Balsa or Bass

Locked
tying15
Member
Member
Posts: 29
Joined: September 29th, 2009, 5:10 am
Division: B
State: KS
Has thanked: 0
Been thanked: 0

Balsa or Bass

Post by tying15 »

Should me and my partner use balsa or bass? We're thinking of bass but we would still like some advice.
I got 2nd place in WIDI Kansas state competition in 2010-2011!
robotman
Admin Emeritus
Admin Emeritus
Posts: 1447
Joined: June 29th, 2008, 7:37 pm
Division: Grad
State: TX
Has thanked: 0
Been thanked: 3 times
Contact:

Re: Balsa or Bass

Post by robotman »

I have never really seen too much of a differance just in general building properties
But i do think balsa is lighter
Edit the Wiki.
Upload to the Image Gallery
[medals]Get Medals[/medals]
[chat][/chat]
User avatar
blue cobra
Exalted Member
Exalted Member
Posts: 417
Joined: April 9th, 2009, 6:10 pm
Division: Grad
State: NY
Has thanked: 0
Been thanked: 0

Re: Balsa or Bass

Post by blue cobra »

I prefer bass. Amazing structures have been built out of both. It's not the wood, it's how you use it.
In full color since 2006
dragonfly
Member
Member
Posts: 75
Joined: May 3rd, 2009, 6:18 pm
Division: Grad
State: PA
Has thanked: 0
Been thanked: 0

Re: Balsa or Bass

Post by dragonfly »

If you want really detailed information on the comparison of the two refer to last year's (or the previous year's) forums on Elevated Bridges!

I'm a big fan of balsa, but many find using bass or combining the two works well too! Test it out, and see what you like and works best.
``````( ) ( ) /
------------
``````( ) ( ) \

PA 2009, 1st Bridges : 2010, 1st Bridges, 1st WM : 2011, 1st ED, 3rd Towers, 4th Heli
Nats Augusta 2009, 4th Bridges : Illinois 2010, 3rd Bridges, 9th ED : Wisconsin 2011, 3rd Heli, 5th Towers : Orlando 2012, 2nd ED, 5th Towers
Event Supervisor Balsa, ED
User avatar
Littleboy
Member
Member
Posts: 373
Joined: March 14th, 2010, 4:53 pm
Division: C
State: MI
Has thanked: 0
Been thanked: 0

Re: Balsa or Bass

Post by Littleboy »

Balsa has the higher efficeny but a well built bass bridge beats can beat a descent balsa bridge. I may be a toss up.
User avatar
lllazar
Member
Member
Posts: 839
Joined: November 19th, 2009, 7:20 pm
Division: C
State: IL
Has thanked: 0
Been thanked: 0

Re: Balsa or Bass

Post by lllazar »

As Blue Cobra said, its not the wood, its how u use it - it depends on ur design and remember, you should always experiment - this event isnt just about figuring out the "best" design (and there never is a best), because in order to find the best design, you must consider all the parts (wood, glue, design, build techniques, etc).
2011 Season Events~

Fossils (Regionals ~1st) (State ~6th)
Towers (Regionals ~1st) (State ~3rd)
Helicopter (Regionals -3rd gahhh) (State ~5th)
Wind Power (Regionals ~1st) (State ~3rd TIERED!)

Hooray for getting everything i wanted?
old
Member
Member
Posts: 56
Joined: February 6th, 2010, 4:48 pm
Division: C
State: CA
Has thanked: 0
Been thanked: 0

balsa is not balsa

Post by old »

The range of characteristics of balsa is wider than any other wood. Balsa is actually considered to be a hardwood, but it's density ranges from 24 lbs/ft cu to well below 4 lbs/ft cu. Some balsa is as soft as a sponge while other pieces can be denser and stiffer than bass. The range in important structural characteristic (Young's modulus for pieces in compression, tensile strength for pieces in tension) varies much more than the density. Also remember that the density of balsa does not directly relate to other characteristics. I have seen extremely low density pieces that were stronger than pieces with twice the density. I have also seen pieces of low density balsa that had virtually no strength at all, in some cases it would simply disintegrate with the slightest strain. My research seems to indicate that a good piece of balsa has the highest specific strength of any wood, but the strength and modulus of elasticity (young's modulus/stiffness) also varies from one sample to another more than any other wood.

