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newSchoolWorks.com › VoTechWorks › Building & Construction › Welding › Fabrication: Layout, Fitting, and Structural Assembly › Lesson 2
BLD-WELD01-11 · Lesson 2 · 12 clock hours · lab

Material Preparation: Cutting, Grinding, and Edge Prep

Objective. Students will cut structural steel members to length using band saw, angle grinder, and plasma cutter, then prepare groove and fillet weld joint edges that meet AWS D1.1 edge prep requirements.

Material Preparation: Cutting, Grinding, and Edge Prep

Proper material preparation is the foundation of every sound weld. AWS D1.1 makes clear that base metal condition directly affects weld quality: contaminated, poorly cut, or incorrectly beveled edges cause porosity, incomplete fusion, and dimensional errors that must be repaired at significant cost. This lab teaches you to cut structural steel accurately, produce compliant edge preparations, and certify that surfaces are clean before fit-up.

Cold Saw and Horizontal Band Saw Cutting

The horizontal band saw is the workhorse for cutting structural sections to length. Its blade is a continuous loop of bi-metal or carbide-tipped steel that runs at a feed rate and blade speed matched to the material being cut.

Blade speed and feed: For carbon steel such as A36, a blade speed in the low-to-mid range recommended by the saw manufacturer for ferrous material is correct. Running the blade too fast overheats the teeth and shortens blade life; running too slow wastes time and can cause the blade to wander. Always consult the machine's speed chart or the blade manufacturer's data for the specific tooth pitch and material thickness you are cutting.

Workholding: Secure the workpiece firmly in the saw's vise before energizing the blade. Never hold material by hand. The vise jaw must be tight — a shifting piece can snap the blade or pinch fingers. Position the cut line slightly outside the vise jaw so the blade clears metal without binding.

Squareness check: After each cut, use a machinist square on two faces. The cut end should be square within the tolerance on the print. For this exercise the requirement is ±1/16 inch of specified length. Measure from a scribed or marked reference line, not from a rough original end.

Angle Grinder Safety and Technique

Angle grinders are among the most hazardous tools in a fabrication shop. Before each use:

Grinding vs. flap-disc wheels: A Type 27 grinding wheel removes material aggressively and is used for heavy stock removal. A flap disc blends and smooths; it is preferred for final bevel finishing because it leaves a cleaner surface and is easier to control at the edge. Use each wheel only for its rated purpose — never use a cutting wheel for side grinding.

Producing a 22.5° Bevel for a V-Groove Joint

A single-bevel of 22.5° on each mating plate produces a 45° included angle when the two pieces are brought together, creating a standard V-groove joint. AWS D1.1 specifies groove angle tolerances for prequalified joint details; verify your specific joint type against the current edition's joint detail tables.

Technique: Mark a bevel guide line on the plate face with a soapstone or scriber. Set your body position so the grinder moves along the edge consistently. Use the bevel protractor to check the angle frequently — do not wait until the end. Work in passes rather than trying to reach final depth in one stroke. Keep the wheel moving to avoid localized overheating, which can introduce a heat-affected zone that must then be ground away.

Acceptable tolerance for this exercise: ±2.5° of the specified 22.5° bevel, confirmed with an adjustable bevel protractor.

Deburring and Root-Face Preparation

Every cut and ground edge must be deburred. Burrs prevent tight fit-up, trap slag, and can deflect the arc. Run a file or flap disc lightly along the cut edge until no raised metal remains. The root face (the flat land left at the bottom of a bevel) controls burn-through; if a root face is specified on the print, grind it to dimension and check it with calipers.

Joint Cleaning Station

AWS D1.1 requires base metal surfaces to be free of rust, scale, moisture, grease, and other foreign material that would prevent sound welds. The cleaning sequence:

1. Wire brush to knock off loose scale and grinding dust.

2. Acetone wipe with a clean lint-free rag. Apply acetone to the rag, not directly to the part. Work in a ventilated area away from open flames — acetone is highly flammable. Wear nitrile or chemical-resistant gloves in addition to your leather PPE.

3. Visual and tactile inspection: Look for laminations (delaminated layers visible at the edge), deep gouges from cutting, and remaining mill scale. Mill scale is the dark oxide layer from hot-rolling; it must be removed in the weld zone. Record all findings in the fabrication traveler before presenting the part to your instructor.

Fabrication Traveler

The fabrication traveler is the document that travels with each part through every stage of preparation, fit-up, welding, and inspection. Entries must be legible, dated, and signed. Recording defects found during edge prep — and the corrective action taken — creates the quality record required on structural projects that reference AWS D1.1.

Pass Criteria

You pass this lab when an instructor verifies: (1) cut length within ±1/16 inch, (2) bevel angle within ±2.5°, and (3) all edges free of burrs, scale, and contamination. All three must be met on the final prep set.

Key terms8

Bevel angleThe angle between the prepared edge of a plate and a line perpendicular to the plate surface; a 22.5° bevel on each piece of a butt joint produces a 45° included (groove) angle.
Included angleThe total angle of a groove joint formed by the two beveled faces when the joint members are assembled; equals the sum of both bevel angles.
Root faceThe flat, unbeveled portion of a prepared edge at the root of a groove joint; controls penetration and helps prevent burn-through.
Mill scaleThe dark iron-oxide layer formed on hot-rolled steel during the rolling process; must be removed from the weld zone because it can cause porosity and poor fusion.
LaminationA planar internal discontinuity in rolled steel, visible at a cut or ground edge as a separation between layers; parts showing laminations must be evaluated before welding.
Fabrication travelerA shop document that accompanies a weldment through every production step, recording dimensions checked, defects found, corrective actions taken, and inspector sign-offs.
Lockout/Tagout (LOTO)An OSHA-required procedure for isolating and de-energizing equipment before maintenance or wheel changes, preventing accidental start-up and injury.
Flap discAn abrasive wheel made of overlapping coated-abrasive flaps bonded to a backing plate; used for blending, surface finishing, and controlled bevel work on an angle grinder.

