Hi Adrian
For number 1) thank you very much! I will try it!

For number 2) I am sorry, I can only take the
measurements of a number of diameters, as I
described.Even a rough formula may be satisfactiry.
But something more accurate than simply averaging the
diameters and using the average as it it were a
perfect circle.
Thanks!
Justin

--- Adrian Rossiter <adrian_r@...> wrote:

> Hi Justin
>
> On Fri, 10 Nov 2006, justinasia wrote:
> > 1) On a lathe, I need to know an angle for the
> taper. It boils down to
> > this:
> > Length = 2cm
> > Taper = .5mm (and some others too).
> >
> > So what is the formula? It seems to be a right
> angled triangle, with
> > one length 20mm and one length .5mm, so what does
> that make the small
> > angle? (Also the actual formula would be useful as
> I need it for other
> > tapers too.)
>
> If the angle is A, it sounds like the calculation
> you want is
>
> tan A = 0.5 / 20
> A = arctan(0.025)
> A = 1.43 degrees (3 sig figs)
>
> If A is small then tan A is an approximation of A
> measured
> in radians. In this case
>
> 0.5/20 radians = (180/PI) * 0.5/20 degrees
> = 1.43 degrees (3 sig figs)
>
>
> > 2) I have to measure the internal dimentions of a
> tube with an
> > iregular surface. So, I want to know the
> crossectional areas. At
> > regular intervals down the length of the tube, I
> will take a number of
>
> Could you do something physical? Maybe you could
> take a water
> holding mould of sections of the tube (plasticine
> lined with
> cling film?). Add water to the mould to around the
> level of the
> cross-section of the mould you want to measure. Add
> a known
> volume of water to raise the level a little. Then
> you have the
> volume of the pipe between the two levels, and can
> calculate
> the average cross-sectional area between those two
> levels
>
> avg_cross_sect_area = volume_added /
> (final_level - initial_level)
>
> Adrian.
> --
> Adrian Rossiter
> adrian@...
> Home: http://antiprism.com/adrian
>




________________________________________________________________________________\
____
Yahoo! Music Unlimited
Access over 1 million songs.
http://music.yahoo.com/unlimited