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John Stevenson
11-04-2007, 03:46 PM
OK it's cold and dark here and the path down to the workshop is haunted so not going out to get my calipers and screw gauges.

On the parallel port you have these little retaining screws that the cable screws into, any idea what thread it is as I have to make a couple of new ones about 5/8" long to take a gender changer.

Mutzi Gratzi Penus, [ that's Spanish for thank you cock.........]


.

small.planes
11-04-2007, 03:50 PM
John,
ISTR they are a BA size? Not sure, Ill go and have a look for you (My workshop isnt haunted:p )

Dave

matador
11-04-2007, 03:59 PM
I've just checked one,and it looks to me like it's #4x40 UNC.You could probably rob the screw of an old printer connector or similar.They seem to have fairly long screws.

lazlo
11-04-2007, 04:00 PM
I just happened to have a thread gage on my desk: #4 x 40 TPI.

Peter N
11-04-2007, 04:00 PM
I think the male standoffs are 6-32 UNC, and I believe the the thumbscrews that are normally attached to the plug and screw into these are 4-40 UNC John.
Not positive, but I seem to remember checking this out a couple of years ago.

Peter

small.planes
11-04-2007, 04:15 PM
Seems others know without having to go outside into the cold...

Dave

lazlo
11-04-2007, 04:17 PM
By the way John, it's the same screw that's on an RS-232 shell. Sow you can steal the screws off an old serial connector...

old-biker-uk
11-04-2007, 04:25 PM
[QUOTE=Mutzi Gratzi Penus, [ that's Spanish for thank you cock.........]./QUOTE]

Having a several Spanish biker friends I can say with some insider knowledge that it isn't !!!
BTW Spanish swearing tends to concentrate on milk, faeces, mothers, sisters, The Virgin Mary & God in some interesting combinations.
Mark

Oh yes - the original question - 5BA looks pretty close.

Evan
11-04-2007, 09:09 PM
The standoffs are metric 3.5 x .8 that is so close to 6-32 that it doesn't matter . The thumb screw thread is 4-40.

Lew Hartswick
11-04-2007, 09:23 PM
The standoffs are metric 3.5 x .8 that is so close to 6-32 that it doesn't matter . The thumb screw thread is 4-40.
OK Evan HOW !!! did that happen? I can't see part of the design being
done in China ( :-) ) and the rest in the USA. :-) Come on tell us.
...lew...

lazlo
11-04-2007, 10:37 PM
The thumb screw thread is 4-40.

So we now have four votes for #4-40. Anyone else? :)

gzig5
11-05-2007, 12:01 AM
So we now have four votes for #4-40. Anyone else? :)

The thumbscrews we use on feedback cables at work are 4-40. I remember someone mentioning that the male thread on the standoffs was a bit out of the norm.

darryl
11-05-2007, 02:59 AM
It's not really a 4-40- it's a 3.624-36 :)

John Stevenson
11-05-2007, 03:45 AM
Thanks for that guys.
Need to have a look around for some taps then in #4 x 40, may have the odd one as the small numbered series never came into play here in the UK.

For years we were on BA sizes and then these were phased out onto metrics. About the only numbered series UN's are to be found on older imported USA made equipment.

There are specialised fastner companies who cater for this in standard fastners but expensive and I want something non standard.

.

lazlo
11-05-2007, 08:20 AM
How many do you need John?

They have bags of them at Frys for a pittance -- I'd be glad to drop some to you by US Postal Service, which is surprisingly cheap to the UK.

Paul Alciatore
11-05-2007, 08:44 AM
I stock these things by the dozens/humdreds. Truth be known, different manufacturers have used both English and metric threads. Someone forgot to write/enforce a standard. 4-40 is the most common. I really haven't seen any 6-32 but I'm sure someone has done it. Not sure what the metric size is as I avoid it.

If you only need a few, I may have what you want. If you are making a gender-bender, I would use a standard male-female standoff and add a female-female cut to the correct length. Both items should be available from electronic distributors at reasonable prices.

Evan
11-05-2007, 08:51 AM
OK Evan HOW !!! did that happen? I can't see part of the design being done in China

Metric is the norm, it's the 4-40 that is the odd one out. Business machines have been metric since Xerox went international in the 60s. They switched to all metric in the late 60s, long before anybody else in the US was seriously considering it. Because Xerox formed partnerships with Fuji and Rank Corporations they had to unify their design base. This influenced the rest of business equipment manufacturing. The metric 3.5mm by .8 pitch is so close to 6-32 that they could officially switch without introducing any incompatibility. 4-40 doesn't have a close match and the specs for the D-sub connectors predate the switch to metric. The 3.5x.8 is used all over computers including case screws and motherboard screws and standoffs.

ptjw7uk
11-05-2007, 09:02 AM
John,
Try these people they do a 17mm long section
http://www.toby.co.uk/content/catalogue/products.asp?series=M40000E%2D6xxxx
Peter

lazlo
11-05-2007, 10:45 AM
Metric is the norm, it's the 4-40 that is the odd one out.

