For You Engineer Guys

[caryc]

I spent a lot of time working in aircraft job shops and learned quite a bit about flat pattern layout. Also had to make a lot of form blocks to make certain parts in a press. I got a good education there but, I got to thinking about something today. I was looking at a barrell and got to wondering...is there some formula for laying out a flat pattern for a barrel hoop? Seems like it would be pretty complicated. Put your brains in gear guys.

 

[Ale-8(1)]

Pretty sure the latest CAD solid-modeling technology would be able to design such a hoop and provide both machine control programming as well as a flat layout if desired.

 

[Watertender]

It's diameter of the barrel x 3.15 and add 4 to 6 inches for the overlap. They are formed in a 3 roll bench roller. For tapered hoops they are hammered on the edge with a cross peen hammer on the anvil horn. The tightness of the hoop depends on if it's slack or tight cooperage. Slack is for dry contents and tight is for liquid

 

[caryc]

For what you said above, isn't that just finding the length of the hoop? If you took a barrel hoop and laid it out flat, wouldn't it have a curve to it? It's not going to be just a straight piece of metal, is it? I was wondering how one would find the radius of that big curve. When forming in a bench roller, is that top roller actually set at an angle so it's actually forming one side tighter than the other? I know in those aircraft job shops I've use a shrinker or stretcher to form some things. Start shrinking one side of a piece of metal 2" X 10" and it will start forming a contour. Maybe I'm just thinking it to be more complicated than it is.

By the way Ale, why am I not showing the Supporting Member any more?

 

[Jeepnik]

Never did anything barrel wise. But WT seems to have nailed it.

I have however designed a reverse taper tank. Most tapered chemical tanks have a slightly larger bottom diameter than top for stability.

I needed a tank to fit a specific space. Where in order to maximize volume had a base considerably smaller than the top. I used Solid Works to design the tank and the fabricator used the sdr file to construct it.

My point is that today’s design software integrates well with other software used in fabrication. Many of the calculations are done for you greatly speeding up the process.

 

[Bob Wright]

As a matter of interest, folks in Ohio across the river from Weirton, WV, refer to residents of that area as "hoopies" as at one time there was a factory there that made barrel hoops.

Seems to me what Cary is getting at is that the sides of the barrel where the hoops fit and sloping, so the bottom edge of the hoop is slightly longer that the top?

Incidentally, the hoops children played with were circular, not tapered.

Bob Wright

 

[Watertender]

The formula is from the cooperage book that used to be at the family homestead. They had a cooper shop there that ran into the early 1900's. The book is long gone with all of my other books and papers but I remembered the specs. The number of hoops and also the configuration of the staves determined the type of barrel. They had machines to make the staves and heads of the barrels. Tight cooperage has fixed heads and slack cooperage has a removable head.

 

[Dave P.]

IF...IF.. I actually had to make a few manually I see how wide you want the strap. measure the barrel where the sides of the strap
land, cut it to length. Calculate the angle (more likely just eyeball it), set my slip roller and run it through. Weld the ends and maybe a final
pass through the roller, ending up with a very truncated cone.
Yes I know doing this would not generate the slight radius needed in the band but I'm clueless if real barrel bands
have one anyway. If they did, a quick roll through the English wheel would do it.
The bands are going on...wood...not really a high precision operation.

 

[Watertender]

I was going to mention an English wheel. The 4 to 6 inch overlap accommodates the taper. Like you said, it's not high precision. If you get really fancy you can trim the overlapped material to make a straight fit along the edges. The barrels they built were not decorative but were solid and durable.