do we have a cooper member?

[DavidF]

Dave---------this thread has been haunting me:-D .

Just another view: If you make a segmented solid cylinder with x number of sides----at xdegree bevel (pending the number of sides) then mount that cylinder in a lathe. Turn it to a barrel shape inside and outside---those bevels have not changed------true or not?:eusa_thin

And--------if you have a flat stave pattern for outside dimension for width, cut the bevel along the arc of the stave pattern, by bandsaw or routerbit and template, before bending the same bevel should work.

Jerry

If you make a segmented solid cylinder with x number of sides----at xdegree bevel (pending the number of sides) then mount that cylinder in a lathe. Turn it to a barrel shape inside and outside---those bevels have not changed------true or not

True, In theory, but not a real representation of the argument. Because of the curvature of a barrel you would need staves that where the same thickness as the radius of the barrel!

And--------if you have a flat stave pattern for outside dimension for width, cut the bevel along the arc of the stave pattern, by bandsaw or routerbit and template, before bending the same bevel should work

That is the question!! I don't think so! If you make a cylinder then the bevel as we have said is (360/#staves)/2 and they will make the cylinder, but as you bend the tops in towards each other to form the barrel then they become compound - don't they????????

 

[Gofor]

Yes, they become compound, just like a piece of crown molding that is installed at 30 degrees to the wall. As the stave is curved toward the end, it is changing the miter angle. When installed, it also slopes toward the center, which changes the bevel. For something like a nail keg, I think the bevel change is only a degree or two, but that would be enough to prevent a water-tight fit. To further muddy the issue if calculating it, you would also need to know if the rate of curve is circular,elliptical, or parabolic, and my guess is that would be affected by the thickness and species of wood, width of stave, and heigth of barrel.
After you get the staves right, you also have to cut slanted dados to hold the top and bottom when you jam down the hoop, not to mention making the top and bottom. Really makes you appreciate the art involved in the cooper trade!!

 

[DavidF]

Yes, they become compound, just like a piece of crown molding that is installed at 30 degrees to the wall. As the stave is curved toward the end, it is changing the miter angle. When installed, it also slopes toward the center, which changes the bevel. For something like a nail keg, I think the bevel change is only a degree or two, but that would be enough to prevent a water-tight fit. To further muddy the issue if calculating it, you would also need to know if the rate of curve is circular,elliptical, or parabolic, and my guess is that would be affected by the thickness and species of wood, width of stave, and heigth of barrel.
After you get the staves right, you also have to cut slanted dados to hold the top and bottom when you jam down the hoop, not to mention making the top and bottom. Really makes you appreciate the art involved in the cooper trade!!

This is exactly how I saw it when I watched the "cooper" at Williamsburg. I am sure he either didn't understand the question, didn't know the answer or just wanted rid of me!!

I understand that the Cooper apprenticeship is 5 years and I guess it would take that long to just get the bevel angle right!!!!