[tjb1]

BTW Neilw20, Joseph Whitworth STANDARDISED the nut and bolt industry way back when, which previously was a random and personal preference "system" used by various engineers of the 1800's etc, and far from being a "sub standard" led the World in standardisation procedures.

Personally I prefer the Metric system both for measurement and thread range.

Almost all digital calipers and dial calipers are to .01mm resolution, which is approx 1/2 a thou, so when compared to an Imperial system it is more accurate because Imperialists only go down to .001".

Most Imperial micrometers also resolve to .001", (some to .0001"), and most metric micrometers resolve to 100th of a mm which is .01mm or half a thou about, again Metric is more accurate.

One day the Yanks will go Metric totally, and Napoleon can give himself a pat on the back.
Ian.

I know this is old but it got to me... Metric is not more accurate, the damn tool you were using had a higher resolution. Has nothing to do with the system you use, in the end it is just a number with a unit attached. That same micrometer that was "more accurate" in metric would give you the same dimension in the imperial system.


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[neilw20]

Old thread? like some of the posters.
In Australia, in the 70's, I believe, people were killed by the metric conversion. I remember sale of imperial measuring tools was against the law, for a while.
A two post car hoist had the vertical pillars made of 1/4" steel.
Yeah, that's OK. Just us 6mm for the pillars. You can't buy 1/4" any more. Against the law!
Until some hoists started dropping cars on workers and killing them.
I remember, one of our departments, doing some frantic reworking of components so they were strong enough.
I won't say the company, but a few others might remember this lesson.
40 years. ANYONE? Nearly past the statute of secrets?

edit:
OH, and I remember, fascinated, seeing my first CNC, paper tape, Cincinnati mill, and I guess it was all without a CPU, and hardwired, with wire wrap (done by another paper tape machine).

I am still friends with the paper tape punching programmer, with regular emails. times have changed, and so have the threads, no pun intended.

[handlewanker]

I know this is old but it got to me... Metric is not more accurate, the damn tool you were using had a higher resolution. Has nothing to do with the system you use, in the end it is just a number with a unit attached. That same micrometer that was "more accurate" in metric would give you the same dimension in the imperial system.


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I think you missed the point.........anyone using a micrometer with graduations in .01", (that is one div = ten thou in case anyone thought I left a nought off), would be hard pressed to make anything more accurate than to the nearest .01".

That is why when you use the Metric system you are reading to .01mm on most measuring devices, or .0393"......do the sums for a conversion to the old fashioned and practically obsolete Imperial system.

It's still widely used as a standard measuring system in the USA.....one day they will come round and adopt it instead of just occasionally using it.
Ian.

[RICHARD ZASTROW]

They won't let me work in milimeters anymore, now it's microns.LOL

Good thing my AutoCad lets me dual dimension everything. Those who can't make the change can read 'em both.

Dick Z

[handlewanker]

Microns........do you use a micronometer to measure them....LOL.

I don't think any two people can measure the same piece of work to Microns and get the same reading and a lot would depend on the time of the year when the reading was taken.
Ian.

[neilw20]

Yes, Ian, and we both understand the years part, but why do they hide our age on the left of the post. Are we all ageless?

[broby]

WOW, this thread has sprung back to life with a vengeance or what?
Makes for fun reading tho...

[neilw20]

Well, Brian. After 2.69 years, Did the 2" BSW end up fitting, whatever it was?
I guess you still have another 20 or 30 years to figure it.
It is a little early in the morning for you?

[broby]

Hey Neil, Yes the part fitted... well I suppose it did because the part did not come back from the customer!
No it is not that early... been at work since 6am and it is now 7:55am.

[andypugh]

I have always been under the impressin that Nappy B invented the Metric system and made it the standard for the Frenchies.

At the same time, while Thomas J was deeply being involved with French politics regarding the Revolution era, it is little wonder that he recognised a better way to do things, but getting the message home would have been his real problem.

I know this is a really old thread (I found it trying to work out what dimensions to make some 3/4" x 16tpi nuts to) but I felt I had to share this.

According to this book:
World in the Balance: The Historic Quest for an Absolute System of Measurement - Robert P. Crease - Google Books
The US would have been metric now, were it not for the fact that the chap bringing a platinum metre standard to the US (a gift from Napoleon) was waylaid by a British privateer, who nicked it. This was during the war of 1812, when Britain accidentally ended up at war with basically everyone. (It's complicated, but basically Britain had conscription, especially including sailors, and there was some disagreement about whether British sailors could adopt US citizenship to avoid being conscripted to fight Napoleon. So a war broke out).
So, in all likelyhood, if that metre standard had arrived, the US would have been metrificated.

Also, I am quite a fan of Whitworth, he chose 55 degrees as that was (according to his calculations) the optimum angle. That seems like a better reason to choose an angle than "it's easy to draw with just compasses".

[RICHARD ZASTROW]

Another factoid?? In the 19th century there was a need to supply accurate meter standards to the world governments. SIP was supposed to manufacture them. Then SIP discovered the existing government standards were not correct and had to replace them all. Or so SIP said in their 75th or 100th anniversary book. (I'm old enough to have recieved them) LOL

[handlewanker]

Hi, I guess there will always be people who grind things down to the smallest factor before they can attempt to work with them.

Then there are others who see a bright light and see more than just a way to see in the dark.

Put simply, when it comes to preventing something from falling off something else and there are threads involved on a spiral form, anything that allows that to happen is good.

I doubt that most threading with single point tooling adheres strictly to the tables for thread calculations, although when making a screw thread in the lathe I do look up the info to get the pitch and depth of thread and the hole size for a nut that will give 75% thread engagement, but with a single point tool sharpened to the right angle, it still has the end just rounded off with a stone to approx. the radius as indicated in the tables, which makes fitting the two threads to one another a trial and error function.....the last thou or two of thread depth determine if the thread fits or not........ that interprets as skill.

You still need a gauge to determine the final product accuracy, even if it's a nut that has been cleaned out with a tap or a bolt that appears to be nice and clean.

I doubt that many people have lathes with lead screws so accurate that they pass scientific standards of thread measurements.......over long lengths that is.....for short length single point threading, the errors in a cheaply made lead screw will not be noticed or cause any concern.

Once you adopt the Metric system with it's ten base practicality, the Imperial system becomes a museum piece.

It's been many years since I used the half nut unclasping at the end of a thread run method to cut threads, and running in reverse to the start for a new cut is so much simpler and fool proof.
Ian.