Unit 5: Designing with Data (Safer Buildings) Contents

Transcription

1 Contents 1. Working with Balsa Wood and Foam Core. 1 a. Cutting & Safety 1 b. Joining 2 c. Aligning & Squaring Building the Base 3 3. Building the Roof Load Holder Working with Balsa Wood and Foam Core a. Cutting & Safety. Balsa and foam core are soft enough to cut easily by hand with the right blades. Here are a few tips for doing this: (examples are shown on the right) Use X-Acto knives, razors, or boxcutters to cut beams or foam core. Use a cutting mat to protect the surface from the blade. Keep your fingers out of the path of the blade in case it slips. You can use scissors to cut thin balsa beams or balsa sheet. b. Joining. Hot glue is recommended for joining materials in this unit. It sets quickly, and you can test it soon after gluing the full structure together, unlike when using other glues. Here are a few tips on this: Sometimes you may have to notch the corners of a square piece of balsa sheet to help it fit better against four corner beams. Be sure to glue against all surfaces that touch other parts. Example: glue all four of these parts. Requests to reproduce any part of this material may be made to Engineer Your World. Page 1 of 5

2 You may want to use waxed paper to protect surfaces from hot glue, and to allow for easy clean up. If you repair a broken beam, or if you join two beam segments together to make one longer beam using hot glue, the new long beam will be significantly weaker, because the glue joint is flexible. To regain some of the original strength, support the joint with other pieces of balsa. In general you should avoid using joined beams if solid longer pieces are available. The images below indicate how you should join 2 pieces of balsa together. 1. Before. 2. Glue the 2 pieces together. 3. using small scraps of 1/16 x 1/16 balsa, 4. Finished product. apply external supports to the joined pieces. Requests to reproduce any part of this material may be made to Engineer Your World. Page 2 of 5

3 c. Aligning & Squaring. You should make sure your parts are properly aligned so that pieces fit together and the final structure stands upright. Here are some tips to help you do this: Use any available tools to help you check alignment quality as needed. T-squares, bubble levels, laser levels, rulers, and solid right-angles will help you keep your structure square and upright. Double-check measurements when marking pieces for cutting. Use blades or sandpaper to shave down beam lengths if needed. 2. Building the Base The recommended base to use for your model structures is drawn below. You can make it out of 0.5 cm thick foam core material. It consists of a 15 cm x 10 cm flat rectangle, with 1 cm high foam core supports sticking up out of it. The supports help prevent the base from bending during tests, and they give more surface against which you can glue the supporting columns of a model. The 6 cm dimensions are internal dimensions. 6 cm 6 cm 1 cm 15 cm 10 cm The finished product is shown in the diagram above. In order to make this structure, you will need to cut the following parts from the large piece of foamboard: One 15 cm x 10 cm piece Two 15 cm x 1 cm pieces Two 6 cm x 1 cm pieces Requests to reproduce any part of this material may be made to Engineer Your World. Page 3 of 5

4 Glue all parts together so that the 6 cm x 6 cm base of the structure fits in the center square opening (image shown to the right), and with the structure properly aligned without tilt. 3. Building the Roof Load Holder The recommended roof load holder is drawn below. You can make it out of 0.5 cm thick foam core material. It is basically a box without a bottom piece. Instead a piece of foam core lies glued in the middle (as shown in the image below) on which weights will rest to simulate the roof load. 10 cm 5 cm 8 cm 7 cm 8 cm Requests to reproduce any part of this material may be made to Engineer Your World. Page 4 of 5

5 The parts to cut for this are: One 7 cm x 7 cm piece (middle) Two 10 cm x 8 cm pieces (side walls) Two 10 cm x 7 cm pieces (side walls) When glued together, it should be able to slide over the top of a 6 cm x 6 cm structure and sit stably while holding weights inside (shown in image to the right). Requests to reproduce any part of this material may be made to Engineer Your World. Page 5 of 5