Elevated Bridge B/C

[smartkid222]

As a side note i found the link for hoods woods http://hoodswood.com/
interesting theory nejanimb. it makes sense
Jim Y, thats a lot for me to digest but it looks good too.
fyi i posted this before i read the above post^

[Fireheart347]

With the new season approaching, can anyone give me any good places to by wood based on density?

[smartkid222]

bring a scale with you to a local hobby shop and weigh your wood there.
online sources include:
http://www.specializedbalsa.com/products/index.php
http://www.northeasternscalelumber.com
http://hoodswood.com/

[JimY]

northeasternscalelumber.com does not differentiate materials by density. You just get what you get. The density of bass is about 26 lb/cubic foot and consistent enough that I've never been concerned about it. If you want a lighter piece, you just go smaller. Good luck to all once the rules come out.

[nejanimb]

northeasternscalelumber.com does not differentiate materials by density. You just get what you get. The density of bass is about 26 lb/cubic foot and consistent enough that I've never been concerned about it. If you want a lighter piece, you just go smaller. Good luck to all once the rules come out.

Urgh. That's unfortunate. I suppose we'd have to try it out - maybe we will. Thanks for the advice.

To Fireheart, without a doubt if you want to buy on density then SpecializedBalsa.com is your place - they're great for that. Out of curiosity, what school are you at in PA?

[Fireheart347]

Thanks for the sites. I am the the Southeastern PA area.

[soobsession]

okay, so because of my coaches, im working on unelevated bridges...we tested one of them it tore at the joints. i think im going to use gussets next time and i heard basswood is less likely to tear. any other suggestions? thanks in advance.

[andrewwski]

What kind of joints? Lap joints or end (butt) joints?

End joints are not very strong on their own. If you add gussets, they become much stronger. Lap joints are generally strong enough on their own.

Basswood won't tear as easily as it's a denser wood and has much denser grains. However, the joint may still fail - no joint is ever failproof. The wood may still tear, or the glue may tear from the wood, etc.

How did the joint fail? Did it shear, or rip apart?

[nejanimb]

Thanks for the sites. I am the the Southeastern PA area.

Aha, me too. C div? What school? I guess I'll see you at regionals either way.

Soobsession, definitely don't use straight butt joints, and gussets can help a lot. Though, I still think it's insane that you're not doing elevated bridges...

[soobsession]

What kind of joints? Lap joints or end (butt) joints?

End joints are not very strong on their own. If you add gussets, they become much stronger. Lap joints are generally strong enough on their own.

Basswood won't tear as easily as it's a denser wood and has much denser grains. However, the joint may still fail - no joint is ever failproof. The wood may still tear, or the glue may tear from the wood, etc.

How did the joint fail? Did it shear, or rip apart?

i used lap joints...is an end joint with gussets any stronger?

umm...whats the difference between shearing and ripping???

i wasnt exactly there when my partner tested it (i know...fail). but this is how it was described

"the glue stayed on the main part of the bridge but the top connectors (the connectors are the pieces near the load block) when they came off
there was no glue on them"

Soobsession, definitely don't use straight butt joints, and gussets can help a lot. Though, I still think it's insane that you're not doing elevated bridges...

blame my coaches. the alternative is not being on the team at all.