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Woodworking - Barrel Stave Pattern

JWaldo

New member
I've got to build a jig for a small production run.

My initial assumption was, wider in the middle, narrow at the ends, just draw in a fair curve and you're good to go.

Wrong. (at least, the trial pieces didn't work)

So, mathematically, I've got a curve section, turned into a curved sheet that intersects a plane at an angle. Slice it off at the plane intersection, flatten it out, and there's the plan pattern for the stave. College 3D geometry was 40 years ago, and while I vaguely remember intersecting cylinders with planes at angles, I don't remember enough of the math to do it now.

Rather than try to re-create the math, does anyone know of a stave pattern calculator available anywhere? (I've searched the web extensively - it's like any pattern is the super secret, only if you know the handshake, ingredient - perhaps only given to apprentice coopers after 10 years of slaving?) Lots of stuff on making barrels, some video, but nothing so far on the actual plan pattern for a stave. Could do a trial and error, but would like to take a more engineered approach.

Thanks,
Jim.

P.S. Yes, the sides of the stave's are beveled. Got that part worked out (% of circumference * 360 / 2). It's the plan view of the stave that's giving me trouble.
 

SAG 180

New member
I'd be inclined to play around with a spreadsheet and make a few assumptions/approximations: you know that there will be circular sections along the barrel axis at various points along it, you know how many staves you want in your barrel. If you assume that the width of the flat staves are close enough to the circumference divided by the number of staves you get an approximate width for the stave that is a little bit wider than the real stave for that part of the barrel at that point along the axis.

Circumcircle of a Regular Polygon - Math Open Reference

http://www.mathopenref.com/polygonradius.html

"Given the length of a side:
By definition, all sides of a regular polygon are equal in length. If you know the length of one of the sides, the radius is given by the formula:
"

sideradius.gif

where
s is the length of any side
n is the number of sides
π is PI, approximately 3.142
sin is the sine function calculated in radians



You then have to relate that stave width (s) at that point along the barrel axis to a point along the length of a straightened stave.
 

johnoder

Moderator
Pattern will be entirely dependent on amount of "belly".

You have to decide on what "belly" your barrel will have and work from there.

I would do it based on the multiple diameters of barrel based on ever so much height steps, like every 2".

Number of staves divided in to the individual circumferences is how wide, circumferentially, the stave is at that point

J.O.
 

JWaldo

New member
Did the spfeadsheet calcs and plotted the results.
Also determined the belly vs end diameters.

Fairing the curve between the plotted points appears to be the difficulty. I now suspect, after the initial bend around the belly or equator of the barrel, that the curve stops and the line needs to become straight. Or at least, straighter. (Barrels seem to not be watermellon shaped. After the fat middle they seem to flatten out and become more conic.)

Would have bet money a 5 minute Google search would have turned up patterns but no luck (or my google-fu is really bad).

Anyone with any practical experiene?
All suggestions welcome!

Thanks,
Jim.
 

oldbrock

New member
staves

I tried a google search too and came up with nothing useful. A few thoughts. I'd forget the computer stuff and try a practical approach. If you soaked and formed the stave blank to the belly shape you want and fastened it to a form clamp type of fixture then cut the correct included angle along each side in the fixture would this not result in a set of fitting staves? I'm just inclined to try it for myself to see if it works. Just my 2c Peter
 

Forrest Addy

Moderator
Barrel making is an old craft and there are many books on the topics. The trade is called "coopering" and a barrel maker is a "cooper"

A barrel shaped by the staves that comprise it and derives its strength and integrity by the hoops that constrain it. The curvatue of the stave edges vary with the width of the invidual staves if the barrel is to be round and have coconsistent shape. Plus the edge bevels vary with the stave width. If you are lucky enough to make staves all of a common width all of your staves can be equal. Hoiwever the best barrels are made with rived staves split from green bolts. Thus the width of the stave cn vary considerablt. A good cooler can make casks and barrels that are round and consistant in shape having in internal volume to close tolerances and he does it all with simpel tools and considerable experience.

I've made a few barrels for stage props and even fake barrels require some fancy work if they are to look real from 50 feet. My hat's off to a cooper who cank knock out 20 good barrels a week working single-handed.

Start with the terminology: Cooperage - The Making of a Wine Barrel
 

Chip Chester

Active member
This isn't a template, but rather a technique...

How A Traditional Wine Barrel Is Made - YouTube

and a few more on that page.

