DePew Engineering
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Monday, April 11, 2011
Descriptive Geometry
Discriptive geometry is a way of manipulating picture planes in order to identify:
- True Size
- True Shape
- True Length
- True Angle
- Intersestion Points
- Distances
True Length Lines
- If a line is parallel to a fold line in one view, it is true length in the next view.
Point View
- Must first have true length line
- Fold line must be perpindicular to the true length line
The Add-A-Line Method
The addaline method is a faster method due to the fact that it allows you to skip drawing a view that you would usually have to draw in order to find a true length line.
Wednesday, February 16, 2011
Auxiliary View Notes
- Sometimes 3 views aren't enough to show all that you need.
- Auxiliary views are secondary views used to show true size and shape (TSS) of a surface that is not well represented in a traditional view.
- A SURFACE IS TSS WHEN ITS EDGE IN THE NEXT VIEW IS PARALLEL TO THE FOLD LINE.
- Skip a view, measure back.
Tuesday, February 15, 2011
Tolerance Notes
- Necessary to hold tolerances to insure interchangeability of parts.
- Tolerance is the amount a dimension can vary from its theoretical size.
- Basic Size is the exact theoretical size of a dimension.
- Features are used to identify the geometry being referenced
- Limits are the minimum and maximum allowable size.
- Allowance is the limit where smallest clearance or largest interference occurs.
Styles:
- Limits Dimension
- +/- Dimension
- Symmetrical Dimension
MMC = maximum material condition (limit of a dimension where the maximum material is left)
LMC = least material condition (limit of a dimension where the least material is left)
Fit:
- Clearance fit = All dimension combinations produce clearance between parts.
- Interference fit = All combinations of dimensions will produce a force fit.
- Transitional fit = Different combinations will produce different fits.
Dimension Notes
- Height, Length, Width
- Dimensions are drawn for the convenience of the reader.
- No calculations should be necessary.
- Do not double dimension.
- 3/8 in. from the object line
- Don't dimension to hidden lines
- Smallest dimension closest to object
Leaders
- Leader Scale = Dimension Scale
- Arrow to an edge
- Dot to a surface
- Not horizontal
- Not vertical
Ordinate Dimension
- Uses distances via (x, y)
- Command = UCS, MOVE
Counterbore
- Used when a bolt needs to sit flush with the level surface.
Countersink
- Allows a screw to sit flush with a surface.
Tuesday, November 30, 2010
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