toSketch

( FreeCAD workbench to add toSketch Facility )

The main emphasis of the facilities in this workbench are to help with remodelling of existing models. When a STEP model is imported into FreeCAD you have a a viewable model but no details about how it was created or Parametric properties that you can change.

Installation

It can be installed via the Addon Manager (from Tools menu)

Alternative Installation

Clone into FreeCAD's Mod directory see https://wiki.freecadweb.org/Installing_more_workbenches

• Change to FreeCAD Mod directory

• git clone https://github.com/KeithSloan/toSketch.git

• Start/Restart FreeCAD

Use

Face to Sketch : toSketch

• Select a single planar Face
• Click on toSketch Icon - Should create a new sketch from the selected Face

Create Plane : toPlane

• Select the toPlane Icon to create a Plane
• Edit properties to adjust Plane i.e Axis XY, XZ, YZ, Offset

Section Plane to Sketch : toSketch

• Select Plane in treeView
• Select Objects
• Click on toSketch Icon - Should create a section of the Plane and the selected Object or Objects that is then opened as a new sketch

Remove Outer Box

• Where the resulting sketch has an Outer Box this allows it to be removed.

Sketch to Macro ( Alpha - Under Development )

• Select a sketch

• Click on ToMacro

  Creates a macro name (sketch.FCMacro) in the user Macro directory

Currently supports ( More to follow )

  * Points
  * Lines
  * Circles
  * ArcOfCircle
  * BSpline ( Initial Attempt )
  * Ellipse

When executing the macro

 If there is a an ActiveSketch, the geometry is added, otherwise a new sketch is created.

Constraints

 The following types of constraints are exported if present in the selected sketch.

     * Coincident
     * Vertical
     * Horizontal

toLineCurve ( Alpha - Under Development )

Select a Sketch and click on toLineCurve will create a new sketch. Where lines are within 0.012 radians or 3.14 - 0.12 radians they are combined into one line.

Otherwise if there at least three lines a BSpline curve is fitted.

If there is less than three lines, they are transferred to the new sketch.

note: Currently the items in the sketch must be in order, which should be the case with the toSketch command

toCurveFit ( Alpha - Under Development )

Select a sketch and click on toCurveFit will fit a BSpline to all the Straight line points.

You can control where new BSpline curves start as follows.

First review the target sketch and decide where new curves should start. With an unconstrained sketch add single points near where new curves should start. Add a conincident constrant for the where the new curve should start and the added single point. The order should be to select a point on one of the existing lines, then click on the single point. Otherwise the line will move.

Then when invoking the toCurveFit a panel will open, select 'Break at Coincident Constraints'

Note the curvefitting is performed by

Creating a Part.BSplineCurve with s number of control points as the number of line ending. Need to find a way of fitting with a minimum of control points

Section a Mesh Cross Section : to CurveFit - not in current code but saved

Need to look at possiblity of determining minimum number of control points

Requires NURBS-Python ( geomdl ) see https://nurbs-python.readthedocs.io/en/5.x/

• To Install

  • From FreeCAD python console
  • import os
  • print(os.environ)
  • Note one of the library paths [path]
  • pip3 install geomdl -t [path]

• To Use

  • Load/Create a Mesh

  • Use Mesh Design workbench to create a section

    Toobar - Meshes | Cutting | Cross-Sections

    Creates a Mesh Cross-Section

  • Select Cross-Section in Tree View, click on 'To Sketch' icon

    Creates a Raw Sketch

  • Select Created Sketch, click on 'To CurveFit' icon

    Creates a Sketch with some line and Curve Fitting

Constraints

Note: Ideally constraints should be set on a geometric basis, however there is always the option to fix all points with the installable Macro SketcherFixAllPoints.FCMacro see Addon Manager for installation.

toPlane to PartPlane

Creates a new PartPlane from a toPlane

Section | Wire to sketch

Under development

BSpline to Arc

For future development Test each BSpline in a sketch and if the curve would fit an arc of a circle, replace BSpline with Arc of Circe.

The following are intended to help with Objects created via import of STEP files

Create Scale Object : to Scale

Aimed at scaling objects imported from a STEP file, provides the ability to scale a selected Object as follows

• Select the object to be Scaled.
• Click on the to Scale icon
• A new object is created where the Shape from the selected Object is stored.
• The original selected object is then deleted
• By changing the Objects Properties from the inital values of ONE the Shape of the object can be reScaled

Reset Origin

When STEP files are imported into FreeCAD their Placements are all set to zero and the Shapes are all created accordingly. This means if you try and Rotate an object that has been imported into FreeCAD it does not rotate correctly.

Selecting an Object and clicking on the Reset Origin icon results in the following

• A new PartFeaturePython object is created and stores a copy of the selected objects Shape.
• The Objects Placement is set based on the Shapes Bounding box and drawn at the same position.
• The Selected Object is removed

The display of the Object will not change, but the Placement will be updated and it can be correctly rotated.

For the new object

• The Origin can be changed via the Object Type Parameter using the Parameter window between

  • min x/y/z
  • Center of Mass
  • Original ( as created by STEP import )

• The parameter window shows readonly Bounding box info

• The Origin type can be changed via the Objects Parameter Placement setting.

• Apart from when the Origin Type is set to Original the Object should now rotate correctly

Acknowledgments

Thanks to the following FreeCAD forum members

 * suzanne.soy
 * wmayer
 * Ed Williams edwilliams16

Icons thanks to jmaustpc

Remove Outer Box - icon is a modified version of href="https://icons8.com/icon/nerFBdXcYDve/trash">Trash icon by Icons8