Seems like every process is misnamed by the narrator, but it's a start.

Like: "Takes a master cooper years to achieve this by hand..." while we
see the cooper is using a machine, not hand tools...

Still educational, though...

Chip
 

ZAGNUT

New member
some 15 years ago i helped a carpenter friend devise a system for cranking out perfect staves. once we wrapped our heads around what needed to be done the solution was pretty simple and the correct machine was the panel saw.

the "pattern" was just a cradle of steel reinforced wood with the negative form of the belly of the barrel. this sat in a fixture on the sliding carriage of the saw that allowed the pattern to be easily lifted and turned around 180 deg. a clamping board with the positive shape of the belly and a way to clamp it to the main pattern was also made up.

in use he would tilt the blade to the proper angle, clamp up a pre-bent stave blank, run it through the saw, turn the pattern around in the fixture and then run it through again. because of the clamping method the bends in the staves don't need to be perfect.

with this system he put out enough staves for a couple hundred small barrels in no time and made good money on the project.
 

gwilson

New member
In Williamsburg,the coopers run STRAIGHT pieces of white oak(best if riven) over a cooper's jointer,of which I have made a few for them. They bevel the straight staves just by eye. When they are all done,the staves are assembled together at one end,and successive hoops driven over the "V" shaped assembly until the staves are forced into a barrel shape. Then,they build a fire inside a cage inside the barrel,charring the inside of the barrel,and setting the staves into their bowed shape. Then,the charring is scraped out,heads are fitted,and permanent hoops are put on.

In the 19th.C.,stave saws were invented,which look like big circular saw blades,but are bellied like a wok. They saw curved staves. Then,it is a simpler matter to bevel the staves and make a barrel.

The old way was best,as it made a barrel that would stand pressure from fermenting liquids better.

In England,a cooper had to make 2 barrels a day to not starve back in the 1960's,and the coopers we have in the museum had to do that the old,hard way,working in a shack with NO WINDOWS(why was that???) and just a candle or 2 for light.
 

stephen thomas

Active member
wood is not homogenous and its bending characteristics may not be uniform. Conditions for which a cooper accomodates unthinkingly.

But for purposes of a pattern, lets assume straight grain, all quarter sawn blanks would behave close enough to the ideal. I'd start as others noted by picking the belly diameter, and each end diameter & divide by the number of staves. Then I'd mess around with a caternary curve to fit the points & maybe adapt it a little 'til it "looked right".

smt
 

rklopp

Active member
In the 19th.C.,stave saws were invented,which look like big circular saw blades,but are bellied like a wok. They saw curved staves. Then,it is a simpler matter to bevel the staves and make a barrel.

In England,a cooper had to make 2 barrels a day to not starve back in the 1960's,and the coopers we have in the museum had to do that the old,hard way,working in a shack with NO WINDOWS(why was that???) and just a candle or 2 for light.
I remember as a kid going to the "barrel factory" in Shelburne, Nova Scotia, and seeing one of the "Wok-blade" saws in action. The outfit mainly made barrels for salt cod back in the day, but had become a bit of a tourist attraction. It was a lot of fun to watch, in any case, especially for a family of gear-heads on vacation.

Then there's the French oak fermented tanks at some of the super-high-end wineries in Napa, CA. They make my home furniture look like c*ap!
 

JWaldo

New member
Drmrecoop,

Thanks! I have sent you an email under separate cover.

Since my last post here, I have been climbing the learning curve, and have gained several useful and interesting insights.

Thanks,
Jim.
 

stolzdm

New member
barrel making

Unless it is a trade secret, how about sharing the results that work for you?
Inquiring minds want to know.
 

dberm22

New member
Rather than try to re-create the math, does anyone know of a stave pattern calculator available anywhere? (I've searched the web extensively - it's like any pattern is the super secret, only if you know the handshake, ingredient - perhaps only given to apprentice coopers after 10 years of slaving?)

P.S. Yes, the sides of the stave's are beveled. Got that part worked out (% of circumference * 360 / 2). It's the plan view of the stave that's giving me trouble.

I've searched high and low for a stave design manual, calculator, etc, but was unable to find anything, either. I am attempting to make a bar-height pub table and wanted to use a barrel as the base, but was unable to find a barrel 41-42" tall (all I could find is the normal 36" barrels). As a mechanical engineer by trade (and education), I took a crack at making a calculator / template creator myself. I haven't actually tried to use this yet to make a barrel, but the math should be correct. At least, the output looks correct.

