5.1 Extrude Boss/Base End Conditions
Key Takeaways
- Extruded Boss/Base turns a closed sketch contour into solid material; the end condition controls how far and against what the solid grows from the sketch plane.
- Blind uses a typed depth; Mid Plane splits depth both ways; Through All and Up To Next/Surface/Vertex link the solid to existing geometry so modifications can update the extrude without retyping depth.
- Offset From Surface and From/To (or similar surface-bounded options) are exam tools when the drawing shows a boss that must stop a fixed offset from a face or span between two references.
- Direction reverse flips which side of the sketch plane receives material; wrong direction is a silent mass killer if the sketch is not midplane-symmetric.
- Merge result combines the new solid with the existing body when checked; unchecking can create multibody parts that break later cuts or mass assumptions on CSWA.
5.1 Extrude Boss/Base End Conditions
Quick Answer: Extruded Boss/Base adds solid material from a sketch. Choose the end condition that matches the drawing: Blind (typed depth), Mid Plane (symmetric both sides), Through All / Up To Next / Up To Surface / Up To Vertex / Offset From Surface / From–To when depth is defined by existing geometry. Set direction, optional draft, and Merge result before OK. Wrong end condition or reverse direction changes volume and mass—CSWA’s graded answer.
On the Certified SOLIDWORKS Associate (CSWA) exam, basic and advanced part questions almost always begin with a profile sketch and an Extruded Boss/Base (or Extrude). Getting the sketch right is necessary but not sufficient: the end condition decides how much solid exists after the feature. Because answers are mass, volume, or center of mass, a 2 mm depth error or an extrude that stops short of a mating face is a full-point miss—even if the plan-view sketch is perfect.
Boss/Base workflow on CSWA
- Fully define a closed contour (or select the correct region with Contour Select—covered in 5.3).
- Start Features → Extruded Boss/Base (or Extrude).
- In the PropertyManager, set Direction 1 end condition, depth or reference, and optional reverse.
- Optionally enable Direction 2, Draft, Thin Feature, or clear Merge result only when you truly need a separate body.
- Preview the translucent solid; confirm it fills the volume the drawing implies, then OK.
- On modification steps, edit the extrude feature (or its driving sketch) and rebuild before recomputing mass.
The first extrude in a new part is often called a Base; later extrudes that add material are Bosses. The dialog is the same tool.
End condition reference table
| End condition | What you specify | Solid behavior | Typical CSWA cue |
|---|---|---|---|
| Blind | Depth value (e.g., 25 mm) | Extrudes that distance from the sketch plane in the chosen direction | Section view shows a numeric thickness/height |
| Through All | Direction only | Continues through all existing geometry in that direction (boss use is rarer; see cuts) | More common on cuts; for bosses, usually when building against a multibody context |
| Up To Next | Direction | Stops at the next face the extrude encounters | Boss should land flush on the next wall/face without a typed depth |
| Up To Surface | Selected face/surface | Stops on that surface (even if not the “next” one) | Drawing ties boss height to a named/planar face |
| Up To Vertex | Selected vertex | Stops in a plane parallel to the sketch plane through that vertex | Height defined by a corner or tip on the model |
| Offset From Surface | Surface + offset distance | Stops offset from the surface (toward or away per options) | Boss ends 3 mm short of a face, or clearance gap |
| Mid Plane | Total depth | Half the depth each side of the sketch plane | Symmetric thickness about the sketch plane / midplane |
| From/To (or From Surface / Up To Surface pair) | Start reference + end reference | Bounds the solid between two surfaces/planes | Thickness spans between two given faces rather than from sketch plane alone |
Exact menu labels can vary slightly by SOLIDWORKS version, but the concepts above are what CSWA drawings test: numeric depth, symmetric depth, or geometry-driven depth.
Blind — the default thickness tool
Blind is the most common boss end condition on CSWA base plates, blocks, and prismatic bosses. You type the depth that matches the drawing (often the thickness in a side view). Confirm document units (MMGS is frequent) so “12” means 12 mm, not 12 inches.
Design intent: Blind is ideal when thickness is an independent parameter the exam will later change (“change base thickness from 10 mm to 12 mm”). Keep thickness as the feature depth, not a second sketch dimension on an edge-on profile, unless the problem was clearly modeled that way.
Trap: Preview can look “thick enough” while the value is wrong. Always re-read the section-view thickness after typing. A factor-of-two error (confusing radius-like callouts or reading the wrong view) destroys mass.
Mid Plane — symmetry about the sketch plane
Mid Plane extrudes half the total depth in each direction. If the sketch sits on the Front plane and the part is symmetric front-to-back, Mid Plane with total depth equal to overall thickness keeps the midplane at the sketch plane—excellent for assembly mating later and for center-of-mass on the origin plane.
When the exam modifies thickness, Mid Plane keeps both sides balanced. Blind on one side only would shift material entirely to one side of the sketch plane and move center of mass even if volume matched—an advanced trap when CoM is scored.
Geometry-driven ends: Up To Next, Up To Surface, Up To Vertex
These conditions link the boss to existing solid faces so you do not hard-code a depth that becomes wrong after an upstream edit.
- Up To Next: Useful when a secondary boss should stop exactly when it hits the next body face along the extrude direction—for example, a rib or pad growing until it meets a wall. If nothing is “next,” the feature fails or behaves unexpectedly—check direction.