No. Almost all the PC connectors are IEEE or EIA standards (the American Institute of Electrical and Electronics Engineers, Inc), which used imperial connectors up to the 80's. So the parallel port spec is IEEE 1284, and the spec specifies a DB-25 connector for the host and a Centronics 36-pin connector for the device connection, both of which use Imperial hardware.

Similarly, the serial port connection standard is EIA (the American Ellectronics Industry Association) RS-232C, which has a variety of connector options, all with imperial hardware (most with #4-40 shell connectors).

Same deal with the Molex (power) connectors and the IDE connectors: they're American standards, with inch (.1") pin spacing.

lazlo
11-05-2007, 11:18 AM
The standoffs are metric 3.5 x .8 that is so close to 6-32 that it doesn't matter.

Evan's comment about the standoff screws being Metric struck me as odd, since all the other hardware in the PC is Imperial. So I just went through my junk box, and measured a couple of the standoffs I have.

About half the standoffs are #4-40, and the other half are #6-32. So I think using Metric 3.5 x 0.8 standoff screws may just be a convenience for countries that don't have a cheap supply of Imperial screws.

On the left is a #6 x 32 standoff. In the middle is a #4 x 40 Serial/Parallel shell screw. On the right is a #4 x 40 standoff:

http://i164.photobucket.com/albums/u15/rtgeorge_album/StandoffScrewss.jpg

Evan
11-05-2007, 02:26 PM
Evan's comment about the standoff screws being Metric struck me as odd, since all the other hardware in the PC is Imperial. So I just went through my junk box, and measured a couple of the standoffs I have.
You misunderstand. I said the DB25 shell spec predates the switch to metric and so it was imperial with 6-32 and 4-40 threads. Since the switch there is no need to respec the 6-32 since the metric 3.5x.8 fits fine.

This is the contents of a hardware kit for a computer.

http://vts.bc.ca/pics3/metriccomp1.jpg

It has two types of threads on the screws and standoffs for the motherboard, 3.5 x .8 and 2mm x .5.

http://vts.bc.ca/pics3/metriccomp2.jpg

The 4-40 standoffs you have are from the connector standoffs. The rest of the computer is metric although 6-32 will fit wherever the 2.5 x .8 is used. The 2mm screws are commonly used on CD and Floppy drives as well as some motherboard screws.

Computers are a worldwide product and metric is the rule, not the exception. A few things are grandfathered like the standoff thread for the D-sub shells and the 3/8 etc socket drives.

lazlo
11-05-2007, 08:01 PM
Hi Evan,


This is the contents of a hardware kit for a computer.

It has two types of threads on the screws and standoffs for the motherboard, 3.5 x .8 and 2mm x .5.

That's the kit of Chinese motherboard screws that you, a computer salesman in Canada, were getting from your distributor.
In the 'States, we get 4-40, and 6-32 screws at Frys, or Best Buy, or CompUSA,...


The 4-40 standoffs you have are from the connector standoffs.

Right, but the 6-32 standoff on the far left is a standard ATX motherboard standoff:

15 standoffs Brass Computer Motherboard Standoff 6/32 (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180176264913)

http://img.auctiva.com/imgdata/0/0/6/4/3/6/webimg/577742_tp.jpg


The rest of the computer is metric although 6-32 will fit wherever the 2.5 x .8 is used.

No, it's not. PC motherboards are built to the ATX standard, which uses all Imperial measurements, from the board dimensions, to the hole spacing, to the hole sizes. So an ATX motherboard is spec'ed as 12" x 9.6", a Mini-ATX is 11.2" x 8.2",...

This is described in the ATX 2.2 spec, which you can read here:
http://www.formfactors.org/developer%5Cspecs%5Catx2_2.pdf

...and is summarized in this excellent ASCII picture showing all the ATX motherboard variants and the required mounting hole dimensions (as it's spec'ed in inches) here:

Motherboard Form Factors (http://users.erols.com/chare/atx.htm)

http://i164.photobucket.com/albums/u15/rtgeorge_album/motherboard.gif

The mounting holes that you're putting M3 standoffs in are standard 5/32" through holes, as described in the ATX spec. Just because you're putting a metric screw a nut into it, doesn't mean it's a metric standard :)

So John's 4-40 serial port screw is not an except to the rule -- the entire ATX PC standard, including screws, all the IO and power connectors, cables, and connector pinouts use imperial dimensions. The PC cases themselves, coming from Asia, sometimes use metric screws in the PCB through-holes, depending on which country you're in.

As usual, Wikipedia has an excellent summary of PC hardware:

http://en.wikipedia.org/wiki/Computer_case_screws

6-32 Screw

This screw is by far the most common screw found inside computer cases[1]. The 6-32 a UTS screw and commonly appears in lengths of 0.15 and 0.25 inches. Nearly every brand new computer case comes with a bag of these. They are used:


To fasten the power supply to the case
To fasten the hard disk drive to the case
To hold the expansion cards in place by their metal slot cover (such as PCI, ISA)
To fasten case components to one another
Usually, but less frequently, a 6-32 screw holds the main cover on the case. When it's not a 6-32, a larger 8-32 is the most likely alternative.


