Wednesday, March 28, 2012

To Make a Single Ox Yoke, Part 1

The Old Yoke

Scout the Ox has outgrown his old yoke. The spacing of the bows has become too narrow on his neck, pinching him, and riding up too high on the withers. The top bridge of the yoke has run out of room for enlarging it again (link here) without weakening it. It is time for a new yoke.
Young Ayrshire Ox Pulling Sled in Woods

The old yoke was satisfactory for light duty work during Scout the Ox's training. It was made of readily available dimensional lumber (a discarded stair rail, and a discarded aspen timber.)It appeared awkward, in spite of the fact that it has functioned reasonably well.

Young Ayrshire Ox Hauling Firewood on Woods Trail

In making the yoke, I broke with my own maxim of learning how to do a thing the established way, before going off on my own to find a better way.

The question then begs to be asked "Why not just follow the pattern of a traditional yoke?"

Let me explain.

My use of an ox is recreational, even though I use him for accomplishing work. Oxen, in our part of the world, greatly lack the efficiency of a small tractor or an automobile. So, unless there were no gas, or there were no money, it would be difficult to justify using an ox here for other than recreational work, recreational transportation, historical preservation, or aesthetics.

Part of my recreation is to design and build my own efficient and comfortable yoke using the skills and supplies available to me, on my very small farm here in the 21st century.

Connecting oxen to a load or an implement is an unnatural en-devour. This presents a nice challenge. In the end I may find I have only reinvented the traditional yoke.

This will not be a How-to series of articles as this yoke is to be only my fourth yoke, for my first ox. This series of articles will simply outline my thoughts, at this point, on my steep learning curve. I also hope to document my successes or failures.

Links to past yokes I've used on Scout the Ox.
Just A Rope
Yoke 2: PVC Pipe
Yoke 3 Part 1  Yoke 3 Part 2
Yoke 4

Coming soon! To Make an Ox Yoke, Part 2: The Plan

Tuesday, March 27, 2012

To Make an Single Ox Yoke, Part 2

The Ox Yoke Plan

I've begun with a little internet study of Ox Anatomy 101

Advanced Agricultural Training 
(photo digitally altered i.e. Ox Anatomy 101)

From an anatomical point of view a head-yoke
appears to have some distinct advantages.

Jacques-Raymond Brascassat - "A Bull Fight" (1855)
detail from original (link)
 If you have ever watched two bulls fight you know they can do a lot of pushing with their heads. The one who pushes the hardest and the longest wins; making for an evolutionary propensity to excel in strength and endurance while pushing.

Teamsters who use head-yokes advocate for their superiority. I wonder about the possibility of broken horns, or injury, in the case of an accident, the discomfort of being restrained to that degree (especially when two oxen are yoked together), and the possibility of a headache for the animal who is pushing long or hard.

I see that competitive ox-pullers in the Northeastern U.S. prefer neck-yokes. I presume this is to take advantage of the strength of the neck for lifting the load. The competitive pull is extremely heavy but of a short distance.
Oxen Withers, Anatomical Shoulder, and Angular Musculature

For my yoke, I will concentrate on taking the power off the ox at the base of the neck and the front of the withers. It seems to be the logical position for pulling moderate loads for sustained periods of time.

Ox walking, stride, 6 ft. (c1881)
digitally altered background

The muscles at the base of the neck, and the withers, are relatively stationary while the ox is walking.

Skeleton of the Ox as Covered by the Muscles
Cattle and
 their Diseases, by Robert Jennings (link)        annotations added by me
These muscles provide a somewhat plastic, shock absorbing cushion over the skeleton.

Withers Yoke (Link)
The withers-yoke, common in many parts of the world, takes advantage of that large natural hump of Bos indicus cattle. The hump, or withers, though much smaller on Bos taurus cattle (like my Ayrshire) will also help to keep my yoke from sliding back while under load.

I will extend the yoke seat down the sides of the neck as far as possible without interfering with the for-and-aft movements of the ox's shoulders while walking. This in theory will help solve the side-to-side instability of the single ox yoke, as well as distribute the pressure of the working yoke over as large an area as possible.

The Muscular Anatomy of the Ox
(private collection, annotations added by me)


In this position the forward thrust of the spine is centered on the yoke seat. The major muscles of the legs transfer their tremendous power to the head via the rigid spine. 

Cow Anatomy Dorsal Skeleton
Das Rind (link)
annotations added by me
The yoke is to be tapered in a half-cone shape to accommodate the neck, and to lodge firmly around the spine while under load.

Ox with Britchen Harness on Single Yoke
Rather than sitting square on the neck, the face of the yoke will sit at an angle to accommodate the angular musculature above the ox's anatomical shoulders.

A "bow" will keep the yoke from being thrown off, and a britchen harness will keep it from sliding down the neck when the ox put's his head down, or when he is holding, or pushing back a load.

Metal eyelets will accommodate the reins and serve to attach the pull chains. There will be three possible positions to allow adjustment of the height of the hitch point. 

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Monday, March 26, 2012

To Make a Single Ox Yoke, Part 3

The Ox Yoke Pattern

While sketching the pattern for the new ox yoke, I have used the old yoke as a guide to size the pattern. Of course I have enlarged it to take into account Scout the Ox's growth.
Pattern-making for ox yoke, front (head) facing side
The cardboard pattern represents the critical measurements. I will streamline the yoke later.

