Conduit Bending Flashcards

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Questions and Answers

How to calculate DBB (distance between bends)?

DBB = bend multiplier X rise of the offset

How to calculate shrinkage?

Shrink = shrink constant X rise of offset

What is the formula for finding the shrink constant?

Angle number divided by 120

What is the distance multiplier for 5 degrees?

<p>11.4</p> Signup and view all the answers

What is the distance multiplier for 10 degrees?

<p>5.76</p> Signup and view all the answers

What is the distance multiplier for 15 degrees?

<p>3.86</p> Signup and view all the answers

What is the distance multiplier for 22.5 degrees?

<p>2.61</p> Signup and view all the answers

What is the distance multiplier for 30 degrees?

<p>2</p> Signup and view all the answers

What is the distance multiplier for 45 degrees?

<p>1.41</p> Signup and view all the answers

What are the steps to making offsets?

<ol> <li>Measure rise of offset 2. Choose bend angle 3. Identify bend multiplier 4. Calculate distance between bends 5. Find chosen angle shrink constant 6. Calculate shrink 7. Determine location of first bend 8. Determine the location of the second bend 9. Bend</li> </ol> Signup and view all the answers

What is the first step for parallel 90's?

<p>The smallest conduit (interior conduit) will be the starting conduit, this conduit will be laid out and fabricated as normal.</p> Signup and view all the answers

What is the first step for parallel offsets?

<p>Designate one offset as the starting offset. When marking conduit #1, no adjustment factor is needed; layout and mark as normal.</p> Signup and view all the answers

What is the second step for parallel offsets?

<p>Determine the center to center spacing of your conduits.</p> Signup and view all the answers

What is the third step for parallel offsets?

<p>Find the parallel offset multiplier (angle number divided by 120).</p> Signup and view all the answers

What is the fourth step for parallel offsets?

<p>Calculate parallel offset adjustment constant (A = C to C times multiplier).</p> Signup and view all the answers

What is the fifth step for parallel offsets?

<p>Beginning with conduit #2, add or subtract the adjustment constant to mark 1 of your starting offset.</p> Signup and view all the answers

What is the sixth step for parallel offsets?

<p>Repeat step 5 when laying out conduit #3, taking care to now use conduit #2 as the reference.</p> Signup and view all the answers

What is the seventh step for parallel offsets?

<p>Continue the same method with any subsequent offsets.</p> Signup and view all the answers

What is the second step for parallel 90s?

<p>Determine the center to center spacing of the conduit.</p> Signup and view all the answers

What is the third step for parallel 90s?

<p>To layout the second 90, add the C to C spacing to the measurements of both the stub and the leg of the first conduit.</p> Signup and view all the answers

What is the fourth step for parallel 90s?

<p>Bend 90 as usual.</p> Signup and view all the answers

What is the fifth step for parallel 90s?

<p>Repeat for any further 90s.</p> Signup and view all the answers

What is the first step for three bend saddle?

<p>Measure the height of the obstruction (you will need to add a small amount to this measurement about a quarter to half an inch depending on the size of the conduit used or the type of obstruction).</p> Signup and view all the answers

What is the second step for three bend saddle?

<p>Choose bend angles. The multiplier of smaller angles will determine the best angles to use.</p> Signup and view all the answers

What is the third step for three bend saddle?

<p>Find distance between bends. Multiply the chosen angles (bend multiplier X rise of the saddle).</p> Signup and view all the answers

What is the fourth step for three bend saddle?

<p>Find chosen angle shrink constant. Find using the formula angle divided by 120.</p> Signup and view all the answers

What is the fifth step for three bend saddle?

<p>Calculate shrink. Multiply shrink constant X rise of saddle.</p> Signup and view all the answers

What is the sixth step for three bend saddle?

<p>Determine center of center bend: measure from the reference end of the conduit to the center of the obstruction, add shrink to this measurement; this will be the measurement to the center bend.</p> Signup and view all the answers

What is the seventh step for three bend saddle?

<p>Determine the center of the two smaller bends: measure DBB to the left from mark 1 to find mark 2; measure from DBB to the right from mark 1 to find mark 3.</p> Signup and view all the answers

What is the eighth step for three bend saddle?

<p>Total length of conduit: total length = measured length + (2 X shrink).</p> Signup and view all the answers

What is the ninth step for three bend saddle?

<p>Bend</p> Signup and view all the answers

What is shrink?

<p>Shrink = shrink constant X rise.</p> Signup and view all the answers

What is gain?

<p>Total length before hand or stub + leg after bend.</p> Signup and view all the answers

What is leg?

