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newSchoolWorks.com › VoTechWorks › Building & Construction › Welding › Fabrication: Layout, Fitting, and Structural Assembly › Lesson 9
BLD-WELD01-11 · Lesson 9 · 8 clock hours · lab

Fabrication Capstone Mini-Project: Layout Through Inspection

Objective. Students will independently complete a short fabrication task—from blueprint reading and layout through fit-up, welding, inspection, and documentation—demonstrating integrated mastery of all course skills under time and quality constraints.

Fabrication Capstone Mini-Project: Layout Through Inspection

This lab brings together every skill you have practiced in this course. You will receive an unseen shop drawing, fabricate a small structural component from start to finish, inspect your own work, and submit a complete documentation package alongside the physical assembly. No coaching is available during the lab. The goal is to prove you can perform the full fabrication cycle independently—exactly as an entry-level structural fabricator is expected to do on the job.

Reading the Shop Drawing Before You Touch Any Steel

Before picking up a scribe or a torch, spend time studying the drawing. Identify the bill of materials (BOM), all dimensions, weld symbols, and the specified welding process. Confirm the base metal designation—for this lab it is A36 structural steel. Note every tolerance callout. If a dimension carries no explicit tolerance, apply the shop standard: ±1/16 inch for cut lengths and ±1/8 inch for overall assembly dimensions. Verify the weld symbol notation for each joint: fillet size, groove angle, and whether a weld is to be made in the field or in the shop. Record your interpretation of each symbol in your fabrication traveler before layout begins.

Layout and Cutting

Transfer all member dimensions from the drawing to the steel using a soapstone or scribe, a steel tape, a combination square, and a center punch. Double-check every measurement before cutting—measure twice, cut once is not a cliché; it is cost control. Mark your cut lines clearly. When using an angle grinder or cutting wheel, clamp the workpiece securely so it cannot shift. For thermal cutting, verify that the surrounding area is clear of combustibles and that a fire watch is in place if required by your shop's hot-work policy. After cutting, verify each member against the drawing dimension before moving to fit-up. Record actual cut dimensions in the traveler.

Fit-Up and Tack Welding

Assemble members in the sequence shown on the drawing or, where no sequence is given, from the inside out to control distortion. Use clamps, squares, and strongbacks to hold parts in position. Check squareness and alignment with your combination square and tape before applying any tack welds. Tack welds must be sound—a cracked tack that breaks during welding changes your fit-up and your distortion. Place tacks at intervals and sizes consistent with the base metal thickness; undersized or poorly fused tacks are a quality defect, not a shortcut. Record your fit-up dimensions—root opening, joint angle, land—in the traveler.

Welding with Distortion Control

Weld the assembly using the process specified on the drawing (SMAW or GMAW). Apply a distortion-control sequence: backstep welding on long joints, balanced welding on symmetrical members, and skip sequences where indicated. Do not chain-weld long joints in a single continuous pass without considering shrinkage. Inter-pass temperature limits apply when they are specified; check the drawing notes. Clean slag fully between passes on SMAW joints before depositing the next pass—slag inclusions are a code-rejectable discontinuity. No one will remind you during this lab. The instructor observes technique only and gives no corrective feedback until after you submit your work.

Visual and Dimensional Inspection

Once the assembly has cooled to a safe handling temperature, perform your own inspection using the gauge set. AWS D1.1 visual acceptance criteria for fillet welds include: minimum fillet size per the drawing; no cracks; no incomplete fusion visible at the weld toe; undercut not exceeding 1/32 inch for primary members in most cases; porosity within the limits stated in the code; and weld face that is reasonably uniform without excessive overlap or convexity. Use a fillet weld gauge to verify leg size and a bridge cam gauge to measure undercut depth and weld profile. Measure overall assembly dimensions with your tape and combination square. Compare every measured value to the drawing and record accept or reject for each inspection point in your inspection report. If a weld fails visual criteria, note it honestly—falsifying inspection records is grounds for disqualification from AWS and ASME certification programs and is a serious professional violation.

Documentation: Traveler, Weld Log, and Inspection Report

Your documentation package is as important as the hardware. The fabrication traveler records each production step with the responsible person's initials. The weld log identifies each weld joint, the process used, filler metal classification, heat settings (amperage or voltage range), and the welder's ID. The inspection report lists each inspected attribute, the measured or observed condition, the acceptance criterion, and a pass/fail determination. Close the package with your overall accept or reject determination for the assembly. Submit the package with the physical part. Incomplete documentation fails the lab regardless of weld quality—on a real job, an undocumented weld is a non-conforming weld.

