Towers B/C

[wzhang5460]

I built 4.97-gram tower, held all 15kg. Was hoping for lighter but I messed up on the legs by choosing the wrong density wood. Thanks, Dale for teaching me, you are a towers god.

Lost to Murphy by less than 100, could've beat them if we just used the tower I built last week. Lol.

[MadCow2357]

Nice... assuming that you went for bonus, you scored 4024? Amazing!

[Cow481]

Pretty sure they did a non bonus so score would be 3018

[waffletree]

I have a tower that keeps breaking in the middle, at the place where the two halves of the tower are glued together. The top kinda falls through sometimes, and I'm pretty sure the top just fell over once. I've been making sure that the legs match up, and using a level to make sure it's straight. Does anyone have any idea how to fix this problem?

[MadCow2357]

I have a tower that keeps breaking in the middle, at the place where the two halves of the tower are glued together. The top kinda falls through sometimes, and I'm pretty sure the top just fell over once. I've been making sure that the legs match up, and using a level to make sure it's straight. Does anyone have any idea how to fix this problem?

I had the same problem with my first tower. It had a square base, and it was built in two parts with no jig. It was probably not a surprise that it only held 6.8 kg.

But to answer your question, I fixed this problem by formulating a whole new rectangular base design that looks like this:
https://drive.google.com/file/d/1v4_KYi ... sp=sharing
You basically build the two sides of the tower on a board, and you lace the sides together on a jig that looks a little bit like this:
viewtopic.php?t=3076&start=30
Of course, my jig's dimensions are not identical to the diagram. I can post a picture of my jig if you are interested in the idea of a rectangular base tower if you like. But, keep in mind, I can only speak from my experiences. I am also relatively inexperienced compared to all of the OP people on this forum, who mostly all recommend square base towers (I would build square base, but I don't have time to build a good square base tower jig before my next competition).

Hope this helped.

[waffletree]

I have a tower that keeps breaking in the middle, at the place where the two halves of the tower are glued together. The top kinda falls through sometimes, and I'm pretty sure the top just fell over once. I've been making sure that the legs match up, and using a level to make sure it's straight. Does anyone have any idea how to fix this problem?

I had the same problem with my first tower. It had a square base, and it was built in two parts with no jig. It was probably not a surprise that it only held 6.8 kg.

But to answer your question, I fixed this problem by formulating a whole new rectangular base design that looks like this:
https://drive.google.com/file/d/1v4_KYi ... sp=sharing
You basically build the two sides of the tower on a board, and you lace the sides together on a jig that looks a little bit like this:
viewtopic.php?t=3076&start=30
Of course, my jig's dimensions are not identical to the diagram. I can post a picture of my jig if you are interested in the idea of a rectangular base tower if you like. But, keep in mind, I can only speak from my experiences. I am also relatively inexperienced compared to all of the OP people on this forum, who mostly all recommend square base towers (I would build square base, but I don't have time to build a good square base tower jig before my next competition).

Hope this helped.

I have been using a square base, so maybe I could build a square jig. Thanks!

[Cow481]

If it is collapsing in in the middle, try adding a piece of 1/8 x 1/8 at the top of the base part between the legs, they don’t need to be from heavy wood, like 0.9 per 36 inches.

[Girlpower05]

I have a tower that keeps breaking in the middle, at the place where the two halves of the tower are glued together. The top kinda falls through sometimes, and I'm pretty sure the top just fell over once. I've been making sure that the legs match up, and using a level to make sure it's straight. Does anyone have any idea how to fix this problem?

Try leaning in your chimney a little.

[dholdgreve]

I have a tower that keeps breaking in the middle, at the place where the two halves of the tower are glued together. The top kinda falls through sometimes, and I'm pretty sure the top just fell over once. I've been making sure that the legs match up, and using a level to make sure it's straight. Does anyone have any idea how to fix this problem?

