Even though it's easy to walk into a hardware or plumbing supply store and buy pre-threaded pipes in almost any length, they may not fit your needs exactly and will mean that some other part of the piping system will have to "give" so that the stock length of pipe will work. Cutting the pipe manually will mean you can have exactly what you want. Using a manual thread cutter and die to cut threads into steel pipe isn't quite the lost art that you would think, nor is it something that's difficult to learn to do. With some practice, you can have the custom length of threaded pipe you want.
Things You'll Need
Pipe die head
Thread cutting oil
Secure the pipe in a pipe vise. Use a pipe cutter to cut the end of the pipe square.
Use a pipe reamer to remove any burrs from the freshly cut end of the pipe by inserting the reamer into the end of the pipe and turning the reamer.
Choose the die head for the material and pipe size, with the correct pitch for the thread you wish to cut. Insert the die head into the threader ratchet.
Slide the pipe guide located at the rear end of the threader over the pipe. Engage the riding pawl of the ratchet. Apply pressure to the front of the die head while you are moving the handle of the threader down; this will start the threading process.
Continue to ratchet the die head into the pipe until the die head is flush with the end of the pipe. Remove the threader by using the handle to "unscrew" the threader from the pipe.
Your weight should be above the pipe when hand threading; use all weight, not just your arms.
Use a good quality thread cutting oil. Poor quality oil means poor threads, leaky joints and shortened life for your tools.
Do not use a“cheater” pipe on the handle. You're more likely to slip or overbalance and injure yourself.