Cheaper still is the Yooper method, works every time, well sort a. Take a bunch of the races that screw on to the fork tube. These are hardened and tougher than the fork tube steel. Put the fork in a vice with wood blocks to protect it. Use a big pipe wrench and tighten the race beyond where there are threads. Use cutting oil as you go. Go back and forth. When the threads get shallow and it is too hard to turn the race, discard the race and use another one. Keep doing this until you have the desired thread depth. I have done this many times over the last 40 years and never had one get loose. You have to use the pipe wrench or plumbers pliers to tighten the race for final adjustment on the bicycle and also to remove it for cleaning and greasing. I figure that is better than spending $ I don't have to. I always save a bag full of races in case I want to do this again. If I have a more valuable bike, like the 30s Colson truss rod fork I put on my 1940 CWC then I take it to the bike shop. Here it is $20 for threading a fork. I almost always use the Yooper thread cutter methodology cause its free.