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There have been many times I scratched my head, wondering "what is a ten penny nail?" I was further confused by vague references to a ‘d’ when I tried to consult charts in the hope of obtaining an explanation. In the end I decided to do some research, and after much reading, I have come up with the answer to the question. So, in the spirit of this web site, I though I would share it with you.
What follows is not the final word on the subject but the best answer I can find after going through a multitude of sources. There are other explanations, but if you apply them to the full range of nails available, they don’t fully explain the facts.
In England of the 1400’s, you would have to pay your local blacksmith 6 pennies to make you 100 two inch nails. This was shortened to 6 penny or 6d, which was quicker and faster to use. Through the centuries, this system of using price as way to reference a nail of a certain length stuck, leaving us with this unique and highly confusing system of classification.
The symbol ‘d’ was used to further abbreviate the word penny – probably a necessity considering your average carpenter or joiner at the time had little if any formal education. The ‘d’ is short for denarius, the name of and old Roman coin that bore a striking resemblance to the English penny.
The hand wrought nails of the 1400’s gave way to the cut nails of the 1700’s and finally, the wire nails we know today. Even though inflation caused the price used for classifying nails to become outdated by the year 1500, we are still confounded by this blasted system to this very day.
Today, nails are available in an astounding variety of types: common, finishing, tacks, Norm Abram’s favorite – brads, escutcheon pins, box, spikes, roofing, paneling, siding, and so on ad nauseum. Because you are reading this article, located on a woodworking web site, I have to assume you are interested in the nails used for furniture, cabinets, and other, finer forms of woodcraft. For that reason, we will stick to the discussion of finishing nails. Fine woodworkers do use brads but suffice it to say that they are finer and shorter than finishing nails, being usually 18 gauge in thickness and under 1 ¼ inches in length.
Finishing nails are available in a much wider range of lengths, and to understand them better, I offer the following chart to assist you.
|
Penny Size |
Length |
Shank Gauge |
Head Gauge |
Approximate Number per Pound |
|
2d |
1" |
16 ½ |
13 ½ |
1350 |
|
3d |
1 ¼" |
15 ½ |
12 ½ |
850 |
|
4d |
1 ½" |
15 |
12 |
575 |
|
5d |
1 ¾" |
15 |
12 |
500 |
|
6d |
2" |
13 |
10 |
300 |
|
8d |
2 ½" |
12 ½ |
9 ½ |
192 |
|
10d |
3" |
11 ½ |
8 ½ |
122 |
|
16d |
3 ½" |
11 |
8 |
90 |
|
20d |
4" |
10 |
7 |
60 |
If you aren’t familiar with the wire gauge system, here is a table showing that information.
|
Gauge |
Inches |
|
18 |
0.0475 |
|
16 ½ |
0.058 |
|
15 ½ |
0.067 |
|
15 |
0.0720 |
|
13 ½ |
0.086 |
|
13 |
0.0915 |
|
12 ½ |
0.099 |
|
12 |
0.1055 |
|
11 ½ |
0.113 |
|
11 |
0.1205 |
|
10 |
0.1350 |
|
9 ½ |
0.142 |
|
8 ½ |
0.155 |
|
8 |
0.1620 |
|
7 |
0.1770 |
I have run across little calculations that are supposed to simplify things and help you figure out the size of a nail in pennies, but mainly they are just bunk. For example, Bob Vila’s web site says to subtract a half inch from the length of the nail then multiply by four to give you the penny value. This works great for an 8d nail but a 60d nail would have to be 15 ½ inches long to fit the equation. In reality a 60d nail is only 6 inches long. Steer clear of little formulas. The tend to be fine for mid range nails but they don’t usually fit nails of every length.
So, now that you know an 8d nail is 2 ½ inches long, when is it proper to use a nail of that length? After looking at piles of nailing charts a vague 1:2 ratio of nailed board to substrate thickness seems to materialize. In other words, if you are nailing a board an inch in thickness to a substrate, the nail should penetrate that substrate by two inches. Therefore, you would require a three inch nail. This is a very rough generalization of course, but if you were to follow it, a ¾ inch thick cherry face frame should be nailed to a cabinet with a 2 ¼ inch nail (which penetrates the cabinet wall 1 ½ inches). To my knowledge there is no such thing as a 7d nail so it would be necessary to choose between an 8d and a 6d nail. A crude convention as, in this situation, I think an 8d nail would be too long for the application (and too easy to drive through the side wall). There is, however, a much easier rule to remember.
Somewhere, I don’t recall the source unfortunately, I ran across an old rule of thumb for deciding on how long a nail to use. I use it all the time with great results. Simply, you use as many pennies as there are 1/8ths of an inch in thickness of the wood to be nailed. Let’s go back to our example of the cherry face frame being nailed to the cabinet front. Since the face frame is ¾ of an inch thick, and there are 6 eighth inch increments in ¾ of an inch, you use a 6d nail to fasten it to the carcass. Simple.
So, now you have a chart that shows you what a 6d nail is, and you know when to use that nail. There really is no mystery to it all and it makes perfect sense (to a fifteenth century blacksmith). Perhaps your new found knowledge will save you some frustration – and save your spouse from a severe bout of sailor talk (as my wife calls it). Good luck, be safe, and happy woodworking.
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