Common sizes for robotics:

Metric:        (for M3-M6 bolts)
├─ 2.5 mm: Clearance for M2
├─ 3.3 mm: Tap hole for M4
├─ 4.2 mm: Clearance for M4
├─ 5.1 mm: Tap hole for M6
└─ 6.5 mm: Clearance for M6

Non-metric:    (imperial)
├─ #40 (3.2 mm): Small assemblies
├─ #10 (4.7 mm): Medium assemblies
└─ #F (6.6 mm): Large bolts

Material types:
├─ High-speed steel (HSS): General purpose, cheap
├─ Cobalt (HSSE): Harder materials, lasts longer
└─ Carbide: Very expensive, for production

Steps:

1. Mark location with center punch
   └─ Small dent guides drill, prevents slipping

2. Start with pilot hole
   └─ Use smaller bit first (reduces wear)

3. Use cutting fluid
   └─ Aluminum: Cutting oil
   └─ Steel: Soluble oil (mixed with water)
   └─ Plastic: Light oil or dry
   └─ Benefit: Reduces friction, extends bit life

4. Drill with steady pressure
   └─ Let the drill bite (don't force)
   └─ Too fast → bit breaks
   └─ Too slow → dulls bit
   └─ Medium speed works best

5. Back out occasionally
   └─ Clears chips from flutes
   └─ Prevents jamming and bit breakage

6. Stop before bit exits
   └─ Last moment high pressure breaks bit
   └─ Slow down as you exit

Pros: Portable, simple, inexpensive
Cons: Hard to keep vertical, less precise, slow
Speed control: Manual (squeezing trigger)
Best for: Quick holes, field repairs, single parts

Pros: Very precise, vertical guaranteed, handles large bits
Cons: Stationary (big workspace needed), expensive
Speed control: Belt/pulley adjustment, automatic feed
Best for: Production runs, precise holes, thick material

Best for: Cutting aluminum tube/bar

Technique:
1. Secure work in vise
2. Mark cut line with marker
3. Use steady downstroke, light upstroke
4. Keep blade perpendicular to work
5. Let saw do the work (don't force)
6. Last few strokes: slow pressure (prevent snap)

Speed: 1-2 inches (25-50mm) per minute

Maintenance:
├─ Replace blade when dull
├─ Keep blade teeth clean
└─ Check tension regularly (should be tight)

Cutting discs: Small, fast cutting

Best for: Plastic, acrylic, thin aluminum

Technique:
1. Secure work properly (it will try to spin!)
2. Use low angle to material
3. Let tool speed do cutting (don't force)
4. Wear face shield (sparks!)
5. Keep hands clear of rotating disc

Speed: Very high (30,000+ RPM)
Result: Fast cuts but less precise than saw

Safety: Discs shatter if bent, can cause injury!

Cutting discs: Large, powerful

Best for: Steel, thick aluminum

Setup:
├─ Large disc (4-5 inch)
├─ Very high speed (12,000 RPM)
├─ Powerful motor
└─ Serious tool!

Technique:
1. Secure work in vise or clamp
2. Wear full face shield (sparks fly far!)
3. Grip grinder firmly with both hands
4. Let disc speed do cutting
5. Don't twist disc in cut (will bind, throw work)

Safety: ⚠️ Respect this tool! Serious injury possible

Advantages:
✓ Precise cuts (±0.1mm)
✓ No heat affected zone
✓ Works on ANY material
✓ Complex shapes possible

Disadvantages:
✗ Expensive service ($30-100 per hour)
✗ Long lead times
✗ Minimum batch cost

Best for: One-off parts, production runs, prototypes

Electric bench grinder:

Setup:
├─ Coarse wheel (grinding)
├─ Fine wheel (finishing)
├─ Eye shield
└─ 3000-5000 RPM

Uses:
├─ Sharpen tools
├─ Smooth welds
├─ Remove burrs
├─ Flat surfaces

Technique:
1. Secure work against toolrest (not moving wheel!)
2. Light pressure (wheel does work)
3. Multiple passes (don't grind hard)
4. Keep surface wet to prevent overheating

Safety:
✓ Wheel guard installed
✓ Eye protection mandatory
✓ No dangling clothing

Types:
├─ Flat file: General smoothing
├─ Round file: Internal curves
├─ Triangular file: Corners
└─ Needle files: Small details

Technique:
1. Secure work in vise
2. Cut on forward stroke (pressure)
3. Light on return stroke
4. Steady angle (don't rock)
5. Use full length of file

