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Best nail design?


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Is a Round shank or Square shank nail better or worse? And why?

I read an article the other day on Vikings and how the archaeologists decided that they had visited our (USA) coast, was that they found round shank nails and they said American Colonials used square shanks.

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All else being equal, length, diameter, surface finish... square shank nails hold better because the flat side surfaces of the shank grip the wood fibers better than the rounded surfaces of round shank nails. Quality large size boat building nails are square shank.
Joe B

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The square nail has more surface area, providing friction for resistance against removal. Additonaly, the square nail cannot loosen by rotation, perhaps, what Stewart is refering to?

Also, I can't imagine the Vikings using round instead of square, if square were better. They must have had a reason to make them round.

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My understanding is that square shanked nails were at one time the hand made standard, now they are mostly punched from plate. round shank nails since they take more work to make by hand, were a luxury item. Now round shank nails are easiest to make from heavy guage of wire. just cut to length and then cold forge a nail head.

I believe all that has been said is true. square shanked nails have more surface area therefore hold better in wood than round nails do. round nails are cheaper there for less of a luxury items now compared to years past.

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While I agree that square nails grip the wood better... I note that all nails of those eras were handmade and an individual craftsman could upset conclusions based solely on such simplistic evidence. The Vikings used iron nails to build their ships and in such applications the nails were usually clenched (their style of planking is called clinker-built). Clenched nails hold is so tenacious that any shank style would be quite adequate. Another bit to think about is that recently built replicas of Viking ships that have actually sailed the seas have astonished the skilled seamen who sailed them by their amazing flexibility as they rode the waves. It is quite possible that a round nail in such an application might outlast a square one by causing less wear on the holes through the planking where they were seated. In effect the clenched nails perform more like rivets than as ordinary nails.

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While I agree that square nails grip the wood better... I note that all nails of those eras were handmade and an individual craftsman could upset conclusions based solely on such simplistic evidence. The Vikings used iron nails to build their ships and in such applications the nails were usually clenched (their style of planking is called clinker-built). Clenched nails hold is so tenacious that any shank style would be quite adequate. Another bit to think about is that recently built replicas of Viking ships that have actually sailed the seas have astonished the skilled seamen who sailed them by their amazing flexibility as they rode the waves. It is quite possible that a round nail in such an application might outlast a square one by causing less wear on the holes through the planking where they were seated. In effect the clenched nails perform more like rivets than as ordinary nails.


Just a question to clarify for a thicko like me, were they clenched, or were they roved? (Like clenchd but through a washer type fitting)
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While I agree that square nails grip the wood better... I note that all nails of those eras were handmade and an individual craftsman could upset conclusions based solely on such simplistic evidence. The Vikings used iron nails to build their ships and in such applications the nails were usually clenched (their style of planking is called clinker-built). Clenched nails hold is so tenacious that any shank style would be quite adequate. Another bit to think about is that recently built replicas of Viking ships that have actually sailed the seas have astonished the skilled seamen who sailed them by their amazing flexibility as they rode the waves. It is quite possible that a round nail in such an application might outlast a square one by causing less wear on the holes through the planking where they were seated. In effect the clenched nails perform more like rivets than as ordinary nails.


Excellent thinking. Something like that crossed my mind but was very fleeting.
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the shape of a square nail, because it has flat sides, adds to the torque one needs to remove the nail, it is a matter of geometry and physics, as well as surface area...........an equivalent area ROUND would take less torque to remove the nail, because of the shape!


Sorry, Stewart, having a hard time following you here. To me, tourque always relates to rotational force. Is there a definition I am unfamiliar with?
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From Lee Valley Tools Website: http://www.leevalley...t=3,41306,41324


Square-Cut Nails
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Besides having the advantage of being historically accurate (they are made the same way now as they were in 1819), these nails are superior to conventional nails. Cut nails have two features lacking in wire nails:

1. They are near constant thickness but tapered in width. Aligning the parallel sides of the nail with the grain, the square tip shears fibers and the nail then bends fibers downwards as well as compressing them as it is driven. The fibers then act like a featherboard on a table saw, preventing the nail from withdrawing.

2. Because the square tip shears the fibers, there is no wedging action across the grain; you can nail near the end of a board with no splitting. A wire nail tends to split the wood.

The decorative wrought head and common rose head are ideal for rough-sawn siding, face-nailed floors, batten doors, and framing. While both brads are popular for cabinetmaking, the slender headless brad excels at furniture repair and picture frames.

Approximate nail count per box listed in brackets below.

The wrought-head nails have a black oxide finish; the others are unfinished steel.

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Well thanks for all the feedback, that is probably one of the most informative answers (collectively) that I have ever gotten.. Now I need to make a header for square nails as well!

Also I didn't know that the Viking boats were nailed and clinched, just that they were nailed.

Well I learn something new every day!

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I can add some practical insight to the differences between square and round nails. I was a timberframer for 15 years and in addition to our main business of making traditional timberframes we also would do renovations and restorations on historic barns and farmhouses, usually 2 or 3 each year. As a result I've sunk and pulled tens of thousands of each kind of nail.

Cut or forged nails do indeed pull harder than a comparable round nail, but ONLY for the first 1/16" of movement. Then you rapidly get into the area where the taper of the nail is smaller than the taper of the hole and they will pop right out.

Round nails pull easier, but they require almost constant pressure on your tool for the length of the nail.

Complications and Caveats: Wrought iron nails tend to break more as the material seems to be weaker. They also tend to break somewhere along the shank of the nail, whereas a wire nail will often have the head pop off. Also, once rust enters the picture all bets are off. We all know that WI seems to have better corrosion resistance than steel, and if a round nail gets wet for 10 years it will be every bit as hard to pull as a square nail that's been there for 100.

THE BIG TRICK to pulling square nails is to drive them FURTHER into the wood with one good hard blow before digging in with your cat's paw or pry bar, thus enlarging the hole a little and breaking loose any rust around the nail. This tip has saved me untold aggravation over the years and I highly recommend it.

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