Part and PartDesign: Difference between revisions
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==Overview== |
==Overview== <!--T:1--> |
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There has been much discussion of this over the years about the differences and ramifications of using the [[File:Workbench_Part.svg|24px]] [[Part Workbench|Part]] and the [[File:Workbench_PartDesign.svg|24px]] [[PartDesign Workbench|PartDesign]] workbenches. |
There has been much discussion of this over the years about the differences and ramifications of using the [[File:Workbench_Part.svg|24px]] [[Part Workbench|Part]] and the [[File:Workbench_PartDesign.svg|24px]] [[PartDesign Workbench|PartDesign]] workbenches. |
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It is a good idea to use one or the other until the user is comfortable with one, then learn the other. It is also typically recommended that new users not mix them until the ramifications are of doing so are understood. |
It is a good idea to use one or the other until the user is comfortable with one, then learn the other. It is also typically recommended that new users not mix them until the ramifications are of doing so are understood. |
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Let's talk about those ramifications. |
Let's talk about those ramifications. |
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==Part Workbench Concepts== |
==Part Workbench Concepts== <!--T:5--> |
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It is often said Part WB is more [[Constructive_solid_geometry|CSG style modeling]]. This is where the operator combines various primitives to end up with a lump in the desired shape. |
It is often said Part WB is more [[Constructive_solid_geometry|CSG style modeling]]. This is where the operator combines various primitives to end up with a lump in the desired shape. |
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(In fact Part WB goes one step further than just primitives and allows the operator to use a sketch+extrude operation to create random shapes as well.) |
(In fact Part WB goes one step further than just primitives and allows the operator to use a sketch+extrude operation to create random shapes as well.) |
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When each primitive or shape is created, it has no relationship to other objects created, it is a single solitary solid. |
When each primitive or shape is created, it has no relationship to other objects created, it is a single solitary solid. |
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[[File:Part_CSG_Prims.png|frame|centre|Solitary solids]] |
[[File:Part_CSG_Prims.png|frame|centre|Solitary solids]] |
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This condition remains so, until, the operator uses some operation to combine them (typically a Boolean that adds or subtracts them). |
This condition remains so, until, the operator uses some operation to combine them (typically a Boolean that adds or subtracts them). |
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The take away is the single solitary solid bit and the combining them bit. |
The take away is the single solitary solid bit and the combining them bit. |
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==PartDesign Workbench Concepts== |
==PartDesign Workbench Concepts== <!--T:10--> |
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In the PartDesign WB the Body object represents a single solitary cumulative solid. The first lump created under the Body (be it a Pad from a sketch, or a BaseFeature from outside the Body) represents a lump of raw material that will be further processed to refine it to the desired final shape (solid). It is cumulative in the sense that each operation adds or removes material. The lowest/last operation (the current Tip of the Body) is the current state. Any other feature under the Body but above the Tip, does not represent a complete/stand alone solid. Only the Body (basically a proxy for the tip) or the Tip represent a complete solid. |
In the PartDesign WB the Body object represents a single solitary cumulative solid. The first lump created under the Body (be it a Pad from a sketch, or a BaseFeature from outside the Body) represents a lump of raw material that will be further processed to refine it to the desired final shape (solid). It is cumulative in the sense that each operation adds or removes material. The lowest/last operation (the current Tip of the Body) is the current state. Any other feature under the Body but above the Tip, does not represent a complete/stand alone solid. Only the Body (basically a proxy for the tip) or the Tip represent a complete solid. |
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[[File:Part_Design_Cumulativ.png|frame|centre|Cumulative Body Solid]] |
[[File:Part_Design_Cumulativ.png|frame|centre|Cumulative Body Solid]] |
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This image shows a Body. It is a cumulative solid that consists of a padded sketch and a cone primitive. This is a single solid. Neither the pad or the cone can exist separately. |
This image shows a Body. It is a cumulative solid that consists of a padded sketch and a cone primitive. This is a single solid. Neither the pad or the cone can exist separately. |
