Exercise your brain

[mklotz]

If you're going to make tools you need to keep your brain agile. Here's an exercise in that direction...

Wooden barrels are difficult to make. It takes specialized skills and tools to construct one. A cylindrical barrel would be much easier to make. So, why are barrels the shape they are? And, for extra credit, how does this relate to railroad wheels?

[Toolmaker51]

Individual slats making up barrels are more or less flat and parallel initially. The 'cooper' [barrel-maker] traditionally shaves them into staves.
As staves, ends taper a fair amount in width and somewhat in thickness. The sides also have taper much as the keystone in a masonry arch. The wider side is the barrel exterior.
Assembled, tapers form tight joints retained by iron bands, curvature and tapers resist collapse. The bands are conical form matching angles formed by tapered staves. Staves are notched at at least one end for a barrel 'head' that start the assembly with staves upright. Aside from mating angles, widths anywhere along the individual staves represent their portion of a 360* circle. Mechanically, it produces how an eggshell 'works' by nature. Curved sides direct a lot of weight to a small area when barrel is on it's side, yet form is still resistant to leaks, and far easier to move and handle.
A cylindrical form tall enough to to offer useful capacity would buckle. Why steel drums have circumferential beads formed while being rolled from sheet stock.
Speculation as railroad wheels go, with lazy Sunday morning as an excuse. Surfed answers aren't the challenge; maybe creating the search phrase is, but only with 'auto-suggestions' turned off. Don't let tech do what creative thinking should do first.
Not too familiar with locomotives or railcars; IF they were spoked way back when; that eased casting and weight savings. The 'tire' acted as a barrel band, spokes worked as radial staves, to support the hub; effectively a barrel head. Each is dependant on the other maintaining integrity. Spoked wood wagon wheels as well, including a shrunk on band, called the tire.
I'm anxious to see how responses to Marv's tickler filter in. I'll offer that acuity can [and should] be practiced in vast yet converging manners. One favorite is to visualize and produce clear descriptions in text. The 'what is this tool?' threads offer that in a different manner too. A mechanical thought process looks at features to conceive how they interact, quite like a detective sorting out clues.

[kngtek]

Picking up from Merv Klotz's 'brain stretcher' post, here is an old 'off-the-beaten track' brain teaser for all you machine-builders; read to my 10th grade English class by the teacher many decades ago. Oliver Wendell Holmes Sr.'s poem 'The Wonderful One-Hoss-Shay' describes what, ostensibly, is an example of the PERFECT mechanical design of a one horse shay (two-wheeled cart). I will leave it to you machine builders to decide if you agree.

The following link (Eldritch Press) shows the poem. Explanatory remarks listed there suggest that many years later Henry Ford purportedly sent his engineers to scrap yards searching for junked Fords so as to identity those parts which hadn't failed so that Ford (the company) could re-engineer the non-failed parts to make them weaker - thereby reducing the cost - perhaps the first example of planned obsolescence?

Back to the poem - In my view the shay wasn't perfect, but as OWH says, it was perfectly logical - clearly a satirical view of planned non-obsolescence (from the pov of a machine builder).

Enjoy,

Gary (kngtek)
Calgary, AB Canada

[kngtek]

Sorry, in my previous response to your question Merv I forgot to give you my take on the barrel and railway wheel questions - so here goes!

Barrels (used for liquor storage as opposed to e.g. petroleum storage barrels) are frequently moved by rolling, not lifting, since one man can roll a barrel without the need for a lifting device. Consequently a liquid-filled barrel is bowed in the middle to make it easier to roll i.e. to directionally control movement during rolling - correspondingly, a cylindrically shaped barrel would be much more difficult to directionally control during rolling. When rolling left for example, the bowed barrel rides down to a slightly smaller diameter to accommodate the shorter distance that a leftward-curved track has relative to a straight-line track.

