Week 7 — Computer-controlled machining

This week’s topic: Computer-controlled machining. For my individual assignment I designed a flat-pack little dog bed, exported 2D joint geometry as DXF, generated toolpaths in Mastercam X6, and cut the parts on the lab wood CNC (TC1325B). Below I document the design intent, CAM settings, full machine workflow, assembly, and downloadable source files. The group section keeps the shared TC1325B safety and operating procedure we documented in the lab.

Individual assignment — little dog bed (design + CNC + assembly)

Why a dog bed

The Fab “make something big” brief pushes you to think at furniture scale: joints, sheet nesting, and a machine that can hurt you if you treat it casually. I wanted an object that was personal but still forced me through the full loop—2D CAD → CAM → fixturing → cut → dry-fit → assemble. A small dog bed fit that: flat panels with visible joinery, a curved headboard and footboard for character, and a finished piece I could actually use at home instead of a throwaway test bracket.

I measured our board stock at about 18.2 mm and designed the slot-and-tab joints around that thickness rather than assuming “18 mm on the label.” That single number drove every pocket width and every clearance decision later in Mastercam.

How this page meets the assignment

Mapping to the Fab Academy computer-controlled machining checklist:

Requirement	Evidence on this page
Linked group assignment	Group section — TC1325B procedure and safety
Documented object design	Design — flat-pack panels, 18.2 mm joints
Documented CAM / toolpaths	Mastercam X6 — contour ops, tool, feeds
Documented machining (fixturing, feeds, depth, joints)	CNC cutting — setup photos and video
Problems and fixes	Lessons
Design files + hero shot	Downloads; hero photo

Design — flat-pack panels and joints

I modeled the bed as separate 2D profiles meant to be cut from one sheet and assembled with press-fit slots: two end panels with curved tops (headboard and footboard), two long side rails with matching notches, and a rectangular base platform. Every slot is sized for 18.2 mm material—the measured thickness of our density board—so the tabs on the crossing members should slide in without guessing at the label thickness.

The curved silhouette on the end panels is decorative but still CNC-friendly: outside contours and interior pockets only, no impossible inside corners without planning for tool radius. I exported the layout as DXF for the lab CAM station rather than trying to post G-code myself on the first pass.

CAM — Mastercam X6 toolpaths

At the lab we opened the DXF in Mastercam X6, defined the stock, and built 2D contour toolpaths for the outlines and joint pockets. I watched the sequencing closely because this was the first time I saw how “inside before outside” keeps the sheet stable while small features are still tied to the parent panel.

Parameters I recorded from the CAM session:

Tool: 8 mm flat end mill (#1 — M8.00 FLAT in the toolpath manager)
Spindle speed: 15 000 rpm
Feed rate: 5 000 mm/min
Cut type: 2D contour / 外形铣削 with step-down entry (步降下刀)
Compensation: computer (left), wall stock −0.2 mm for joint clearance
Ramp depth: 3.0 mm on contour entry
Operations: two contour groups — 18 chained loops (interior features and detail) and 5 chained loops (outer separation)

The negative wall stock was the detail I did not appreciate until assembly: a hair of extra width on slots makes press-fit parts actually go together after a real bit radius, without redrawing every pocket in CAD.

Mastercam X6 contour toolpath menu over the dog bed DXF layout — Figure 1: Opening the **Contour** (外形铣削) toolpath on the nested dog-bed panels.

Mastercam chaining options for selected contour geometry — Figure 2: Chaining geometry — selecting closed loops before posting cuts.

Mastercam contour parameters: 8 mm tool, 5000 mm/min feed, −0.2 mm wall stock — Figure 3: Contour settings — 8 mm flat tool, 15 000 rpm, 5 000 mm/min feed, −0.2 mm wall stock for slot clearance.

Mastercam toolpath manager listing two contour operations for the dog bed — Figure 4: Toolpath manager — two contour groups (18 chains + 5 chains) before posting G-code.

