Case length

[redding]

Right, I feel as thick as s*^t.

 

I can not get my head around thousands of an inch on my digital caliper, like what do the numbers mean!

 

(1) Dummy round to lands measures 2.333 (done to get maximum length)

 

(2) My current reloaded round measures 2.303

 

(3) Standard Winchester .308 factory round measures 2.172

 

All measured with Hornady tool from base of the case to the ogive (150 grn Sierra SP)

 

So how much "jump" do the bullets have in 3 and 2, I dont know if its thousands or hundreds.

 

I know that the difference between 3 and 1 is 0.161, great, 0.161 what?? Like said thick!

 

Can someone please put it in plain English because I am obviously incapable of reading a caliper, (I have also Googled it and cant make sense of it)

[Laurie]

I sometimes have to start at the point and as I go to the right muttering 'tenths', 'hundredth', 'thousandth' as I confuse myself too. (Easily done, well that's my excuse!)

 

So-o-o-o .... 2.333 - 2.303 = 0.030, three hundredth of an inch which is another way of saying 30-thou as there are 10 thou' to each 100th

 

....................2.333 - 2.172 = 0.161, one hundred and sixty one thou' as going right from the point, 0.1 = a tenth of an inch or 100 thou', 6 = six hundredth or 60 thou' and finally 1 solitary thou' in the third column.

[hughes.s]

2.333,In long numbers is 2 thousand 300 hundred and 33 thou, there are one thousand thou"s to the inch, so the first number is inches, = 2 inches, the first number after the point ( or dot ) is hundreds, = 3 hundreds, the second number, is tenths, =30, the third number is thousands, =3. add them together as you did in school useing columns.

 

So the bullett jump for two is.030 wich is 30 thousands. Basically the numbers are units of comparison against each other, you could call them apples, drebs, peaches, whatever you like.

 

 

 

Hughes.s, pm me if you need

[bradders]

.161" is 161 thousands of an inch (there are 1000 of them in an inch)

 

If you are a metric oriented person and having trouble picturing it, look at it like this, 1mm is 0.3939",or just under 40 thou.

Therefore to be clear, 1 mm is .040" or forth thou.

Therefore your 0.161" is approx 4mm

[gbal]

2.333,In long numbers is 2 thousand 300 hundred and 33 thou, there are one thousand thou"s to the inch, so the first number is inches, = 2 inches, the first number after the point ( or dot ) is hundreds, = 3 hundreds, the second number, is tenths, =30, the third number is thousands, =3. add them together as you did in school useing columns.

 

So the bullett jump for two is.030 wich is 30 thousands. Basically the numbers are units of comparison against each other, you could call them apples, drebs, peaches, whatever you like.

 

 

 

Hmmm ....is not the first digit after the point "tenths",the second "hundredths" and the third "thousandsths"?

 

.030 is "no tenths" "three hundredths" and 'no thousandths" ie "three hundredths",or "30 thou"

.123 would be one tenth and two hundredths and three thousandths.Since each one is is ten of the preceding (ten thousandths are one hundredth,and ten hundredths are one tenth) .123 is also "123 thou",just as .030 is "30 thou"(or three hundredths)

 

.006 is six thou,if you add three more thou its .009 nine thou,and if you add another thou its....ten thou,or one hundredth .010

 

the basic is 10 (ten) 100 (hundred) (1000) thousand,so the places after the decimal are 0 (tens) 00 (hundreds) and 000(thousands)

 

Now,I can't read a vernier scale so I buy digital,which shows as the above! whether its inches or metric,of course.

 

gbal

 

 

 

 

Hughes.s, pm me if you need

[redding]

Thanks, getting there I think, in Lauries answer he says

"....................2.333 - 2.172 = 0.161, one hundred and sixty one thou'

 

Is one hundred and sixty one thou not a massive jump!

especially when other gurus talk about a bullet having a "30 thou" jump to the lands

 

PS. the caliper I have is digital

[hughes.s]

gbal

 

.123 is prounouced one hundred and twenty three thou. How can you say three hundredths (300) is 30 thou (thirty)?

 

edit Thats the way its said. he did ask for it in plain english.

