Make a high quality cone wrench for all of your bicycles from an adjustable wrench.
Step 1: What You Need
Buy a good quality 8 inch adjustable wrench. The jaws should be tight and move smoothly. You will also need a grinder, an oilstone, and some light oil.
Step 2: Grind the Wrench Slowly
Close the jaws tightly and place the handle of the wrench in a vise. Grind from the side with the metric scale. An angle head grinder works well. Be patient. Grind slowly. Cool often. Do not let the steel discolor from heat. Dip in water. Do your grinding forward of the openings inside the jaws so you do not cut into them. Grind the thickness of the jaws down to about 2 - 2.5 mm. in thickness. The grinding process requires about one hour.
Step 3: Finish With a Handstone
A power grinder does a good job, but you can get more precise results by finishing the ground surface with an oilstone. Use thin oil to flush grit out of the jaws so they work smoothly. Work the jaws back and forth. Repeat flushing with oil until there is no more gritty feel.
Step 4: Using the Wrench
Place the jaws around the bearing cone with the ground side up. This allows room for another adjustable wrench or a fixed wrench to loosen or tighten the locking nut. You now have a quality cone wrench that fits any bearing cone and will not distort under use because it is made from quality tool steel.