Key Takeaways
- Establish a method for bending a three-quarter inch pipe accurately.
- Use bender marks to calculate gain and back of 90 efficiently.
- Apply these techniques for consistent and precise pipe bends.
Determining Gain for a Three-Quarter Inch Pipe
Initial Marks for Pipe Bending
To determine the gain for a three-quarter inch pipe, begin by marking your pipe. Mark four inches from the end to achieve a 10-inch 90-degree angle. Then, place an additional mark at 30 inches as a reference for a 20-inch tail.
Bending a 10 Inch 90 Degree Angle
Align your mark with the arrow on the bender and proceed to bend. After the bend, check your measurements. The stub should measure 10 inches.
Measuring the Resulting Tail Length
After the bend, measure from the back of your 90-degree angle. Although the intended length was 20 inches, the resulting tail is actually 23 and 3/8 inches. This difference, calculated as 3 and 3/8 inches, represents the gain for this setup.
Calculating the Gain
Understanding Gain
To calculate the gain on a three-quarter inch piece of pipe, you first need to mark your pipe at specific points. Start by marking four inches to achieve a 10-inch 90-degree bend. Then, mark at 30 inches for a 20-inch tail. Although the tail measurement can extend beyond 20 inches, in this scenario, it results in 23 and 3/8 inches. The difference between the expected 20 inches and the actual length is the gain, which is 3 and 3/8 inches.
Gain represents the additional length gained from bending the pipe. It's a crucial measurement that helps in planning and executing precise bends. Knowing this gain enables you to calculate other critical measurements in the bending process, such as the back of 90.
Applying Math to Determine Back of 90
To determine the back of 90, subtract the gain from the stub. With a stub of 6 inches and a gain of 3 and 3/8 inches, you perform the calculation: 6 - 3 and 3/8. This results in 2 and 5/8 inches. From the initial mark used for the stub, measure 2 and 5/8 inches back. This point represents your back of 90.
Place your bender on the star mark, as this spot aligns with your calculated back of 90. This method ensures accurate bending and aligns with second 90-degree bends. Use a tape measure between the arrow and the star marks on the bender to solidify your back of 90 measurement.
Using the Bender Marks
Aligning Marks on the Bender
When preparing to bend a pipe, start by marking specific measurements. For a 10-inch 90-degree bend, mark the pipe at 4 inches and again at 30 inches to achieve a desired 20-inch tail. In practice, the tail length often ends up at 23 3/8 inches due to gain. This gain, calculated as the difference between the expected and actual tail lengths, is 3 3/8 inches in this example.
To find the "back of 90," subtract the gain from the 6-inch stub length, resulting in 2 5/8 inches. Measure this distance from your starting arrow mark to identify your "back of 90" mark, typically aligned with the bender's star mark.
Adjusting for Back-to-Back 90 Degree Bends
For making back-to-back 90-degree bends, use the star mark from the first bend as the reference for the second. Once you've marked your pipe for the second 90-degree bend, align the mark with the star mark on your bender. This ensures that the new bend fits perfectly at the desired 20-inch mark.
By consistently using this method, you can accurately determine and make back-to-back 90-degree bends. This technique is adaptable across different bender sizes and types.
Practical Application
Marking for a Second Bend
To ensure accuracy when marking for a second bend, begin by determining your back of 90, which can typically be found at the star mark on the bender. If this mark is not present, you can calculate it mathematically. Take the stub length, which in this example is 6 inches, and subtract the gain, which is 3 and 3/8 inches. This calculation gives you a distance of 2 and 5/8 inches from your initial arrow mark to the star mark. Use this measurement to mark for your second 90-degree bend.
Achieving Precise Bend Placement
After marking your pipe for the desired tail length (such as 20 inches), align the mark with the star on the bender to execute the back-to-back 90-degree bend with precision. Set the pipe on the star mark to ensure that the bend will meet the specified measurement requirements. These steps verify that your second bend accurately aligns with the desired 20 inches for consistent results in pipe bending tasks.