CNC cutting — machine setup and run

I followed the same TC1325B sequence documented in the group assignment, but this section is my own job: loading the posted .NC file, fixturing the panel, setting work zero, and supervising the cut through to free parts. The controller preview showed the nested bed outlines before we started the spindle.

1. Load G-code

CNC controller displaying the dog bed G-code preview — Figure 5: G-code loaded — wireframe preview of nested bed panels on the controller.

2. Place and clamp the panel

Placing the MDF panel on the CNC table — Figure 6: Panel placed within machine travel, table cleaned first.

Clamping the workpiece on the CNC bed — Figure 7: Toe clamps — firm hold without interfering with the toolpath.

3. Tool, guard, and Z setup

Installing the CNC end mill — Figure 8: Tool change — 8 mm flat end mill installed with spindle stopped.

Spindle dust guard closed — Figure 9: Dust hood / guard closed before the run.

Operator confirming Z height and parameters at the CNC controller — Figure 10: Touching off Z and confirming parameters against the CAM setup.

4. Run and monitor

I stayed at the machine for the full job, dust extraction on, listening for chatter or loose parts. When inner pockets finished before outer contours, the sheet still had enough connection to stay put—exactly why we sequenced small/internal cuts first in CAM.

Figure 11: Video — spindle start and beginning of the cut.

Figure 12: Video — mid-cut with dust collection engaged.

CNC bed after cutting — dog bed parts still tabbed in the sheet — Figure 13: Cut complete — parts still in the sheet; slots and curved profiles visible in the swarf.

Assembly

After breaking parts out and brushing off chips, I dry-fit the rails into the end panels, then pressed the base platform into the slot grid. The −0.2 mm CAM wall stock was enough that I did not need aggressive filing, though I still checked each inside corner where the round bit left a small radius.

Assembled little dog bed — hero shot with curved headboard and footboard — Figure 14 (hero): Assembled dog bed — press-fit joinery, level on a flat surface, ready for a cushion.

Problems, checks, and what I would change

Design for measured thickness: modeling at “18 mm” would have been wrong; the real board was 18.2 mm. I will keep thickness as a named parameter in future flat-pack CAD.
Clearance belongs in CAM, not hope: the −0.2 mm wall stock did more for fit than redrawing slots by eye. Next time I would still run a small test pocket before committing the full sheet.
Cut order matters: interior pockets before outer contours kept the panel stable; I saw why Alison’s write-up stressed “inside to outside, small to large.”
Supervision: long outer passes throw a lot of MDF dust; keeping extraction on and staying at the pause/E-stop station is non-negotiable on a shared lab machine.

Design files (download)

Source geometry and the posted program from this run. Save explicitly if the browser previews text instead of downloading.

Reference walkthrough with a similar chair workflow: Alison Yang — Week 7 documentation.

Group assignment

Guangzhou (Chaihuo) — group documentation: wood CNC operating procedure and safety (TC1325B).

Wood CNC engraving machine — operating procedure and safety

Equipment: TIANCHENG XINLI Wood CNC engraving machine TC1325B
Manufacturer: Shenzhen Tiancheng Xinli CNC Equipment Co., Ltd.

Overview: This is a three-axis CNC machine for woodworking. It supports automated carving, cutting, and milling, and is suited to furniture production, woodcraft design, and panel processing. Refer to the machine nameplate, factory manual, and on-site training for X/Y/Z travel, spindle power, maximum speed, and control system type. The “1325” designation often indicates a larger-format panel-style router; specifications may vary by batch or custom configuration.

I. Operating procedure (recommended order)

The following order is typical for a lab or workshop: prepare the workpiece and tool, establish coordinates and height, then run the program.

1. Load G-code into the machine

Transfer the program to the CNC controller via USB drive, network, or host software.
Open the file on the controller. Check the program name and any displayed estimates (time, line count). Confirm that the active work coordinate system (e.g. G54) matches the zero point you set on the machine.

