Elevated Bridge B/C

[Hola]

What sort of scores do people tend to get in Division C?
In the state competitions?
What have you gotten? What place did that give you in Regional/State?

[Bjsong]

Can you guys post what was the 1st place efficiency at your state for elevated bridge so that I could get an idea of what competition at national will be like.

[hbk.showstopper]

Is it your first time going to nationals?

[quickestwinne]

http://picasaweb.google.com/smartkid222 ... 0022392354

In this picture there are 4 pieces of wood 1/8 x 1/16. Notice how the top 2 and the bottom one look fairly the same, but the 3rd one from the top is ligher in color. Is this b/c of grain or density? I dont' know much about grain which is why i'm asking this. Also can someone tell me what grain are these pieces? How can you tell?

Difference in color seems to be one of those natural variations in balsa. Not sure what drives it, I suspect trace mineral content, but only suspect. Lighter color is typically, but not always less dense. Some sources of balsa seem to be naturally whiter while others are more tan. Also some sources seem to have a very fine grain like that third piece while others have a much coarser sturcture with prominent growth rings like the second and fourth pieces. Personally if I can find it, I find the fine grain stuff like that third piece tends to be better suited for my projects. More even properties across a sheet. The wood with distinct dark growth rings tends to vary more across a sheet.

Grain (as in A, B, or C) doesn't really seem to change color to my eyes, changes the look of the wood. A grain just looks like normal wood with growth rings. C grain looks all flecky and sparkly. Does that third piece change to match the other three if you flip it 90 degrees? If so, the effect is from looking at the A or C side. If not, just from different trees or different parts of the same tree.

As to which grain those pieces are, hard for ME to tell with pieces that small. If I HAD to guess, the second and fourth look more like A grain to me, while the first and third look kinda (but only kinda) like C grain. Though for the first one, I can't tell if the fleck I identify with C grain is grain or a cutting artifact. While the third may just be a very fine grain A.

PS, this is one reason why I buy only sheets. Easy to tell A from C grain then and I just orient the sticks cut from the sheet to have the grain the way I want.

PPS, everyone does realize a square stick has either two A and two C grain faces or all four B grain faces. A or C are just perpendicular or tangential to the growth rings. B is just in between.

Jeff Anderson
Livonia, MI

I believe the third is light because its from a different part of the tree.

Our scores from Kansas were around 2000 for both divisions. maybe a little higher.

Expect scores around 2500 for tops at nationals.

[gandhiji]

Can you guys post what was the 1st place efficiency at your state for elevated bridge so that I could get an idea of what competition at national will be like.

first place in division b of delaware was 1530

[frontlineballer1]

Division C in delaware was 1740

[hbk.showstopper]

what was the weight of the bridge???

[wyu1229]

does anyone know the tensile strength of basswood, with the stress applied parallel to the grain?

[sewforlife]

Can you guys post what was the 1st place efficiency at your state for elevated bridge so that I could get an idea of what competition at national will be like.

770. not that great

[sewforlife]

oops i forgot to mention in division b