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1:1 gasket CAD · ASME / EN library · photo tracer · mm / in

Exhaust Flange Gasket DXF Generator

Bore, bolt spacing, slot and ear radius make the outline — a smooth hull around the body and the ears — with the web around every hole checked as you type.

Worked
examples

View A · 2D blueprint

Min web—SAFE—
PROOF ONLY — NOT 1:1 SCALE
OUTER_CUTINNER_BOREBOLT_HOLESCENTERLINESweb < 2.5 mm
Outer × inner
—
Bolt pattern
—
Bolt chord S
—
Ligament S − d
—
Hole → bore
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Hole → outer edge
—
Area
—
Weight
—
Cut outer (+kerf)
—
Cut bore (−kerf)
—
Cut bolt hole
—

    View B · 3D extrusion

    drag to orbit · wheel to zoom
    Hole coordinates · polar & XY from the centre
    HoleAngleRadiusXY

    Export

    this exact gasket
    Free screen proof · not to scale
    Pro 1:1 production files
    Early Launch Price

    How to

    Measure, type, check, cut

    1. Measure the bore and studsBore Ø, stud centre-to-centre (2 bolts) or bolt circle (3–4 bolts), stud hole Ø.
    2. Shape the earsEar radius around each stud and the body margin around the bore set the hull outline.
    3. Add slots if studs are offSlot length stretches each hole along its radius.
    4. Pick copper or aramidThen export the 1:1 DXF, or the kerf SVG for a fiber laser or waterjet.

    Measuring

    How to measure a 2-bolt exhaust flange

    All dimensions from the 2.5-inch example below.

    centre-to-centre spacing 105.0 bore Ø63.5 ear R13 slot Ø12 +3
    2-bolt flange: Ø63.5 bore, studs 105.0 mm apart, Ø12 holes slotted +3 mm, ear radius 13 mm, body margin 6 mm.

    Lay the old gasket or the flange face on paper, measure across the bore twice at right angles and take the larger value. For the studs, measure from the near edge of one hole to the far edge of the other and subtract one hole diameter: that is the centre-to-centre spacing.

    The outline is the convex hull of a circle around the bore and one circle around each ear, joined by tangent lines. Wider ears mean more web around the studs; a larger body margin means more web around the bore.

    Web rules

    Why the web around the ears matters

    The studio checks four webs: bore to outer edge (the body margin), slot to bore, slot to ear edge and, with three or four bolts, between neighbouring holes. The thinnest one is shown big and drawn in red on the blueprint when it falls under 2.5 mm.

    Try it on the 2-bolt example: drop the ear radius from 13 to 9 mm and the slot-to-ear web falls to 1.5 mm, the hull shrinks to 123.00 × 75.50 mm and the canvas, the status chip and the Pro card all turn red together.

    Heat and material

    Exhaust gaskets see several hundred °C. Annealed copper (cut on a fiber laser or abrasive waterjet) and aramid or graphite fibre sheet survive it; TPU, silicone and nitrile do not, so the studio's material note warns you when you pick them.

    Examples

    The three examples, side by side

    ExampleSizeBolt patternMin webWhereArea · weight
    2-Bolt Automotive Exhaust Manifold High-Temp Flange (2.5" bore)131.00 × 75.50 mm · bore Ø63.502 × Ø12.00 slots (+3.00 mm) at 105.00 mm spacing5.5 mmslot → ear edge30.0 cm² · 53.7 g
    3-Bolt Header Collector Flange (2.5" pipe)110.60 × 100.00 mm · bore Ø64.003 × Ø10.50 on PCD 100.00 mm6.0 mmbore → outer edge34.7 cm² · 12.5 g
    4-Barrel Carburetor / Throttle Body Base Gasket150.00 × 160.00 mm · 4 × Ø44.00 ports4 × Ø8.40 studs on 130.00 × 140.00 mm5.8 mmstud → plate edge176.7 cm² · 47.7 g

    4-barrel carburetor base layout

    The carb base is a 150 × 160 mm plate with R6 corners, four Ø44 ports on a 56 × 58 mm pitch and four Ø8.4 stud holes on 130 × 140 mm. Its weakest web is 5.8 mm from each stud to the plate edge; ports keep 12 mm between them.

    Use cases

    Who cuts exhaust and carb gaskets

    FAQ

    Questions from the shop floor

    Short, specific answers. Open a question to read it.

    How do I measure a 2-bolt exhaust flange?

    Measure the bore (the pipe opening), the centre-to-centre distance between the two studs, the stud diameter and the radius of the rounded ears around each stud. Enter the spacing as "Bolt circle PCD": with two bolts the PCD is simply the centre-to-centre distance.

    Why use slotted bolt holes?

    Exhaust manifolds and headers grow when hot and the studs rarely line up perfectly on old castings. Slots let the gasket slide over studs that are a millimetre or two off. Set the slot length in mm; 0 gives round holes, written as CIRCLE entities in the DXF.

    What is a safe web around the ears?

    Keep at least 2.5 mm of material between a slot and the ear edge; below that the studio shows THIN WARNING because the edge cracks when the flange is torqued and heat-cycled. On a 2.5-inch flange with Ø12 holes, a 13 mm ear radius and 3 mm slots leave 5.5 mm.

    Which material for an exhaust gasket?

    Annealed copper (fiber laser or abrasive waterjet) or aramid / graphite fibre sheet. Do not use TPU, silicone or nitrile on an exhaust: they soften or burn far below exhaust temperature. Copper should not go in a CO2 laser because it reflects the beam.

    Can I make a 4-barrel carburetor base gasket here?

    Yes — use the 4-barrel carb example. It is a rounded plate with 1, 2 or 4 ports and four stud holes; the web check covers stud to plate edge, port to port, port to stud and port to plate edge. The example ships with a 0.15 mm kerf already set.

    Does the DXF include the slots as arcs?

    Yes. Slots are closed polylines with two straight sides and two exact semicircle bulges on the BOLT_HOLES layer, so CAM software sees true arcs instead of hundreds of tiny segments. The kerf SVG offsets them inward by your kerf value.

    The gasket family

    Same engine, a page for each job

    Every tool page opens the same studio with its own examples; the guides explain the numbers.