Intellectual Property Center, LLC | Ak Shaf
In your question, you actually ask two different questions. Whether or not you can use a product and modify it for use in a new way is different than whether you can patent it. You can patent something which is novel, non-obvious, patentable subject matter and useful. Whether or not you can use it depends on the facts of the case and on facts which were not provided. I would suggest contacting an attorney to advise you regarding the specifics of your question. Good luck.
Answer Applies to: Kansas
Rhema Law Group | John D. Tran
This really depends on how substantial your modifications are and how the patent was claimed. Legally, you will need to compare the accused product to the patent claims to determine whether infringement occurs. It is highly advised that you speak to a patent attorney to help you determine any potential infringement issues.
Answer Applies to: California
Barton Barton & Plotkin | Maurice Ross
It sounds like you have made an "improvement" to a product that may already be protected by a patent. Further, you are apparently using (but modifying) parts covered by patents (and apparently making improvements to them or changes to make an improved product). It is hard to give you definitive advice without knowing the details, but in general if you make an improvement on existing patented product, you may need a license to use the existing patent product and/or parts before you can sell your product. The fact that you modified and improved the existing product and/or parts does not necessarily mean that your new product and/or the parts you use would not infringe existing patents on the old product. You might be entitled to an "improvement patent" but that does not mean you are necessarily free to use the pre-existing patented product and parts without obtaining a license. This is a quite common problem, and a complex area of patent law. You need to retain IP counsel with experience in this area to advise you, and chances are you will need to attempt to negotiate licenses for the right to use the existing product and/or parts.
Answer Applies to: New York