M3 Screw

This screw is the second most common screw found in PCs[1]. This is a metric screw, and just about every case manufacturer provides a package of M3 screws as well as 6-32's. Specifically, the screw type is M3-0.50, meaning the threads of the screws are 0.50mm apart. Normally, M3 refers only to the reference diameter of 3 millimeters, and other industries may use coarser 0.70mm threads - but in the context of PCs, 0.50mm threads are implied.

M3 screws are used for fastening CD-ROM drives and floppy drives. They will fit in 6-32-threaded holes, but their narrower diameter and finer thread pitch causes them to seat only loosely in the hole. Nevertheless they are often placed there by amateur PC builders who are unaware of the distinction.

Standoff Screw

Most cases use standard-threaded brass standoffs for attaching the motherboard to the case. The standoff provides a margin of space between the motherboard and the case. Without the space, the motherboard would be in physical contact with the case, which would cause it to not function because its various solder points would be in contact with the case's metal, which forms a short circuit with the computer's electrical ground.

There is no rigid standard for what measurements a case's standoffs use. However, use of M3 and 6-32 threads is nearly universal.

Each standoff has a "male" portion that screws into the case, and a "female" portion that receives a screw that has passed through a specially grounded pre-drilled hole in the motherboard. Standoffs that use strictly M3, strictly 6-32, or a combination (male portion 6-32, female portion M3) are all fairly common.

4-40 Screw

Another type of screw threading is used for I/O ports on the back of the computer. This typically includes VGA, DVI, serial, parallel, and legacy game controller ports. This screw threading is 4-40, which is also a UTS screw. This screw has 40 threads per inch, and despite its threads visually appearing similar to M3, they are not interchangeable at all. (When placed side by side, the difference is much more apparent.)

Each I/O port usually has two 4-40 receptacles for securing the cable - one on either side of the port. The 4-40 is usually just a removable standoff that has been screwed into the port's connector with a relatively tight torque.

Evan
11-05-2007, 10:04 PM
What's with all the red highlighting? I already said the connectors have 4-40 thread.

These screws are commonly found in a computer.

http://vts.bc.ca/pics3/screws.jpg

All are metric including the "6-32" screws. If you measure the OD over the threads on those "6-32" screws you will find that they are consistently several thou smaller than screws sold as 6-32 screws. That's because they are really 3.5 x .7. They will usually measure about .131 to .135" OD. 3.5 mm is .1377". With a clearance allowance .135 is correct for a m3.5 screw. A 6-32 screw has a nominal diameter over the threads of .138".

BTW, you left out one little bit from that wikipedia quote.



This article needs additional citations (http://en.wikipedia.org/wiki/Wikipedia:Citing_sources) for verification (http://en.wikipedia.org/wiki/Wikipedia:Verifiability).
Please help improve this article (http://en.wikipedia.org/w/index.php?title=Computer_case_screws&action=edit) by adding reliable references (http://en.wikipedia.org/wiki/Wikipedia:Reliable_sources). Unsourced material may be challenged (http://en.wikipedia.org/wiki/Template:Fact) and removed. (September 2007)

lazlo
11-05-2007, 10:19 PM
What's with all the red highlighting? I already said the connectors have 4-40 thread.

Because you said most of the screws in a PC are metric, which is wrong. Most of the connectors in a PC are imperial, and 4-40 that John has is not the exception, it's the rule.


BTW, you left out one little bit from that wikipedia quote.

Didn't need to Evan, I already posted a bunch of citations. Did you read that ATX motherboard spec yet?

So you understand now that the PC motherboard is spec'ed entirely in imperial dimensions, with imperial through-holes, that you're using for the metric screws you're getting in Canada?

Here's another citation for you, after you get done reading the 5 references posting the same information in my previous post.

http://www.dansdata.com/danletters053.htm


Screwed

I'm building a custom computer case and eventually I will need to drill out and tap the threads for the motherboard standoffs. My problem is the tap, I looked everywhere on the Web for some threading information for it. Also the standoffs - I plan on using have the same threading as a standard hard drive screw.


Answer:

The standard coarser thread computer screws, as used to secure hard drives, hold most cases together and hold most motherboards down on their standoffs, are UNC 6-32 thread. The ends of the standoffs are generally 6-32 as well, which is why bored geeks can screw them into each other and make long brass sticks.

The finer pitched screws used to secure floppy and optical drives, and also thread into a few kinds of motherboard standoff, are metric M3s.

lazlo
11-05-2007, 10:24 PM
Here's another cite for you Evan, from the Intel Pentium 4 Package/Thermal/Mechanical Design Guide:

http://download.intel.com/design/Pentium4/guides/24934801.pdf

2.2 Chassis Design

The retention mechanism is attached to the chassis via four (4) standoffs, as shown in Figure 3. These standoffs are in addition to the standard ATX mounting holes defined in the ATX Specification, Version 2.03 [That I linked in my post above]

The four (4) standoffs for the retention mechanism must be the same height as the standard ATX board standoffs and compatible with 6-32 (x 1/2 inch - 3/8 inch) pan-head or round-head screws.