Best for: Final finishing touches, deburring

Removes sharp edges after cutting/drilling

Methods:
├─ Hand file: Manual, controlled
├─ Chamfer bit: Quick, consistent
├─ Sandpaper: Fine finishing
└─ Deburring tool: Specialized, expensive

Why important:
✓ Prevents cuts
✓ Improves appearance
✓ Reduces stress concentration
✓ Better mechanical fits

Typical: 0.5mm chamfer on all edges

Soldering iron: 25-60W for electronics
Gas torch: For larger pieces

Types:
├─ 60/40 solder: Lead (toxic), easier to use
├─ Lead-free: Environmental, higher temp
└─ Silver solder: Stronger, more expensive

Steps:
1. Clean surfaces
   └─ Remove oxidation with brush/sandpaper
   
2. Apply flux
   └─ Chemical cleaning agent
   └─ Helps solder flow
   
3. Heat joint (not solder!)
   └─ Temperature > solder melting point
   └─ Heat metal to accept solder
   
4. Apply solder
   └─ Solder flows on hot metal
   └─ Fills gap between parts
   
5. Cool without moving
   └─ Solder hardens
   └─ Joint is complete

Lap joint (strongest):
  ┌─────┐
  │     │ ← Overlap area
  └─────┘

Butt joint (weaker):
  ┌─────┐ ┌─────┐
  │     │ │     │ ← No overlap
  └─────┘ └─────┘

Tee joint:
  ┌─────────┐
  │         │ ← T-shaped
  │    ┌────┘
  │    │
  └────┘

Good solder joint:
✓ Shiny appearance
✓ Smooth surface
✓ Solder fully flows
✓ No voids or cracks

Bad solder joint:
✗ Dull/grainy appearance
✗ Lumpy surface
✗ Cold joint (not fully melted)
✗ Cracks visible

Fix: Reheat and reflow

Most beginner-friendly welding

Setup:
├─ Wire fed automatically
├─ Gas (Argon/CO2) shields weld
├─ Handheld gun
└─ 120V household outlet

Advantages:
✓ Easy to learn
✓ Fast process
✓ Clean joints
✓ Good for thin materials

Disadvantages:
✗ Less strength than TIG
✗ Quality varies with technique
✗ Requires ventilation

Best for: Learning, thin aluminum, general fabrication

Most precise welding

Setup:
├─ Tungsten electrode (non-consumable)
├─ Separate filler rod (manual feed)
├─ Gas (Argon) shields weld
└─ Foot pedal controls heat

Advantages:
✓ Very strong joints
✓ Precise control
✓ Works on all metals
✓ Best quality

Disadvantages:
✗ Steep learning curve
✗ Slow process
✗ Requires steady hands
✗ More expensive

Best for: Critical structures, aerospace applications

Traditional method

Setup:
├─ Coated electrode (consumable)
├─ Direct current
├─ Flux coating creates shield

Advantages:
✓ Very robust
✓ Works outdoors
✓ Strong joints

Disadvantages:
✗ Dirty (creates slag)
✗ Requires cleanup
✗ Less precision

Best for: Heavy structural work, outdoor fabrication

Setup:
1. Clean joint area (remove oxide)
2. Clamp pieces at correct angle
3. Set correct amperage for material/thickness
4. Secure ground clamp to workpiece

Process:
1. Position torch/gun at 45° angle
2. Strike arc (touch electrode to metal)
3. Maintain short arc (3-4mm gap)
4. Move steadily along joint
5. Build bead (overlapping passes)
6. Let cool (don't move immediately)

Result: Strong permanent joint

Characteristics:
├─ Low melting point (660°C)
├─ Corrodes easily
├─ Oxidation layer prevents bonding
└─ Excellent thermal conductor

Cutting:
✓ Use sharp blades (dull bits grab)
✓ High speed (2000+ RPM for small bits)
✓ Cutting fluid mandatory
✗ Slow feeds cause heating
✗ Soft metal – handle carefully

Drilling:
✓ Use aluminum-specific bits if available
✓ Slow speed (500 RPM for 10mm bit)
✓ Cutting fluid essential
✓ Support from underneath (prevent tear)

Welding:
✓ Use TIG or MIG with Argon gas
✓ Remove oxide layer with stainless wire brush first
✓ Higher heat than steel
✓ Cools quickly (can distort)

Best fastener: Aluminum or stainless (steel rusts in aluminum)

Characteristics:
├─ High melting point (1500°C+)
├─ Very strong
├─ Rusts without protection
└─ Magnetic

