Sproket Assembly project

In this project we created the all the parts to create an assembly of a sproket

 The 2d sectiond layout of all the parts required to create the sproket assembly

the sectiond assembly of the final product

isometric views of all the parts

the exploded assembly of the sproket

Descriptive Geometry

What is descriptive geometry?
      manipulating (rotating) picture planes or surfaces to identafie the folowing-

• True length lines- if a line is paralell to a fold line in a view, then its true length in the next view
• Point view- first you must find the true length create a fold line perpondicular to the TL line, Command-PO to locate point change pdmode to 96 and pdsize to .1
• True size surfaces-find TL of one line, make fold line perpondicular to the TL to get the edge view of the surface, now create a fold line paralell to the edge view and this will get you the TSS

Addaline

• allows you to skip a step in finding the TSS of a surface
• first, make a line paralell to a fold line from a givin pt. in a view, now project that line up so it shows in a diffent view, now create a fold line paralell to the edge view to find the TSS of the surface

Aux Views

Why use AUX views

• "Sometimes you need more thatn 3 views to tell the whole story"

Auxiliry view

• secondary view used to show the TSS, true shape and size, of a surface that shows foreshortend in all traditional views. " front, right, top"

• A surface is TSS when its edge in the next view is paralell to the fold line
• to make Aux view, SKIP A VIEW AND MEASURE BACK to get proper dims

Tolorance notes

Why are they necessesary

• they hold precise tolorances to insure interchangeability of parts
• process of determining the amount a dim can change fromm its tolorance size

How accurate can 1/4'' be mesured

• .25
• .250
• .2500

Terms

• basic size- the exact size of a dim
• tolorance- amount dims can vary from basic size
• feature- used to identifie the geometery of the drawing being referanced
• limits of size- max and min size allowed
• allowance- limits are where the smallest clearance or largest interfearance occure, measured in MMC

Tolorance Styles

• limits dim- shows the acceptable min and max acceptable dims
• plus or minus dim/ diviation dims- show amount added and subtracted from basic sized to show acceptable dims
• symetrical dims- when + and - are equall

MMC

• max material condition
• the limit of a dim, where the max material is left on the part

LMC

• least material condition
• the limit of a dim where the least amount of material is left on the part

Types of Fit

• clearance- all dim combos produce clearance between parts
• interfearance fit- all combos of dims produce a force fit
• transitional fit- diff combos of dims, produce differant fits  

dim notes

American National Standards Institute (ANSI)

• Establishes the dim standards
• Rules Don't change
• Makes the rules for dim positioning

Why use dims

• discribe the size of an object
• locate details on an object

Basic Rules

• Should be convienent for readers
• no calculations necessary
• no duplications of dims
• first dim line should not be closer than 3/8'' from object
• lines/symbols inside extension lines, if not possible text inside,lines out,if not all outside
• extension lines give a 1/16'' gap between them and object

Leaders

• leader scale = dim scale
• run at angle
• arrow = edge, dot = surface
• cross as few lines as possible
• don't pass through corners

Linear dims

• first 3 big dims: height, width, depth
• between views
• come from view where detail is best shown
• dont dim to hidden lines
• locate from common corner
• smallest dim = closest to object

Angle dim

• drawn at same angle as dim
• use degree symbol: make by typing %%d after text

Circular dims

• Arc = dim as radius
• circle dim as diameter
• cylender dim in side view
• hole dim were its shown with leader

Finished surface

• use a check mark 1/4'' tall

Ordonate dims

• uses distances on X and Y cordonates
• UCS- user cordonate sysyem
• typ: ucs, press enter,move,enter,then pic new origin

Counterbore/ Countersinks

• c'bore is used when a bolt or caphead needs to be flush with a surface, Drill hole is the small hole, c'bore hole is the big hole, in cad type c'bore before diameter of c'bore hole and after type diameter of hole through

Symbols

• Counter bore = a squaired off u
• Deep = an downward facing arrow with horozontile line on top
• Counter sink = V

• c'sinks allows screw head to sit flush
• c'sink anlgle is 82 degrees