It is the responsibility of the chassis vendor to supply the four (4) 6-32 screws with the chassis.

torker
11-05-2007, 10:44 PM
I think the male standoffs are 6-32 UNC, and I believe the the thumbscrews that are normally attached to the plug and screw into these are 4-40 UNC'le John.
Not positive, but I seem to remember checking this out a couple of years ago.

Peter

Peter...I fixed that for you :D
(Sorry...thought a bit of humour may fit this thread about now)
Russ

wierdscience
11-05-2007, 11:00 PM
Isn't it possible those are "Chinese fortune cookie screws"?

"All your threads are today being stripped by little Chinese girls with air screwdrivers":D

Evan
11-06-2007, 02:47 AM
Because you said most of the screws in a PC are metric, which is wrong.

So, with the singular exception of 4-40 and all the rest of the fasteners being metric that somehow makes MOST of the screws imperial. You seem to be ignoring the simple fact that "compatible with 6-32" also includes metric 3.5 x.7 screws. There is also the little detail that I spent 23 years working on this equipment with Xerox and another 9 years running my own computer store. All Xerox supplied after about 1980 and all I ever used were metric tools, even for the 5mm hex on the "6-32" motherboard standoffs. They aren't 6-32. Measure a few yourself.

Joel
11-06-2007, 03:20 AM
How are the electronics on the mill coming along Evan?

John Stevenson
11-06-2007, 03:32 AM
All are metric including the "6-32" screws. If you measure the OD over the threads on those "6-32" screws you will find that they are consistently several thou smaller than screws sold as 6-32 screws. That's because they are really 3.5 x .7. They will usually measure about .131 to .135" OD. 3.5 mm is .1377". With a clearance allowance .135 is correct for a m3.5 screw. A 6-32 screw has a nominal diameter over the threads of .138".

Evan,
That OD sizing on screws such as this is irrelevant as screws that are mass produced and plated can't hope to keep to any standards and measuring a screw thread over diameter is the last way to do it.
Only last night I removed a broken shaft from an air cylinder to make a new one and the 3/8" thread on it,in good condition, measures 0.367, 9 thou under but it's still 3/8" fine


BTW, you left out one little bit from that wikipedia quote.


This article needs additional citations (http://en.wikipedia.org/wiki/Wikipedia:Citing_sources) for verification (http://en.wikipedia.org/wiki/Wikipedia:Verifiability).
Please help improve this article (http://en.wikipedia.org/w/index.php?title=Computer_case_screws&action=edit) by adding reliable references (http://en.wikipedia.org/wiki/Wikipedia:Reliable_sources). Unsourced material may be challenged (http://en.wikipedia.org/wiki/Template:Fact) and removed. (September 2007)

Here you are then you now have a job.

.

lazlo
11-06-2007, 08:06 AM
Because you said most of the screws in a PC are metric, which is wrong. Most of the connectors in a PC are imperial, and 4-40 that John has is not the exception, it's the rule.
So, with the singular exception of 4-40 and all the rest of the fasteners being metric that somehow makes MOST of the screws imperial.

So aside from the fact that 6-32 screws are, by far, the most common screw found inside computer cases, and aside from the fact that the motherboard dimensions are in inches, and the standoff screw hole spacing is in inches, and the through holes are in inches, yes that somehow makes MOST of the screws in a PC imperial. :rolleyes:



It is the responsibility of the chassis vendor to supply the four (4) 6-32 screws with the chassis.

6-32 Screw

This screw is by far the most common screw found inside computer cases[1]. The 6-32 a UTS screw and commonly appears in lengths of 0.15 and 0.25 inches. Nearly every brand new computer case comes with a bag of these. They are used:


To fasten the power supply to the case
To fasten the hard disk drive to the case
To hold the expansion cards in place by their metal slot cover (such as PCI, ISA)
To fasten case components to one another
Usually, but less frequently, a 6-32 screw holds the main cover on the case. When it's not a 6-32, a larger 8-32 is the most likely alternative.

Evan
11-06-2007, 11:59 AM
That of course is the US-centric view (imperialist? :D ).

Ask the question in just about any other country and it becomes metric. As for hole spacing, who cares? The inch is metric anyway. Hole spacing isn't relevant since I can't go buy a package of hole spacers I don't need to worry about some sort of standard.


So aside from the fact that 6-32 screws are, by far, the most common screw found inside computer cases

No. As I posted in the pic above they are all metric. 4-40 is the exception.

John,

While undersize is to be expected if the m3.5x.8 were to be made to the nominal .1377" it wouldn't fit a lot of the time. I don't know if you have any "real" 6-32 screws on hand but Robert does. The difference is consistent and easy to measure.

lazlo
11-06-2007, 12:05 PM
No. As I posted in the pic above they are all metric. 4-40 is the exception.

So Intel's requirements for 6-32 screws are wrong, and you're right?



It is the responsibility of the chassis vendor to supply the four (4) 6-32 screws with the chassis.

...and Wikipedia is wrong?

6-32 Screw

This screw is by far the most common screw found inside computer cases.

...and the ATX Form-Factor spec is wrong?

http://www.formfactors.org/developer%5Cspecs%5Catx2_2.pdf

...and this guy is wrong too?

http://www.dansdata.com/danletters053.htm

The standard coarser thread computer screws, as used to secure hard drives, hold most cases together and hold most motherboards down on their standoffs, are UNC 6-32 thread.

John Stevenson
11-06-2007, 01:53 PM
That of course is the US-centric view (imperialist? :D ).

Ask the question in just about any other country and it becomes metric. As for hole spacing, who cares? The inch is metric anyway.


The Mars lander didn't think so :D

.

matador
11-06-2007, 03:23 PM
Sweet lord,don't you people have any machining to do?:D.

Inch is Metric?????????????.

Oldguy
11-06-2007, 03:32 PM
I'm not a big history buff, but I do seem to recall that the inch system of measurement was developed/evolved quite a while before the metric system was developed.

John, to your original question - the thread you're asking about is a 4-40.

Glenn

oldtiffie
11-06-2007, 06:41 PM
Sweet lord,don't you people have any machining to do?:D.

Inch is Metric?????????????.


Hi matador.

A real good focused post.


[QUOTE=matador]Sweet lord,don't you people have any machining to do?:D.

Answer: dunno. But assuming there is such an omnipotent entity outside this thread, I can only say that "He" (or in this PC age "She"? "Person?") sticks to "machining" and not "machinations".

Re. inch = metric.

It sure is - as defined in Wikipedia:
http://en.wikipedia.org/wiki/Inch


International inch
In 1958 the United States and countries of the Commonwealth of Nations defined the length of the international yard to be exactly 0.9144 meters. Consequently, the international inch is defined to be exactly 25.4 millimeters.

The international standard symbol for inch is in (see ISO 31-1, Annex A). In some cases, the inch is denoted by a double prime, which is often approximated by double quotes, and the foot by a prime, which is often approximated by an apostrophe. For example, 6 feet 4 inches is denoted as 6′4″ (or approximated as 6'4").

So, Evan is dead right.

As regards the screws for computers - who cares other than a pedant?
http://www.tfd.com/pedant

ped·ant (pdnt)
n.
1. One who pays undue attention to book learning and formal rules.
2. One who exhibits one's learning or scholarship ostentatiously.
3. Obsolete A schoolmaster.

The imperial/inch and metric sizes are so close even at standards size that it doesn't matter. At manufactured sizes it would be practically impossible to tell the difference in terms of size or performance.

Even when you speak in or use "inch" units you are in fact using a unit that is derived from or defined as or in metric units.

It seems that the last bastion of "Foot and inch" (the USA) had been "metricated" after all - must of "snuck up" - a "stealth attack"? - while we weren't looking? And with the concurrence of the USA too!!

The dastardly deed was done in 1958 - nearly 50 years ago!!

Oh dear.

http://i200.photobucket.com/albums/aa294/oldtiffie/Finish1.jpg

matador
11-07-2007, 12:22 AM
I hate to fall into the trap of getting too involved in semantics,but "oldtiffie"'s link does not state that an inch is a metric measurement,which was my interpretation of Evan's statement.It merely gives a definite figure of 25.4 mm to the inch for conversion purposes.
Then again,I'm just a dumb Dutchman.:D
My late father was a cabinetmaker,and he used to refer to nails by the"thumb"size.Now that I think about it,this was probably a Dutch "translation" of the inch.
I also remember in the 1960's,there were still references in the clothing trade to an "ell" as a measurement for cloth of a roll.I have no idea how long said "ell" actually was,I was but a nipper then(I'm a 1951 model).

dp
11-07-2007, 01:17 AM
I hate to fall into the trap of getting too involved in semantics,but "oldtiffie"'s link does not state that an inch is a metric measurement

From WikiPedia: In 1958 the United States and countries of the Commonwealth of Nations defined the length of the international yard to be exactly 0.9144 meters.

That means if the rest of the world redefines the length of a meter to be the distance between the knees of a giraffe, the yard will be 0.9144 times that new length. The length of the yard is tied to the length of the meter by this 1958 definition. The yard is subordinate to the meter. There is no standard yard. It is, therefore, metric in origin.

oldtiffie
11-07-2007, 03:07 AM
Quote:
Originally Posted by Evan
That of course is the US-centric view (imperialist? ).

Ask the question in just about any other country and it becomes metric. As for hole spacing, who cares? The inch is metric anyway.


The Mars lander didn't think so :D
.


John, I think it was Kilometer and Mile.

I can't remember which one was correct (Mile or Km), but as I recall NASA erred by using the wrong one and the and the vehicle only did as it was told.

Depending on which was the wrong unit, the error would have been a factor of about 1.6 or 0.6.

But anyway, it seems that whatever was used it was ultimately in metric units as mile is a sub-set of yard which is defined as 0.9144 metre.

But back to the topic of threads used on computers, it matters not which is used as the differences between the "inch" and equivalent "metric" items are inconsequential as regards practicalities - in the HSM work-shop or on the HSM computer.

Evan is also correct as regards availability of screws etc. in "foreign" countries such as Australia (which has been "metricated" since about 1960).

Computer stores here are pretty well exclusively stocked with the metric units. So far as I know, everybody accepts it, nobody seems to notice the difference (or cares), it works, and there are no complaints.

lazlo
11-07-2007, 11:09 AM
Hi Tiffie.

