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Week 07 - Computer Controlled Machining

CNC Machining

SSTM

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This lesson is all about computer controlled machine, and Lesson i will focussed is:

  • Importance of proper feeds and speeds
  • CNC fixturing is critical
  • Parametric design saves time
  • Press-fit tolerances must be tested
  • Three-axis toolpaths improve surface quality

Individual Assignment

Assignment Objective

Design, mill, and assemble a meter-scale object using CNC machining.

For more Credit Goals I am trying to work to meet: - No glue or fasteners - Include curved surfaces - Use three-axis toolpaths

My Project: CNC Modular Stool (~1 Meter Scale)

I designed a large interlocking modular stool made from 18mm plywood. The structure uses press-fit joints and curved side panels.

1. Design Phase

Software Used - Fusion 360

Design Features - Height: 900 mm - Width: 400 mm - Slot-based interlocking system - Parametric design (material thickness adjustable) - Curved side panels - Internal support ribs

Joint Design - Press-fit joints (18mm material + 0.2mm tolerance adjustment) - Dogbone fillets for internal corners - No glue used - No screws in final assembly

2. CAM Preparation

Tool Used - 6mm Flat End Mill

Operations - 2D Pocket (internal cutouts) - 2D Profile (outer shape) - Tabs added for stability - Dogbone fillet toolpath - Three-axis finishing pass on curved surface

Toolpath Settings - Spindle Speed: 18000 RPM - Feed Rate: 2500 mm/min - Stepdown: 3 mm - Stock thickness: 18 mm plywood alt text

3. Milling Process

Steps 1. Secured plywood sheet to bed using screws 2. Zeroed machine (X, Y, Z) 3. Verified toolpath simulation 4. Turned on dust extraction 5. Started machining 6. Supervised entire process

4. Assembly

After cutting: - Removed tabs manually - Sanded edges - Press-fit parts together - Assembled structure without glue or screws

The joints were tight and stable. The structure supports full body weight.

Final Result

  • Meter-scale object
  • No glue
  • No fasteners
  • Curved surfaces included
  • Three-axis toolpath used

Challenges

  • Initial joints too tight → adjusted tolerance
  • Minor tear-out on plywood edges
  • Needed sanding for smoother fit alt text

Documentation Images

week07 Group assignment

Neccessary links for inventory seek
https://inventory.fabcloud.io/