Week 9 - Attachment Feature Creation - Challenge 2

Cosmetics.

If cosmetic are a concern, avoid thick sections that will be susceptible to sink. One common problem area is bosses located on or near exterior walls, we recommend moving these inwards. In addition, as a rule of thumb, we advise no more than 60 – 70 percent of the adjacent wall thickness for bosses.

Strength.

Screw bosses can be reinforced with ribs or gussets for added strength and durability. As we mentioned above, a boss should not be next to exterior walls, but you can use coring ribs to keep it connected to the part’s exterior wall without risking sink.

Materials.

Softer, less brittle materials work best for molded parts that need to accept screws. If your part is polycarbonate, for example, consider blending it with ABS.

Insert Molding.

Consider using threaded inserts rather than molding bosses if your part will need to be threaded multiple times. Plastic bosses are typically only good for a single use, since the threads are cut by the screw as it’s placed into the part.

Create a two circle where the screboss is required. The circle dia should be the calculated with the thickness of the component. Incase we are using M6 screw the inner size of the hole should be 5 or 5.2mm.

For the outer screw boss, the thickness of the component is 0.6 times the thickness.

In that case, 2.5(thickness of the component)* 0.6 = 1.5 / sides

Therefore 5.2 + 3(per side) = 8.2 (ideal screw boss dimension)

The Final Output

DOG HOUSE

Procedure:

• Doghouse wall thickness at the intersection of the part wall ( C ) should be 40% or less than the main wall stock ( T ).

• Height of ( B ) should be between 3.0 – 6.0 mm

Now for creating the dog house extract the bottom surface of the coin holder and untrim the surface. After that go to the sketch and draw an rectangle with the centred rectangle option. Make sure one side has to be opened. For that make one side of the line as construction line.

After drawing the line sweep the line with the draft direction in the subtype and use the angle as 1.5 degree. After the construction of the rectangle it has to be closed for that offset the extracted surface in the bottom to the height of the rectangle and trim it.

Now for making the inner wall thickness offset the extracted bottom surface to 4mm above unhide the surface used for creation of doghouse. Now offset the doghouse surface to 1mm inside and extrapolate it. Now it as the image. Now for the screwboss has to come to top of the doghouse for that can the values of Y axis in the translation made.

Draft Analysis:

The doghouse will clear the ejection process.

Result:

With the given coin holder screw boss and doghouse is created. And even draft analysis is performed.