#10 screw and 3/16 screw

[oldtiffie]

Use it or lose it.

It seems that as a general statement of what seems to be case here, that those of us in "metric" countries (most who "grew up" with "imperial" and adopted and adapted to "metric") accept and use and work in and with "imperial" every day of the week.

Its almost if as we are bi-lingual in that sense as we are quite comfortable working with both systems.

Many in the US seem to be "in denial" that metric even exists let alone is used and useful by anyone (else) anywhere (else).

The US is quite free and within its rights to "stay imperial" and most of the metric world is quite prepared to let it - as it should.

I have quite a few tools that are "inch" - dial indicators are good case in point - that are calibrated to 0.0005" ("five tenths" or "half a thou"). As 0.01mm is precisely 0.0003937" is is more than good enough to say the 0.01mm = 0.0004".

It is easy to see by eye - without any conversion that "half a thou" (0.0005" = 1 1/4 x 0.01 = 1.25 x 0.01 ~ 0.0125mm - or put another way 0.01mm ~ 0.0004 ~ 4/5 x the 0.0005" calibration.

I can work just as well using metric indicators and converting to "inch".

The best and ideal way of course is to use digital tools (micrometers, DRO's, calipers etc., set them to your dimension and system of choice and then press the "in/mm" conversion button and there you are - instant conversion.

My bet is that the trade stockists in the metric countries have a better "inch" range of product than the "inch" country (USA) has of "metric" stock.

[jdunmyer]

I, too am beginning to love the standardization of Metric. Sunday, I made a new jet for a snowmobile carburator. First thing was to figure out what thread it was, assuming metric, as it's a Yamaha from Japan. Hmmm... looks to be about 5mm. Check my Metric tap & die set to see what thread it might be and find....let's see....can it be? Yes, I have FOUR choices in a 5mm size: .75, .8, .9, and 1.00 pitch!

God only knows how many different 5mm threads there'd be if Metric wasn't so standardized.

[tyrone shewlaces]

Ssshhh Tim,
Don't let on that old Joseph who set the first standards up before American was even found and used 55 degrees with rounded roots and flanks is still the strongest thread form to date.somewher

Now see there ya go braggerin' er sumthin'.
So 55 degress is stronger and the rounded root & flanks is stronger. No argument from me there. But is 55 the magic number? Maybe 54-1/2 is even stronger and 55 degrees is just a lazy cop-out.
So going 60 degrees is a lazy cop-out to begin with. Those rounded root and flanks is what you get after a bit of production dulls the tool anyway, so no need to spec it. Management cost-savings. Cop-out.
A Whitworth form of some size will fit somewhere inside the cross section of a 60-degree V after all. It's in there somewhere.
Technically 60 degrees is 1/3 of an about-face. It's that fraction thing again I think. We like fractions here.

In actuality, just making a bolt bigger than needed will do fine, and does, unless weight is an issue. So do they use Whitworth in Aerospace? Probably should. Probably don't.
60 degrees is metric and metric is all scientific and aerospace is all scientific too. Probably just metric fasteners. Another cop-out.

But as my pappy always said - "If it weren't fer half-assed, nothing would ever get done."

[Uncle O]

It seems that as a general statement of what seems to be case here, that those of us in "metric" countries (most who "grew up" with "imperial" and adopted and adapted to "metric") accept and use and work in and with "imperial" every day of the week.

Its almost if as we are bi-lingual in that sense as we are quite comfortable working with both systems.

Many in the US seem to be "in denial" that metric even exists let alone is used and useful by anyone (else) anywhere (else).

The US is quite free and within its rights to "stay imperial" and most of the metric world is quite prepared to let it - as it should.

I have quite a few tools that are "inch" - dial indicators are good case in point - that are calibrated to 0.0005" ("five tenths" or "half a thou"). As 0.01mm is precisely 0.0003937" is is more than good enough to say the 0.01mm = 0.0004".

It is easy to see by eye - without any conversion that "half a thou" (0.0005" = 1 1/4 x 0.01 = 1.25 x 0.01 ~ 0.0125mm - or put another way 0.01mm ~ 0.0004 ~ 4/5 x the 0.0005" calibration.

I can work just as well using metric indicators and converting to "inch".

The best and ideal way of course is to use digital tools (micrometers, DRO's, calipers etc., set them to your dimension and system of choice and then press the "in/mm" conversion button and there you are - instant conversion.

My bet is that the trade stockists in the metric countries have a better "inch" range of product than the "inch" country (USA) has of "metric" stock.

