I’ve just posted a short video on the machine and hand processes that go into making a pair of Crucible dividers. You can check it out here if you like.
— Christopher Schwarz
Day: October 13, 2016
Clinching Nails
This is an excerpt from “The Joiner and Cabinet Maker” by Anon, Christopher Schwarz and Joel Moskowitz.
Clinching (sometimes spelled “clenching”) is when you drive a nail that passes through both thicknesses of wood you are fastening. The tip of this nail sticks out about 1/4″ and is bent over and driven into the wood.
Clinching adds remarkable strength to a joint. A 1948 study by the U.S. Forest Products Laboratory concluded that clinching can increase the holding power of a nail between 45 percent and 464 percent – depending on a variety of factors, including the species of wood and its moisture content.
Also interesting: The study concluded that bending the tip across the grain increased the holding power by 20 percent compared to a nail clinched along the grain.
But how do you best clinch a nail? There are several methods.
Four Ways and a Trick
Here’s how automated clinching machines do it: They fire a nail in at an angle, and there’s a steel plate waiting for the nail’s tip when it emerges. When the nail hits the steel it bends over into the wood – essentially it ricochets like a bullet or pool ball.
I’ve never tried this with a pneumatic nail gun, but it sounds like fun on a Friday afternoon.
For the hand clinchers, there are at least two common techniques. The first one is to first drive the nail through the work. Rest a steel plate, anvil or a second heavy hammerhead on the nail’s head. Then tap the tip of the nail with your hammer. It will curl over. Then you can drive the drooping tip back into the wood.
The second technique is similar to the machine process. You drive the nail through the work and against a waiting “bucking iron,” which curls the tip and forces it back into the wood.
I have a steel plate behind the head of this nail as I clinch it. Here is the nail tip right before the first strike.
The head begins to bend after the first strike.
After two strikes the nail’s tip is at a 90° angle to where it was originally.
Three strikes and you’re down. (Note: Thomas does this in the book with one less strike. Precocious boy.)
One final strike drives the tip back into the wood. This is as dead as a doornail.
There’s one more technique I’ll sometimes use when I’m being really, ahem, retentive. I’ll drive the nail through. Then I’ll use needlenose pliers to bend the tip to the angle I want. Then I’ll drive it into the work. This results in a tidy appearance. I admit it’s a bit much.
When I have a lot of clinching to do, I’ve found that a cast iron table saw wing can be your best friend when clinching at work – doors, lids and the like. Lay the cast wing on your bench and you have a nice big area to support your work as you merrily clinch away. And no, the clinching does not really mar, crack or otherwise defile the cast iron wing.
— Meghan Bates
The Palm, the Ban Qi and “The Young Mechanic”
Several commenters to yesterday’s post about the origin of the Chinese planning stop, known as the palm, offered some additional information and a Western version.
In the wheelwright’s shop shown in the 12th-century scroll “Qingming shanhe tu” we see a palm at the end of the bench. It is made of two pieces of wood nailed to the bench.
The palm was later known as the Lu Ban qi, or Lu Ban’s wife, because the palm was the brilliant idea of Lu Ban’s wife. (Not to mention she no longer had to act as the planing stop or sustain injury when Lu Ban got a little crazy with the planing). Ban Qi is still used as a term for a planing stop. A modern version of the V-shaped palm is below and is adjustable.
A Western planning stop with similarities to the palm comes from “The Young Mechanic” by James Lukin published in 1872:
Another version using two pieces of wood and wedges to secure the work piece:
My thanks to our readers for joining the discussion and offering more ideas!
-Suzanne Ellison