WRAP LOGIC FIELD GUIDE
Jacket layouts

Concentric reducer

Cones, tapers and concentric reducers. Enter the two insulation ODs and the length; it works out the apex, both radii and the step-off, so there's nothing to draw out first.

Inputs

From the Knauf chart, or type your own
From the Knauf chart, or type your own
Length is
1 for a one-piece cone; more if it's too big for the sheet
0Outer radius (apex to large end)
0Inner radius (apex to small end)
0Slope length
0Pattern angle
0Step-off on outer arc (1/16)
0Check: chord across the pattern

Pattern, to scale

  1. Draw a start line from the apex. Swing the outer radius, , and the inner radius, , from the apex.
  2. Set dividers to and step off 16 spaces along the outer arc from the start line. That is the large circumference. Step one more for the lap.
  3. Draw a line from the apex to the last mark.
  4. For notches or crimp: swing the inner arc ½" shorter, , and the outer arc ¾" longer, . Add ¾" for the safety edge.
  5. Watershed tabs, if needed, go on an arc 1" up from the small end.

Method: Advanced Metal Jacketing (IIIATF), Task C.1 (cone) and C.2 (concentric reducer). Allowances from C.2 step 10. Check the first piece on the job before cutting a batch.