This entire post is laughable....who said we don't/can't use both Imp/metric
daily ? It is nothing to convert one to the other or switch the machinery over to read one or the other. What ever gave you the idea that you were so special ?

[oldtiffie]

OK - now convince the rest of 'em

OK - you've convinced me - now convince the denialist anti-metric brigade who don't/won't/can't see any use for or use metric at all.

I didn't claim to be special at all - just an ordinary one of a large group of the great unwashed in metricated countries and industries.

As I said, it seems to me that the metric people are more acceptable/adoptive of/to inch than the "inch" users are of metric.

[Rich Carlstedt]

I blame the inventor of the screw cutting lathe, Mr Henry Maudslay ( A Hero in my book !)

Had he left the dam change gears out, We all would be cutting 4 threads per inch, no matter what diameter the shaft/shank was..!

Thats where it all started..
And as to who is right ..I use all threads..I have BA (47 1/2 deg !) ,ME (55 deg) ,NC,NF,NEF,metric (all 60 deg) and a few Whitworth (55 deg) in my home shop.
Most resistance to metrics in the USA is not by manufacturers ...its a consumer issue. The world market place has forced them to respond years ago
Our Autos here have been metric for 20 years.
Mechanics I know work with both with ease , as do I
The machines we made at work were of either fastener ..whatever the customer desired
I think home shop folks like we have here, resist the metrics becauuse of the cost to upgrade their inventory and tools....no small change.
Is there conflicts in metric 'rules" ?..... absolutely !

but consider this:
I would say that since Mr Whitworth ( a Prime Apprentice of Maudslay)started the practice of standardization of threads, the only real thread is his..... But our friends in Britain deserted their great hero and went elsewhere..so their knickers aren't clean either

Lets all return to Whitworth !
Any thread not a Witworth is a devient !
Oh, I almost forgot..he used inch dimensions..

Rich

[JoeCB]

Back to the topic of old standard threads... The old American standard threads are sometimes encountered when working on period machines. Outboard motors from as late as the 1920's sometimes used # 14-20 (.242) and #16 -20 (.268) screws. Since these are often encountered in aluminum, sometimes even with aluminum screws it's not umcommon for a newbe to get in trouble trying to use modern 1/4 -20 hardware and tools.
Joe B

[Blueskys]

So, what's the deal with #10-24 and 3/16-24? I feel like such a space cadet.

If that was the worst that happened to me today it would be my best day
since I was about 4 years old.

I would tell no one, burn the box and reciept and pretend they were 10-24s.
And maybe use a little locktite.

[tyrone shewlaces]

As I said, it seems to me that the metric people are more acceptable/adoptive of/to inch than the "inch" users are of metric.

ah HA! That's true. There's the proof that imperial makes more sense. Imperial users don't like the metric with all it's different useless units, all being 1/10 of each other, buggering up the system and being all uppity.
Metric users on the other hand, secretly yearn to dip their toe into the refreshing pool of imperial-ity.

Ahhh yesss.
All I need now is a martini.

Don't be too jealous though. It's not all hams & plaques. We do have to put up with the occasional metric blueprint now & then. It's just annoying.

[kc5ezc]

Yep, 12x24. I tried to get them at Fastenal, but the counter guy said they we not allowed to keep any #12 screws. Had to go to Home Depot.

[oldtiffie]

Unscrewed up

I'm feeling like an idiot. I have box of set screws marked 3/16-24. I was looking at my tap & die set and noticed that I don't have a 3/16-24 tap, but #10-24 looked almost identical so I used that. It worked although the set screw felt a little loose.

So, what's the deal with #10-24 and 3/16-24? I feel like such a space cadet.

Rotate.

This should go a fair bit of the way to helping you.

Note that as this is an OZ book and that we are metricated that the tapping and clearance holes sizes are (in) metric (mm).

Just divide by 25.4 (or multiply by 0.04) and you will have a conversion to inch.

[J Tiers]

Actually, I like MM, I just like thousandths better than 0.01 MM increments for small stuff..... You can measure thousandths by hand, and they are small enough.

The 0.01 MM is in the tenths, actually 10 microns, too fine for good shop hand measurements, as we often discuss right here. On the other hand, 0.1mm is awfully coarse...... basically 4 thous.

MM are good for hand-sized measurements. Metres are good for large measurements like ships.

Where is the unit for people-size measurements? Metres are too big, you need too many decimal places. MM get ridiculous as you get into thousands of them.

