bowl gouge flutes

[allen thunem]

I need some SIMPLE CONSICE clarification on what constitutes a parabolic flute.
What makes this type of flute different than a V OR U shaped flute.

[Richard Coers]

My thought is that if you looked at a cross section of the steel, all 3 have different elipitcal shapes. And most of the shape difference is at the small radius end of the ellipse. The V has the tightest radius and fairly straight sides, the parabolic is in the middle with radius sides, and the U has the biggest radius with fairly straight sides. No technical info to back my statement, just my interpretation.

[John Keeton]

Allen, the following may be helpful, however, keep in mind that when folks say "parabolic" that usually means a profile "generally" approaching a parabola - not necessarily a "true" parabola.

This is a straight on shot of Doug Thompson's gouges provided by him in a prior thread -
THOMPSON V AND U.jpg
This is a parabolic curve -
parabola-hi.png
And, this article may assist even further as it has the Ellsworth gouge included, and it is often referred to as a parabolic gouge. http://www.woodturner.org/community/...deToGouges.pdf

[Thom Sturgill]

To take this a step further, I own both regular 'V' shaped and Doug's 'Jimmy Clewes' special V (tighter more closed V). On both I can lay a straight edge tight to the top half of the flute. On my Ellsworth if I try that the straight edge will only touch at the rim and end with a visible arc along the middle. This affects the shape of the edge even when they are both ground with the same settings. They difference is minor, but it is there. As I understand, the V shape is easier to machine than the parabolic shape. The 'U' shape is of course much wider at the bottom and the 'sides' (the portion above the curve) are shorter and vertical as seen in John's pictures.

[Reed Gray]

Parabolic means that the flute design isn't straight like a V or an arc of a circle. The curve is steeper/tighter in the bottom of the flute, and flattens out as you go up the sides of the flute. V is more closed, and straighter sides. C is pretty much a radius like a spindle roughing gouge. U is almost a parabola, with sides going more out than straight up. Confused yet?????

robo hippy

[Harry Robinette]

John
Thanks I was never sure what a parabolic looked like. Now it makes sense after seeing your picture thank you.
I thought that Glasser tools were parabolic flutes but the inside of the wing is straight in the picture from the AAW magazine. The only parabolic is Ellsworth's gouge.

[Dale Bright]

John's pics and description of the shapes are right on target. You will find the Sorby, Henry Taylor, OneWay and Woodcut gouges have parabolic flutes. I am pretty sure the new Stuart Batty gaouges are parabolice as well. Doug Thompson's "V" gouges have a wider and more rounded bottom to the flute and I think that makes them alomst a hybrid. The Begamin's Best gouges from Penn State have what is called a "Deep V" that has a very narrow bottom.


I prefer the parabolic over any other, by far.

Dale

[Ralph Lindberg]

Benjamen's Best also tend to be not centered (I have three). Also D-Way's gouges are parabolic