Wednesday, April 17, 2024

Kalishnikov's Constant (Cumberland Saga)

Walter and Amira’s arrival in Copperhead Cove had a galvanizing effect on the crew that was clearing forest to increase pasture and cropped land.

Before Walter and Amira showed up, the issue of housing had a hazy, distant feel to it.

Even Gregor showing up didn’t increase the sense of urgency. Young men were always drifting-in and drifting-out. Sometimes it was because they were healing from accidents. Sometimes it was economic necessity. Sometimes they were recovering from failed relationships. The slice of women who were compatible with the men from Copperhead Cove was a very thin slice. For that matter, the slice of men who were compatible with the women who left Copperhead Cove was also a thin slice.

Based on previous “crisis”, Roger and Sig judged that the population might double from twenty (give or take a few) to forty. Single people could be wedged into many odd corners but families were much harder to place.

After much serious debate that involved contributions from Alice, Ellie and Sarah, the wood-cutting crew decided to erect three simple buildings. They were to be identical in plan and were decidedly NOT compliant with common building codes.

No indoor plumbing. 24'-by-24' footprint and three sleeping spaces. The thought that people might have so many 'things' that they required more than 100 square-feet of indoor space per person was totally alien to most of the residents of Copperhead Cove.


Abe found himself working with Roger as he was “trained” to use a simple jig and a plunge-router to punch holes-and-slots into green lumber.

Lliam had been upgraded to lumber-man assistant and Gregor was temporarily assisting the milling crew until they learned their roles.

Logs that were nominally 8’-3” long were loaded into the portable sawmill and were squared up by shaving off 1-1/8” thick, raw-edge planks. Lliam stacked those off to the side. They would have their edges trued later on.

Depending on the log size and the species, some of the logs were left as 9” square “sills” for ground contact.

The cores of the less durable species were milled into 2-1/4” by 9” rough-cut lumber or 1-1/8” planks of whatever width for headers and for roof-joists.

The Copperhead Cove carpenters decided to use post-and-beam construction with vertically hung planks pegged with dowels for sheathing since they would be working with a dog’s-breakfast of lumber whose only commonality was that it was as green-as-grass.

“Why don’t we just buy plywood?” Abe asked. It seemed stupid to jump through hoops to use every odd-bit of wood.

The fact that Roger was paired with Abe was partly by design and partly a happy-accident. Abe liked to ask questions. Roger liked to explain things.

“Plywood costs money” Roger explained, “that is, if you can get it.”

“You still have the issue of screwing or nailing dry wood to green-wood. Something is going to buckle.”

The pattern of holes and slots Abe was supposed to put in each vertical plank seemed, well, weird.

Regardless of the width of the plank, he was to put in four round-holes and one slot. One slightly smaller hole and a horizontal slot (in the installed position) on the end that was supposed to be the top and two, larger round-holes near the bottom.

“I don’t get it” Abe said. “How does this make any sense?”

Roger’s wry sense of humor exposed itself. “Never worked with wood before, have you?”

“Nope” Abe replied, succinctly.

“Green wood don’t shrink the same in every direction. If you think of the end of a log as being like a bicycle wheel, it shrinks about one-part-in-eight in the direction of the tire and about half that in the direction of the spokes” Roger said.

Abe blinked. “You are making my head hurt.”

Roger held up a plank and pointed to the end. “Look at the grain. Look at the rings. Do you see the tire?” as his finger traced the curvature of the rings.

Since the planks had been shaved off the log while squaring it up, the rings were mostly parallel to the long dimension of the plank’s cross-section.

“Yeah, I guess so” Abe said, without a lot of confidence. 

Board-and-Batten siding is a common feature in "Western" frontier town construction. Presumably for the same reasons Copperhead Cove will use it. Green lumber shrinks, pulls nails and leaves huge gaps between the boards. Battens both secure the boards and cover the gaps.

“So if wood shrinks one-part-in-eight and you have 3” between holes, how much shrinkage do you have to account for?” Roger asked.

Abe’s brain locked up…

“You are making it way too hard” Roger said, gently. One-part-in-eight means one-eighth inch per inch so three inches between the holes means you need to figure out a way to let the wood shrink or you will end up with a very ugly crack in the plank.”

Enlightenment dawned. “ that is why there is the the plank can shrink without cracking.”

“So why are the holes in the bottom both round?” Abe wanted to know.

“Because wood shrinks a little bit along the length of the grain” Roger said. “Not very much. Maybe a quarter-inch for every eight-feet. For now, that is close enough to the same for across-the-plank as along-the-plank to make the holes oversized and round.”

"If you only remember one thing I teach you today, it is Kalishnikov's Constant" Roger said.

"What is that?" Abe asked.

"Clearance is good. More clearance is better" Roger said.

Abe carefully filed that in his memory. He had no idea what Roger meant but maybe it would make sense later.

Lliam had been patiently waiting for Roger to get Abe “started” and had overheard everything that was said. He had a much quicker grasp of the characteristics of wood shrinkage. Heck, any idiot could look at the cracks in rounds of dried fire-wood and instinctively grasp what Roger was telling Abe.

The milling crew was going to rotate through their jobs at morning break, lunch and at afternoon break. One of the adults was going to be running the saw but Lliam and Abe were going to be trading off between plunge-routing and moving cut lumber.

The current plan was to have the team-member who was to haul the cut lumber fetch the water used to lubricate the saw-blade and to have the plunge-router stacking and stickering the finished sheathing planks. The young men didn’t know it, but Gregor and Roger had a small side-bet. Roger was betting that the plunge-router would end up taking-on the water-fetching.


  1. Board on Batten lasts a good while if built where termites infestation maintenance is routinely done (destroying dirt tunnels up the the foundation from soil). Dad built a board on batten wall where his parents kitchen was and its been 60 years and still going strong.

    Good building lessons here, we live mainly in slab on grade foundation on masonry veneer walls down here, not many wood homes unless they are built on concrete piers.

  2. I've seen quite a bit of B&B siding, and always wondered what the optimum gap between vertical boards is; I know it should>/i> vary based on wood species, moisture content, fasteners used, structural members, etc. but I've not been able to find any consistent reference data onit.

  3. Great info. I did some b and b with cypress wood siding back in the 80s. It was just to match existing siding and was dried wood. Worth knowing about the shrink. Helped with a log building once. They had verticals bolted thru the wall to keep the logs straight. I was told not to let them touch the slab. They would warp the wall. Is wood ever really dead? 😉

  4. Interesting insight. I assume the second occasional layer is to cover shrinkage in the primary members.

    I'd have to check their county, but in general rural Tennessee doesn't have code enforcement so building codes don't matter.

  5. About 50 years ago I resided a small barn with B+B and nailed the boards along both edges. I learned the hard way. ---ken

  6. My brain was like Abe's until "more clearance". Kalishna...Ah, got it! I read that you hafta have new information be related to something you already know in order to have it make sense. Or something like that. Never heard of Board-And-Batten before.

  7. Oh yes. Many houses built in the 1800s in Louisiana were board and batten, as they had to build to have a place to live. And that shrinkage DID play into their plans.


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