Balsa Wood Grain
-
- Member
- Posts: 171
- Joined: March 16th, 2017, 3:34 pm
- Division: C
- State: CA
- Has thanked: 2 times
- Been thanked: 2 times
Balsa Wood Grain
Hi,
This may be well known to expert, but I just found it now after using balsa wood for so many years.
The lines you see on the end grain of balsa wood is RAY not RING.
We ordered C-grain 1/4X1/8X48 balsa sticks for the compression member following Aia's Boomilever Guide. Before they arrived, I was wondering why. When you look at the end, c-grain, I assumed that stronger lines (ring) all parallel to the shorter edge of 1/4 X 1/8 rectangle. It should be bad, not good for boomilever.
I was happy to see the stronger lines are parallel to the longer edge after I received the sticks. Guessing they may have sent us the A-grain because our teacher told them there are for Boomilever. This is perfect. We got second place in NoCal State yesterday (weight 7.57g, holding 14.03 kg).
After search internet for a few hours, I finally found they are c-grain and for balsa wood, the lines you see are ray not ring.
Jinhu
This may be well known to expert, but I just found it now after using balsa wood for so many years.
The lines you see on the end grain of balsa wood is RAY not RING.
We ordered C-grain 1/4X1/8X48 balsa sticks for the compression member following Aia's Boomilever Guide. Before they arrived, I was wondering why. When you look at the end, c-grain, I assumed that stronger lines (ring) all parallel to the shorter edge of 1/4 X 1/8 rectangle. It should be bad, not good for boomilever.
I was happy to see the stronger lines are parallel to the longer edge after I received the sticks. Guessing they may have sent us the A-grain because our teacher told them there are for Boomilever. This is perfect. We got second place in NoCal State yesterday (weight 7.57g, holding 14.03 kg).
After search internet for a few hours, I finally found they are c-grain and for balsa wood, the lines you see are ray not ring.
Jinhu
-
- Member
- Posts: 86
- Joined: March 14th, 2016, 7:07 pm
- Has thanked: 0
- Been thanked: 0
Re: Balsa Wood Grain
Sorry I'm a bit confused about your post. Did you end up using C grain or A grain? And how much does the grain actually matter? I tried making a design with 1/4x1/8 balsa sticks today and it barely held any sand before the whole compression structure began to bow upwards. I did put the 1/4" end vertically so I'm not sure what caused this.
- MadCow2357
- Exalted Member
- Posts: 774
- Joined: November 19th, 2017, 9:09 am
- Division: C
- State: RI
- Has thanked: 211 times
- Been thanked: 56 times
- Contact:
Re: Balsa Wood Grain
Did you use buckling members to decrease the unsupported length intervals?sciencecat42 wrote:Sorry I'm a bit confused about your post. Did you end up using C grain or A grain? And how much does the grain actually matter? I tried making a design with 1/4x1/8 balsa sticks today and it barely held any sand before the whole compression structure began to bow upwards. I did put the 1/4" end vertically so I'm not sure what caused this.
-
- Member
- Posts: 86
- Joined: March 14th, 2016, 7:07 pm
- Has thanked: 0
- Been thanked: 0
Re: Balsa Wood Grain
What do you mean by buckling members? If you mean bracing, I did ladders on the top and bottom of the 1/4x1/8 members and then added zigzags on each side so overall they formed X's.MadCow2357 wrote:Did you use buckling members to decrease the unsupported length intervals?sciencecat42 wrote:Sorry I'm a bit confused about your post. Did you end up using C grain or A grain? And how much does the grain actually matter? I tried making a design with 1/4x1/8 balsa sticks today and it barely held any sand before the whole compression structure began to bow upwards. I did put the 1/4" end vertically so I'm not sure what caused this.
-
- Member
- Posts: 171
- Joined: March 16th, 2017, 3:34 pm
- Division: C
- State: CA
- Has thanked: 2 times
- Been thanked: 2 times
Re: Balsa Wood Grain
We added 8-10 X bracing on top and bottom of the 2 compression members.
The bracing is 1/16X1/32, cutting from sheet 1/32 X 3 X 36, 8 gram.
We use C-grain.
You will also need some vertical bracing from the compression member to tension member. Without it, the compression member will bend around 3 kg.
For us, we add 3 or 4 vertical bracings. It hold 14 kg.
Our boomilever: 7.57g holding 14kg.
The bracing is 1/16X1/32, cutting from sheet 1/32 X 3 X 36, 8 gram.
We use C-grain.
You will also need some vertical bracing from the compression member to tension member. Without it, the compression member will bend around 3 kg.
For us, we add 3 or 4 vertical bracings. It hold 14 kg.
Our boomilever: 7.57g holding 14kg.
- MadCow2357
- Exalted Member
- Posts: 774
- Joined: November 19th, 2017, 9:09 am
- Division: C
- State: RI
- Has thanked: 211 times
- Been thanked: 56 times
- Contact:
Re: Balsa Wood Grain
Vertical members? Not sure how else to explain it...sciencecat42 wrote:What do you mean by buckling members? If you mean bracing, I did ladders on the top and bottom of the 1/4x1/8 members and then added zigzags on each side so overall they formed X's.MadCow2357 wrote:Did you use buckling members to decrease the unsupported length intervals?sciencecat42 wrote:Sorry I'm a bit confused about your post. Did you end up using C grain or A grain? And how much does the grain actually matter? I tried making a design with 1/4x1/8 balsa sticks today and it barely held any sand before the whole compression structure began to bow upwards. I did put the 1/4" end vertically so I'm not sure what caused this.
-
- Member
- Posts: 10
- Joined: January 25th, 2019, 11:00 am
- Division: Grad
- State: OK
- Pronouns: She/Her/Hers
- Has thanked: 0
- Been thanked: 0
- Contact:
Re: Balsa Wood Grain
Pretty sure it's bracing between the tension members and compression members.sciencecat42 wrote:What do you mean by buckling members? If you mean bracing, I did ladders on the top and bottom of the 1/4x1/8 members and then added zigzags on each side so overall they formed X's.MadCow2357 wrote:Did you use buckling members to decrease the unsupported length intervals?sciencecat42 wrote:Sorry I'm a bit confused about your post. Did you end up using C grain or A grain? And how much does the grain actually matter? I tried making a design with 1/4x1/8 balsa sticks today and it barely held any sand before the whole compression structure began to bow upwards. I did put the 1/4" end vertically so I'm not sure what caused this.
-
- Member
- Posts: 171
- Joined: March 16th, 2017, 3:34 pm
- Division: C
- State: CA
- Has thanked: 2 times
- Been thanked: 2 times
Re: Balsa Wood Grain
It is the vertical bending that will kill the boomilever and the bracing between compression and tension are better pulling than pushing.
When you range the stick, you will orient it so that it will bend down not up. To enforce it, the compression member ends, which touch the wall, have some small angle, not exactly normal to the sticks. These will force the stick to bend downward.
Because we more worry about vertical bending, the C-grain is better for compression members.
When you range the stick, you will orient it so that it will bend down not up. To enforce it, the compression member ends, which touch the wall, have some small angle, not exactly normal to the sticks. These will force the stick to bend downward.
Because we more worry about vertical bending, the C-grain is better for compression members.
Who is online
Users browsing this forum: No registered users and 4 guests