Safety During the Capstone Lab

All standard PPE is mandatory for the full session: welding helmet with the correct shade lens for the process, leather gloves, flame-resistant jacket, leather boots, and safety glasses under the helmet. Before energizing any equipment, inspect leads, gun liner, and ground connection. Keep your work area clear. When grinding, use the guard and wear a face shield over your safety glasses. When the assembly is hot, use insulated tongs—never bare hands. If you must leave your station, de-energize the machine and secure the electrode holder or gun. Report any equipment malfunction immediately; do not attempt repairs yourself.

Passing This Lab

All four criteria must be met: cut and layout dimensions within ±1/16 inch; all welds meeting AWS D1.1 visual acceptance criteria as confirmed by instructor re-inspection; final assembly dimensions within ±1/8 inch of blueprint; and a fully completed, accurate traveler and inspection report with a correct accept/reject determination. Failing any single criterion requires a remediation plan before re-submission.

Key terms10

Fabrication travelerA document that accompanies a weldment through every production step, recording dimensions, processes, and responsible personnel at each stage to create a traceable quality record.
Bill of materials (BOM)A table on a shop drawing that lists every piece of material needed for the assembly, including quantity, size, material specification, and part mark.
AWS D1.1 visual acceptance criteriaThe minimum quality standards defined in the AWS D1.1 Structural Welding Code—Steel for evaluating welds by eye and simple gauges, covering cracks, undercut, porosity, fusion, and profile.
Fillet weld gaugeA shop inspection tool used to measure the leg size and throat of a fillet weld and verify conformance to the size specified on the drawing.
Bridge cam gaugeA multi-function weld inspection gauge used to measure undercut depth, weld reinforcement height, fillet leg size, and other profile dimensions against code limits.
Distortion-control sequencingA planned welding order—such as backstep, skip, or balanced welding—that limits heat accumulation and differential shrinkage so the finished assembly stays within dimensional tolerances.
Weld logA project record that identifies each weld joint by number, lists the process, filler metal, parameter range used, and the welder's identification for traceability.
Accept/reject determinationThe inspector's formal conclusion, based on measured or observed conditions compared to specified acceptance criteria, stating whether a weld or assembly conforms to the applicable code or drawing requirements.
UndercutA groove melted into the base metal at the weld toe that remains unfilled after welding; AWS D1.1 limits its depth because it acts as a stress concentrator and reduces the effective throat of the base material.
Backstep weldingA distortion-control technique in which individual weld passes are deposited in segments whose direction of deposition is opposite to the overall direction of progression along the joint.

