Stupid Question?

[DaveK]

I'm suprised nobody mentioned the most straightforward method of conversion. Get a nice poster of tap-drill-english-metric conversion table. I use the one from my old MSC catalog, I've been known to tear out hair when it goes missing (thankfully a rare occasion, to the relief of my barber). Here is an example :

http://www.evergreen.edu/biophysics/technotes/fabric/drill_conv.htm

On the topic of precision, I recall a lot of confused young engineers when the topics of accuracy, precision, and error were first introduced. It takes some understanding of these subjects to understand that 13mm is not the same as 13.000mm. Then, of course, there is the more important concept of "good enough".

Dave, who knows that real precision must also include other parameters such as temperature (for things that expand and contract) or perhaps moisture content for wood or nylon.

 

[Chris]

On the topic of precision, I recall a lot of confused young engineers when the topics of accuracy, precision, and error were first introduced. It takes some understanding of these subjects to understand that 13mm is not the same as 13.000mm. Then, of course, there is the more important concept of "good enough".

Dave, who knows that real precision must also include other parameters such as temperature (for things that expand and contract) or perhaps moisture content for wood or nylon.

touche

 

[PetreeCues]

I was wondering what you cue makers use to measure the " Millimeters " of the shaft.

I have a dial caliper but it is in thousanths, up to 6 inches, am I missing the MM measurement or do you guys use a different tool, or do you just use a conversion rate to go from Thousandths?

I know most of this stuff is Elementary to you guys but if you could help I would really appreciate it.

And remeber ....I have alot more questions to ask, and if you want to be apart of me becoming a great cuemaker , you need to get in here early

THANKS GUYS

Inches X 25.4 is the formula.

Example:
0.5119 X 25.4 = 13mm

 

[pdcue]

I'm suprised nobody mentioned the most straightforward method of conversion. Get a nice poster of tap-drill-english-metric conversion table. I use the one from my old MSC catalog, I've been known to tear out hair when it goes missing (thankfully a rare occasion, to the relief of my barber). Here is an example :

http://www.evergreen.edu/biophysics/technotes/fabric/drill_conv.htm

On the topic of precision, I recall a lot of confused young engineers when the topics of accuracy, precision, and error were first introduced. It takes some understanding of these subjects to understand that 13mm is not the same as 13.000mm. Then, of course, there is the more important concept of "good enough".

Dave, who knows that real precision must also include other parameters such as temperature (for things that expand and contract) or perhaps moisture content for wood or nylon.

All these points are true, conversion charts were mentioned, BTW.

if you read Chris's most recent troll-post, you should notice
his mistake is thinking a metric only caliper is somehow more
precise than a decimal caliper

the true precision of the device is limmited by the physical parameters
specifically, a rack,device much like the one on your lathe that
makes the carriage-thingy move when you turn the little wheely-thing.
not the display

all those who think Starett makes two different racks for calipers,
please raise their hands

 

[Chris]

All these points are true, conversion charts were mentioned, BTW.

if you read Chris's most recent troll-post, you should notice
his mistake is thinking a metric only caliper is somehow more
precise than a decimal caliper

the true precision of the device is limmited by the physical parameters
specifically, a rack,device much like the one on your lathe that
makes the carriage-thingy move when you turn the little wheely-thing.
not the display

all those who think Starett makes two different racks for calipers,
please raise their hands

I DO NOT troll. If you read my post, it explains why a measurement is more precise when taken with an instrument with a smaller increment of change between any two adjacent readings. It doesn't matter if you are talking about length, width, or mass. I'm sorry if you were unable to comprehend my explanation.

 

[Xanadu]

/trollmode on

You can see the difference between mm and inch measurement, if you see the precision of an Mercedes and the trash like a caddy........

