Template Making — Flat Plate and Brackets

Why Templates Matter in Shipfitting

In marine fabrication, a structural bracket must fit precisely the first time. Steel plate is expensive, cutting time is limited, and a bracket that lands even 1/8 inch off its mating surface can force costly rework or compromise the structural integrity of the hull. The template — a full-size pattern cut from cardboard or thin sheet material — is the step between the drawing and the steel. A good template lets you verify every dimension before a single torch strike or shear cut touches metal.

This lesson covers how to make a flat-pattern cardboard template for a structural bracket, how to account for bend deduction, how to mark the template correctly, and how to verify it against the detail drawing to the required tolerance of ±1/16 inch.

Reading the Bracket Detail Drawing

Before you cut any cardboard, study the drawing completely. Identify:

• Overall flat-blank dimensions — the length and width of the plate before any bending
• Bend lines — where the metal changes direction; shown as dashed or phantom lines on the drawing
• Material specification — grade of steel or aluminum, and plate thickness
• Part number, heat number block location, and any weld-prep or hole callouts
• Reference datums — the edges or centerlines from which all dimensions are measured

Never scale a drawing. Always use the printed dimensions. If a dimension is missing or contradictory, stop and ask your instructor or the lead shipfitter before proceeding.

Flat-Pattern Layout and Bend Deduction

When a flat plate is bent, the outer surface stretches and the inner surface compresses. The neutral axis — roughly in the middle of the plate thickness — stays the same length. The material you must subtract from the flat blank to account for this stretching is called the bend deduction (BD).

For shop-level template work, your detail drawing will normally give you either the finished dimensions of each leg plus the bend deduction, or it will give you the flat-blank dimension directly. Always confirm which method your drawing uses before you begin.

A simple formula used in the trade:

Flat blank length = Leg A + Leg B − Bend Deduction

The bend deduction depends on the material thickness and the inside bend radius. Standard bend-deduction tables are posted at the press brake and in your NCCER Shipfitting module. Use the table that matches your material and radius — do not guess.

Grain Direction

Steel plate has a rolling direction, sometimes called grain direction. For brackets that will be bent, orient the bend line perpendicular to the grain whenever the drawing or procedure sheet specifies it. Bending parallel to the grain increases the risk of cracking along the bend, especially in higher-strength steels. On your template, draw an arrow indicating the rolling direction and label it "GRAIN" so the person cutting and bending the steel has the information right on the pattern.

Fabricating the Cardboard Template

1. Transfer dimensions from the drawing to the cardboard using a straight-edge, combination square, and scribe or marking pen. Work from one datum corner; do not chain-measure across multiple steps without checking back to the datum, as small errors accumulate.

2. Mark all bend lines clearly with a solid line and the label "BEND LINE."

3. Mark reference points — centerlines, hole centers, weld-prep limits — using a compass or square.

4. Add part information in a block in one corner: part number, revision level, material (e.g., A36 steel, 3/8 in. thick), heat number block placeholder, template maker's initials, and date.

5. Cut the cardboard carefully with scissors or aviation snips, staying just outside your layout line. Trim to the line with a straight-edge.

6. Fold the template at the bend lines to simulate the finished bracket shape if needed for a 3-D check.

Verifying the Template

Verification is not optional — it is the whole point of making a template. Use your rule and digital calipers to measure every critical dimension listed on the fit-check sheet:

• Lay the flat template over the drawing and compare outline dimensions
• Check each leg length from the bend line to the edge
• Check hole locations or cutout positions from the correct datum
• Confirm the overall flat-blank length matches the drawing's flat-blank callout (or your calculated value)

All dimensions must fall within ±1/16 inch of the drawing dimension. Record every measured value on the fit-check sheet. If any dimension is out of tolerance, trim or re-cut that portion of the template and re-measure. Do not submit a template with a correction made by adding tape or filler — make a clean replacement section or start a new template.

Safety in the Layout Area

• Snips and scissors have sharp edges; keep fingers clear of the cutting jaw and store tools with guards or sheaths when not in use.
• Keep the work surface clear of loose tools; a straight-edge or caliper falling from a table can cause injury.
• Marking pens used in confined layout areas may have solvent fumes; ensure adequate ventilation.
• Housekeeping: cardboard scraps create tripping and fire hazards in a welding shop — dispose of them promptly in designated bins away from hot-work areas.
• When you eventually transfer the template to steel for layout, you will be in a hot-work area. At that point, all standard PPE (safety glasses, steel-toed boots, gloves) applies.

Connecting to Your Credentials

Accurate template making is tested knowledge in NCCER Shipfitting. AWS welding codes and ABS/USCG inspection standards both require that fabricated parts meet dimensional tolerances before welding begins. A template that is off means a part that fails first-article inspection — a habit of accurate template work protects your reputation and your employer's bottom line from the very first day on the job.