Extruded cut in Solidworks - Deep Dive

Overview - Extruded cut

What is it?

An extruded cut is a feature in SolidWorks that removes material from a 3D model by extending a 2D sketch shape straight through the part. It works like pushing a cookie cutter through dough to create a hole or cavity. This tool helps shape parts by cutting away unwanted sections based on the sketch. It is one of the most common ways to modify solid models.

Why it matters

Without extruded cuts, designers would struggle to create holes, slots, or complex shapes inside parts easily. It solves the problem of shaping 3D objects by removing material precisely where needed. This makes manufacturing designs accurate and efficient, saving time and reducing errors. Without it, parts would be bulky, less functional, and harder to produce.

Where it fits

Before learning extruded cuts, you should understand basic 3D modeling and how to create sketches in SolidWorks. After mastering extruded cuts, you can learn more advanced features like revolved cuts, lofted cuts, and combining multiple features for complex designs.

Mental Model

Core Idea

An extruded cut is like pushing a flat shape straight through a solid to carve out material along that path.

Think of it like...

Imagine using a cookie cutter pressed straight down into dough to cut out a shape. The cookie cutter's shape is the sketch, and the dough is the solid part. The cut removes the dough inside the cutter's shape.

┌─────────────┐
│   Sketch   │
│  (2D shape) │
└─────┬───────┘
      │ Extrude cut direction
      ▼
┌─────────────┐
│   Solid    │
│  (3D part) │
└─────────────┘

Cut removes material along the arrow path inside the sketch shape.

Build-Up - 7 Steps

1

Foundation

Understanding 2D Sketches

Concept: Learn what a 2D sketch is and how it defines shapes on a flat plane.

In SolidWorks, a sketch is a drawing made on a flat surface. It uses lines, circles, and other shapes to create a closed outline. This outline is the base for creating 3D features. Without a closed sketch, you cannot make an extruded cut because the software needs a defined area to remove material.

Result

You can create simple shapes like rectangles or circles on a plane, ready to be used for cutting or adding material.

Understanding sketches is crucial because every 3D feature, including cuts, starts from a 2D shape.

2

Foundation

Basics of Extrusion

Concept: Learn how extrusion turns a 2D sketch into a 3D shape by extending it in one direction.

Extrusion takes your flat sketch and stretches it straight out to add or remove material. For an extruded cut, the extrusion removes material inside the sketch area. You choose how far to extrude and in which direction. This is the simplest way to create holes or slots.

Result

A flat sketch becomes a 3D cut that removes material from the part.

Extrusion connects 2D sketches to 3D modeling by adding depth, enabling precise shaping.

3

Intermediate

Defining Cut Depth and Direction

🤔Before reading on: Do you think extruded cuts can only go one way or both ways? Commit to your answer.

Concept: Learn how to control how far and in which direction the cut removes material.

When creating an extruded cut, you can specify the depth of the cut, such as 10 mm deep. You can also choose to cut in one direction, both directions, or up to a surface. This flexibility lets you make shallow holes or cuts that go completely through the part.

Result

Cuts can be shallow, deep, or through the entire part, depending on settings.

Knowing how to control cut depth and direction allows precise control over the part's shape and function.

4

Intermediate

Using Sketch Relations for Accuracy

🤔Before reading on: Do you think sketch relations affect the cut shape after extrusion? Commit to your answer.

Concept: Learn how sketch constraints keep your cut shape accurate and linked to other features.

Sketch relations are rules like 'this line is horizontal' or 'this circle is centered here.' They keep your sketch stable and predictable. When you extrude a cut, these relations ensure the cut shape stays correct even if you change other parts of the model.

Result

Cut shapes remain consistent and update automatically with design changes.

Using sketch relations prevents errors and saves time by making your cuts adaptable.

5

Intermediate

Cutting Through Complex Geometry

Concept: Learn how extruded cuts interact with complex shapes and multiple bodies.

Extruded cuts can remove material from parts with curves, holes, or multiple solid bodies. You can select which body to cut or cut through all bodies. This allows creating complex internal features like channels or pockets inside parts.

Result

You can create detailed internal shapes by cutting through complex models.

Understanding how cuts work with complex geometry expands your design possibilities.

6

Advanced

Advanced Cut Options and Features

🤔Before reading on: Can extruded cuts be combined with other features like patterns? Commit to your answer.

Concept: Explore advanced options like draft angles, thin cuts, and patterning extruded cuts.

You can add draft angles to cuts to taper the walls, useful for molding. Thin cuts let you create narrow slots by cutting only a thin area around a sketch line. You can also pattern extruded cuts to repeat holes or slots evenly across a part.

Result

Cuts become more versatile and tailored to manufacturing needs.

Mastering advanced cut options lets you design parts ready for real-world production.

7

Expert

Performance and Feature Management

🤔Before reading on: Do you think many extruded cuts slow down your model? Commit to your answer.

Concept: Learn how multiple extruded cuts affect model performance and how to manage them efficiently.