[redding]

gbal

 

.123 is prounouced one hundred and twenty three thou. How can you say three hundredths (300) is 30 thou (thirty)?

 

edit Thats the way its said. he did ask for it in plain english.

See what I mean, its as clear as mud now!

[jcampbellsmith]

See what I mean, its as clear as mud now!

 

0.123 inches becomes 123 thou if you move the decimal point 3 places to the right. However, if all this is a struggle, don't reload. Regards JCS

[Laurie]

Thanks, getting there I think, in Lauries answer he says

"....................2.333 - 2.172 = 0.161, one hundred and sixty one thou'

 

Is one hundred and sixty one thou not a massive jump!

especially when other gurus talk about a bullet having a "30 thou" jump to the lands

 

PS. the caliper I have is digital

 

 

Yes, that's kind of a lot! That's the sort of reason we handload - tailoring the ammo to the rifle. When I say it's a 'lot', it is still only a bit over a tenth of an inch. If you start your shooting and handloading as I did with Her Majesty's castoffs (actually in most cases His majesty's they were so old), or the onetime property of one A. Hitler (deceased) of Linz, Vienna and Berlin, you usually talk a few tenths of an inch jump. Likewise the clapped out 7.62 TR rifles I used to buy a long time ago for £100 each - one had 'freebore' getting on for a half inch I reckon.

[gbal]

Three hundredths is .03 (No tenths,3 hundredths,and no thousands) and is better written as .030

ie thirty thousands (you'd say "3 hundredths" if the 'accuracy ' was only measured to two decimal places ie hundredths (.03),but it's the same actual size measure.

 

JCS Is it not more correct to say that if you move the decimal three places to the right (ie multiply by one thousand) then

.123 becomes123 (123.0 if you wish) ie one hundred and twenty three inches.?

 

123 thou would be quite a large jump off the lands,but possible-the usual range is more like 0 (Touching) to maybe ten thou,or thirty thou.Errors of measurement do occur,as distinct from errors of decimal useage.

 

Just remember,as Laurie says,the figures are whole units before the decimal,then tenths hundredths thousands of a unit after it,in that order,and there are ten max in each (0-9),after 9,the preceeding place goes up one (ten thou become one hundredth) .008,.009,010,.011,.012......019,020...021,.022....etc

 

2.568 is two inches and 5 tenths, six hundredths and eight thousandths of an inch( two and 568thou inches) said as two point five six eight inches;

just as 4.3 is four and 3 tenth inches:said as 'four point three inches;and

7.69 is seven and 69 hundredth inches,said as seven point six nine inches.

 

It's like 'whole numbers' really:

5472 is 'five thousands,four hundreds,seven tens,and two units"-imagine four piles of Monopoly money,each pile for notes worth ten times more(or less the other way) than the pile next to it.The Monopoly unit here is £1

 

How do lathes work?Seems tougher than mathes to me.

 

gbal

[hughes.s]

redding asked for plain english.

What I did was to convert into machine shop language the figures he gave. Nobody has ever said to me this part measures " two inches and 5 tenths,(=500) six hundredths (=60) and eight thousandths(=8) of an inch" (wich I conceed is correct) but nobody reads a micrometer like that, it is read as 2.568, wich we both agree on. You automaticaly convert the 5 tenths into 500, the six hundredths into 60, and the eight thousands into well 8 thousands. What is missing from your criticism of my post is you fail to explain to redding that the tenths, hundredths, and thousands, are a percentage of the whole inch.

I thought the way I explained in easy numbers was a way to understand the corrolation of his figures, as I said you can call the units apples if you want. Who would ask for a square window frame to be made 3 foot, 6 inchs 2 quarters 1 eights and 2 sixteenths. Wich is ........................ answers on the back of a ten pound note please.

I was trying to help the man out but instead got drawn into a discussion of the "correct terminology " to use, never again.

 

Hughes.s

[Big Al]

When I was at school we learned in hundreds, tens and units, I expect you did also redding? The sam applies in both imperial and metric except in metric we don't worth to so many decimal places as a sing mm is a lot smaller than a single inch.

