MECHANICAL MODELLING

This week the project is to present design in 2D and 3D. Choose the possible design to do related to the final project.

MODEL IN AUTOCAD

The AUTOCAD program was chosen to realize the 2D and 3D design, to realize the design of the pieces and later assembly.

COMANDS AUTOCAD FOR DESIGN 2D

To perform the 3D design in autocad was used commands like: "EDIT POLYLINE" that joins the lines that form a figure. "POLAR ARRAY" that helps me generate a uniform distribution of figures on a circumference (helped me design the gears). "TRIM" is used to cut flat figures. "MIRROR" to duplicate a figure in symmetry also works on 3D. "OFFSET" to generate offsets in 2D figures used to generate thickness on the plates.

COMANDS AUTOCAD FOR DESIGN 3D

To perform 3D design in autocad the following commands were used: "EXTRUDE" to generate 3D parts from 2D figures. "REVOLVE" to generate a 3D figure from a 2D figure making it revolutionize in 360 degrees and forming a solid. "SWEEP" to generate a 3D figure from a 2D figure by following a figure (such as triangle, circumference, etc.) through a path (curve, line, spiral). "SOLID, UNION" to join several 3D pieces. "SOLID, SUBSTRACT" to subtract overlapping 3D parts. "SLICE" to cut 3D figures from a 2D reference figure. "PRESSPULL" to extend surfaces or remove surfaces in 3D figures

MECHANICAL SYSTEM DESIGN OF CURTAINS

Using the above commands, the transmission could be designed as shown in the figure.
The transmission consists of: an engine, 2 gears (to generate enough force and reduce speed), and a pulley for the curtain rope that will show knots each distance.
The figure shows the part of the system.

A description of the project is shown.

MECHANICAL SYSTEM DESIGN OF DOOR

Using the above commands, the transmission could be designed as shown in the figure.
The transmission consists of: a motor, 1 gear (to generate enough force and reduce speed), and a mechanical zip rack that will open or close the door. In addition another system was added on the door, this will turn the door knob.
The figure shows the part of the system.

A description of the project is shown.

MECHANICAL SYSTEM DESIGN OF WINDOW

Using the above commands, the transmission could be designed as shown in the figure.
A straight mechanical zipper, an engine; Which will open or close the window..
The figure shows the part of the system.

A description of the project is shown.

Download

- Model in Autocad mechanical system design of Curtains: Download here

- Model in Autocad mechanical system design of Door: Download here

- Model in Autocad mechanical system design of Window: Download here

MODEL IN RHINOCEROS

The rhinoceros program is a 3D and 2D modeling platform with 4 views that accepts various formats

To design the gears in this program the following steps were performed

step 1

Open the website and create the gear you need with the parameters shown in the image

http://hessmer.org/gears/InvoluteSpurGearBuilder.html

- Circular pitch (the circumference of the pitch circle divided by the number of teeth)

- Pressure Angle (common values are 14.5, 20 and 25 degrees)

- Clearance (minimal distance between the apex of a tooth and the trough of the other gear; in length units)

- Backlash (minimal distance between meshing gears; in length units)

- Profile Shift (indicates what portion of gear one's addendum height should be shifted to gear two. E.g., a value of 0.1 means the adddendum of gear two is increased by a factor of 1.1 while the height of the addendum of gear one is reduced to 0.9 of its normal height.)

- Wheel 1 Tooth Count (n1 > 0: external gear; n1 = 0: rack; n1 < 0: internal gear)

- Wheel 1 Center Hole Diameter (0 for no hole)

- Wheel 2 Tooth Count

- Wheel 2 Center Hole Diameter (0 for no hole)

- Rotation steps per tooth angle when assembling the tooth profile (3 = draft, 10 = good quality). Increasing the value will result in smoother profiles at the cost of significantly higher calcucation time. Incease in small increments and check the result by zooming in.

- Number of segments per 360 degree of rotation (only used for circles and arcs); 90 is plenty

step 2

When the gear is ready for export, you need to click on "update"

Then we click on "generate DXF"

step 3

To download the gear you must click on "generate DXF" -> "download DXF"

THEN

step 4

When you drag the files to rhinoceros the following windows will appear and you will accept all

Then we will locate the file in the work area of ​​Rhinoceros

To create the solid we will extrude the surface with the tool that is observed in the following image

Then enter the thickness of the gear and the finish product is this

The 2D works to make figures the most used command is polyline and there are two types: drawing with polar coordinates and drawing with distance restriction

CONCLUSIONS

Advantages of Autocad:
-First develop the 2D design and then use tools to convert from 2D to 3D.
-Autocad is versatile to define dimensions, generate figures, presents tools for figures in 2D and 3D.
- Generates design sheet where you can dimension and place the 3D figures in standardized formats.
- Can be used to draw very fast sketches as your environment allows.
-Export files in STL and DXF
Disadvantages of autocad:
- Does not present mechanical design libraries
- It can design gears but it takes a lot of time.
-It does not have many formats to export to CNC, etc.
Advantages of Rhinoceros:
- First develop the 2D design and then use tools to convert from 2D to 3D
- Present different plugins to develop numerical control works.
- Has work views immediately.
- It has mechanical design bookstores.
- It has different formats for exporting files.
- Mechanical design time is very fast.
Disadvantage of Rhinoceros:
-It can not do different jobs at once. It becomes slow.
- Rhinoceros work with commands and this makes it more dynamic, but does not show a previous use of their commands like Autocad.

Download
- Archive: Download here