A real good focused post.

Your efforts to rescue Evan are admirable.


So, Evan is dead right.
As regards the screws for computers - who cares other than a pedant?

No one cares. As long as Evan doesn't claim that the PC is a metric standard, and that John's 4-40 screw is an oddball.

The PC was developed by Intel, an American company, so not surprisingly, all the PC specifications, including the motherboard dimensions, the peripheral card (graphics and video) dimensions and connecting hardware, the IO connectors and connecting hardware, the power connectors and cables, and DRAM connectors and sockets, are all in Imperial dimensions.

The fact that Metric countries stick M3 screws into the 5/32" holes that Intel documents are designed for 6-32 standoffs doesn't make it a Metric standard.
I can stick a Whitworth screw in a PC standoff hole, but that doesn't make it a Whitworth standard.



Re. inch = metric.

It sure is - as defined in Wikipedia

How does that relate to this discussion? Does that mean I can cut Metric threads on my Imperial lathe? :)

So the inch is referenced off the meter, and the meter is referenced of the distance light travels in 1⁄299,792,458 of a second.
Does that mean I can stick photons in my motherboard standoffs? :rolleyes:

http://www.intel.com/support/motherboards/desktop/sb/CS-020836.htm

Install the Desktop Board
...

The recommended torque range for standard low carbon steel # 6-32 screws is 6 - 10 in-lb.
http://www.intel.com/support/motherboards/desktop/sb/img/install.jpg

Doh! Intel specifies the torque for the 6-32 motherboard standoff in Inch-Pounds. But Pounds are actually a Kilograms, right? :D

Evan
11-07-2007, 06:49 PM
The PC was developed by Intel, an American company

That would be Xerox, if PC means Personal Computer. If it means IBM compatible then it would be IBM but Xerox was first by years.

The Xerox Alto in the 1970s was the first system to be sold and used outside of a research lab and the Xerox Star was the first "real" PC. It was developed in 1977 and sold to the public in 1981, the same year as the IBM PC. The Star was light years ahead of the IBM with a full graphical user interface using windows, icons mouse and pointer ( the WIMP interface).

http://vts.bc.ca/pics/xstar.jpg

lazlo
11-07-2007, 07:00 PM
That would be Xerox, if PC means Personal Computer.

Nice try to deflect the conversation Evan. But as you know, we're talking about the x86 PC that almost all of us are using to post here.

John Stevenson
11-07-2007, 07:03 PM
John,

While undersize is to be expected if the m3.5x.8 were to be made to the nominal .1377" it wouldn't fit a lot of the time. I don't know if you have any "real" 6-32 screws on hand but Robert does. The difference is consistent and easy to measure.


Evan,
You have me confused now.
You say the difference is consistent and easy to measure, you also say the inch is metric anyway.

So do I use my imperial micrometer or my metric one ?:D

And why then do we have both if the inch is metric ?

Off the bed now seeing as we have just altered the clocks and only have 20 hours in a day now, 10 in the morning and 10 in the afternoon, roll on Imperial March :D


.

Evan
11-07-2007, 08:02 PM
I simply use my metric inch calipers.

http://vts.bc.ca/pics/mcal2.jpg

Evan
11-07-2007, 08:06 PM
But as you know, we're talking about the x86 PC that almost all of us are using to post here.

Intel didn't invent the PC, they invented the microprocessor. The Alto didn't use a microprocessor, it used ECL bitslice logic. Just correcting your statement that Intel invented the PC.

lazlo
11-07-2007, 09:22 PM
Intel didn't invent the PC, they invented the microprocessor.

Keep trying Evan. I never said Intel invented the PC.


The PC was developed by Intel, an American company, so not surprisingly, all the PC specifications, including the motherboard dimensions, the peripheral card (graphics and video) dimensions and connecting hardware, the IO connectors and connecting hardware, the power connectors and cables, and DRAM connectors and sockets, are all in Imperial dimensions.

Evan
11-08-2007, 03:22 AM
Keep trying Evan. I never said Intel invented the PC.

I didn't mention that the Star also owed nothing to Intel and the microprocessor as it too used bit slice logic. Given the obvious advanced nature of the Star and it's operating system it's pretty hard to wiggle out of your statement.

Personally, I would say that the microprocessor as has been "developed" by Intel over the years has greatly retarded the development of the PC. The byzantine architecture of the X86 series of CPUs has only served to make software and hardware development more difficult.

Nice try on the semantics but since few inventions are the result of inspiration now and most are the result of developments in research laboratories the word "develop" is synonymous with "invent" for practical purposes. The history of patents granted for "inventions" certainly support that contention.

John Stevenson
11-08-2007, 04:16 AM
Oh for fücks sake Evan give it a rest.

I asked a simple question, got a simple answer, [ #4 x 40 thanks everyone ] but you,as always, have to develop this into a pedantic dick slapping contest that doesn't add anything to the OP.

What we need now is Tod Tolhurst to enter the fray. Evan has 17,600 odd post to his name, Tod has 400 odd and of that 400 odd 300 odd have been put downs where he has won everytime, bar none.