 

When you see an imperial vernier reading it will usually contain 4 or 5 digits depending on how good the vernier is and how low it will resolve. When I say resolve I mean how small it will measure down to, for example some of the cheaper ones will only measure down to a single thousandth of a inch or 'thou' as we call it, this looks like this 0.001 - If the vernier can measure to tenths of thousandths of an inch there will be a fifth number at the end like this 0.0015, that extra 5 at the end in this example signifies five ten thousandths which is half of one thousandth so the reading is one and a half thou.

 

Some examples,

 

On a 5 digit reading it starts with a single digit to the left of the point (2.0000) which is the full inch value, then its hundredths, tenths, thousandths, ten thousandths.

 

2.0000 = 2 inches, no hundredths, no tenths, no thousandths on ten thousandths

 

2.1610= 2 inches and 161 thousandths, no ten thousandths.

 

2.1615 = 2 inches 161 thousandths and 5 tenths of a thousandth or 2 inches 161.5 thou or 2161.5 thou

[gbal]

redding asked for plain english.

What I did was to convert into machine shop language the figures he gave. Nobody has ever said to me this part measures " two inches and 5 tenths,(=500) six hundredths (=60) and eight thousandths(=8) of an inch" (wich I conceed is correct) but nobody reads a micrometer like that, it is read as 2.568, wich we both agree on. You automaticaly convert the 5 tenths into 500, the six hundredths into 60, and the eight thousands into well 8 thousands. What is missing from your criticism of my post is you fail to explain to redding that the tenths, hundredths, and thousands, are a percentage of the whole inch.

I thought the way I explained in easy numbers was a way to understand the corrolation of his figures, as I said you can call the units apples if you want. Who would ask for a square window frame to be made 3 foot, 6 inchs 2 quarters 1 eights and 2 sixteenths. Wich is ........................ answers on the back of a ten pound note please.

I was trying to help the man out but instead got drawn into a discussion of the "correct terminology " to use, never again.

 

Hughes.s

Hughes,your intentions were not in doubt,but you got the 'columns' after the decimal in the wrong order...it has to be tenths,hundred,thousandths...each column(place after decimal) is 1/10 of the preceding column...the decimal system.

I think it's a little tricky-as seen by the posts-to explain if someone has not done this( I am baffled by machine jargon-I was

probably doing math(s) instead of useful practical skills (or typing). Using 'correlation' is perhaps not the best word either as it means something quite different when comparing numbers(It's the extent to which an increase/decrease in one set of measures corresponds to an increase/decrease inanoher set of measures. Inch measures will coorelate perfectly with metric measures,of course."apples etc....' maybe better to keep to same domain-eg lengths,whether in iimperial inches or metric cms.

The aswer to your window frame is actually fairly straightforward.. (4/16+4/16+2/16+1/16) is 11/16ths,so window size is three foot six and eleven sixteenth inches. No charge. (putting all the fractions as sixteenths makes it easy to add them up)

 

The focus on columns for tenths,hundredths and thousands is basic,and I hope my example of Monopoly money makes it so clear that most will realise they actually are familiar with the principle,though less so with quite how it works after the decimal point-essentially the same,with a few practices anyone can do it (unlike a lathe,where I'd be counting fingers on each hand,frequently...five apples on the right,five oranges on the left...hey,it's five for each,but easier to cal them fingers,unless we go digital-5digits on each).

The reds(£1000) go in column one,the buffs (£100) in column two,the greens(£10) in column3,and the yellows £1 in column4: ten yellows equals one green,ten greens equals one buff,ten buffs equals one red .

 

I recall trying to explain a statistics proceedure ( a set of maths operations)..breakthrough was saying "cooks do it all the time...its a recipe .' Principle clear,proceedures can be done one by one (what is 'blanching?",how much is a pinch? I could get the hang of it,I think).

 

atb

g

ps in Algebra ( 2a+4b+ 3c=16,that malarky) then the a,b,c can indeed be anything(apples,bananas,chairs)-when young Einstein realised that he saw the point of it all.

[Big Al]

Three hundredths is .03 (No tenths,3 hundredths,and no thousands) and is better written as .030

ie thirty thousands (you'd say "3 hundredths" if the 'accuracy ' was only measured to two decimal places ie hundredths (.03),but it's the same actual size measure.

