Week 8 - Challenge 2 - Base Bracket Design

AIM: To create a model from the provided class-A surface

INTRODUCTION:

CLASS-A SURFACE: A surface made by the designer which is given as an input to the plastic modeler to work on. It is the aesthetic surface and the outer most surface.

CLASS-B SURFACE: A surface below a certain thickness from the class-A surface is the class-B surface. This is the surface that contains engineering aspects of a model.

CLASS-C SURFACE: A surface that joins the class-A and class-B surfaces is the class-C surface.

METHODOLOGY:

In this model we have focused on the following things:

1. Tooling axis

2. Draft analysis

3. Class-B surface

4. Class-C surface

5. Making a solid model from the surface

Following tools were used to reach the final step:

1. Extract

2. Un-trim

3. Trim

4. Extrapolate

5. Offset

6. Edge fillet

7. Boundary

8. Sweep

9. Join

10. Close (part design)

FOR TOOLING AXIS:

1. First ensure the class-A surface is properly joined and has no discontinuity on it. For this we can use the boundary command or join command.

2. Analyze the model manually or visually to see in which direction it's the most suitable for the tooling axis.

3. As in the 3D view, we can see 2 holes and a flat surface, we can directly take the tooling axis perpendicular to that but to be sure, let us analyze from all the views. The below images of the front side and top views shows the areas that we have to keep in mind while choosing the tooling axis. As from X we cannot see one hole so we cannot take axis along this. In Y we cannot see any holes so here too we cannot take tooling axis. But in Z we can see 2 holes and flat surface so we can take tooling axis.

4. Intersect the ZX plane of the axis system with the input and we can see that there is no surface that can create problem during tooling in this direction.

5. Intersect ZY plane and we are unsure of these two surfaces, so we make a line and bisect them both and this will be our tooling axis which, not so surprisingly, it's the same as our guessed tooling axis.

FOR DRAFT ANALYSIS:

1. Go to Insert>Analysis feature>Draft analysis.

2. Align the tooling axis with the compass

3. Click on the surface and see that the surface is within the permissible limit of the draft values

4. The surface should be green and in the column proper value (3deg) should be inserted.

FOR CLASS-B SURFACE:

FLAT SURFACE:

1. Extract the flat surface

2. Un-trim the surface

3. Extrapolate it

4. Offset it by 2.5mm i.e. thickness

SLANT SURFACE:

1. Extract the slant surface

2. Un-trim the surface

3. Extrapolate it

4. Offset it by 2.5mm i.e. thickness.

RIB SURFACES:

1. Extract the rib surfaces (1 rib at a time)

2. Un-trim the surface

3. Extrapolate it

4. Offset it by 2.5mm i.e. thickness

5. Trim to get the desired shape

6. Repeat it with the second rib too

Once we have finished doing this, we have to trim the surface to get exact shape of the class-A surface (without fillet) below 2.5mm. After the trimming part is done, fillet the model. Formula for filleting= fillet value+thickness (if the surface is below), we get our class-B surface.

FOR CLASS-C SURFACE:

1. Extract the boundary of the class-A surface

2. Extract the boundary of the holes on the class-A surface

3. Use sweep command on the boundaries one by one to get the class-C surface

FINAL BASE BRACKET:

1. Join the class-A and class-C surfaces together

2. Trim the class-B surface with the join created earlier

3. Go to part design and close the model

Tree structure: