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Forum Link Code:	[gal2]1881\|52/25.1.JPG[/gal2]
Description:	Mass: 9.86g, Load: 12.125kg, Efficiency: 1232 This was my Regionals bridge. Mass distribution: pieces connecting compression and legs .4g apiece, a lamination of two 1/8" by 3/16" pieces; compression members totaled 2g (1/8" square pieces); all the 1/8 by 1/16" fan pieces totaled 1.5g ; tension 1/8" square totaling 1.5g, horizontal: 1g/stick low density 1/8" square; legs weighed .2g, .22g, .21g, .21g at 1/8" square size; the laminate on legs were 1/8" by 1/16" .6g per stick density; lateral bracing was cut from .55g per 36" stick 1/8" by 1/16"; underneath pieces are low density 1/4" by 1/16". For most of this bridge, I used 5-15sec CA glue on lap joints and 1-3sec CA glue on butt joints.
Username:	Aia
Date:	14.08.2009 19:02
Hits:	294
Downloads:	10
Rating:	0.00 (0 Vote(s))
File size:	316.0 KB
Added by:	Aia

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Byline:	Picasa 3.0

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gatorboy
Guest

whats it made of?

19.10.2009 18:08

Aia_
Guest

Both bridges 10 and 25 are constructed entirely from balsa wood.

22.10.2009 17:29

permutations
Guest

are lap joints or butt joints better?

and why did you use a lot of laminated wood, is it better than just using a thicker piece of wood?

nice work!

thanks in advance :)

23.10.2009 16:02

Aia_
Guest

By and large, lap joints are more effective than butt joints due to their better surface area for connection. However, there are some instances where butt joints are better- for example, in this particular bridge, the four "corners" of the bridge where compression, tension, and legs all met are double butt joints. I wanted the load from the compression to transfer directly down from the compression to the legs. If I had made a lap joint connecting the compression and tension members at that point, then I would only be testing the strength of the glue joint because the load would no longer be able to transfer straight down.

Lamination versus thicker pieces of wood- I think you might also want to consider denser pieces of wood in this debate as well. I think deciding which of these three options is the best depends on the location/function of the piece. Again, for example, look on my bridge above where a piece has been labeled with team name. That piece is laminated- two 3/16 by 1/8 low density pieces together. From experimentation, I found that that particular lamination was better than a smaller piece or single piece of the same weight in that location. So, while I can't tell you which of the three options is most effective in all cases, I can say that you can find what does work best by experimenting and testing more structures.

Hope that helps.

31.10.2009 10:19

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