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(Another thing mentioned often is a Body '''''MUST''''' be a single contiguous solid. This means all geometry created by a feature in the Body ''must'' touch it's predecessor.) |
(Another thing mentioned often is a Body '''''MUST''''' be a single contiguous solid. This means all geometry created by a feature in the Body ''must'' touch it's predecessor.) |
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==The Ramifications== |
==The Ramifications== <!--T:15--> |
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People get caught when they attempt to use some feature under the Body (rather than the Body itself) as one selection of a Part WB Boolean operation. This is a problem, because the selected feature does not represent a complete solid. |
People get caught when they attempt to use some feature under the Body (rather than the Body itself) as one selection of a Part WB Boolean operation. This is a problem, because the selected feature does not represent a complete solid. |
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In a sense, from a Part WB standpoint, the Body represents another primitive. So, using a Body (remember it is a proxy for the tip) and a Part WB object to do a Boolean is valid. But the resulting object is a Part WB object. And, thus PartDesign WB tools can't be used on it any longer. |
In a sense, from a Part WB standpoint, the Body represents another primitive. So, using a Body (remember it is a proxy for the tip) and a Part WB object to do a Boolean is valid. But the resulting object is a Part WB object. And, thus PartDesign WB tools can't be used on it any longer. |
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And, it can get even more complicated. If you create a new Body and drag the result from the previous paragraph into it, a BaseObject is created. And you can go off an use the PartDesign WB tools on it. |
And, it can get even more complicated. If you create a new Body and drag the result from the previous paragraph into it, a BaseObject is created. And you can go off an use the PartDesign WB tools on it. |
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==The Caveats== |
==The Caveats== <!--T:19--> |
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There is a caveat with the Tip and it's representation of the single solid in the Body. ''If'' the tip is a subtractive feature and is used in a dress up operation, for instance a Mirror, the Mirror is operating on the underlying feature (a pocket for example). Thus the cumulative solid is not mirrored, but the subtractive feature is. The result of this must create a single solid. |
There is a caveat with the Tip and it's representation of the single solid in the Body. ''If'' the tip is a subtractive feature and is used in a dress up operation, for instance a Mirror, the Mirror is operating on the underlying feature (a pocket for example). Thus the cumulative solid is not mirrored, but the subtractive feature is. The result of this must create a single solid. |
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In this example, a mirror of the tip (which is the pocket of the slot) around any of the base planes, or even a face of the solid will not produce a mirrored solid of the entire model. (In fact, it will produce a Mirrored feature in the tree that is essentially empty.) |
In this example, a mirror of the tip (which is the pocket of the slot) around any of the base planes, or even a face of the solid will not produce a mirrored solid of the entire model. (In fact, it will produce a Mirrored feature in the tree that is essentially empty.) |
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[[File:PhantomMirror.png|frame|centre|Solitary solids]] |
[[File:PhantomMirror.png|frame|centre|Solitary solids]] |
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In this example, a mirror of the tip (which is the pocket of the slot) is performed around the datum plane and produces a mirrored slot: |
In this example, a mirror of the tip (which is the pocket of the slot) is performed around the datum plane and produces a mirrored slot: |
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[[File:MirroredSlot.png|frame|centre|Solitary solids]] |
[[File:MirroredSlot.png|frame|centre|Solitary solids]] |
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See the [[File:PartDesign_Mirrored.svg|24px|link=PartDesign_Mirrored]] [[PartDesign_Mirrored|PartDesign Mirrored]] tool wiki page for more information. |
See the [[File:PartDesign_Mirrored.svg|24px|link=PartDesign_Mirrored]] [[PartDesign_Mirrored|PartDesign Mirrored]] tool wiki page for more information. |
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==Conclusion== |
==Conclusion== <!--T:26--> |
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Part and PartDesign workbenches can be used together with some care, creating quite complex models. |
Part and PartDesign workbenches can be used together with some care, creating quite complex models. |
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Revision as of 22:22, 5 May 2021
Overview
There has been much discussion of this over the years about the differences and ramifications of using the Part and the PartDesign workbenches.
