For the 32 hole rear wheel you will need 18 spokes of a certain size for the drive side and 18 spokes of a certain size for the non-drive side. To get these spokes you can either purchase spoke blanks, or cut them and thread them yourself with the Hozan Spoke Threading Machine. In this video we'll demonstrate how to do that using 310mm spoke blanks.
After setting up the Hozan and marking your spokes, all you need to do is clamp your spoke into the Hozan and start turning the lever. The Hozan has a "tap" that forces the threads into the spoke in a process similar to cold forging. This is better than actually removing material, which would weaken the spokes. As you thread the spoke into the Hozan, it will follow the existing threads on the spoke, you will feel more resistance while turning the Hozan as it starts to create new threads. Make sure to calculate the distance you need to thread the spoke, because you do not want to add any more threads than you need. In the video we needed to thread on another 11mm, and then cut off some of the spoke. After you hit your thread mark, back the spoke out of the machine.
The next step is to cut off the excess spoke material. First thread on a nipple. This will straighten out the threads when you remove it after cutting the spoke. Make sure it is a brass nipple and not an alloy nipple, because a brass nipple is harder than the spoke material.
Thread on the nipple until only the amount of excess you need to cut off is showing above it. Then use some kind of wire clips or cable cutter to cut the spoke. After cutting the spoke, clean up the spoke with a metal file until you have removed the imperfections caused by cutting it.
Then as you remove the nipple, it will ensure that the threads aren't messed up. Now grab a beer, put on some classic rock, and repeat 31 more times! Or go to your LBS and get them to cut some blanks for you. Either way.
Some bike shops own the Phil Wood Spoke machine, but it costs $3,500, so it's not really cost effective for individual use. But if your LBS has one, then definitely go get them to cut you a set. If you want a cost effective, but more time consuming way to do it yourself, the Hozan Spoke Threader is for you.