12-23-2009, 10:16 PM
With my inquisitive nature, and with the longevity of my train building and layout at stake, I thought up several tests on the screws versus nails issue. I performed one of them tonight which, to my halfway scientific mind, tested the shear strength of the wood/fastener combination, since that is what is important. The experiment with the screw driven only halfway in and then broken off with a hammer is just not representative of the forces we are looking at.
So here is the experiment (moderators, if I am straying to far off the topic of trains, just let me know):
I attached an 8 foot long 2x4 to my 4x6 post, first with nails, then with screws. The 4x6 post is solidly attached at top and bottom, so it doesn't move. Once the 2x4 was attached, I put 5 - five pound boxes of screws in a bucket, then placed the bucket on the 2x4 near the post and slowly moved it away.
Here are the nails and the screws. The screws are 3" gray coated screws. The nails are about 3/4" longer and bigger in diameter.
Here is the setup. The 2x4 is suspended in the air, held up by only the nails or screws at the post. The nails/screws were placed horizontally along the length of the 2x4 and were spaced 3 inches apart.
Then I took the bucket with 25 pounds in it, and slowly slid it down the 2x4 away from the post. With the nails and the screws, the 2x4 began deflecting at around 18", and the deflection increased as I moved the bucket away from the fulcrum point. Now, with the nails, at 5 feet from the fulcrum, the bucket touched the ground as shown in the photo:
At 5 feet, the screws were still holding the weight up. Not as much deflection as the nails. The photo shows the bucket above the ground - this is at the same distance as where the nails let the bucket touch. I then moved the bucket even further down. The bucket didn't touch the ground until I got to 6.5 feet.
Between testing the nails and screws, I had to remove the board from the post. With the nails, a little tug and they pulled right out of the post. But with the screws, they actually pulled through the 2x4, heads and all, and stayed in the post. They were bent, so I couldn't remove them with the screwgun, so I whacked them with the hammer and they broke off.
I repeated the experiment just to make sure, and had the same result again. And, what if I had used screws that were equivalent in diameter to the nails? Maybe I'll try some more of the experiments I thought of. Also, anyone want me to try anything in particular?
Thoughts anyone?
So here is the experiment (moderators, if I am straying to far off the topic of trains, just let me know):
I attached an 8 foot long 2x4 to my 4x6 post, first with nails, then with screws. The 4x6 post is solidly attached at top and bottom, so it doesn't move. Once the 2x4 was attached, I put 5 - five pound boxes of screws in a bucket, then placed the bucket on the 2x4 near the post and slowly moved it away.
Here are the nails and the screws. The screws are 3" gray coated screws. The nails are about 3/4" longer and bigger in diameter.
Here is the setup. The 2x4 is suspended in the air, held up by only the nails or screws at the post. The nails/screws were placed horizontally along the length of the 2x4 and were spaced 3 inches apart.
Then I took the bucket with 25 pounds in it, and slowly slid it down the 2x4 away from the post. With the nails and the screws, the 2x4 began deflecting at around 18", and the deflection increased as I moved the bucket away from the fulcrum point. Now, with the nails, at 5 feet from the fulcrum, the bucket touched the ground as shown in the photo:
At 5 feet, the screws were still holding the weight up. Not as much deflection as the nails. The photo shows the bucket above the ground - this is at the same distance as where the nails let the bucket touch. I then moved the bucket even further down. The bucket didn't touch the ground until I got to 6.5 feet.
Between testing the nails and screws, I had to remove the board from the post. With the nails, a little tug and they pulled right out of the post. But with the screws, they actually pulled through the 2x4, heads and all, and stayed in the post. They were bent, so I couldn't remove them with the screwgun, so I whacked them with the hammer and they broke off.
I repeated the experiment just to make sure, and had the same result again. And, what if I had used screws that were equivalent in diameter to the nails? Maybe I'll try some more of the experiments I thought of. Also, anyone want me to try anything in particular?
Thoughts anyone?
Three Foot Rule In Effect At All Times