Editing Python Solution to Dimension Tracking

= The Problem =

To make FreeCad work you often need to enter values of various dimensions.  There does not seem to be a method internal to FreeCad ( and probably there should not be ).  These dimensions come from various sources: 
* Spec. sheets.
* Measurements
* Calculations
* Design decisions.

You more or less need some notes to keep track of this stuff.  Some of this may be paper sketches, paper notes, and digital documents ( many may choose spreadsheets ).  I find spreadsheets to be very error prone so I looked for a python solution.  The very simple version of this is shown in:  [[FreeCad Gear Box]]  This has now evolved, and this document will describe the solution.  For the actual code contact: [[User:Russ_hensel]] 


= A Python Solution =

My Python solution consists of a set of interacting classes:

== PartDimension ==
This class holds a single dimension.  Of course you can just go:   a_dimention = 22.  What is wrong with that?  This dimension has a name and a value.  What it does not have is units or a type that may help distinguish between pure numbers ( teethe on a gear ), angles, and linear dimensions.  Also I have upgraded the class so that it does easy unit conversions and is easy to print.

Here is what you might get when you print a PartDimension:

<pre>

print a_dimension

output:

          bolt_sep            ( mm ) = 25.0
</pre>

And here is what you get with a fairly fancy getter method:

<pre>

In:
    a_dimention   = PartDimension( "part name two", dim_type = "linear", radial = False, value = 27.3, units = "in")
    print( a_dimention )

    print( a_dimention.get_value( units = "ft" ) )

Out:
          part name two       ( mm ) = 693.42
2.275

</pre>

A couple of implementation details.

* Dimensions are always stored in some base units, linear in mm, angles in radians, the getter methods convert to the desired units.  There are a couple of helper classes for the conversion:

** LinearConverter
** AngleConverter 

=== ===

== ==



[[Category:FreeCad]] [[Category:Python]]
@@ Line 1: / Line 1: @@
-This is about half written, if interested email '''[[User:Russ_hensel]]'''  And since written it has been substantially expanded and revised.  I will return to this documentation soon, I hope.
 = The Problem =
@@ Line 11: / Line 7: @@
 * Design decisions.
 You more or less need some notes to keep track of this stuff.  Some of this may be paper sketches, paper notes, and digital documents ( many may choose spreadsheets ).  I find spreadsheets to be very error prone so I looked for a python solution.  The very simple version of this is shown in:  [[FreeCad Gear Box]]  This has now evolved, and this document will describe the solution.  For the actual code contact: [[User:Russ_hensel]]
 = A Python Solution =
@@ Line 54: / Line 51: @@
 ** AngleConverter
-== PartInfo ==
+=== ===
-Of course a part does not have a dimension it has many dimensions.  So PartInfo is a collection of Part Dimensions all of which can be manipulated as a unit.  There are methods to:
-* Support naming of PartInfos ( say "My Gear # 3 " ).
-* Add a dimension ( or a set of dimensions ).
-* Access dimensions or there values one by one or as a unit.
-* Print out all the part dimensions in any particular set of units.
-== PartStack ==
-This is a collection of PartInfo items, the idea is that this represents several parts that are stacked up to be 3D printed as a unit.  Perhaps more detail later.
-= Use =
-I am still working this out but here is an approach:
-*In an empty file import the code above ( now cad.py )
-*Write a function to generate a PartInfo object.  I call my first one something like my_standards_factory:
-<pre>
-# ---------------------------------------------
-def standards_42_factory():
-    """
-    this holds standards
-    """
-    a_part                  = cad.PartInfo( "Cad Standards #42 "  )
-    a_part.freecad_name     = "standards_42"
-    a_part.create_part_dimension(  "washer_thick",       dim_type = "linear", radial = False, value = .1   )
-    a_part.create_part_dimension(  "gear_clear",         dim_type = "linear", radial = False, value = .2    )
-    a_part.create_part_dimension(  "gear_thick",         dim_type = "linear", radial = True , value = 4.5      )
-    a_part.create_part_dimension(  "plate_thick",        dim_type = "linear", radial = False, value = 2.0      )
-    ....... more
-</pre>
-* and use it:
-<pre>
-    my_standards    = standards_42_factory()
-    my_standards.print_part()
-</pre>
-The print is just to verify the factory.
-Then  ....... more coming .....
+== ==
 [[Category:FreeCad]] [[Category:Python]]