1.4.14 - Skill Check - Level 02
1.4.14 - Skill Check - Level 02
Section titled “1.4.14 - Skill Check - Level 02”🛠️ Skill Check: The 3D Print Jig Challenge
Objective: Demonstrate precision measurement, hand-tool proficiency, and mechanical assembly by creating a matching component for a “blind” 3D printed fixture.
Objective: Use the interactive viewer below to inspect the assembly, check hole alignments, and understand the internal component layout.
🚦 The Challenge Rules
- The Observation: You have 5 minutes to inspect the 3D printed Jig. You may measure it, but you cannot keep it.
- The Blueprint: You must create a hand-sketch “drawing” of your tube requirements (length, hole locations, and diameters).
- The Fabrication: Once the 5 minutes are up, the Jig is taken away. You must cut your 1x2 tube and drill all holes using only your drawing.
- The Assembly: You receive the Jig back only when your tube is finished. You must select the correct hardware and assemble the parts without damage.
📊 Technical Evaluation Matrix
| Category | Emerging (1 pt) | Proficient (2 pts) | Mastery (3 pts) |
|---|---|---|---|
| The Blueprint (Drawing) | Missing info or uses vague terms like “middle.” | All 4-5 holes have dimensions, but not measured from datum corner. | Fully constrained drawing; includes bit sizes (e.g., #21 for 10-32 tap). And Dimensions are measured from a single datum corner. |
| Precision Cut (1x2 Tube) | Tube is ±1/8” or cut has a visible “bevel” (not 90°). Holes are too large/small. | Tube is within ±1/16”; cut is square enough to stand on end without tipping. Holes are not of correct diameter. | Tube is within ±1/32”; cut is perfectly square (checked with a machinist square). And holes are correct diameter. |
| Hole Alignment (Y-Axis) | Holes are “stair-stepped” or drifted off center-line of the tube. | All holes are centered on the 1x2 face; bolts pass through with light pressure. | Holes are perfectly linear; 3D print “drops” onto the tube with zero friction. |
| Hardware & Thread Care | Picked 8-32 or other screw by mistake; stripped threads on the tapped insert. | Correct 10-32 hardware selected; bolts thread into inserts by hand. | Hardware length is optimal (0.25” past nut); washers used to protect the 3D print. |
| Fastening Torque | Fasteners are loose/spinning OR the 3D print shows white stress fractures. Alumiunium tube shows screw compression and is bent. | Part is rigid; bolt heads are flush but print shows slight “sink” into plastic. Slight deformation on aluminium part. | Perfect Torque: Part is immovable; no deformation or “crazing” on the 3D printed Jig or aluminium. |
🔍 Visual Reference for “Mastery”
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The “Datum” Layout To hit Mastery on the drawing, students should not measure from “hole to hole.” They should pick one corner as (0,0) and measure every hole from that same point. This prevents “Tolerance Stack-up” where small errors add up to one big mistake at the end.
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Squaring the Cut A “Mastery” cut isn’t just the right length; it’s perpendicular in both directions. If the student cuts at an angle, the 3D print will sit crookedly on the tube, causing the bolts to bind.
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Mechanical Sympathy (Torque) Students often think “tighter is better.” In this challenge, they must account for the Compressive Strength of the 3D print.
- Mastery: The nut is “Snug-plus-a-quarter-turn.”
- Failure: Using a drill/driver to “impact” the bolt until the plastic cracks.
📝 Final Checkout Checklist
- Deburring: Did the student file the sharp edges of the tube? (Automatic -1 if sharp).
- Swart Management: Is the student’s work area clean of metal chips? (Automatic -1 if messy)
- Tool Return: Are the drill bits, calipers, and squares back in their labeled foam cutouts? (Automatic -1 if not returned)
Total Score: _____ / 15 (12+ required for Level 1 Fabrication Sign-off)