Loading G-code on the CNC controller — Loading G-code

2. Place the workpiece (wood panel)

Clean the table and the bottom of the workpiece so chips do not cause rocking or gaps.
Place the panel within the machine’s usable travel (check the nameplate or manual for work envelope). Leave clearance for the tool and fixturing.
Ensure the cut area is supported (vacuum table, blocks, or clamps) to avoid chatter, tool breakage, or unsupported cuts. Large panels: check table load capacity and flatness.

Placing the wood workpiece on the CNC table — Placing the workpiece

3. Secure the workpiece (fixer / clamps)

Use toe clamps, a vise, dedicated fixtures, or the lab-approved fixer. Clamping must be firm and must not interfere with the toolpath.
Keep bolts/clamps low relative to the machined surface, or verify the path clears them; use low-profile clamps or side clamping if needed.
After clamping, push the workpiece lightly to confirm it cannot shift.

Clamping the workpiece on the CNC table — Clamping the workpiece

4. Change the tool (cutter)

Only install or remove tools when the spindle is fully stopped and the machine is in a safe state (e.g. program stopped or emergency stop as required by your site rules).
Install per the collet/chuck type; tighten to the specified torque. Check stick-out: enough for the cut, not so long that rigidity suffers.
If dust collection or a guard is used, check clearance between tool length and the shroud.

Changing the CNC cutting tool — Changing the tool

5. Close the spindle guard / dust hood

Install and latch the spindle guard, viewing cover, or dust port to limit chip throw and entanglement.
Confirm the guard cannot collide with clamps or the workpiece anywhere in the travel.

Spindle guard and dust cover closed — Spindle guard / dust cover closed

6. Set the work coordinate zero on the machine

Common methods: touch plate, edge finder, or trial cut to set XY at a agreed corner of the panel (must match the CAM part origin).
Z zero is often on the top of the stock or the table top, per CAM; a mismatch causes wrong depth or a crash.

7. Adjust height (Z axis and tool setting)

After setting XY and Z in the work coordinate system, move the tool to a safe clearance height.
If you use a touch plate or gauge block, follow the manual for tool length offset or Z confirmation.
Before the first run of a new program, raise Z and dry-run the path, or run in single-block mode, to verify motion.

Adjusting Z and tool setup on the wood CNC — Adjusting parameters / Z and tool setup

8. Start cutting

Operator in position; wear required PPE (see below).
Close or verify all doors/covers per procedure; start the spindle to the program speed if not commanded by the program.
Run the program. Stay at the machine; listen for abnormal noise and watch chips and dust. On any fault, hit emergency stop immediately.

II. Safety during use

(A) General

Read and follow the manufacturer’s safety chapter and your lab or shop rules.
Wear safety glasses; use a dust mask when fine dust is produced, and confirm dust collection or exhaust is connected and working.
Tie back long hair; no loose clothing, scarves, or gloves near a rotating spindle (gloves can be pulled in).
If you are unsure of a program, use single-block, dry run, or reduced feed override first.

(B) Mechanical / motion

Before cycle start, ensure no hands, tools, or rags are inside the envelope; keep the table clear.
Never reach into the machining zone while the machine is running. To clean or adjust, stop the spindle, then stop the program or E-stop, and wait until everything is still.
Know where the emergency stop is and that you can reach it at all times.

(C) Tool and workpiece

An improperly secured tool can eject at high energy—recheck after installation.
Loose fixturing can shift the part, break tools, or eject the workpiece; recheck clamps at the start of a session or before long runs.
Excessive depth or feed risks broken tools and flying fragments; start conservative for material and tool, then tune.

(D) Electrical and dust (woodworking)

Do not touch electrical parts with wet hands; route cables away from moving parts and heat.
On the TC1325B, sawdust and fines increase slip and fire risk: clean the table and floor; keep dust hoses clear; no open flame nearby; follow local fire rules.

(E) Program and coordinates

Mismatched zero, tool length, and stock thickness versus CAM is a common crash cause; after any tool change, reload, or workpiece move, re-touch off or re-verify Z.
After editing G-code, re-check units (inch/mm) and that safe clearance heights are present.