<p>Distance from bend to end of conduit or another bend.</p> Signup and view all the answers

What is stub up?

<p>A 90 bend in conduit made perpendicular to the original length of the conduit with the conduit extending a specified length from the back of the bend.</p> Signup and view all the answers

Flashcards

DBB Formula

Distance Between Bends equals the bend multiplier times the rise of the offset.

Shrink Formula

Shrink equals the shrink constant times the rise of the offset.

Shrink Constant Calculation

Angle number divided by 120.

Distance Multiplier @ 5 degrees

11.4

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Distance Multiplier @ 10 degrees

5.76

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Distance Multiplier @ 15 degrees

3.86

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Distance Multiplier @ 22.5 degrees

2.61

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Distance Multiplier @ 30 degrees

2

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Distance Multiplier @ 45 degrees

1.41

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Steps to Making Offsets

Measure the rise, choose the angle, calculate DBB & shrink.

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Parallel 90s Procedure

Start with the smallest conduit, then add center-to-center spacing to stub and leg measurements for others.

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Parallel Offsets Procedure

Designate a starting offset, then adjust subsequent offsets using the parallel offset multiplier.

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Three Bend Saddle Steps

Measure the obstruction height, choose bend angles, calculate distance between bends and total length.

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Shrink Calculation

Shrink constant multiplied by the rise.

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Gain Definition (Conduit)

Total length of conduit before a bend plus post-bend leg length.

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Leg Definition (Conduit)

Distance from the bend to the conduit end or another bend.

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Stub Up Definition

A 90-degree bend perpendicular to the original conduit length.

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Optimal Bend Angle for Saddles

Use a small bend angle multiplier.

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Extra Height for Obstruction

Adding a quarter to half an inch to obstruction height

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Parallel Offset Adjustment

Adjust the adjustment constant and mark conduits accordingly

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Distance Between Bends

Use the formula DBB=Bend multiplier x Rise

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Finding the Shrink Value

You can find the shrink value by dividing the angle number by 120.

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What to measure for a bend

Measure the rise of the offset and choose the bend angle.

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Beginning your Bends.

Start small, bend, then ensure the proper spacing

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Account for Center to Center

Account for the center to center spacing to start, adjust from there.

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Starting Point

One is a ground zero

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Measure Height

Height with an extra .25 to .5 inch, depending on size.

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Total conduit length

Measured length plus 2 x shrink

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Calculate Shrink

Shrink Constant x Rise

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What Does Gain Refer To?

Length before + Length After Leg Bend

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Study Notes

Calculating Bends and Shrinkage

  • Distance Between Bends (DBB) is calculated using the formula: DBB = bend multiplier x rise of the offset.
  • Shrinkage is determined by the formula: shrink = shrink constant x rise of the offset.
  • Shrink constant can be found by dividing the angle number by 120.

Distance Multipliers for Angles

  • The distance multiplier varies based on the bend angle:
    • 5 degrees: 11.4
    • 10 degrees: 5.76
    • 15 degrees: 3.86
    • 22.5 degrees: 2.61
    • 30 degrees: 2
    • 45 degrees: 1.41

Steps to Making Offsets

  • Measure the rise of the offset and choose the bend angle.
  • Identify the bend multiplier and calculate the DBB.
  • Find the shrink constant for the chosen angle and calculate shrink.
  • Determine locations for the first and second bends, then proceed to bend.

Procedure for Parallel 90s

  • Start with the smallest conduit, laying out and fabricating it as normal.
  • Determine center-to-center spacing of conduits.
  • For the second 90, add C to C spacing to stub and leg measurements of the first conduit.
  • Bend 90 degrees as usual and repeat for additional bends.

Procedure for Parallel Offsets

  • Designate one offset as the starting point; no adjustment factor is needed.
  • Measure center-to-center spacing between conduits and find the parallel offset multiplier.
  • Calculate adjustment constant and mark conduit locations accordingly for each subsequent offset.

Steps for a Three Bend Saddle

  • Measure the obstruction height, adding a quarter to half an inch.
  • Choose bend angles, using a smaller angle multiplier for optimal results.
  • Distance between bends is found by multiplying bend multiplier by the rise of the saddle.
  • Calculate the total length of the conduit: total length = measured length + (2 x shrink).

Additional Definitions

  • Shrink: Calculated using the formula shrink = shrink constant x rise.
  • Gain: Total length of conduit before a bend plus post-bend leg length.
  • Leg: Distance from the bend to the conduit end or another bend.
  • Stub Up: A 90-degree bend perpendicular to the original conduit length, extending a specified length from the back.

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