That guy has the biggest bullshït meter I have ever seen.

.
[EDIT] Nice meeting you folks, as this thread will either be removed, locked or I'll get banned..............

.

oldtiffie
11-08-2007, 06:31 AM
Hi Tiffie.

A real good focused post.

Your efforts to rescue Evan are admirable.



No one cares. As long as Evan doesn't claim that the PC is a metric standard, and that John's 4-40 screw is an oddball.

The PC was developed by Intel, an American company, so not surprisingly, all the PC specifications, including the motherboard dimensions, the peripheral card (graphics and video) dimensions and connecting hardware, the IO connectors and connecting hardware, the power connectors and cables, and DRAM connectors and sockets, are all in Imperial dimensions.

The fact that Metric countries stick M3 screws into the 5/32" holes that Intel documents are designed for 6-32 standoffs doesn't make it a Metric standard.
I can stick a Whitworth screw in a PC standoff hole, but that doesn't make it a Whitworth standard.



How does that relate to this discussion? Does that mean I can cut Metric threads on my Imperial lathe? :)

So the inch is referenced off the meter, and the meter is referenced of the distance light travels in 1⁄299,792,458 of a second.
Does that mean I can stick photons in my motherboard standoffs? :rolleyes:

http://www.intel.com/support/motherboards/desktop/sb/CS-020836.htm

Install the Desktop Board
...

The recommended torque range for standard low carbon steel # 6-32 screws is 6 - 10 in-lb.
http://www.intel.com/support/motherboards/desktop/sb/img/install.jpg

Doh! Intel specifies the torque for the 6-32 motherboard standoff in Inch-Pounds. But Pounds are actually a Kilograms, right? :D

Thanks laslo.

First of all, I read your post about 12 hours ago and had a response ready but we had to go out for the day. In the meantime, this thread has "moved on".

(Truth is I had just about finished - in a hurry - and instead of hitting the "send" key I closed the application (HSM) and lost it - I really fu**ed up - but I did have to go out).

Bummer.

Now back to your post and the issues of screwing up computers.

Good response and questions which I will try to respond to.


Your efforts to rescue Evan are admirable.

I am neither "rescuing" nor defending Evan. Evan is more than capable of making defensive and offensive posts of his own without the assistance of or from or reference to me (Yeah, I saw the irony in that too when I re-read it!!).

I try to restrict myself to responding to an issue and to agree or disagree (or something in between) and just "play the ball and not the man". (Don't always succeed though).


As long as Evan doesn't claim that the PC is a metric standard, and that John's 4-40 screw is an oddball.

I am not responsible for Evan (now THAT has some connotations!! WOW!!) or what he says, thinks, says or does or doesn't do about anything. That is Evan's domain. I'm sure that Evan can look after himself in that regard.


The PC was developed by Intel, an American company, so not surprisingly, all the PC specifications, including the motherboard dimensions, the peripheral card (graphics and video) dimensions and connecting hardware, the IO connectors and connecting hardware, the power connectors and cables, and DRAM connectors and sockets, are all in Imperial dimensions.

That is way out of my competence to respond to. I just started using IBM-compatible 8088/8086 computers on an APC111 with a Japanese (NEC) OS and an IBM compatible boot-up disc for use with AutoCAD 2.17 in about 1986 or thereabouts. I then had a Compaq 386/20, and IBM-compatible Intel 4 machine then various OEM's through W2K and XP. I am just a "Taxi Driver" as I don't know much about what goes on under the hood.

I have no problem with anything dimensioned in "inch" units - at all.


The fact that Metric countries stick M3 screws into the 5/32" holes that Intel documents are designed for 6-32 standoffs doesn't make it a Metric standard.
I can stick a Whitworth screw in a PC standoff hole, but that doesn't make it a Whitworth standard.

Agree 100% - no argument there at all - never has been.


How does that relate to this discussion? Does that mean I can cut Metric threads on my Imperial lathe?

Answer to your first paragraph?: no idea.

Answer to second paragraph: Sure does.

Or more particularly on your lathe with an imperial/inch lead-screw - with a 127 tooth gear or one of the other several similar ratios or approximations mentioned in other threads.

The converse equally applies for me to cut "inch/imperial" threads on my lathe with a metric lead-screw and a 127 tooth gear.


So the inch is referenced off the meter, and the meter is referenced of the distance light travels in 1⁄299,792,458 of a second.

Well - sort of.

See this, its a good read: http://en.wikipedia.org/wiki/Inch


1 inch = SI units
25.4×10−3 m 25.4 mm
US customary / Imperial units
83.33×10−3 ft 27.78×10−3 yd

International inch
In 1958 the United States and countries of the Commonwealth of Nations defined the length of the international yard to be exactly 0.9144 meters. Consequently, the international inch is defined to be exactly 25.4 millimeters.

The international standard symbol for inch is in (see ISO 31-1, Annex A). In some cases, the inch is denoted by a double prime, which is often approximated by double quotes, and the foot by a prime, which is often approximated by an apostrophe. For example, 6 feet 4 inches is denoted as 6′4″ (or approximated as 6'4").