It is a good idea to use one or the other until the user is comfortable with one, then learn the other. It is also typically recommended that new users not mix them until the ramifications are of doing so are understood.
Let's talk about those ramifications.
Part Workbench Concepts
It is often said Part WB is more CSG style modeling. This is where the operator combines various primitives to end up with a lump in the desired shape. (In fact Part WB goes one step further than just primitives and allows the operator to use a sketch+extrude operation to create random shapes as well.) When each primitive or shape is created, it has no relationship to other objects created, it is a single solitary solid.
This condition remains so, until, the operator uses some operation to combine them (typically a Boolean that adds or subtracts them).
The take away is the single solitary solid bit and the combining them bit.
PartDesign Workbench Concepts
In the PartDesign WB the Body object represents a single solitary cumulative solid. The first lump created under the Body (be it a Pad from a sketch, or a BaseFeature from outside the Body) represents a lump of raw material that will be further processed to refine it to the desired final shape (solid). It is cumulative in the sense that each operation adds or removes material. The lowest/last operation (the current Tip of the Body) is the current state. Any other feature under the Body but above the Tip, does not represent a complete/stand alone solid. Only the Body (basically a proxy for the tip) or the Tip represent a complete solid.
This image shows a Body. It is a cumulative solid that consists of a padded sketch and a cone primitive. This is a single solid. Neither the pad or the cone can exist separately.
(Another thing mentioned often is a Body MUST be a single contiguous solid. This means all geometry created by a feature in the Body must touch it's predecessor.)
The Ramifications
People get caught when they attempt to use some feature under the Body (rather than the Body itself) as one selection of a Part WB Boolean operation. This is a problem, because the selected feature does not represent a complete solid.
In a sense, from a Part WB standpoint, the Body represents another primitive. So, using a Body (remember it is a proxy for the tip) and a Part WB object to do a Boolean is valid. But the resulting object is a Part WB object. And, thus PartDesign WB tools can't be used on it any longer.
And, it can get even more complicated. If you create a new Body and drag the result from the previous paragraph into it, a BaseObject is created. And you can go off an use the PartDesign WB tools on it.
The Caveats
There is a caveat with the Tip and it's representation of the single solid in the Body. If the tip is a subtractive feature and is used in a dress up operation, for instance a Mirror, the Mirror is operating on the underlying feature (a pocket for example). Thus the cumulative solid is not mirrored, but the subtractive feature is. The result of this must create a single solid.
In this example, a mirror of the tip (which is the pocket of the slot) around any of the base planes, or even a face of the solid will not produce a mirrored solid of the entire model. (In fact, it will produce a Mirrored feature in the tree that is essentially empty.)
In this example, a mirror of the tip (which is the pocket of the slot) is performed around the datum plane and produces a mirrored slot:
See the PartDesign Mirrored tool wiki page for more information.
Conclusion
Part and PartDesign workbenches can be used together with some care, creating quite complex models.
