On 12/15/2011 6:47 PM, Kevin Miller wrote:
On 12/14/2011 02:20 PM, Dan Coby wrote:
On 12/14/2011 1:25 PM, DJ Delorie wrote:
Dan writes:
I see two red circles and two blue circles. The red circles are the
inner and
outer radii. One of the blue circles shows the inner edge of the
segments. However
the purpose of the other blue circle is a mystery to me.

What is the purpose of the second blue circle?

The inner blue circle is for the clamping brace. The outer blue circle
is the cutoff for when you switch to the other set of equations - it
identifies the size where you start getting end grain issues, too. When
the OD matches that blue circle, the OD circle is tangent to the edge of
the segment right at the intersection with the adacent segment.

Thank you for the information. I had noticed that as I change ratio of the
sizes of the outer and the inner radii, that the 'mysterious' blue circle
did converge onto the outer radius when we hit the crossover point between
the 'thick' and 'thin' segment logic. However I had not made the connection
about 'cutting uphill' when turning. (I am not a turner.)

I have been enjoying playing with your calculator so I would also like to
thank you for your efforts in creating it and making available to others.

Many thanks to both you and DJ.

Cutting uphill refers to cutting in a direction that lifts the wood fibers from the piece. I assume you are a wood worker, so it's essentially the same thing as running flat stock
through a jointer or planer with the grain facing the wrong direction.

When turning a piece with the grain parallel to the lathe bed, you want to cut from the widest part inward towards the center. That way the wood fibers are supported by the wood
underneath them as you cut. When doing bowl turning where the grain is perpendicular to the lathe bed you do the opposite - you cut from the center area outwards...

Yes. I understood what DJ meant by 'cutting uphill' why it is a situation
to be avoided. I had not made the association between the blue line and
cutting uphill until DJ explained the purpose of the line.

Dan