"Oh, it's about 1.21 metres"............ that's just silly. but "it's about 4 feet" is perfect.

That is the good thing about inches... they are "right sized" for people-size stuff. Even feet are a good unit for people-sized stuff. Metres are not, way too big.

"Meters" might be, they tend to be about 2" or 3" diameter, and so they are a useful sized unit....... but you might have to call them out as air, steam, or volts. And carrying them is an issue.

[spope14]

Bottom line here is that you have to work with both these days if you are in any machine shop, dealing with repairing any item, and even in the home shop. Many cabinet wood applications went to a 35mm basis years back as well.

I apprenticed and went to college during the great metric change over, then falter, had to know both to design and produce with linear measurement in precision applications.

This all said, I have most of my fasteners and drill tools in english because this is what I pick up at the yard sales. Any more though, when buying met fasteners for a specific repair job, I pick up several to get supplies up in that regard.

[oldtiffie]

Jump

Actually, I like MM, I just like thousandths better than 0.01 MM increments for small stuff..... You can measure thousandths by hand, and they are small enough.

The 0.01 MM is in the tenths, actually 10 microns, too fine for good shop hand measurements, as we often discuss right here. On the other hand, 0.1mm is awfully coarse...... basically 4 thous.

MM are good for hand-sized measurements. Metres are good for large measurements like ships.

Where is the unit for people-size measurements? Metres are too big, you need too many decimal places. MM get ridiculous as you get into thousands of them.

"Oh, it's about 1.21 metres"............ that's just silly. but "it's about 4 feet" is perfect.

That is the good thing about inches... they are "right sized" for people-size stuff. Even feet are a good unit for people-sized stuff. Metres are not, way too big.

"Meters" might be, they tend to be about 2" or 3" diameter, and so they are a useful sized unit....... but you might have to call them out as air, steam, or volts. And carrying them is an issue.

Well - let's see.

The 0.01 MM is in the tenths, actually 10 microns, too fine for good shop hand measurements, as we often discuss right here. On the other hand, 0.1mm is awfully coarse...... basically 4 thous.

0.01mm ~ 0.0004" ("four tenths") - just under 0.0005" ("half a thou") and well with the reach and capability of most HSM-ers and 0.10mm ~ 0.004" ("four thou") - also easily related to.

The biggest PITA with metrics are the bloody drills as they have increments of 0.50mm (~ 0.020" ie "20 thou") where-as I prefer the "inch" sets with increments of 1/64" (= 0.0156" ~ 0.016" - ie "16 thou") as it "fits in" better for me with the smaller "jumps" or "steps". I use "inch" "number" and "letter" drills as well - so "inch" is a clear "winner" in that regard.

I suppose that we "metricated" people were pretty well forced or obliged to "go metric" because of "pressure" and "circumstance" and perhaps if we weren't a lot of us would have "stayed inch" as seems to be the case in the US.

But having said that and having had to "make the break" from our "inch" "comfort zone", I am glad we had to do it at the time we did.

Having broached the subject of metric and inch drills and conversions etc., I felt obliged to post a table that pretty well sorts it out.

I hope it helps:

[whitis]

So, what's the deal with #10-24 and 3/16-24? I feel like such a space cadet.

3/16 is 187.5mils and #10 is 190mils.

In days of yore, there were way too many "standard" thread sizes (not to mention non-standard ones). There were the gauge (machine screw) sizes and the fractional sizes. It was decided over time to throw out the fractional sizes below 1/4" and throw out the gauge sizes above #12 as well as most of the odd sizes. In 1920, machine screw sizes went up to #30, which was 450mils in diameter; even back then, the National Screw Thread Commission recommended that sizes above #12 not be used. And SAE only recognized fractional sizes above 1/4". The Unified Thread Standard adopted in 1949 after all the interoperability problems in world war II, excludes fractional sizes below 1/4" and gauge sizes over #12. Even in 1864, it appears that William Sellers' United States Screw Thread Standard dealt with fractional sizes only down to 1/4". Also, the preferred thread pitch for many sizes changed over the years. So, it seems that even a century ago 3/16-24 was a bastard size.

Imagine all the combinations of diameter, thread form, pitch, length, fastener type, etc. Some varieties were killed off or made non-prefered. Whitworth and straight V threads were harder to make than Sellers, UNC is more common that UNF, odd numbered gauge sizes are rare, etc.

And metric may eventually kill off the imperial sizes.