My point is that you can't simply go out and buy a certain density of balsa and think that it is going to be even remotely close in strength to other similar density pieces. You will even find that different portions of a single piece of balsa will vary in significantly in strength.
dragonfly
Member
Member
Posts: 75
Joined: May 3rd, 2009, 6:18 pm
Division: Grad
State: PA
Has thanked: 0
Been thanked: 0

Re: balsa is not balsa

Post by dragonfly »

old wrote:My point is that you can't simply go out and buy a certain density of balsa and think that it is going to be even remotely close in strength to other similar density pieces. You will even find that different portions of a single piece of balsa will vary in significantly in strength.
To this is why, as has been said before, you must be very careful in massing your pieces, checking grain, strength, stiffness, straightness, and all other aspects. Essentially: make sure you've got good pieces before you start building your competitive structures! As the density increases you'll likely find less variation, but once you get down to the extremely thin, small and light ones you'll have to carefully inspect every one! Good preparation and materials is essential to creating a good structure.
``````( ) ( ) /
------------
``````( ) ( ) \

PA 2009, 1st Bridges : 2010, 1st Bridges, 1st WM : 2011, 1st ED, 3rd Towers, 4th Heli
Nats Augusta 2009, 4th Bridges : Illinois 2010, 3rd Bridges, 9th ED : Wisconsin 2011, 3rd Heli, 5th Towers : Orlando 2012, 2nd ED, 5th Towers
Event Supervisor Balsa, ED
User avatar
lllazar
Member
Member
Posts: 839
Joined: November 19th, 2009, 7:20 pm
Division: C
State: IL
Has thanked: 0
Been thanked: 0

Re: Balsa or Bass

Post by lllazar »

Ive always wondered - is there a significant variance of characteristics in a single stick of balsa - for example, can the density in a 3ft x 1/4 in x 1/4 in stick of balsa be significantly different from region to region?
2011 Season Events~

Fossils (Regionals ~1st) (State ~6th)
Towers (Regionals ~1st) (State ~3rd)
Helicopter (Regionals -3rd gahhh) (State ~5th)
Wind Power (Regionals ~1st) (State ~3rd TIERED!)

Hooray for getting everything i wanted?
old
Member
Member
Posts: 56
Joined: February 6th, 2010, 4:48 pm
Division: C
State: CA
Has thanked: 0
Been thanked: 0

Re: Balsa or Bass

Post by old »

lllazar wrote:Ive always wondered - is there a significant variance of characteristics in a single stick of balsa - for example, can the density in a 3ft x 1/4 in x 1/4 in stick of balsa be significantly different from region to region?
Absolutely! We have found that the density range in a single stick of balsa can vary by 2:1 or more and the tensile strength and modulus can vary much more than that. If you cut your sticks from boards/planks the variation can be even greater. Pieces cut from one part of a board, especially lower density boards, can vary through almost the entire range of densities of balsa wood (<4 to >20 lbs/ft cu). When we (my partners and I) were building bridges and we decided that we wanted to win at nationals, we had to weigh and measure the significant characteristics (depending on whether the piece was in tension, compression or shear) of every single piece we used. We threw out 20 pieces for every one that we used. Some pieces were like magic, they were so strong and light, while other pieces were almost completely without strength (sometimes almost crumbling in our hands). We cut all our pieces from boards, to save money, so the cost of individual pieces was extremely low. I would guess that we paid less than $100 for all the wood we used for 4 years of SO structures (dozens of them), but the work was oppressive. I don't even want to think about how much of my time was spent sorting through mountains of sticks or balsa. One thing that you really need if you want to be competitive is a very sensitive scale so that you can see the difference in mass of very small pieces. 0.01 gram sensitivity is the minimum that is useful but 0.001 or even better would be useful. The only problem with the extremely sensitive scales is that they require an environment totally free of air currents to read below about 0.01 gram differences. Even at 0.01 gram sensitivity you will easily see the air currents from people gently moving around the room. Using such a scale in a room with an A/C going would render it useless. Most of these scales come with a glass enclosure to keep out air currents but often your pieces will not fit inside so you have to find a way to minimize the air currents around the scale.
Locked

Return to “Towers B/C”

Who is online

Users browsing this forum: No registered users and 6 guests