On 17-10-2012 16:02, Le_Forgeron wrote:
> Le 17/10/2012 15:40, HenryW a écrit :
>> The first one consists of a lathe object shaped into a bulb, referenced with a
>> negative scale component to create a hourglass shape then a scaled down version
>> (0.995) is differenced from it. You can see banding which looks to me as if the
>> glass does not have a uniform thickness.
>
>
>
> Hint: if you scale, the object get a dilatation.
>
> E.g. Value of 1 scaled 0.995 becomes 0.995
> Value of 10 scaled 0.995 becomes 9.95
> Value of 100 scaled 0.995 becomes 99.5
>
> Width at 100 / scaled : 0.5
> width at 10 / scaled : 0.05
> width at 1 / scaled : 0.005
>
> If you want a constant "horizontal" thickness, you need to translate the
> curve of the lathe BEFORE rotating it. (assuming a vertical axis for the
> lathe / sor )
> (it's only horizontal : the slant of the curve might very well impact
> the overall perception of thickness, you would need to draw a second
> curve using fixed-width-discs along the first curve to really have a
> uniform thickness: I can do it on a paper, but it's a nightmare to
> program that for all possible curve )
>

Well... this is an answer to Stephen's lathe problem ;-)

Thomas

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