- Up To Surface: Pick a specific face (planar or otherwise, depending on capability). Prefer this when “next” is ambiguous because multiple faces could be hit first.
- Up To Vertex: Height is controlled by a vertex’s position parallel to the sketch plane. Handy when a tapered or stepped part has a clear corner that defines stop height without a clean planar face at that elevation.
CSWA modification angle: If the wall you extrude up to moves because you changed another feature, Up To Surface/Next updates automatically. A Blind depth would stay fixed and leave a gap or intersection—wrong volume.
Offset From Surface and From/To
Offset From Surface stops the extrude a specified distance from a face. Exam drawings sometimes show a boss that must leave a clearance gap, or a pad that ends 5 mm below a top face. Model that as offset, not as Blind with a hand-calculated depth that you forget to update when the reference face moves.
From/To (and related “start condition” options in modern PropertyManagers) let the solid begin and end at chosen references rather than always starting at the sketch plane. Use when the sketch plane is a construction midplane or offset plane, but the solid must live only between two model faces. Mis-setting start conditions leaves material on the wrong side of a reference—again a mass error.
Direction reverse
The extrude arrow in the graphics area shows Direction 1. Reverse Direction flips material to the opposite side of the sketch plane. On a Front-plane sketch of a bracket elevation, reverse chooses whether the solid grows “into” the screen or “out.”
Checklist:
- Does the isometric or section on the exam sheet put material on the side you preview?
- If you used Mid Plane, reverse is less critical for symmetry about the plane, but Direction 2 options and drafts still need care.
- For bosses added onto existing faces, sketching on a face and extruding away from the solid vs into the solid changes boss vs accidental multibody/intersection behavior.
Wrong reverse with Blind depth still “uses the right number” but places volume incorrectly relative to holes, fillets, or coordinate systems used for CoM.
Draft while extruding (intro)
The Extrude PropertyManager can apply draft as the feature builds—angles the side walls outward or inward by a typed angle. CSWA may show a simple drafted boss rather than a separate Draft feature (Draft feature is covered later in the guide).
Intro rules for the exam:
- Draft while extruding is convenient for a single prismatic boss with uniform draft from the sketch.
- Confirm draft outward vs inward against the drawing (mold-style callouts or section angles).
- Draft changes cross-section along the depth, so volume is not simply sketch-area × depth. If you ignore a 3° draft, mass will be wrong even with correct end depth.
- Complex multi-face draft or neutral-plane draft is usually a dedicated Draft feature after the boss exists.
Merge result
Merge result (typically checked by default when a solid body already exists) fuses the new boss into the existing body so you still have one solid. CSWA part questions almost always expect a single body for mass properties unless the problem is explicitly multibody.
If Merge result is unchecked:
- You create an additional body.
- Later Extruded Cut end conditions, shells, or mass tools may not behave as you assume.
- Some exam workflows break (cut does not remove material from the body you think is active).
Leave Merge result on unless you have a deliberate multibody reason (uncommon on standard CSWA mechanical design parts).
Direction 2 and two-direction blinds
You can enable a second direction with its own end condition and depth. Example: sketch on a mid construction plane; Direction 1 Blind 10 mm one way, Direction 2 Blind 15 mm the other for an asymmetric total of 25 mm. Prefer Mid Plane when the drawing is symmetric; use dual directions when the drawing is intentionally asymmetric about the sketch plane.
Exam workflow: matching the sheet to an end condition
| Drawing evidence | Prefer |
|---|---|
| Numeric thickness only; first feature in empty part | Blind (or Mid Plane if symmetry about sketch plane) |
| Boss height equals distance to an existing face | Up To Surface or Up To Next |
| Height set by a pointed corner | Up To Vertex |
| Gap or stand-off from a face | Offset From Surface |
| Symmetric about sketch plane | Mid Plane |
| Material only between two faces | From/To style bounds |
| Side walls angled in section | Draft on extrude or separate Draft feature |
Worked mental model
A base plate sketch on Top plane, overall 100 × 60 mm, thickness 8 mm, symmetric about Top: Mid Plane, depth 8 mm, Merge N/A (first feature). A rectangular pad sketched on the top face should use Blind 12 mm away from the plate (confirm arrow). A rib sketched on a midplane that must meet an outer wall should use Up To Next or Up To Surface on that wall so when overall width changes, the rib still meets the wall. After a modification “base thickness → 10 mm,” edit the base Mid Plane depth; pad Blind stays 12 mm unless the problem also changes it; mass updates from base volume change only.
Pre-OK checklist for every boss on CSWA
- Correct contour selected; sketch fully defined.
- End condition matches drawing language (number vs face-driven).
- Depth/offset value and units correct.
- Direction arrow agrees with isometric/section.
- Draft angle present only if the drawing shows draft.
- Merge result on for single-body parts.
- Preview volume looks complete—no unintended gaps to target faces.
Master end conditions and you control volume at the feature level. The next section applies the same PropertyManager logic to removing material with Extruded Cut—the other half of almost every CSWA part score.
A CSWA base plate sketch lies on the Top plane and the part must be 12 mm thick, symmetric above and below that plane. Which Direction 1 end condition best matches that intent?
Why prefer Up To Surface over a hand-calculated Blind depth when a pad must end exactly on an existing planar face?
On a part that already has a solid body, what does leaving Merge result checked typically do for a new Extruded Boss?
You enter the correct Blind depth but reverse the extrude direction relative to the exam isometric. What is the most likely scoring impact?