Key Takeaways
- Plan and measure conduit length accurately.
- Use a 2.0 multiplier for 30-degree bends.
- Verify final measurements to ensure accuracy.
Overview of 30-Degree Offset Bend
A 30-degree offset bend requires careful planning and precision. Start with a 40-inch length of conduit, but remember you can make the bends first and cut later to accommodate shrinkage. The shrinkage for a 30-degree bend is one-quarter inch per inch. For a four-inch offset, adjust for a one-inch shrinkage by cutting the conduit to 39 inches, either before or after bending.
Steps:
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Mark the Conduit:
- Measure six inches from the end as the first mark.
- The second mark should be at 14 inches. This is calculated using a multiplier of 2.0 (4 inches × 2 = 8 inches).
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Make the Bends:
- Secure the conduit in the bender with the arrow on the six-inch mark.
- Bend to 30 degrees, ensuring the handle remains straight.
- Straighten and align with a stable surface to verify accuracy.
Tools and Equipment:
- EMT Benders: Ideal for ensuring precise bends. Available in aluminum and ductile iron.
- Cutting Tools: Utilize hacksaws or bandsaws like DeWalt or Milwaukee for efficient conduit cutting.
Measuring the final product against a straight edge can confirm that both ends have an accurate four-inch offset. Links for further resources and tools are available for those looking to deepen their skills in EMT bending and tools used in the process.
Preparation and Measurements
Conduit Length and Cutting
Start by cutting the conduit to a length of 40 inches, which provides the flexibility to make bends before or after cutting. If you decide to cut after bending, account for shrinkage. For a 30-degree bend where the shrink is a quarter-inch per inch, a 4-inch offset results in a 1-inch reduction. This means you can cut the conduit at 39 inches after bending while achieving the same final length as if you had cut it at 40 inches initially.
Ensure that the bends are straight and aligned, without any dog legs. The conduit should be stabilized in your bender to maintain consistent accuracy. Reaming the conduit is crucial to ensure smooth edges.
Marking for Bend Locations
Make two essential marks on the conduit. The first mark is placed 6 inches from the tail, which is arbitrary, but consistent placement aids precision. The second mark is calculated using a multiplier. For a 30-degree bend, the multiplier is 2.0. Thus, for a 4-inch offset, multiply 4 by 2 to get 8, placing your second mark at 14 inches.
Position the bender’s arrow on the first 6-inch mark and create the first 30-degree bend. Make sure the conduit remains straight and aligned throughout the process. Confirm the 4-inch offset by ensuring the conduit sits flush with a straight edge, achieving an accurate 30-degree offset each time.
Calculating Shrinkage for the Bend
When dealing with a 30-degree offset bend, shrinkage plays a crucial role in achieving the desired measurement. For every inch of conduit with a 30-degree bend, shrinkage equates to one-quarter inch per inch. With a four-inch, 30-degree offset, you should account for one inch of shrinkage. For your specific project, you may cut the conduit at 39 inches after bending or initially at 40 inches, with both methods providing the same result.
To set up, measure and mark your conduit. You want a six-inch tail, which means you should make your first mark at the six-inch mark. The next mark is vital and is calculated by considering the multiplier for a 30-degree bend, which is 2.0. Multiply your four-inch height by two, giving you eight inches between your marks. Thus, your second mark should be at 14 inches.
Once marked, the bending process begins. Place the conduit into the bender with the arrow aligned to your first mark at six inches. Bend it to 30 degrees, using the ground for stability. Make sure your movements are consistent and straight to avoid any dog legs. After bending, check that your conduit maintains the four-inch offset by measuring against a straight edge. Adjust if necessary to ensure precision in your bends. This wrap-up ensures a smooth result, aligning your project measurements accurately.
Bending Process
Executing the First Bend
To begin the bending process, ensure you have a 40-inch piece of conduit and mark off a 6-inch tail. This initial mark is arbitrary but necessary. Now, position your bender's arrow on this first mark. When executing the bend, aim for a 30-degree angle. Place your foot on the handle of the bender, which stabilizes the conduit on the ground, while applying pressure straight downward.
Using the 30-degree setting keeps the handle aligned correctly to achieve a clean bend. Once you have made the first bend, check that the conduit is straight without any dog legs. Proper alignment ensures a successful offset.
Completing the Offset
Make a second mark 8 inches from the first one, as the multiplier for a 30-degree bend is 2.0. This distance accounts for your 4-inch offset. Position the bender’s arrow on the 14-inch mark for the second bend, maintaining the same bending method to form another 30-degree angle. Ensure that you align everything to prevent misdirection.
After completing the bends, place the conduit on a straight edge to verify that both ends measure exactly 4 inches off the surface. This confirms that your offset is accurate and properly executed. Your work should result in a precise and professional offset, ready for further use.
Verification of the Offset
Using a Straight Edge for Accuracy
Place your conduit with the 30-degree offset bends on a straight edge. This helps ensure that the bends are aligned correctly. Measure from the straight edge to the top of the conduit at both ends to confirm they are precisely at four inches. Accuracy here is crucial for the installation.
Use tools like EMT benders and reamers to maintain precision. For efficient cutting, consider using bandsaws from brands such as DeWalt, Milwaukee, Makita, and Bosch. Checking your work with a straight edge verifies that your offsets are consistent and accurate, providing confidence in the result.
Tools and Equipment for Conduit Bending
EMT Benders
An EMT bender is essential for creating precise bends in electrical metallic tubing. You need to place your conduit into the bender, aligning it with the required mark. Maintaining a straight line throughout the bending process ensures accuracy and avoids unwanted "dog legs." Consider using both aluminum and ductile iron benders as they come in various sizes and materials suitable for different tasks.
Cutting and Reaming Tools
After measuring your conduit for the desired bends, cutting tools become crucial. A sharp hacksaw makes precise cuts, ensuring your conduit fits perfectly. Post-cutting, you must ream the ends of the conduit to remove burrs, allowing for seamless connections. Reliable reamers are invaluable for smoothing edges and maintaining conduit integrity.
Band Saws for EMT
When speed is crucial, a band saw significantly accelerates the EMT cutting process. Popular brands offer various features: the DeWalt band saw has a five-inch mouth, ideal for larger cuts. A Milwaukee cordless band saw with a three and a quarter inch mouth offers mobility, whereas Makita and Bosch provide compact options with two and a half inch mouths. These tools enhance efficiency and precision in any project.
Resources and References
Playlist for EMT Bending
Access a comprehensive library featuring 24 videos on EMT bending. These videos cover various techniques and approaches essential for EMT bending tasks. To enhance your skills and gain insights into effective EMT bending, use the playlist. You can find the link to this resource in the video description.