Worked examples3

1. A blueprint calls for a plate to be cut to 18-3/8 inches. After cutting, you measure the part at 18-5/16 inches. Is this within the ±1/16-inch tolerance?
  1. Convert the tolerance to a consistent fraction: ±1/16 inch means the acceptable range is 18-3/8 minus 1/16 to 18-3/8 plus 1/16.
  2. Convert 18-3/8 to sixteenths: 3/8 = 6/16, so the nominal is 18-6/16 inches.
  3. Acceptable range: 18-5/16 (low limit) to 18-7/16 (high limit).
  4. The measured value is 18-5/16. Check: 18-5/16 equals the low limit exactly — it is on the boundary of the tolerance.
  5. 18-5/16 is within ±1/16 of 18-6/16 (it is exactly 1/16 short, which equals the tolerance limit).
Answer: Yes. The part measures 18-5/16 inches, which is exactly 1/16 inch below nominal — equal to, and therefore within, the stated ±1/16-inch tolerance. The part passes the length check.
2. You are grinding a bevel and your bevel protractor reads 19°. The specified bevel is 22.5°. How many more degrees must you remove, and will the part be within the ±2.5° tolerance if you stop at 20°?
  1. Determine the angular error from nominal: 22.5° − 19° = 3.5°. You are 3.5° short of the specified bevel.
  2. The tolerance is ±2.5°, so the acceptable range is 22.5° − 2.5° = 20.0° (minimum) to 22.5° + 2.5° = 25.0° (maximum).
  3. Check whether stopping at 20° is acceptable: 20.0° equals the lower tolerance limit exactly, so it is on the boundary.
  4. You need to grind at least 1° more from the current 19° reading to reach the 20° minimum; ideally grind to closer to 22.5°.
Answer: At 19° you are 3.5° below nominal and outside tolerance. Stopping at exactly 20° places the bevel on the lower tolerance boundary (just barely acceptable). You should continue grinding toward 22.5° to give yourself a workable margin. At 19° the part fails; at 20° it is at the edge of pass.
3. A V-groove joint is made from two plates, each beveled to 22.5°. What is the included angle of the assembled joint, and how does it relate to what AWS D1.1 calls a 45° V-groove?
  1. The included angle equals the sum of both bevel angles when the plates are brought together at the root.
  2. Included angle = 22.5° + 22.5° = 45°.
  3. AWS D1.1 joint detail tables list groove angles in terms of the included angle; a 45° included angle is a standard dimension for a double-beveled V-groove joint.
  4. Each plate contributes half of the total groove opening, so matching both bevels at 22.5° ±2.5° keeps the assembled joint within 45° ±5° of nominal included angle.
Answer: The included angle is 45°. Each 22.5° bevel contributes equally to the total groove opening. This matches the 45° V-groove dimension referenced in AWS D1.1 prequalified joint details.

The math in this lesson2

Learners compute bevel degrees remaining against ±2.5° and double a 22.5° bevel to find the included angle.
7.G.5N-Q.3
Brush up in the math halls at newSchoolWorks.com:
In class: Instructor demonstrates cold saw and horizontal band saw setup, blade speed selection for carbon steel, and safe workholding with a vise; students cut four members to specified lengths and check squareness with a machinist square. · Students use a 4.5-inch angle grinder with grinding and flap-disc wheels to bevel plate edges to a 22.5° bevel (producing a 45° included angle for a V-groove) and deburr all cut edges; instructor checks bevel angle with a bevel protractor. · Joint cleaning station: students wire-brush, degrease with acetone wipe, and visually inspect prepared edges for laminations, gouges, or mill scale that would require additional grinding before fit-up; findings are entered in the fabrication traveler.
Materials: A36 plate (3/8-inch and 1/2-inch), horizontal band saw, angle grinders, grinding wheels, flap discs, cutting wheels, bevel protractor, machinist squares, acetone, rags, wire brushes, face shields, hearing protection, leather gloves, leather apron; AWS D1.1 current edition
Check: Cut length within ±1/16 inch of blueprint; bevel angle within ±2.5° of specified angle; all edges free of burrs, scale, and contamination confirmed by instructor tactile and visual check; pass = all three criteria met on final prep set

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Safety and Health
1. Before changing a grinding wheel on an angle grinder, which action is required first?
Welding Processes and Metallurgy
2. Two plates, each beveled at 22.5°, are fitted together to form a butt joint. What is the included groove angle?
Fabrication and Layout
3. A fabricator measures a cut member at 24-1/8 inches when the print calls for 24-3/16 inches. The tolerance is ±1/16 inch. What is the correct assessment?
Welding Processes and Metallurgy
4. Which of the following correctly describes mill scale and its significance to welding?
Quality Control and Inspection
5. A fabrication traveler is best described as:
Safety and Health
6. When using acetone to degrease a prepared weld joint, which precaution is most important?
Fabrication and Layout
7. A bevel protractor reading shows 26° on a plate that was specified for a 22.5° bevel with a ±2.5° tolerance. What action is required?
Safety and Health
8. Which of the following is the correct reason to ring-test a grinding wheel before mounting it?
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