It might work. I made an adjustable cone wrench by grinding down the jaws of an 8 inch adjustable wrench from one side until only about 2.5 mm of thickness was left. I started with a good quality wrench so there was no slop in the jaws. I ground slowly so I did not overheat the steel and cooled often. I finished it by hand with an oilstone. The wrench cost about $9. It took about an hour of my time. I have been very pleased with the results. (I posted this shortly after I joined BF in March 07 and included a photo. Try searching with my handle.)