/trollmode off

 

[Cue Crazy]

I'm suprised nobody mentioned the most straightforward method of conversion. Get a nice poster of tap-drill-english-metric conversion table. I use the one from my old MSC catalog, I've been known to tear out hair when it goes missing (thankfully a rare occasion, to the relief of my barber). Here is an example :

http://www.evergreen.edu/biophysics/technotes/fabric/drill_conv.htm

On the topic of precision, I recall a lot of confused young engineers when the topics of accuracy, precision, and error were first introduced. It takes some understanding of these subjects to understand that 13mm is not the same as 13.000mm. Then, of course, there is the more important concept of "good enough".

Dave, who knows that real precision must also include other parameters such as temperature (for things that expand and contract) or perhaps moisture content for wood or nylon.

I did mention a drill conversion, only mine is not a poster. I have seen them, but did'nt think of It at the time I posted. They do go up higher then the small one I have, and would be nice to have.

I aggree, Wood does have those issues, and some plastics do. Some plastics even act like metals when It comes to shrinkage after turning due to temp. (some ferrule materials come to mind when I think about It), but wood seems to be alittle more forgiving then metal when fitting a joint or something. I am not a machinist persay, but I do ocasionally use one of My lathes to turn metal parts with, and you almost have to guess the shrinkage, and account for It somehow By oversizing your measurement, or the final fit will turn out very sloppy, especially if it needs alot of sanding and polishing afterwards. that only adds to the problem. I find this especially true when turning and fitting an arbor type setting, where the 2 pieces need a really close snug fit, or press fit. There's not much room for error since It's so hard of a material.
Definatly more thought needed to turn metal IMO. With wood You can get away with just setting Your calibers as someone mentioned, and turn til It fits, altough I do sometimes set My calibers a hair over, and then bump in the last part using a hand fit instead, (I'm talking about on a tenon or something without threads). I'm not saying It's the proper method to use, but It's always worked well for me, so I just stick with what works. It also leaves me some room for error, just In case my measurement of the bore was'nt so good in the first place, because I'd rather come in over then under.

Greg

 

[pdcue]

re-read your own post

I DO NOT troll. If you read my post, it explains why a measurement is more precise when taken with an instrument with a smaller increment of change between any two adjacent readings. It doesn't matter if you are talking about length, width, or mass. I'm sorry if you were unable to comprehend my explanation.

and you'll find this is not what you said
you said CONVERTING from metric to decimal
worked "better" than vice versa - no ref to measuring
instruments

Dale

 

[BLACKHEARTCUES]

We all get the concept of more precise measurement , but it just isn't neccesary when working with wood, for pool cues. Believe me when I say I know about the smallest of measurements. I used to be a design engineer for the WESTCLOX CO. We made watches, clocks & bomb fuses for the military. I designed the watch movements & our measurments were taken in inches & the tollerances were to 4 places (.0005"). Believe me working with wood for pool cues does not require this kind of tollerances. Let's go on to a more useful subject..JER

 

[BHQ]

We all get the concept of more precise measurement , but it just isn't neccesary when working with wood, for pool cues. Believe me when I say I know about the smallest of measurements. I used to be a design engineer for the WESTCLOX CO. We made watches, clocks & bomb fuses for the military. I designed the watch movements & our measurments were taken in inches & the tollerances were to 4 places (.0005"). Believe me working with wood for pool cues does not require this kind of tollerances. Let's go on to a more useful subject..JER

Let's go on to a more useful subject..JER is my taper bar question a useful subject???? do that one next jer,will ya please. thanks buddy

 

[Chris]

and you'll find this is not what you said
you said CONVERTING from metric to decimal
worked "better" than vice versa - no ref to measuring
instruments

Dale

If you don't understand the relation between the two, I guess I'm probably incapable of explaining it to you. A poor teacher does not negate the validity of the information, however.

If you convert from thousandths of an inch to millimeters, the maximum precision you can get is about fortieth of a millimeter increments. Since the decimal system does not work well with fortieths, the maximum precision you can get using the decimal system to convert is tenths of a millimeter. That is not as good as converting from hundredths of a millimeter to 1/2540 of an inch. A measurement in hundredths of a millimeter could even be converted to inches in .0005 inch increments in such a manner as to get the same value from the conversion as would have been obtained by taking the measurement in "five tenths" originally.