- Primitives: Box, Cylinder, Sphere, Cone, Torus, Tube, Create primitives, Shape builder
- Creation and modification: Extrude, Revolve, Mirror, Fillet, Chamfer, Make face from wires, Ruled Surface, Loft, Sweep, Section, Cross sections, 3D Offset, 2D Offset, Thickness, Projection on surface, Attachment
- Boolean: Make compound, Explode Compound, Compound Filter, Boolean, Cut, Fuse, Common, Connect, Embed, Cutout, Boolean fragments, Slice apart, Slice, XOR
- Measure: Measure Linear, Measure Angular, Measure Refresh, Clear All, Toggle All, Toggle 3D, Toggle Delta
- Structure tools: Part, Group
- Helper tools: Create body, Create sketch, Edit sketch, Map sketch to face
- Modeling tools
- Datum tools: Create a datum point, Create a datum line, Create a datum plane, Create a local coordinate system, Create a shape binder, Create a sub-object(s) shape binder, Create a clone
- Additive tools: Pad, Revolution, Additive loft, Additive pipe, Additive helix, Additive box, Additive cylinder, Additive sphere, Additive cone, Additive ellipsoid, Additive torus, Additive prism, Additive wedge
- Subtractive tools: Pocket, Hole, Groove, Subtractive loft, Subtractive pipe, Subtractive helix, Subtractive box, Subtractive cylinder, Subtractive sphere, Subtractive cone, Subtractive ellipsoid, Subtractive torus, Subtractive prism, Subtractive wedge
- Transformation tools: Mirrored, Linear Pattern, Polar Pattern, Create MultiTransform, Scaled
- Dress-up tools: Fillet, Chamfer, Draft, Thickness
- Boolean: Boolean operation
- Extras: Migrate, Sprocket, Involute gear, Shaft design wizard
- Context menu: Set tip, Move object to other body, Move object after other object, Appearance, Color per face
- General: Create sketch, Edit sketch, Map sketch to face, Reorient sketch, Validate sketch, Merge sketches, Mirror sketch, Leave sketch, View sketch, View section, Toggle grid, Toggle snap, Configure rendering order, Stop operation
- Sketcher geometries: Point, Line, Arc, Arc by 3 points, Circle, Circle by 3 points, Ellipse, Ellipse by 3 points, Arc of ellipse, Arc of hyperbola, Arc of parabola, B-spline by control points, Periodic B-spline by control points, B-spline by knots, Periodic B-spline by knots, Polyline, Rectangle, Centered rectangle, Rounded rectangle, Triangle, Square, Pentagon, Hexagon, Heptagon, Octagon, Regular polygon, Slot, Fillet, Corner-preserving fillet, Trim, Extend, Split, External geometry, Carbon copy, Toggle construction geometry
- Sketcher constraints:
- Geometric constraints: Coincident, Point on object, Vertical, Horizontal, Parallel, Perpendicular, Tangent, Equal, Symmetric, Block
- Dimensional constraints: Lock, Horizontal distance, Vertical distance, Distance, Radius or weight, Diameter, Auto radius/diameter, Angle, Refraction (Snell's law)
- Constraint tools: Toggle driving/reference constraint, Activate/deactivate constraint
- Sketcher tools: Select unconstrained DoF, Select associated constraints, Select associated geometry, Select redundant constraints, Select conflicting constraints, Show/hide internal geometry, Select origin, Select horizontal axis, Select vertical axis, Symmetry, Clone, Copy, Move, Rectangular array, Remove axes alignment, Delete all geometry, Delete all constraints
- Sketcher B-spline tools: Show/hide B-spline degree, Show/hide B-spline control polygon, Show/hide B-spline curvature comb, Show/hide B-spline knot multiplicity, Show/hide B-spline control point weight, Convert geometry to B-spline, Increase B-spline degree, Decrease B-spline degree, Increase knot multiplicity, Decrease knot multiplicity, Insert knot, Join curves
- Sketcher virtual space: Switch virtual space
- Additional: Sketcher Dialog, Preferences, Sketcher scripting
- Getting started
- Installation: Download, Windows, Linux, Mac, Additional components, Docker, AppImage, Ubuntu Snap
- Basics: About FreeCAD, Interface, Mouse navigation, Selection methods, Object name, Preferences, Workbenches, Document structure, Properties, Help FreeCAD, Donate
- Help: Tutorials, Video tutorials
- Workbenches: Std Base, Arch, Assembly, CAM, Draft, FEM, Inspection, Mesh, OpenSCAD, Part, PartDesign, Points, Reverse Engineering, Robot, Sketcher, Spreadsheet, Surface, TechDraw, Test Framework
- Hubs: User hub, Power users hub, Developer hub