By the you factor in the time and money you spend building a sufficiently accurate (and rigid) jig to drop the axle, you will have spent a lot more than you would pay someone who knows what he's doing to do the work for you. If you're planning to go into business doing it, and you have a customer base big enough to justify the investment, you'll probably break even about the 10th. axle you drop. That probably doesn't count how many axles you'll ruin during the learning curve.
Jerry