In other words, since a measurement in hundredths of a millimeter is more precise than a measurement in "five tenths," converting from millimeters to "five tenths" will not result in as much error as will converting from "five tenths" to hundredths of a millimeter. This is wholly due to the fact that a hundredth of a millimeter is smaller than a "five tenths."

The same problem would exist in an exaggerated manner if you were trying to convert a measurement of 1.5 km to inches. You could convert an inch measurement to kilometers without losing precision, but to convert from kilometers to inches is a useless endeavor unless you have a kilometer measurement to about seven or more decimal places.

 

[cueman]

I have always used dial calipers. My digital calipers collect dust in a drawer. Since we usually only measure tip and shaft taper in MM instead of inches here is what I do. 13mm is actually .5118". I round that to .512" and call that 13mm. Then for each 1/4mm I want to add or subtract I just go .010". This will get you within about .001" down to 11mm or up to 15mm. Very simple to do in your head. 10 thousandths is almost 1/4mm.

 

[pdcue]

I'll settle for an estimate

If you don't understand the relation between the two, I guess I'm probably incapable of explaining it to you. A poor teacher does not negate the validity of the information, however.

If you convert from thousandths of an inch to millimeters, the maximum precision you can get is about fortieth of a millimeter increments. Since the decimal system does not work well with fortieths, the maximum precision you can get using the decimal system to convert is tenths of a millimeter. That is not as good as converting from hundredths of a millimeter to 1/2540 of an inch. A measurement in hundredths of a millimeter could even be converted to inches in .0005 inch increments in such a manner as to get the same value from the conversion as would have been obtained by taking the measurement in "five tenths" originally.

In other words, since a measurement in hundredths of a millimeter is more precise than a measurement in "five tenths," converting from millimeters to "five tenths" will not result in as much error as will converting from "five tenths" to hundredths of a millimeter. This is wholly due to the fact that a hundredth of a millimeter is smaller than a "five tenths."

The same problem would exist in an exaggerated manner if you were trying to convert a measurement of 1.5 km to inches. You could convert an inch measurement to kilometers without losing precision, but to convert from kilometers to inches is a useless endeavor unless you have a kilometer measurement to about seven or more decimal places.

of when you think you will be able to grasp that
one can measure in decimal MUCH more precisely
than 1/1000?

substitute, oh say, 1/100,000 and your argument
falls apart instantaenously

one more estimate of time till graspage
how long is it going to be till you realise
everyone else in this thread understands
the subject better than you?

FWIW, I noticed you still are ducking the fact you
orig posted about converting, not measuring,
will you perhaps be moving on to econometrics soon?

HTH
Dale

 

[Chris]

of when you think you will be able to grasp that
one can measure in decimal MUCH more precisely
than 1/1000?

substitute, oh say, 1/100,000 and your argument
falls apart instantaenously

one more estimate of time till graspage
how long is it going to be till you realise
everyone else in this thread understands
the subject better than you?

FWIW, I noticed you still are ducking the fact you
orig posted about converting, not measuring,
will you perhaps be moving on to econometrics soon?

HTH
Dale

I'm grasping this just fine. What I am try to explain to you is that for any number of significant figures, be it four or four hundred, you are always going to get a more precise conversion going from the smaller unit to the larger unit. Going the other way will always result in more error.

You seem to be the only one that isn't comprehending this basic concept.

 

[pdcue]

Yet another explaination...

I'm grasping this just fine. What I am try to explain to you is that for any number of significant figures, be it four or four hundred, you are always going to get a more precise conversion going from the smaller unit to the larger unit. Going the other way will always result in more error.

You seem to be the only one that isn't comprehending this basic concept.

...that in no way relates to the topic

what's next?

Dale

 

[Chris]

...that in no way relates to the topic

what's next?

Dale

It's exactly the same thing I've been saying this entire thread. I just stated it differently.

 

[MVPCues]

Kelly <=== Buys Chris and pdcue a beer...