Clinching Nails

clinching-nails-1

When your nails are driven home, you’ll have a small forest of nail tips awaiting you on the inside of your bottom assembly. You’ll be turning these over and back into the bottom boards using the power of clinching.

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.

clinching-nails-7

If you don’t have clinching confidence, try bending the tip a bit with needlenose pliers – then drive the nail home.

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

This entry was posted in Uncategorized. Bookmark the permalink.

7 Responses to Clinching Nails

  1. Meghan, there is another method:- drive the nails 1/2 way through then hammer the nails flat against the wood in the direction you want the clinching. Then drive the nails fully through the wood. You will now have a forest of upside down ‘L’ s now it’s a simple matter of hammering the nails over into the wood.

    • I’m aware of most of these (if one must) methods to achieve a clinch within a nailed piece of such work to be performed…

      However (??) I was always taught (and of the view) that proper…Clinch Work…can never be properly performed without a…Clinching Iron. I have even seen a number of Farriers employ such tools in their Craft…I boat building it is commonplace I do believe as well?

  2. Question for Chris: I’m interested in purchasing a user plow plane. What recommendation(s) for vintage or new, wood or metal, would you recommend? Rick

    Sent from my iPad

  3. Are there any special qualities to look for in nails for clinching, or is it simply a case of making sure they’re long enough for the job?

  4. boundboardbag says:

    If you don’t want to buy a clenching iron, and the good ones which are non-marking bronze aren’t cheap. (not sure the difference in spelling of clench vs. clinch) Auto body dollies work well. And you can buy them cheap. Any old piece of iron could work as well as long as it’s smooth.

  5. A little varnish will keep the blue stain at bay if working oak, yet a little more than a $100 for a bronze one isn’t a bad bargain either. So $40 for iron or $100 for bronze is still worthy of consideration perhaps?

    I see (perhaps?) that in some applications a Bucking Iron (the other name) may not be as functional…??…such as in a large door perhaps. This does indeed seem to be more a nautical tool than for standard carpentry that employs clinching nails? I just remember the task of holding the iron and now find myself curious to more history on this subject from a purely carpentry based method of joinery.

    What are the different systems? Was clinching irons only for boat building. Is there forms for general furniture making?

    Thanks again for another interesting topic!

Comments are closed.