please do the Math

[King of Obsolete]

in june the helicopter set these bundle of drill rods on the home made shipping crates. i figured the helicopter was smooth enough to set about 3000lbs per bundle which is what the helicopter can lift. now 5 months later the 4 screws pre board joiner are still holding which is amazing, lol.

i would have not thought this would have not collapsed by now.

thansk
KoO
Published Author

[LW Hiway]

There are times that weight and age don't add up.

[Gadgeteer]

Some math, relating to the holding power of screws, etc., can be found here.

[LKeithR]

If I'm seeing it right all the load on the screws will be in direct shear. If there's no vibration or movement to work things loose it's surprising how much they'll hold. The fact that those legs are on an angle will make a difference as well since it increases the amount of friction between the two pieces of wood. The vector of the downward force is at 90 degrees to the horizontal so for every degree of slope on the leg some of the force is directed down through the wood thereby reducing the shear force on the screws.

To demonstrate that this is in fact what's happening consider this example. Imagine a car sitting on a platform that is perfectly level. At the rear of the platform (behind the car) is a pivot point. In front of the car is an anchor point and between it and the car we have a chain with a strain gauge attached.

It stands to reason that if the platform is level then it is supporting the entire weight of the vehicle and the strain gauge is reading zero. It also stands to reason that if we tilt the platform through 90 degrees so it is dead vertical the strain gauge will read 100% of the weight of the car and the platform will be supporting nothing. If you take successive readings of the strain gauge as the platform is being tilted you'll see that the load on the gauge increases in proportion to the angle. The steeper the angle the more load on the gauge.

You had to ask, didn't you?

[theweldor]

Always a chance also that there is some kind of adhesive used on that joint.

[Gadgeteer]

Great example, Keith... easy to understand. Also, it's a good thing that drill rod is hollow.

[milomilo]

What's the plan for the drill stem?

[King of Obsolete]

once the ground freezes up we will start the drill program again. any damaged drill rods i get for future projects, lol.

also to think that these wood screw when left in the wood and you want the pointie end gone, just hammer them down and they break off. they don't bend but shear off so very high tensile strength ,,i guess?? lol

thansk
KoO
Published Author

[digger doug]

Originally Posted by milomilo

What's the plan for the drill stem?

Lay it on the ground spelling out in very large letters
"King Of Obsolete"

So it shows up on the next pass of the Google satellite.....

[King of Obsolete]

Originally Posted by digger doug

Lay it on the ground spelling out in very large letters
"King Of Obsolete"

So it shows up on the next pass of the Google satellite.....

better yet, once the lawyers are done then a few ariplanes will arrive in the Kingdom so when google earth flys over, the picture will be easy to spot.

thansk
KoO
Published Author