Pattern-making for ox yoke, rear facing side
There will be one pattern for each face of the yoke. The three dimensional aspects of the yoke will be free-handed in during carving.
Single ox yoke pattern

The cardboard spacer between the two patterns was the natural fold of the cardboard box. It will help me visualize the depth of the yoke. (I considered making a 3D model but that would be too time consuming.)
Cutting out ox yoke cardboard pattern.

Cutting out the pattern.
Folding ox yoke cardboard pattern.
Folding the patterns together and making adjustments to get everything symmetrical.
a.) Fitting ox yoke pattern on single ox

Trying it on for size.
b.) Fitting ox yoke pattern on single ox.

Minor adjustments made.

c.) Fitting ox yoke pattern on single ox.

With a good fit we are ready to transfer the patterns onto the front and back of the wood block.

Coming soon --- preparing the wood block for carving.

Sunday, March 25, 2012

To Make a Single Ox Yoke, Part 4

Preparing the Wood for Carving

Yep --- that's my granddaughter! Much credit goes to her dad for finding and delivering the log to me. He is a professional tree trimmer by trade.

What I'm starting with is a North American Ash.(Green or White, I'm not sure which.) It is a short-log that was cut out of the center of a longer log. The longer log had cured for two-years at the time the picture above was taken.

After cutting it into the shorter piece it cured another 6-months. Contrasting the picture above with the one below shows that significant radial cracks have formed on the ends during that period of time.

There is some insect tracking in the wood, but that seems to be contained mostly on one side.  I should be able to get at least one good ox-yoke out of the log.

(The log is not infested with the Emerald Ash Borer. There are native species of insects that also bore in Ash wood. If you are considering using Ash be sure to google the Emerald Ash Borer  for your state or province, and educate yourself. It is an invasive species and can spread in firewood or logs. It has decimated  North American Ash, i.e. White, Green and Black, in some areas, and threatens to do so across the country.)

After trimming about six inches off the top the cracks were removed.

I want a rectangular box shaped block of wood from which to start carving my ox yoke. Having the parallel planes of the rectangular box to work from, will give me clearly defined reference points.

I will cut the log with a chainsaw. My first step is to put on a brand new saw chain to help keep the cuts as straight as possible.

I have nailed a board to the side of the log to act as a visual guide while sawing.

The right-angle (edge) of the board helps me to keep the cut square with the log.

So as not to dull my saw chain on the nails of the pallet, I left the last inch or so of the log uncut, and split it the rest of the way with the iron bar.

Opening up the log gives a better view of the quality of the wood.

The darker wood down the center is the heartwood and is less desirable for carving than the lighter colored sapwood. 

The left end of the log is already squared. (Scout the Ox and Harry the Dog are keeping watch in the background.)

I am squaring the right end, averaging by eye what square is on an irregular log.

I now have two ends at right angles to the large flat side --- or first face.

Using a carpenter's square I have marked out my center-lines and the other three sides of the rectangular end. Two of the corners will be rounded allowing me to get a larger portion of the best wood into the center of the yoke.

Again, measuring and nailing boards as guides for the saw.

The boards have to be parallel up and down and also representative of the plane of the first face.
The chainsaw didn't do perfect work --- so I have to eyeball the average of the plane. I have used a shim to make a correction.

I start the cut on the line I have drawn on the end of the log. 

And use the edge of the two-by-fours as a visual guide, to keep the cutting blade at a right angle all the way through the entire cut from top to bottom.

You can see by the guide-board on the right, how it is square with the heartwood and the newly cut edge on the left, but not square with the edge of the tree (which was wider at the bottom than at the top). My next cut along the edge of the second guide-board will make the face of the block facing the camera into a squared rectangle.

With the four edges of the block at right angles to the first face-cut, it's now fairly simple to align the guide-boards with the lines drawn on the top of the log, and to measure thickness top and bottom, from the first face-cut to the guide-boards, to get the block equally thick on both ends after the next, and last, cut.

After checking everything I nail the guides in place.

You can see I made a small correction again with a shim (wooden wedge)at the top left corner.

The cut is nearly completed.

A first look at the second face of the block.

We now have a block of wood that is nearly the shape of a rectangular box (right cuboid).

Up next --- transferring the cardboard patterns onto the block.
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Saturday, March 24, 2012

To Make a Single Ox Yoke, Part 5

Transferring the Pattern

Using the two cardboard pieces that represent the front and back faces of my yoke, I will trace the patterns onto the wood block.

The trick here is to get the two patterns lined up and matched with each other --- when they are on opposite sides! Extending the ears of the yoke patterns all the way to the bottom edge of the block (top, in the picture)has helped me to do that. 

The lines (I have highlighted in yellow) illustrate the planned cone shape of the yoke-seat. The extended ears of the smaller pattern, on the opposite side, match up with these yellow lines as they cross the narrow, bottom side of the block at converging angles.

The yoke will be the width of my singletree.

Coming soon --- I'll make the rough-cuts in the yoke shaping process.
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