In the case of railway wheels the rolling bearing surface is conical in shape (i.e. smaller in diameter towards the outside of the rail - transitioning to a larger diameter towards the inside of the rail), i.e. not of constant diameter. This design feature is purposeful because, for example, when the railway car is turning right, the leftmost wheels have to traverse a longer distance (larger circumference) than the rightmost wheels do. The conically-shaped wheel pairs accommodate this scenario by shifting left so that the leftmost wheel (in the pair) rides up (to a larger diameter on the conical bearing surface) thereby travelling a greater distance than its rightmost mate. Obviously there must be a limit on the maximum rail curvature that a given conical bearing surface can handle to prevent the wheels 'jumping off the rails'. The flange on the inner surface of the wheel is thus a safety feature to limit lateral wheel movement in the event that: a) the conical bearing surface can't handle the relative left track-right track circumferential difference in distance, and/or b) the centripetal (lateral force) exerted by the railway car (as it traverses the curve) exceeds the conical bearing surface design capability, or c) unevenness in track spacing/curvature.

Regards,
Gary (kngtek)
Calgary, AB Canada

[mklotz]

Well, that didn't take long. Nicely done.

Gary has nailed it perfectly - both the barrel shape question and its relation to the wheels on railroad rolling stock.

The conical wheel shapes lead to another benefit for barrels. In old engravings you may see pictures of barrels being unloaded from a ship by rolling them down two pipes laid between the ship's deck and the wharf. A barrel placed on these two rails will self-correct its motion as it rolls under the force of gravity. As it veers to one side it will be rolling "farther up" the cone on that side, thus covering a greater distance per revolution on that side than on the other. This will act to rotate the barrel away from the veering direction and back toward a centered descent. This method of off-loading would be totally impossible with true cylindrical containers.

Apparently the benefits of steerability were of sufficient value to promote the use of a shape that is not as efficient in terms of storage volume. (A cylinder that occupies the same height/width footprint as a barrel can hold more material.)

OK, on to another storage container question. Amphorae...

https://en.wikipedia.org/wiki/Amphora

have been in use since the Neolithic era; widely used for storage and transport during both the Greek and Roman era.

What exactly was the overpowering advantage of this odd shape that it persisted for such a long period?

It's certainly not built to roll easily.
Unless the stopper was really tight, it would require a stand to keep it upright.
It's not volumetrically efficient like a box.
I'm not a potter but it certainly doesn't look to be the easiest shape to form.

Footed urns, cauldrons, vases and bowls were well known in the same period and those shapes could have easily been adapted for bulk storage and transport yet the amphora won out. Why?

Unlike the barrel question, I don't know the answer to this one but I will certainly welcome your thoughts on the subject.

[Toolmaker51]

Well, that didn't take long. OK, on to another storage container question. Amphorae...have been in use since the Neolithic era; widely used for storage and transport during both the Greek and Roman era.

What exactly was the overpowering advantage of this odd shape that it persisted for such a long period? Unless the stopper was really tight, it would require a stand to keep it upright. I'm not a potter but it certainly doesn't look to be the easiest shape to form. Footed urns, cauldrons, vases and bowls were well known in the same period and those shapes could have easily been adapted for bulk storage and transport yet the amphora won out. Why?

Unlike the barrel question, I don't know the answer to this one but I will certainly welcome your thoughts on the subject.

Both Grecian and Romans were capable seafarers, and maintained trade over ocean and land transit. A ship requires ballast. While stones offer density, an added bed of sand would be a secure means of keeping cargo in position. The pointed foot, or small base some have, would be simple to anchor in sand.
Overland trade would include whatever pack animals were available, including humans. This makes the amphorae [and likely valuable content] adaptable when means of transit changed. The same feature would 'holster' in woven slings securely and remain upright dependably.
Certainly the small neck offers at a few features. Resistance from splashing out, a more convenient size to make of cork or clay, would aid measured pouring; like a milk carton instead of a bucket, and the exterior would be small enough to hold by hand easily. In concert, the tapered end lends itself to pouring also, directly on a surface and rocking in a predictable manner. This seems natural as a few liters of liquid + container have some weight. Small neck or those with loop make it a one handed operation, the other holding the receiving vessel.
No potter here either, but if sat down to make one, the bet is were made butt-end up. The upper end and occasional handle affixed after some drying time to receive a seal.

[kngtek]

Marv, Thanks for providing the description of the unloading tubes for bowed barrels - I didn't know that.

Toolmaker51, Thanks for providing your take on this - It seems logical.

