introduce them into the system id
far greater than simply ordering what was needed and getting the job
done.

To implement your "cost reduction" CRAP would cost the taxpayer far
more, and in a mission critical application, it could even cost lives.
That is unacceptable.

So shut the **** up about that which you obviously know absolutely
nothing about. Not everyone uses the same model you have stuck in your
brain.