Cutting:
✓ Medium speeds (200-500 RPM for 10mm bit)
✓ Cutting fluid important
✓ Steady pressure (doesn't require as much finesse)

Drilling:
✓ Standard HSS bits work well
✓ Slower speeds than aluminum
✓ Cooling fluid reduces bit wear
✓ Easier to drill than aluminum (less grabbing)

Welding:
✓ Any welding method works
✓ Stick welding most common
✓ Simpler technique than aluminum
✓ Cools slower (can distort even more)

Post-processing: Paint or powder coat for rust protection

Characteristics:
├─ Low melting point (160-180°C)
├─ Brittle (cracks from stress)
├─ Transparent
└─ Lightweight

Cutting:
✓ Use band saw or rotary tool
✓ Fast speeds (no cutting fluid)
✗ Slow speed causes melting
✗ Don't use abrasive discs (melt it)

Drilling:
✓ High speed (2000+ RPM for small bits)
✓ Light pressure (don't force)
✗ Metal drilling speeds melt it
✗ Twist drill bit recommended
✓ No cutting fluid (creates toxic fumes with acrylics)

Joining:
├─ Solvent bonding: Apply acrylic cement
├─ Mechanical: Bolts with washers (prevent cracking)
└─ Avoid welding (will melt)

Finishing: Polishing removes scratches and frost appearance

Characteristics:
├─ Extremely strong
├─ Lightweight
├─ Non-conductive (generally)
├─ Composite material (fiber + epoxy)
└─ Very expensive

Cutting:
✓ Use carbide blades (standard bits dull instantly)
✓ Careful cuts (can delaminate)
✗ Standard tools will destroy it

Drilling:
✓ Carbide bits mandatory
✓ Very slow speed (prevent heat/delamination)
✓ Back-up support (prevent tear-out)
✓ Wear respirator (fiber dust harmful)

Best practices:
✓ Mark cut lines carefully
✓ Sharp tools essential (dulled tools cause shattering)
✓ Support edges during machining
✓ Minimize vibration

Avoid: Welding, solvent bonding (damages composite)

Essential tools:
├─ Hand drill (20W, two-speed)
├─ Hacksaw with blades
├─ Assorted drill bits
├─ Files (flat, round, triangular)
├─ Adjustable wrench
├─ Screwdriver set
├─ Hand clamps (2x)
├─ Safety glasses and gloves
└─ Measuring tape

Capabilities:
✓ Drill holes up to 1/4"
✓ Cut aluminum bar/tube
✓ Smooth edges
✓ Basic assembly

Limitations:
✗ No precision (hand-drilled holes ±2-3mm)
✗ Slow process
✗ Difficult for hard materials

Add to above:
├─ Rotary tool (Dremel) with bits
├─ Bench vise (heavy, accurate)
├─ Hacksaw + replacement blades
├─ Cutting/grinding wheel set
├─ Desoldering equipment
├─ Soldering station (better than iron)
├─ Vice grips and C-clamps
└─ Angle ruler and calipers

Capabilities:
✓ Precision holes (±1mm)
✓ Cut plastic, thin aluminum
✓ Basic metalworking
✓ Repair/maintain equipment

Benefits:
✓ Much faster work
✓ Better quality results
✓ Can handle more complex projects

Add to above:
├─ Drill press (stationary)
├─ Angle grinder with cutting wheel
├─ Bench grinder with wheels
├─ MIG welder
├─ Band saw (CNC optional)
├─ Pneumatic impact driver
├─ Precision measuring tools
└─ Work storage/organization

Capabilities:
✓ Production-quality parts
✓ Complex fabrication
✓ Welding capability
✓ Precision measurements

Best for: Serious robotics labs, small manufacturing

Check with calipers (±0.1mm):
├─ Hole diameters match specifications
├─ Edge straightness
├─ Parallel surfaces
└─ Overall dimensions

Tolerance chart:
├─ ±2mm: Basic prototyping OK
├─ ±1mm: Good enough for most robots
├─ ±0.5mm: Precision assemblies
└─ ±0.1mm: High-performance systems

Before assembly:
☐ No cracks or fractures
☐ No surface contamination
☐ Holes free of burrs
☐ Edges properly deburred
☐ Paint/coating smooth
☐ Fastener seats clean

After fabrication:
☐ Parts fit together
☐ Fasteners tight (don't strip holes)
☐ Motion smooth (not binding)
☐ Load-bearing capability OK
☐ Electrical paths isolated (no shorts)