What is wrong with my tower?

[sr243]

This is my tower design, it weighs 8.7 g but it failed because it was slanted slightly, and the sand was on that side. Also, the glue was kinda old and was not holding up. I was wondering how much would the design hold if there was no construction flaw?
http://img153.imageshack.us/i/0312110102.jpg/

[eta150]

First of all, the reasons for failure were the ones you just describe. Slanting and old glue. Contrary to popular belief, though, the sand's position in the bucket does not matter, as it will always be the center of gravity and pull straight down on the tower. If you can fix the slanting, you should be able to hold most of the load with that design. It would be a lot easier to know what the problem is, though, if you told us how much the tower held.

[Littleboy]

Also, can you put a picture in the image gallery?

[sr243]

It held 3.6 kg, the slanted part broke. I know it can easily hold 10kg because that was a design I used a couple years ago. I tried to post a picture in the image gallery but it hasn't been posted yet. I know that the position of the sand doesn't affect the bucket, but I was wondering if swaying the bucket to one side will.

[hogger]

If you think that the slanting is the problem, you probably want to build it without slant next time. Same goes for the glue. I can't tell much from the picture exactly what is wrong, but you may want to build it such that the top portion is slanting inward towards the middle a little bit on all 4 posts. That should help with stability.

[sr243]

I think I am going to try a rectangular base to prevent slanting. It should use about the same amount of wood, but any precautions before I do?

[eta150]

I think I am going to try a rectangular base to prevent slanting. It should use about the same amount of wood, but any precautions before I do?

A square base is much more resistant to tipping over, and with a jig, it can be just as easy to align.

[sr243]

Just wondering how is a square base more resistant to tipping over? I don't have a jig or materials/time to make one. For squares, I have trouble making it all even and perfect sides because the sides tilt inwards.

[hogger]

Just wondering how is a square base more resistant to tipping over? I don't have a jig or materials/time to make one. For squares, I have trouble making it all even and perfect sides because the sides tilt inwards.

Square base has larger area at the base and symmetrical on the two perpendicular direction, while rectangular base is wide on one dimension and much thinner on the other dimension at the base. The thin side is more susceptible to tipping because any slight slanting or leaning error on the thin direction is greater in proportion to the displacement of the base than it would have been if the base was not that thin. Imagine if you were standing straight with feet closed together and got pushed from the side versus you crouch down a little bit with feet apart to the side, which arrangement is harder to be pushed over? To combat that, you try not to build straight up on the thin side, you need to spread the base apart a little bit and lean the 2 sides in such a way that the tower gets slightly smaller and smaller towards the top. Also try to be as symmetrical as you can which means a jig in the middle to clearly align the two sides is probably a good idea.

This video should help with jig for square base:
http://www.youtube.com/watch?v=KOpP7cLvcdk

[sr243]

thanks for clearing things up, I think i know what to do now. I am going to still try a rectangular base but if it isn't as good, I will return to the standard square base.

[iYOA]

You should add those horizontal trusses at base as well. Just like at the top. To save more weight, you can just use Z bracing for the whole tower instead of Xs. It is actually a bit more efficient in my opinion. So for example, with 9-10 z trusses on the base, you would probably use up the same amt of wood. and same for the top

[sr243]

I might try Z bracing for the top, but for the bottom, it is fine. I tested just the base for this design and it held the full 33 pounds for a while. The main problem is the connection and top.