 

 

 

You are right George but they way you describe it looks wrong and is confusing by machine shop standards.

 

Engineers would work on the principle of whole units before the decimal point then hundreds, tens, thousands, tenths of thousands.

 

I would not describe 0.030 as three hundredths even though technically it is, as you also rightly say, it is more commonly known as 30 thousandths of an inch. Both are right but the latter is more commonly used in a practical engineering sense which is the context of this discussion, yours is more the less recognised although factually correct mathematical descriptive.

[gbal]

You are right George but they way you describe it looks wrong and is confusing by machine shop standards.

 

Engineers would work on the principle of whole units before the decimal point then hundreds, tens, thousands, tenths of thousands.

 

I would not describe 0.030 as three hundredths even though technically it is, as you also rightly say, it is more commonly known as 30 thousandths of an inch. Both are right but the latter is more commonly used in a practical engineering sense which is the context of this discussion, yours is more the less recognised although factually correct mathematical descriptive.

Al,I know the machines would be novel tome,but I wasn't expecting the math to be different.

 

No doubt at all that the figures before the decimal are whole units. But in a decimal system,the units descend in order in the following decimal places-tenths,hundredths ,thousandths,tenths of thousands.......

So 0.030 means "no tenths,three hundredths and no thousands' as written. Since there is a zero in the thousandths

,it implies that there could have been another digit-ie the convention is that we are measuring to third decimal accuracy (ie thousandthds) so it would be said as "thirty thousandths",but 0.03 implies that we are working to an accuracy in hundredths,as there is simply no entry for thousandths,so calling it 'three hundredths' is-in that context-appropriate.This is standard scientific reporting nomemclature.I appreciate such crudity of measure won't be typical of skilled machine floor work,and that "three tenths" is virtually automatically translated to "thirty thou" because at least thousandsths if not more accurate-would be typical of precision criteria/tolerance,which is why I also said "thirty thou".But I would not want to assume what machinist say...the '3 hundredths' was to emphasise where the 3 was-in the hundredths column-trying to explain the logic of the maths system precedes typical useage on the shop floor,but they have to be consistent.

 

That's where the twice repeated "after the decimal point its hundreds,tenths and thousands" really jars on me....if so would not 0.03 be " 0 hundredths,three tenths (and zero thousandths)" ie three tenths.........which it is not....it is three hundredths,or thirty thou on the shop floor.All those thousands (not tens or hundreds!) of hours in maths and decimal theory can't be wrong,can they?..surely there is something odd in any system that isn't ,"after the decimal point, tenths,hundredths,thousandths.ten thousandths.......'and so on,so that there is a constant multiplier (10) from one digit to the following one...."

 

can .308 calibre really have bullets that are zero tenths in diameter,rather than three tenths (I know of course that bullet 'size' isn't very consistently labelled,but if we are to have zero diameter bullets,I'm going to do an arts diploma in "touchy feely fuzzies".

 

It;s such a nice day outside too- and yet the world may be in chaos.Best arrange a GP check up...ah,got one for ten thirty thou tomorrow.

;-)

 

g

[Big Al]

I think the confusion or misunderstanding here George is that you are using the terms tenths, hundredths and thousandths and the context you are using them is correct but its not how its referred to in an engineering sense.

 

As a first year apprentice I was taught (very quickly I might as as it was very intuitive and just like I had learned at school) to look at it as hundreds, tens and thousands as multiples of thous, so;

 

.100 was one hundred thou which of course it is, its also one tenth of an inch

 

.010 was ten thou or less commonly referred to as one hundredth

 

.001 was one thou or a thousandth

 

.0005 was 5/10th of a single thou or half a thou or five tenthousandths .

 

I don't see any confusion really, your quoting it one way, myself and Hughes another, still means the same thing.

[gbal]

OK,Al no problem at all with how engineers read the figures-correctly

Take it to basics,and good luck in explaining a decimal system in hundred,tenths and thousandths after the decimal in that order,to someone who has misgivings about math,and no basis in it.Engineere are clearly too smart to be just constrained by words...:-). The examples you give are exactly as I would say-given that they are in three decimal precision mode,so thousands is appropriate.