Regarding the lower section of a tower, the top and bottom are under totally different reactions. The very bottom of the columns are being forced out. away from the center of the tower. To resist this, a "tension band needs to be wrapped around the tower near the bottom. It can be in the form of a horizontal band, or a low profile X brace. Due to the lean of columns, the faces of the columns are not co-planar... they angle in slightly. Because of this, along with the substantial amount of outward thrust on the column bottoms, you may want to increase from 1/32" thick material... maybe 1/20 or even 1/16" just at the bottom. The thrust is greater on the bonus towers than on the non bonus towers. Remember, this will put TENSION on the bottom braces, not compression. As such, they should be glued to the sides of the columns, not butt jointed, like a ladder would be. Because the column faces are not co-planar, as previously mentioned, there are also some shear forces as work here as well, which is why I'm recommending an increased thickness on these braces.

As for the top of the lower section, the upper columns bearing down on the tops of the lower columns will force them inward (not outward like the bottom).. To resisting this, insert a horizontal ladder between the tops of the lower columns. This will be dealing with COMPRESSIVE forces, so it should be placed between the column tops and glued as butt joints on each end. Because it is resisting compression, it needs to be larger than the bottom members, even though it is substantially shorter. At a minimum, it should be at least 3/32" square, or even medium density 1/8" square. Once the joints between upper and lower columns are stabilized, there is still a problem. When a tower is under substantial load (say 10 kg or greater) to top section can "punch" right through the top of the bottom section. I've seen towers where the chimney remains totally intact, but is now inside the lower section of the tower after testing. To compensate for this, consider placing additional ladders just down from the top of the lower section, and make the top tier of bracing a little shorter. Once the forces are redirected around the angle of upper to lower columns, you'll be ok, but getting them to redirect due the vector change can be a real bugger!

[waffletree]

I have a tower that keeps breaking in the middle, at the place where the two halves of the tower are glued together. The top kinda falls through sometimes, and I'm pretty sure the top just fell over once. I've been making sure that the legs match up, and using a level to make sure it's straight. Does anyone have any idea how to fix this problem?

Regarding the lower section of a tower, the top and bottom are under totally different reactions. The very bottom of the columns are being forced out. away from the center of the tower. To resist this, a "tension band needs to be wrapped around the tower near the bottom. It can be in the form of a horizontal band, or a low profile X brace. Due to the lean of columns, the faces of the columns are not co-planar... they angle in slightly. Because of this, along with the substantial amount of outward thrust on the column bottoms, you may want to increase from 1/32" thick material... maybe 1/20 or even 1/16" just at the bottom. The thrust is greater on the bonus towers than on the non bonus towers. Remember, this will put TENSION on the bottom braces, not compression. As such, they should be glued to the sides of the columns, not butt jointed, like a ladder would be. Because the column faces are not co-planar, as previously mentioned, there are also some shear forces as work here as well, which is why I'm recommending an increased thickness on these braces.

As for the top of the lower section, the upper columns bearing down on the tops of the lower columns will force them inward (not outward like the bottom).. To resisting this, insert a horizontal ladder between the tops of the lower columns. This will be dealing with COMPRESSIVE forces, so it should be placed between the column tops and glued as butt joints on each end. Because it is resisting compression, it needs to be larger than the bottom members, even though it is substantially shorter. At a minimum, it should be at least 3/32" square, or even medium density 1/8" square. Once the joints between upper and lower columns are stabilized, there is still a problem. When a tower is under substantial load (say 10 kg or greater) to top section can "punch" right through the top of the bottom section. I've seen towers where the chimney remains totally intact, but is now inside the lower section of the tower after testing. To compensate for this, consider placing additional ladders just down from the top of the lower section, and make the top tier of bracing a little shorter. Once the forces are redirected around the angle of upper to lower columns, you'll be ok, but getting them to redirect due the vector change can be a real bugger!

Thanks for the help! I have been using 1/16 on the bottom, but I've been using a few butt joints.