I want to make an inner hole turning tool, and now I bought a section of stainless steel with a diameter of 25. If you know how to do it, you'd better be more specific. Thank you!

How long are you going to turn the inner hole? If it's short, you can change the length of the 45-degree 90-degree knife. If it's short, I'll add that the back end of the cutter bar can be milled into 20X20, and if it's 20 beds, the front end can be cut into a square hole, and a white steel cutter bar can be inserted and fixed with screws. Personally, I feel that this kind of knife is not easy to use ~ I turned the inner hole lathe myself. When I was in the enterprise, there were the most white steel knives in the whole factory, and more than 400 pieces of light tool fees were deducted in a quarter, all of which were white steel knives. Unfortunately, some of the molding knives involved in the factory patent were given to my master when leaving the factory.