Towers B/C

[MadCow2357]

Does anyone know if 1/32 x 1/32 wood would be strong enough for the chimney X's (provided a fairly tight interval of 8-10 X)? Also, is it necessary to have a ladder at the top of the chimney or is it only needed at the top and bottom of the base?

Seems most elite teams are going with 1/16"*1/32". I think that 1/32"*1/32" would be overkill. I would say the ladder at the top is pretty essential. Mine is a 1/8" stick.

[DarthBuilder]

Does anyone know if 1/32 x 1/32 wood would be strong enough for the chimney X's (provided a fairly tight interval of 8-10 X)? Also, is it necessary to have a ladder at the top of the chimney or is it only needed at the top and bottom of the base?

I’ve actually tried the 1/32 x 1/32

It is going to make the top weaker but it does work. But I wouldn’t use it. You can still get the same weights with 1/16

[MadCow2357]

When I do SFPD tests on my 1/8"*1/8"*12" pieces, I sort the pieces into 4 main groups based on buckling strength: weak(less than 200g), normal (200g to 240g), strong (240g to 300g), and exceptionally strong (300g+). I use the strongest pieces in the chimney, and the moderately strong pieces in all of the other essential load bearing columns. If I do not have enough of those, then I use the pieces with average buckling strength. Then, I use the weak pieces for the tension straps. But then I am always left with a pile of "weak" balsa. What would you guys do with that balsa?

Also, am I sorting my wood correctly (e.g. is less than 200g weak?)? I am referring to ~0.4g 12"*1/8"*1/8" pieces.

[DarthBuilder]

When I do SFPD tests on my 1/8"*1/8"*12" pieces, I sort the pieces into 4 main groups based on buckling strength: weak(less than 200g), normal (200g to 240g), strong (240g to 300g), and exceptionally strong (300g+). I use the strongest pieces in the chimney, and the moderately strong pieces in all of the other essential load bearing columns. If I do not have enough of those, then I use the pieces with average buckling strength. Then, I use the weak pieces for the tension straps. But then I am always left with a pile of "weak" balsa. What would you guys do with that balsa?

Also, am I sorting my wood correctly (e.g. is less than 200g weak?)? I am referring to ~0.4g 12"*1/8"*1/8" pieces.

Anything near 300 give or take is pretty good

[Cow481]

Does anyone know if 1/32 x 1/32 wood would be strong enough for the chimney X's (provided a fairly tight interval of 8-10 X)? Also, is it necessary to have a ladder at the top of the chimney or is it only needed at the top and bottom of the base?

I would say that the wood dimensions don’t matter as much as the weight of the wood for bracings.

[stevepilot]

Ok, thanks for the replies.

[cheese]

Does anyone know if 1/32 x 1/32 wood would be strong enough for the chimney X's (provided a fairly tight interval of 8-10 X)? Also, is it necessary to have a ladder at the top of the chimney or is it only needed at the top and bottom of the base?

I would say that the wood dimensions don’t matter as much as the weight of the wood for bracings.

But there are certain relationships between the size and the strength that could make a difference.

[dholdgreve]

When I do SFPD tests on my 1/8"*1/8"*12" pieces, I sort the pieces into 4 main groups based on buckling strength: weak(less than 200g), normal (200g to 240g), strong (240g to 300g), and exceptionally strong (300g+). I use the strongest pieces in the chimney, and the moderately strong pieces in all of the other essential load bearing columns. If I do not have enough of those, then I use the pieces with average buckling strength. Then, I use the weak pieces for the tension straps. But then I am always left with a pile of "weak" balsa. What would you guys do with that balsa?

Also, am I sorting my wood correctly (e.g. is less than 200g weak?)? I am referring to ~0.4g 12"*1/8"*1/8" pieces.

While I fully support the scientific approach you are taking, I'll throw a couple additional thoughts out there:
SFPD strength and stick weight are both very critical... I can hand you .9 to 1.0 gram 12" sticks in which every single stick will test off the charts in strength... And when you finish your 12 to 15 gram tower you won't be happy!
I'd suggest the you first stratify your sticks by weight (by tenths of a gram)... next, determine the weight of desired columns based on the overall tower weight. If you ultimately determine that .3 to .4 gram columns are needed, grab your pile of preweighed columns within that range and further stratify, using SFPD strength test. Next is where we differ... I believe the higher SFPD testing sticks should be turned into LOWER columns, not upper. The lower columns incur all of the loads the upper columns do, plus since they are at more of an angle will pick up addition shear... If you don't believe me, pick up a 10 pound weight in each hand. Hold one weight straight down by your side (the same angle as the upper column). Hold the other weight out from your body about 18"... approximately the same angle as the lower section of the tower... Hold both weights as long as you can... Which arm gives our first?

This premise is of course based on bracing design and assumes that your unsupported column lengths are similar in both the top and bottom sections. If you were to elect to go with half the number of tiers in the upper section than the lower section, then I believe the upper columns could need to be stronger than the lower columns.

[Cow481]

I know that this is really late in the season but I was wondering whether the bonus was more efficient or the non bonus was more efficient.

[MadCow2357]

Thanks for the long and detailed response. You remind me so much of Balsa Man... may he rest in peace...

Anyways, I will keep what you said in mind. The arm holding the weight goes first.

I am thinking of switching to square base before nationals. How much would I have to spend to build the 2 acrylic panel jig, if I am laser cutting it at a local business?