Capture.jpg

The spreadsheet takes only 2 (required) inputs, height, and # staves, and should scale everything else for you automatically. Outputs are in Blue. I had to make it a *.zip so that it would let me upload an *.xlsx, but the calculator is the only thing in this directory.

P.S. I know this thread is long dead, but I hope this helps other who come after me. It's the first link that pops up when searching for a stave/barrel calculator, so I thought this was the right place to put it. Hopefully someone uses this to actually build a barrel, and report back how it works!
 

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The Wood Tailor

New member
I was looking at your calculator which I must say is excellent and was wondering about something. Here on the island of Barbados we are known for the manufacturing of rum and are the producers of the worlds oldest rum. Hence, any rum related item such as miniature rum barrels are sold very quickly to the tourist who visit our island. Here my query..Can this calculator be utilized for the manufacture of miniature barrels? The barrel height and number of staves will be smaller seeing that it for the calculation of a miniature barrel. Also where you have information pertaining to the "head radius" and "bulge radius" is this the radius you are speaking of or in actuality the "head diameter"? Will the calculation for the head radius be proportionate to the height of the barrel so that the barrel has a nice bulge in the middle and not look rectangular in shape?

I am just trying to wrap my head around the different columns and their significance. I don't mean to seem dumb but a little more clarification would be great as to their usage and meaning. I been getting a little more comfortable as I try to relate what each column means as I look at the graph and the column figures. It is a great...no FANTASTIC job which you have done. There is nothing available or closely related to what you have done and hopefully with a little advice from you, I can look at the possibility of manufacturing the miniature barrels once you have clarified certain things to me.

Looking forward to your reply. Should you wish, I may be contacted directly at [email protected]
 

Flim Flam Sam

New member
Hey dberm22, just wanted to thank you so much for this tool.

I couldn't tell just from doing one calculation and looking at the output if it is a uniform curve, but if it is then there's an easy way to get the curve you're looking for marked onto the wood to be cut. This method requires very few data points.

So, assuming uniform staves with uniform curves, which may or may not be the case for an actual liquore/wine barrel, you can just mark the corner of the stave and the mid point of the curve and then make a uniform curve using the method in the following YouTube video: How to make a Perfect Arch (Tip) - YouTube

After that, it should be easy to make the other side of the stave with the same method after setting the corner points the appropriate width. I have personally used that method to create the a uniform curve for some other projects, so I'm confident it could help here. That won't necessarily give you the bevel, but if the bevel stays uniform as well, the angle should still be easy to grab from traditional math methods as described here: Staves and Segments

As for actually making the cut with both the curve and the bevel simultaneously, your guess is as good as mine and might just take some jiggering to find the right tool/method.

I hope my post isn't confusing for anyone that comes across it, I'm not always as clear in my writing as I am in my head.

The main thing though is just that I wanted to say thank you for coming up with the calculator to begin with. I don't think it would have been an easy enough thing for me to make that I would have followed through with the research it would take to make it.
 

Capytan

New member
Thank you dberm22, best response by far. Do you still have the files available that used to be attached to this post?
Thanks in advance,
Bryan
 

truc

New member
i built round porch columns. they wer straight(9- 10" OD)for the bottom 3 feet and 9 feet tall. after 3 foot height, they tapered with a slight entasis over the next 5 feet. everything was drawn full scale. at regular intervals (6 to 12")draw a plan view section describing one stave with its bevels and inside face and outside face. lay those sections out on a vertical layout rod, working from the center line- describe the outside face. fair a line between all points and that shape will be your template.

screw the template to the bandsawn, rough cut stave.
i used a shaper with a bevel knife and a ball bearing to cut the long beveled & curved edge of the stave. set it up with a feeder so no one has to go near it. cut one edge, flip end for end, cut the other side.

use chains and bolts to clamp it together- the tapers splay badly, and need a lot of tension to pull tight. we went thru several types of chain/bolt combo before we found something stout enuf to draw so hard. i used west epoxy.

the round blanks come out fairly true once you do a few. the outside was turned on a wood lathe modified for the job. it was turned to a pattern with a 3 hp router and a straight bit.

its simple:
draw it up,
make pattern/template,
cut staves on shaper or bandsaw
glue it up,
turn it.

jef
 
 
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