So.

The inch is defined as 25.4 millimeters which is 1/36 of a standard yard which in turn = 0.9144 meter, so an inch = 914.4mm/36 = 25.4mm

Easy - ain tit?

Now - about the meter and the speed of light (meter/second) = 299, 792, 458 m/sec = 299,792 Km/sec
http://en.wikipedia.org/wiki/Metre


The metre or meter[1](symbol: m) is the fundamental unit of length in the International System of Units (SI). The metre was originally defined by a prototype object meant to represent 1⁄10 000 000 the distance between the poles and the Equator. Today, it is defined as 1⁄299 792 458 of a light-second.

Because it is the base unit of length in the SI, all SI units which involve length (such as area or speed) are defined relative to the metre. Additionally, due to the metre being the only SI base unit used to measure a vector (e.g. displacement), all vector units are defined relative to the metre. However, decimal multiples and sub-multiples of the metre— such as kilometer (1000 meters) and centimetre (0.01 metres)— can be formed by adding SI prefixes to metre (see the table below).


Doh! Intel specifies the torque for the 6-32 motherboard standoff in Inch-Pounds. But Pounds are actually a Kilograms, right?

Not quite. Torque is expressed/defined in newton.meter units

For pound see:
http://en.wikipedia.org/wiki/Pound_%28mass%29

International pound
Main article: Avoirdupois
The international avoirdupois pound is equal to exactly 453.59237 grams. The definition of the international pound was agreed by the United States and countries of the Commonwealth of Nations in 1958.

In the United Kingdom, the use of the international pound was implemented in the Weights and Measures Act 1963.[1]

“ The yard or the metre shall be the unit of measurement of length and the pound or the kilogram shall be the unit of measurement of mass by reference to which any measurement involving a measurement of length or mass shall be made in the United Kingdom; and- (a) the yard shall be 0·9144 metre exactly;(b) the pound shall be 0·453 592 37 kilogram exactly.”

Weights and Measures Act, 1963, Section 1(1)
An avoirdupois pound is equal to 16 avoirdupois ounces and to exactly 7,000 grains. The conversion factor between the kilogram and the international pound was therefore chosen to be divisible by 7, and an (international) grain is thus equal to exactly 64.79891 milligrams.

So.

The international pound is defined to = 453.59237 grams = 0.453 592 37 Kilogram (the gram being a sub-set or derivative of the Kilogram).

There is no reason why different methods of measurement should not co-exist so long as they are derived from a common consistent base then any unit in one system can be converted to another and maintain the integrity of both - eg. inch/imperial on the one hand an metric on the other.

The SI metric system is essentially a decimal system to the base 10.

This is not new at all. The dollar/cent, use of logarithmic tables, use of slide rules and calculators, Survey measurement in 1/100 foot for level and 100 link = 1 chain have been around for ever. Digital computers, spread-sheets etc. are quite normal decimal systems. 1/1,000" and 0.001" micrometers etc. are the same.

Currency conversion is all in decimal with either the US dollar, the UK pound, the Japanese Yen and the European Euro etc. are similar examples in everyday use.

So, the inch/foot/mile/pint/gallon etc. is under no threat nor are they out-dated. But their base had been re-defined in International Units (The SI system).

So after all that - back to basics - screw threads in a computer.

They are defined in inch units but most times an equivalent metric screw or nut is interchangeable for all practical purposes.

There are many ways of screwing up a computer with out even touching a screw.

We are all aware that when in a screwing environment when a male screwing instrument is inserted into a female screwing receptacle that great care and sensitivity are required for a successful outcome that is not totally screwed up.

I hope this helps.

Evan
11-08-2007, 06:42 AM
John,

Have you ever noticed that my posts of this nature are always replies?

In case your maths aren't up to it that means that for every post on my total that is accounted for by these discussions there is at least one to someone else's credit as well. You will also note that only a very few people are normally involved.

You know damned well that the overwhelming majority of my posts are both on topic and original showing something to do with machining or useful to this community in some way. I find your constant snide remarks directed at me in various threads tiresome and wonder just what pleasure you take from it.

Allan Waterfall
11-08-2007, 06:46 AM
Blimey.....John only enquired about a thread size and it started a war.:mad:

Allan

oldtiffie
11-08-2007, 07:50 AM
If John and Evan don't stop rubbing each other the way they do, this is what will happen to 'em.

http://i200.photobucket.com/albums/aa294/oldtiffie/picmactchstick.gif

lazlo
11-08-2007, 08:11 AM
John,

You know damned well that the overwhelming majority of my posts are both on topic and original showing something to do with machining or useful to this community in some way.

Really Evan? It seems like the majority of your posts are comprised of you making off-the-wall assertions and then spending 13 pages trying to defend yourself. I looks like you had around 25 posts in the "Higher Mileage" thread when Todd was trying to explain what a derivative was to you.

In this thread, John asked what thread the screws on a parallel port connector were. After I, and 4 other people answered 4-40, you felt necessary to add a 5th reply, with the amusing tidbit that 4-40 was an oddball, because the PC is a metric standard.

So count yourself another 10 - 15 useless post count in this thread too.