Wow, a question where I could actually put my astrophysics degree to use, and
beaten to the punch.

In any case ...

Gravity is a 1/r-squared equation, and the curve is a paraboloid - a parabola
rotated about an axis. And of course you're approximating a 3-dimensional
phenomenon in 2D.

Another common way to model gravity is to stretch really stretchy fabric across
a frame and drop a weight into it. The fabric approximates a paraboloid and
allows you to roll lighter balls into/around the well. Not as elegant as a hard
surface though.

Easy enough to find and print an image of a parabola to make Ed's template.
Scaling it up beyond the limits of a typical lathe seems to be the hardest part.

Let us know how it goes!
-T

Get Outlook for Android<https://aka.ms/ghei36>

________________________________
From: OldTools  on behalf of Ed Minch 
Sent: Saturday, May 23, 2020 8:40:29 AM
To: James DuPrie 
Cc: Tools Old 
Subject: Re: [OldTools] odd question: Gravity well (read for oldtool content -
its really there)

And I also forgot to mention that since it looks like there will be end grain
showing, the ball should not wear a groove for a long log time

Ed Minch

> On May 23, 2020, at 8:13 AM, Ed Minch  wrote:
>
> Sounds like you have it covered.  Seems like a simple lathe job if you ignore
that 20” dimension What does your lathe look like?
>
> Seems simple enough to make a cardboard negative shape to hold up against the
curve as you develope it.  You could also make a carboard shape for the outside
and use a drawknife or big gouge to get close.
>
> There is one at the Franklin Institute in Philly that is about 5 feet across
made of fiberglass and not very fair (is lumpy in other words). You put a coin
in a slot and drop it and the coin rolls on its edge all the way around and down
into the hole - a way to make donating fun for kids.
>
> The math escapes me
>
> Ed Minch

------------------------------------------------------------------------
OldTools is a mailing list catering to the interests of hand tool
aficionados, both collectors and users, to discuss the history, usage,
value, location, availability, collectibility, and restoration of
traditional handtools, especially woodworking tools.

To change your subscription options:
https://oldtools.swingleydev.com/mailman/listinfo/oldtools

To read the FAQ:
https://swingleydev.com/archive/faq.html

OldTools archive: https://swingleydev.com/ot/

OldTools@s...