I remain convinced( thou of hours of theory, and non eng practice) that to describe the second column of digits after the decimal point as 'tens' is fundamentally flawed mathematical /logic;but trains fit rails,and bolts fit rifles,and cartridges chamber,so the engineering works .Just so long as .345 is three tenths,four hundredths and five thousandths-label it "three hundred and forty five thou' ,and Bob is indeed your parent's brother.

 

Conventions are interesting-as I said the scientific one is to not be spuriously accurate-if you can't actually measure in thou,don't speak in thou.It carries over into statistics-that's why 2.4 average is in a sense a nonsense for children in two parent relationships.And if the unit of data collection is ,say £1k for income,then the average should be in whole £ks, ie £18k,not £18,368.25,since that suggests a precision that is not sustainable from the data.Some lies,damn lies and statistics may originate from such like,but it's a misunderstanding-not to say sometimes exploited.

OK these proceedings can be closed,since we all agree in practice,and I shall seek correction from my neighbour,who is a senior management engineer,both shop floor apprentice and hed shed executive. I'm going for a coffee (1.0000.... coffees,precisely,or maybe two smaller ones.)

 

g

 

Sussed it: .100 is one hundred; .010 is ten,and .001 is one : assuming the basic unit is "A THOUSANDTH OF ONE" in engineering parlance;in generic decimal its "one tenth,one hundredth and one thousandth " of ONE,after the decimal point.

 

In general,the decimal system assumes the unit is one(NOT a thousandth of one),so that the first figure after the decimal is tenths,second is hundredths and third thousandths,as in £5.26 -analytically this is 5 pounds,two tenths of a pound (ie 2x10p+20p and 6 one hundredths of a pound (ie 6p).Pound is 100p so we don't have thousandths -'penny' defines the precision if you will.

 

Basic must do in science/measurements is say what the units are.The default in fine engineering is presumably 'a thousandth" of an inch (or cm etc)and that is understandably just assumed-from apprentice on.

The outside world is however full of people who are not engineering or maths apprentices.The engineering system is a sensible adaptation-if 'distortion' until the non engineer wakes up and smells the coffee- of the generic decimal system,but pragmatic,and intuitive-especially if three decimal places are the norm.

 

coffee was Nescafe "Azera",one spoonful (Nigella spoons),bis,to which all blame should be addressed.

 

g

[redding]

Thanks to all who took the time to get it though my thick scull.

I have it now, it just would not click but now it does.

Its simple when someone explains

 

Regards

[hughes.s]

Two great nations divided by a common language. ( Groucho Marks................just kidding). People use the wrong terms daily, I do understand what you are saying, I was taught to read a micrometer that way, (but in practice you out the middle man). Any way I am now going to Hoover, sorry vacume the carpet. Shalll we now go back to daily lives?

 

 

 

Hughes.s

[gbal]

redding and hughes,glad we all got somewhere worthwhile in the end.I learned that engineers have a different way of conceptualising but it works just fine-to three decimal places,in fact,and clearly works from day one apprenticeship. I gather kids do subtraction now differently at school,too-works just as well.

Generally people are abler than they sometimes think,just need to get their head round it in a way that suits them. Cats no doubt hate the idea,but skinning can be done in various ways-I'd imagine the Dyson even has an attachment in their "Animal" models,or have words become vacuous? :-)

g

[That bald headed Geordie]

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARRRRRRRRRRRRRRRRRGGGGGGGGGHHHHHH!!!!!!!!!!

1 + 1 = 2.

2 + 2 = 4.

4 + 4 = 8.

 

Simples!!!!

 

Now were is my butane powered Caliper dial guage (measured in Btus - I think). So how many Btus per 0.001 inch???

[gbal]

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARRRRRRRRRRRRRRRRRGGGGGGGGGHHHHHH!!!!!!!!!!

1 + 1 = 2.

2 + 2 = 4.

4 + 4 = 8.

 

Simples!!!!

 

Now were is my butane powered Caliper dial guage (measured in Btus - I think). So how many Btus per 0.001 inch???

 

C'mon Les,we've been up to 5+5 in your advanced math seminars:remember - both handies,all the little piggies.

 

g