Now on to the question you posed about the raison d'etre for the shape of amphorea. I believe that the amphorea with the pointy bottoms were shipping containers i.e. not intended for domestic use (where a flat surface - table or floor was available to support a vessel with a base). I have no particular knowledge about this subject, but using deductive reasoning following is my take on why they were likely shaped the way they were.

There are several factors that would have been important in choosing and handling shipping containers in the ancient world:
- Durable materials (such as metals or glass) would almost certainly have been too costly to use for storage containers for low value commodities such as wine, water, corn, or wheat. Also I don't think that the manufacturing of glass bottles was even commercialized until the 1800s.
- The classic Amphora shape featuring a pointy bottom, a bulbous middle section, a narrow neck, and two top handles offered the following advantages versus a conventionally shaped clay container:
-- easy to form on a potter's wheel in two sections (a top and a bottom section), then attachment of the two sections together and finally firing in a kiln, - See Note 1
-- didn't require a flat bottom (at extra cost),
-- had a low centre of gravity which would be important for stable, tip-resistant storage,
-- the narrow neck would reduce the liquid surface area at the liquid-air interface thereby minimizing the chance for souring (of wine) - See Note 2
-- had two top handles for tying it down, for handling, and for pouring,
-- would have been cheap to fabricate with semi-skilled workers,
-- a clay vessel (with inherently weak tensile/compressive strength) and with a continuously sloping surface such as this would almost certainly have been structurally stronger than a clay vessel with discontinuities in its shape profile (such as a flat top or bottom).

- Clay and pottery-making skills would probably have been universally available in all ancient cultures at low cost i.e. at a cost commensurate with low value commodities.
- Clay vessels would likely have been cheap enough that they could be considered as one-way containers i.e. it probably wouldn't have made economic sense to either reuse empty clay vessels or to occupy valuable space in the hold of a ship on a return trip. If clay vessels were needed for the next leg of a trip or a return, it would probably have made economic sense to source these at the originating point of the next shipment.
- Clay vessels could have been easily and cheaply broken up at the destination, then landfilled.
- Ocean-going ships as well as wheeled transport carts (both subject to rolling motion) would have had to be equipped with some manner of storage/support to prevent containers from shifting and banging into each other and/or against cargo hold or cart walls. A cheap wooden rack (holding several amphorea) which positioned each amphora apart from its neighbour with ropes through the two upper handles would have been a stable shipping platform.
- It is doubtful that warehouses would have had flat, solid floors i.e. they probably had uneven surfaces such as dirt or stone. So the pointy Amphorea bottoms could have been imbedded in a dirt floor with stabilization provided either by piling sand around them or by placing them in cheap wooden racks.

Note 1: On a trip to Greece in 2007, my wife and I visited the Greek National Museum in Athens. There were amphora artifacts there and a description on one of them said that the top and bottom sections were separately prepared on a Potters Wheel then moulded together, but I can't remember if the sections were partially fired before being moulded together.

Note 2: Early in my working career we lived in an upper duplex in East Montreal. My landlord was a recent immigrant from Italy and crushed his own grapes (imported from CA) and fermented his own wine (150 USG of red & 75 USG of white every year). This wine was stored in Amphora-like glass bottles, each with a 100L (26 USG) capacity and a 1.7m tall neck - 10 or so of them as I recall - Very easy to pour by tilting the bottle over - No souring of the wine because of the long neck.

Regards,
Gary (kngtek)
Calgary, AB Canada

[mklotz]

I did some online searching and discovered several sites that have some interesting things to say on the subject. Allow me to add them as fodder to the discussion...

https://www.quora.com/Ancient-Greece...nted-bottoms-1

Amphorae - The Classical Art Research Centre

http://www.ancient.eu/Amphora/

How Do Amphorae Stack Up? | Nautilus Live

I hadn't considered the notion of "herringbone" stacking in ship holds. Interesting but it still requires packing between layers.

The idea of rolling an amphora along the ground by grasping both handles and twisting is also an intriguing concept.

One source suggests that the pointed-end types were coil-formed rather than being thrown on a wheel. Given the shape, that makes a lot of sense to me.

Thanks to everyone who has commented.