Week 8 - Challenge 1 - Base Bracket Design

AIM- To creat a model from the Class-A surface of Base Bracket.

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 aesthetic surface and the outer most surface.

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

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

Methodology:-

• Tooling Axis
• Draft Analysis
• Class-B Surface
• Class-C Surface
• Finally creating a solid model from the surface.

Following tools and techniques are used to reach the final step:

• Extract
• Un-Trim
• Extrapolate
• Offset
• Boundary
• Sweep
• Join
• Closed (Part Desgin)

Tooling Axis:-

• First ensure the class-A surface is properly joined and has no discontinuity on it. For this we can use boundary command or join command.
• Analyze the model manually or visually to see which direction is most suitable for tooling axis.
  As in 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 analaze 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 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.
• 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.
• 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, is the same as our guessed tooling axis.

Draft Analysis:-

• Go to insert< analysis< feature draft analysis.
• Align the tooling axis with the compass.
• Click on the surface and see that the surface is within the permissible limit of the draft values.
• The surface should be green and in the column proper value (3deg) should be inserted.

Class B-Surface:- The surfaces are divided into four parts. Then woreked out to cerat the B-Surface.

Rib- The geometrical set is divided into 2 parts i.e Rib1 and Rib2 both are created in the similar manner with similar commands as follows.

• Extract
• Untrim
• Extrapolate
• Offset by 2.5mm
• Trim

Slope- The geometrical set is for creation of the slated surface. Followings commands are used for it.

• Extract
• Untrim
• Extrapolate
• Offset by 2.5mm
• Trim

Base- These is the final geometrical set for creation of Class-B Surface. Folloeing commands are used.

• Extract
• Untrim
• Extrapolate
• Offset by 2.5mm
• Trim
• Edge Fillet

Class-C Surface- The C-surface is created by using a gemetrical set C-Surface.

• Extract the boundary of the class-A surface.
• Extract the boundary of the holes on the class-A surface.
• Use sweep command on the boundaries one by one to get the class-C surface.

Finally geomerical set ABC is used to join the final surface. Using Join Command. A body is inserted and solidified the final product in the part design. Named Closed Volume.

The draft analysis was again used to confim that the product satisfies the drafting rules.

The complete Catia file is provided including screen shots.