's statements are somewhat unclear for me. Here is some comments, based on what I think I read:
* jtbonner91 was invited to work for Employer at a significant pay cut. Jtbonner91 took the pay cut with the understanding that he would learn the cabinet making business with the goal of "taking over the business."
* jtbonner91 never stated what "taking over the business" actually means to him. Does it mean that Employer plans to eventually give the business to jtbonner91? ... or ... Does it mean that jtbonner91 runs the business without assistance from Employer, but employer retains ownership of the business, sets pay rates, keeps the profits, etc. Whatever it is, it should be in writing. Otherwise, jtbonner91 may be sacrificing a lot of his future to put money in the pocket of Employer. There is too much at stake not to have a clear understanding. Six and a half years is a long time commitment to be thinking about "raise" rather than "my future with this business." Despite jtbonner91's comments about "taking over the business", is this really just a simple employment situation - pay for work without a real future? If so, it is time to confront Employer and put everything on the table. Otherwise, Employer will keep taking until jtbonner91 says no.
* With sincere respect, jtbonner91's job to build cabinets and doors to customers is a relatively simple and small aspect of the overall business. There is a lot more to the business than just building cabinets and doors. There are laws and regulations, paperwork for local, state, and federal governments, including taxes, labor, etc. There are legal issues, accounting issues, safety and security, and much more. There are many operational aspects to manage and maintain - tracking and ordering supplies and consumables, loss prevention, tool care and management, repairs and other unexpected expenses. You have to keep sales going so that there is always a backlog, or your employees (you?) will be idle. There is also insurance. In my opinion, jtbonner91 has much more to learn about the business. The learning may be more challenging than cabinet and door construction; a lot more challenging.
* If Employer is not willing to share the business in a meaningful way (to jtbonner91) then it is nothing more than a simple employment arrangement. In that case, jtbonner91 must decide what to do next. I wonder if there are other cabinet makers who would be interested in jtbonner91's skills? If so, he can apply elsewhere - with a potential job offer in hand, jtbonner91 can go to Employer and ask for a raise, with the understanding that he must be willing to part ways with Employer, who may not be coming through with the promise to "take over the business."
* At some point, jtbonner91 must fish or cut bait. The current situation is untenable, in my opinion. Jtbonner91 is working for Employer at below reasonable wages, and jtbonner91 should be compensated for his sacrifice to help keep the business profitable. Perhaps Employer cannot afford higher wages, but then jtbonner91 should be rewarded in some other way, perhaps vesting an a percentage of business ownership each year, in a way that jtbonner91 can afford to buy out Employer in the future. Everything must be in writing, or it never happened. There are few people I know who I would trust with a verbal business contract, and they are either family or my closest friends I have known for many decades. I trust them, but everyone else needs a written contract. We are talking about a significant amount of money (think of the tool asset value alone!), so getting a lawyer to help is quite reasonable.
My advice is worth what you paid for it, but I hope it helps to stimulate some realistic thinking on jtbonner91's part.