Midterm Practice

For the next two classes, I want you to finish up anything you have not turned in yet (come up and check the grade book).  Once you are all finished, try out some of the following as a review for the midterm.

Midterm:
For the midterm, you will have to draw a 3D object in cad, create the othogonal views (base view) on a layout with your titleblock (bring in a copy of your titleblock), and dimension it.  There will be no step-by-step instructions, just the dimensions to help you draw it. 


Practice #1
Create the 3D object from the below views.  Use Viewbase to show the three below views, with a 3D view in the upper right hand corner.  Dimension all of your work, and use your title block.

Practice #2
Create the 3D object from the below views.  Use Viewbase to show the three below views, with a 3D view in the upper right hand corner.  Dimension all of your work, and use your title block.

Practice #3:
The following is a little harder than what I will have you do, it's a good exercise to remind you of some of the drawing commands though. 


Draw a guitar:

Start by drawing circles and ellipses along a center line as shown.  Use the trim command to create the final shape. 




Add two horizontal lines to the ends:




MOVE the guitar to be centered on the y axis, then use the MIRROR command.



Move everything down to 0,0
Draw "17" center line, then center "1.5" line, then eyeball sides of the neck.  Make copies of the shown components, and move them to the side.




Extrude body 3 tall.
Use "SHELL" to make body hollow
PRESSPULL out the sound hole.





For the bridge and saddle,
Saddle: 4.5 by 1.5 by .8 tall,
Bridge: 4.5 by .5 by 1.2 tall.
Fillet edge .2
lower into guitar .3




Create a one inch tall block from the bottom of the neck:





Extrude 3, and .7, attach and center to guitar.

Extrude .3, add to top:



Extrude a .4 by .7 triangle

Extend top (Presspull)

Presspull out .4

Create 1.3 by 3.3 rectangles, orient with end.

Presspull


Fillet r = .2




Move UCS to FACE of guitar head, at the corner.
draw 6 circles for the tuning pegs, r=.15, draw 3, use the mirror command



Extrude .4

Make the frets, 2 lines, offset .2.

Trim, extrude .15, move.

Add strings, play around with the colors, done!

Chapter 8: Threaded Fasteners

Fastening: 
Two or more components that are joined.  Do not require orthographic views, just the info to purchase the part.

Permanent Fasteners: 
adhesives, welds, braces, solders, rivets, nails.

Non-Permanent Fasteners: 
Screws, bolts, nuts, pins

  Thread Characteristics:

Direction
Most are right handed (righty tighty, lefty loosy)

Left handed threads - used where right handed threads would become loose in the application (lawn mower blades)

Lead
Distance traveled during one revolution of the fastener.
Lead = Pitch for single threaded screws.




double and triple threaded bolts - one revoltuon = 2 or 3 times the pitch. 

Double and triple threading give rapid motion + large thread surface.

Form
Cross-sectional shape, profile.

N - Rounded V profile (rounded for ease of manufacturing)
ACME - Heavy loads, high accuracy
BUTTRESS - High axial loads
SQ - hard to manufacture

Series
Number of threads per inch for a specific diameter.
coarse - general purpose used for holding
fine - to support added force, used in aircraft and automotive industries
extra fine - for short and small diameter fasteners.

Thread spec's:
3 standard representations:

 Class of Fit - How tight fasteners fit together.

Loose fit (1) for harsh corrosive environments.
Regular and Average fits (2) General purpose
Tight (3) For high pressures, stresses, and vibrating systems.


Thread Notes:
Notes on drawing that provide specs about thread.

Use a "leader" to connect note to thread

English Thread:

Above: Diameter = .25", 28 threads per inch, United National, Fine series, average fit, external, right handed.  (LH would be left handed, nothing written assumes right handed)

Thread Table:
1st column - diameter
(a coarse threaded 1.25" diameter bolt has 7 threads per inch)

Metric:
only listed as coarse or fine.
M - metric
90 - thread diameter
X
6 - pitch (in mm)

metric threads are usually defined by their pitch, that is, how much distance per thread, inch-based standards usually use the reverse logic, that is, how many threads occur per a given distance.Lead is the distance along the screw's axis that is covered by one complete rotation of the screw (360°). Pitch is the distance from the crest of one thread to the next. Because the vast majority of screw threadforms are single-startthreadforms, their lead and pitch are the same. 

Tolerance class: 3, 4, 5, 6, 7, 8, 9 + E, G, H.
#3-9 = tolerance grade (larger num = larger tolerance)

6 = medium = most common

Letter = type of fit:
E = loose
G = regular

H = tight

Head: