- Hello DonaldI am not claiming the better of any measure.But to get an accurate leadscrew for the MM these parts work correct for the needed application.A 10 TPI screw and a 100 division dial gives 0.001 per division.It is the same set up that is on the mill/drill table that I have, Pat has one just like it on his machine. The same set up is used in most of the machines that are out there.To make an 100 division dial is not an easy job. Yes you do need a standard to make the dial.I have a 200 tooth 10 in saw blade that I am going to use as a standard to make the dial I need. Just use everyother tooth and I should get an accurate dial.With The 200 tooth wheel,useing every tooth. it is possible to get a dial .0005th with it.Of course the dial would have to be a large diameter to do this.I not saying that other part would not work fine,but these part are easy to get and work with.Keith
wrote:*Donald H Locker <dhlocker@...>*I'm not confused about the difference between metric and imperial vs decimal and

fractional.

I do claim that decimal division of units is not preferred. As I stated in my

earlier post, it is more difficult to accurately, without a previously existing

standard, divide a physical entity into fifths (hence tenths and so forth) than

it is to divide in halves. In the case of circles, sixths (after halves) are

the logical division.

I'm also suggesting (strongly, true) that the metric system is an attempt to

force a philosophically "pure" measurement system on an impure world, a world in

which factors like the ratio of the circumference of a circle to its diameter,

the number of days in a year, the smallest temperature difference that a human

can detect, the ratio between a DC voltage and a pure sinusoidal AC voltage with

the same heating power, and other measurable quantities are inconstant,

irrational, and VERY USEFUL.

A measurement system should be, first and foremost, of great utility in its

realm of application. Defining a meter to be "one ten millionth of the distance

from the pole to the equator through the prime meridian" is as arbitrary and as

useless as defining an inch to be the length of fifteen [randomly selected]

barleycorns laid end-to-end. At least (at the time of that definition) most

people had access to 15 barleycorns. As far as I know, the originally defined

meter wasn't really accessible to _anyone_.

When I'm doing machining, I deal in inches, and thousandths thereof. A tenth of

a millimtere is too coarse, but a hundredth is often too fine. Buildings are in

feet and tenths or feet and inches, but stage sets are feet and inches. When

I'm doing circles, I use degrees or radians as required. Masses are grams,

kilograms, slugs, poundals or pounds -- again as needed. Electrical stuff is in

amps and volts (seldom do high voltage, so kV don't come into it) but

non-sinusoidal voltages need different analyses and handling than DC and

sinusoidal. Paper is letter, legal, folio, A4, A3, A2, A, B, C. Whatever is

appropriate to the situation.

I'm just grousing, I guess, that so many people want to use metric where it just

isn't an appropriate system. I'll be quiet now. For a while.

Maybe I'm just grumpy about not having built my MultiMachine yet. Or my Urwick

MetalMaster. Or anything useful or fun for the last few years.

Donald.

keith gutshall wrote:

> Hello Ian

> I agree with you, Donald was confused about what I was talking about.

> When I was younger my dad had a ruler that was marked in 100 of a foot. I told him the size in the 100 of the foot side and he measure on the in side and didn't fit.

> Keith

>

> Ian Newman <ian_new@yahoo. com> wrote:

> Hi Donald,

>

> I think you are confusing metric and decimal.

>

> Metric or Imperial - the millimetre or the inch - are

> purely arbitary units. Decimal sub-division can be

> used in either system and is the prefered method in

> both. If you work to a high degree of accuracy in

> Imperial units don't you measure in thous? My Imperial

> slip gauges are in thous/tenths and my Imperial

> micrometers and vernier measure in thous.

>

> The leadscrew pitch proposed by Keith was 5, 10 or 20

> TPI to allow easy decimal measurements.

>

> Ian.

>

> --- dhlocker@comcast. net wrote:

>

>> What is sensible about metric? It's nearly

>> impossible to divide anything real into 10 (or 5)

>> pieces; 2, 3, 4 (hence also 6, 8, 12, ...) are easy

>> and can be reliably verified.

>>

>> Donald.

>>

>> ------------ -- Original message

>> ------------ --------- -

>> From: Ian Newman <ian_new@yahoo. com>

>>> Hi Keith and Jeff,

>>>

>>> --- keith gutshall <drpshops@yahoo. com> wrote:

>>>

>>>> It might be easier to start with a known

>> thread

>>>> and work from there. The prefferd might be 5, 10

>> and

>>>> 20 TPI to work with.

>>>> Just my view on it.

>>>> Keith

>>>>

>>>

>>> As virtually all systems are now metric, wouldn't

>> it

>>> be better to aim for a sensible metric pitch

>> rather

>>> than use Imperial units?

>>>

>>> Ian.

>>>

>

Deep Run Portage

Back Shop

" The Lizard Works"__________________________________________________

Do You Yahoo!?

Tired of spam? Yahoo! Mail has the best spam protection around

http://mail.yahoo.com - Hello DavidI will look around and see what I can find. That help me go in the right direction.Keith
wrote:*"David G. LeVine" <dlevine@...>*

>It sound like a useful item,I have seen self stick tape measure

>In a woodworking catalog I have,but it is marked in 16th.

>I can not seem to find it with the search engine?

>I am thinking maybe the word was misspelled?

>Maybe some more information would be helpful.

>The idea sounds workable.

Well, I didn't bookmark the site where I found them, but Metric tapes

are calibrated in CM/MM and 10 CM is 3.937 inches, so on a 1.253188+"

(about 4 cM) diameter drum, it should work nicely.

David G. LeVine

Nashua, NH 03060

Deep Run Portage

Back Shop

" The Lizard Works"__________________________________________________

Do You Yahoo!?

Tired of spam? Yahoo! Mail has the best spam protection around

http://mail.yahoo.com