Having run a farm implement store and shop, here is my suggestion.  If you are willing to work at a $20/hr rate job along with benefits, your shop rate should be  2.5 times this, which would come to $50/hr.  If you are willing to work at a job for $30/hr and benefits, your shop rate should be $75/hr.  Remember the shop rate is the time that you are punched in working on that piece of equipment.  So if the job took 10 hours, and your shop rate is $75/hr. the charge for that job should be $750. Remember all your hours will not be productive.  You will be filling out paper work, looking up parts, trying to collect your accounts, and also covering costs, such as shop/building payments, tools, manuals and also paying yourself, for liability insurance and health insurance, along with some extra money for paid vacation and holidays.