Tonight's Mill Practice

YOUR STOCK: Plain Steel Flat Bar

WIDTH3/4" (0.75")

THICKNESS1/4" (0.25")

LENGTH3 ft (36")

✂️ Cut Plan — Make 6 Practice Pieces

2"Block 1

2"Block 2

2"Block 3

2"Block 4

2"Block 5

2"Block 6

Hacksaw or bandsaw into ~2" chunks. Leaves 24" of spare stock.

⚡ Speeds & Feeds for Mild Steel (HSS End Mill)

RPM = (SFM × 3.82) ÷ Cutter Diameter
SFM for Mild Steel: 70–100

Examples:
• 1/2" end mill → (80 × 3.82) ÷ 0.5 = 610 RPM
• 3/8" end mill → (80 × 3.82) ÷ 0.375 = 815 RPM
• 1/4" end mill → (80 × 3.82) ÷ 0.25 = 1220 RPM

💧 Use cutting fluid! Steel needs it. Feed by hand — steady, consistent pressure. Chips should curl, not powder.

⚠️ Before You Start

👓 Safety glasses ON
🧤 NO gloves near spindle
👔 No loose clothing, tie back hair
🛑 Find the E-stop
🔑 Chuck key out immediately after use

Tram the Head

Setup Precision

Mount dial indicator in spindle
Sweep indicator across table in X
Adjust head until reading is consistent
Sweep in Y to confirm

Goal: Head square to table within 0.001" across sweep

Indicate Vise

Work Holding Indicating

Clean vise jaws and table
Mount vise, snug bolts (don't fully tighten)
Run indicator along fixed jaw
Tap vise to align, tighten bolts
Re-check indicator

Goal: Fixed jaw parallel to X travel within 0.001"

Edge Finding

Edge Finder Zero Setting

Clamp practice block in vise
Mount edge finder, spin at ~1000 RPM
Slowly approach edge until it kicks
Zero your X DRO/dial
Account for edge finder radius (typically 0.100")
Repeat for Y edge

Goal: Establish accurate X-Y zero on your workpiece

Face Milling — Square the Block

Face Milling Measuring Parallelism

Face top surface — light cuts (0.010–0.020")
Flip part, face opposite side
Measure thickness with mic — check parallel
Rotate 90°, face next side
Repeat until all 4 long faces done
Square the two ends

Goal: Opposite faces parallel within 0.002". All faces square.

Your stock is 3/4" × 1/4" — you're making a small rectangular block. Focus on parallelism and square corners, not final dimension.

Drill & Tap

Coordinate Drilling Tapping

Mark hole location (e.g., center of block)
Edge find to establish zero
Move to hole coordinates
Center drill first
Drill tap drill size (e.g., #7 for 1/4-20)
Hand tap with cutting fluid — back off every half turn

Goal: One clean tapped hole in correct location

1/4" thick stock = not much thread depth. A 1/4-20 tap only gives you ~4 threads. That's fine for practice. Go slow on the tap.

Slot or Shallow Pocket

Slotting Depth Control

Use smaller end mill (1/4" or 3/8")
Set depth stop or note Z zero
Cut a slot across the block — 0.050" deep
Measure slot width and depth
Optional: cut perpendicular slot to make a cross

Goal: Controlled depth cut, clean walls, consistent width

With 1/4" stock, keep pocket depth under 0.125" so you don't cut through. This is about control, not depth.

💡 Go slow. Measure often. The goal is feel, not speed.
Steel teaches you proper technique — respect the material.

🏭 Tonight's Mill Practice

YOUR STOCK: Plain Steel Flat Bar

✂️ Cut Plan — Make 6 Practice Pieces

⚡ Speeds & Feeds for Mild Steel (HSS End Mill)

⚠️ Before You Start