Each extruded cut adds complexity to the model. Too many cuts can slow down software performance. Experts use techniques like combining cuts, suppressing unused features, or using configurations to keep models fast. Understanding feature order also helps avoid rebuild errors.

Result

Models stay responsive and easier to edit even with many cuts.

Knowing how to manage extruded cuts in large models prevents slowdowns and errors in professional design work.

Under the Hood

When you create an extruded cut, SolidWorks takes the 2D sketch profile and projects it along a straight path into the 3D solid. It calculates the intersection between the extrusion volume and the solid body, then removes the overlapping material. The software updates the model's geometry and recalculates features downstream to keep the design consistent.

Why designed this way?

Extruded cuts were designed to be simple and intuitive, reflecting how people think about shaping objects by pushing or pulling shapes. This method is computationally efficient and easy to control, making it accessible for beginners and powerful for experts. Alternatives like sculpting or mesh editing are more complex and less precise for engineering parts.

┌─────────────┐
│ 2D Sketch   │
└─────┬───────┘
      │ Extrude direction
      ▼
┌─────────────┐
│ Solid Body  │
│ ┌─────────┐ │
│ │ Cut Vol │ │
│ └─────────┘ │
└─────────────┘

Cut volume intersects solid and removes material inside.

Myth Busters - 4 Common Misconceptions

Quick: Does an extruded cut always remove material through the entire part? Commit yes or no.

Common Belief: Extruded cuts always go through the entire part.

Reality: Extruded cuts can be set to any depth, including shallow cuts that do not go through the whole part.

Why it matters: Assuming cuts always go through can cause design errors, like unintended holes or weak spots.

Quick: Can you create an extruded cut without a closed sketch? Commit yes or no.

Common Belief: You can extrude cut with any sketch, even if it is open.

Reality: The sketch must be closed to define a valid cut area; open sketches cannot create extruded cuts.

Why it matters: Trying to cut with open sketches leads to errors and wasted time troubleshooting.

Quick: Does changing the sketch after creating an extruded cut break the cut? Commit yes or no.

Common Belief: Once created, extruded cuts are fixed and do not update with sketch changes.

Reality: Extruded cuts update automatically when the underlying sketch changes, keeping the model consistent.

Why it matters: Knowing this helps designers confidently modify sketches without fear of breaking the model.

Quick: Do extruded cuts always reduce file size and complexity? Commit yes or no.

Common Belief: Extruded cuts simplify models and reduce file size.

Reality: Extruded cuts add features and can increase model complexity and file size, especially if overused.

Why it matters: Ignoring this can cause slow performance and difficulty managing large models.

Expert Zone

1

Extruded cuts can be combined with configurations to create multiple design variants efficiently.

2

The order of features affects how extruded cuts interact with other features, impacting final geometry.

3

Using thin extruded cuts can save time and improve performance compared to multiple small cuts.

When NOT to use

Avoid extruded cuts when the shape to remove is curved or complex in multiple directions; use lofted or swept cuts instead. For organic shapes, consider surface modeling or mesh editing tools.

Production Patterns

In production, extruded cuts are often used with patterns to create arrays of holes for screws or ventilation. Designers also use them with draft angles to prepare parts for molding and casting.

Connections

Injection Molding Draft

Builds-on

Understanding extruded cuts with draft angles helps design parts that release easily from molds, connecting CAD modeling to manufacturing.

Database Query Filters

Same pattern

Both extruded cuts and query filters remove unwanted parts—extruded cuts remove material from solids, filters remove data from sets—showing a shared concept of selective removal.

Sculpting in Digital Art

Opposite approach

Extruded cuts remove material by defined shapes, while sculpting adds or subtracts material freely; comparing them highlights different modeling philosophies.

Common Pitfalls

#1 Trying to extrude cut with an open sketch.

Wrong approach:

Select an open line sketch and attempt extruded cut; SolidWorks shows error or no cut is created.

Correct approach:

Close the sketch by connecting endpoints before extruding the cut.

Root cause:

Misunderstanding that extruded cuts require closed profiles to define a valid cut area.

#2 Setting cut depth too shallow or too deep unintentionally.

Wrong approach:

Extrude cut depth set to 0 mm or beyond part thickness, causing no cut or full part removal.

Correct approach:

Specify correct cut depth based on part thickness or use 'Through All' option for full cuts.

Root cause:

Not verifying cut depth leads to unexpected geometry changes.

#3 Ignoring feature order causing cut to fail or behave unexpectedly.

Wrong approach:

Creating extruded cut before the base feature it depends on, causing rebuild errors.

Correct approach:

Ensure base features exist before applying extruded cuts and reorder features if needed.

Root cause:

Lack of understanding of feature dependency and rebuild sequence in SolidWorks.

Key Takeaways

Extruded cuts remove material by extending a 2D sketch shape straight through a solid part.

A closed sketch is essential to create a valid extruded cut.

Cut depth and direction control how much and where material is removed.

Advanced options like draft angles and thin cuts tailor cuts for manufacturing needs.

Managing feature order and model complexity keeps designs efficient and error-free.