Worked examples4

1. Your shop drawing calls for four angle-iron legs, each 14 inches long. After cutting, you measure the four pieces as 14 1/16 in, 13 15/16 in, 14 1/16 in, and 14 in. The shop tolerance is ±1/16 inch. Which pieces, if any, are out of tolerance?
  1. Identify the nominal dimension: 14 inches.
  2. Calculate the allowable range: 14 − 1/16 = 13 15/16 in (minimum); 14 + 1/16 = 14 1/16 in (maximum).
  3. Compare each measured piece to the range [13 15/16, 14 1/16]: Piece 1: 14 1/16 in — equals the maximum limit, therefore acceptable. Piece 2: 13 15/16 in — equals the minimum limit, therefore acceptable. Piece 3: 14 1/16 in — acceptable. Piece 4: 14 in — acceptable.
  4. All four pieces fall within the tolerance band.
Answer: All four pieces are within the ±1/16 inch tolerance; none require re-cutting.
2. Your drawing calls for a 3/8-inch fillet weld. You measure the weld leg with a fillet gauge and read 5/16 inch on one pass. By how many sixteenths of an inch is the weld undersized, and is it rejectable under AWS D1.1?
  1. Convert to a common denominator: required size = 3/8 in = 6/16 in; measured size = 5/16 in.
  2. Calculate the deficiency: 6/16 − 5/16 = 1/16 inch undersized.
  3. Apply AWS D1.1 visual acceptance criteria: fillet welds must meet the minimum size specified on the drawing. An undersized weld leg is a rejectable condition regardless of the magnitude of the deficiency.
  4. Conclusion: the weld is 1/16 inch undersized and is rejectable; it must be built up with an additional pass after cleaning the existing bead.
Answer: The weld is 1/16 inch undersized (5/16 in vs. required 3/8 in) and is rejectable per AWS D1.1. Add a repair pass to achieve the required leg size.
3. Your completed frame has a nominal overall length of 24 inches. The assembly tolerance is ±1/8 inch. You measure the finished frame at 24 3/16 inches. Is the assembly within tolerance?
  1. Determine the allowable range: lower limit = 24 − 1/8 = 23 7/8 in; upper limit = 24 + 1/8 = 24 1/8 in.
  2. Convert the measured value: 24 3/16 in. Convert the upper limit: 24 1/8 in = 24 2/16 in.
  3. Compare: 24 3/16 in > 24 2/16 in (the upper limit).
  4. The measured length exceeds the upper tolerance limit by 1/16 inch.
Answer: The assembly is out of tolerance by 1/16 inch over the upper limit and must be marked as reject on the inspection report. Corrective action (grinding or re-fitting) is required before re-inspection.
4. You are welding a symmetric H-shaped frame with two flanges and one web. If you weld the web-to-flange joint on one side completely before starting the other side, significant angular distortion is likely. Describe the balanced welding sequence that controls this distortion.
  1. Identify the two symmetric fillet weld joints: left flange-to-web and right flange-to-web.
  2. Divide each joint into equal segments of manageable length (e.g., thirds or quarters for a long joint).
  3. Weld segment 1 on the left side, then immediately weld the corresponding segment 1 on the right side before the first side has fully cooled, so both sides contract at roughly the same rate.
  4. Continue alternating—left segment 2, right segment 2, and so on—until both joints are complete. This balances the longitudinal shrinkage forces and minimizes angular distortion of the web.
Answer: Alternate welding equal-length segments on opposite sides of the web sequentially. Balanced shrinkage on both sides keeps the assembly straight and within angular tolerance.

The math in this lesson1

Learners check cut legs and frame length against ±1/16 in and ±1/8 in tolerances and count sixteenths undersized.
N-Q.3
Brush up in the math halls at newSchoolWorks.com:
In class: Each student receives a new, unseen shop drawing for a small structural component (e.g., a welded pipe support bracket or angle-iron frame); they independently lay out and cut all members, prep edges, and fit-up the assembly without instructor assistance, recording steps in their traveler. · Students fully weld the assembly using the process specified on the drawing, applying appropriate distortion-control sequencing; no coaching is provided during welding—instructor observes and notes technique for feedback only. · Students perform their own visual and dimensional inspection using the gauge set and complete the traveler, weld log, and a one-page inspection summary with accept/reject determination; the completed package is submitted with the physical assembly for graded evaluation.
Materials: A36 steel per drawing BOM, full welding station (SMAW or GMAW per drawing), layout tools, cutting tools, angle grinder, fillet weld gauge set, bridge cam gauge, steel tape, combination square, fabrication traveler, weld log, inspection report form, full PPE; unseen shop drawing issued at lesson start
Check: Pass requires: all layout dimensions within ±1/16 inch; all welds meet AWS D1.1 visual acceptance criteria confirmed by instructor re-inspection; final assembly dimensions within ±1/8 inch of blueprint; traveler and inspection report fully completed with correct accept/reject determination; all four criteria must be met to pass

Practice check8

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

Fabrication and blueprint reading
1. Before beginning layout on the capstone drawing, the FIRST step a fabricator should take is:
Layout and dimensional inspection
2. A shop drawing calls for members cut to 18 inches with a tolerance of ±1/16 inch. A piece measures 17 7/8 inches. This piece is:
Visual inspection and AWS D1.1 acceptance criteria
3. During self-inspection of a fillet weld, you find undercut at the weld toe. The correct next action is to:
Distortion control and welding techniques
4. Backstep welding is primarily used to:
Quality documentation and traceability
5. Which document records each production step with the responsible person's initials and travels with the weldment through fabrication?
SMAW process and AWS D1.1 quality requirements
6. On a SMAW joint, a welder deposits a second pass without completely removing slag from the first pass. The likely result is:
Dimensional inspection and accept/reject determination
7. A fabricator measures the finished assembly at 36 1/16 inches against a nominal blueprint dimension of 36 inches with a ±1/8 inch assembly tolerance. The correct inspection determination is:
Professional ethics and quality systems
8. During the capstone lab, a student deliberately records a weld as 'accept' on the inspection report without measuring it, to save time. This action is MOST serious because:
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