I just finished my master's and I am about to start my PhD studies. As I am very used to do many independent projects during my bachelor's and master's, I am willing to continue a side project on a fairly related topic. Actually, this is project is on a topic completely related to my potential PhD project and even during my job interview my supervisor said it is a plus for me to have experience with these kind of projects.
I have been working on this project from second year of my master's and I worked only about 3-4 hours per week on that, so I guess I can manage to keep it as a side project. The thing is it still needs some work to lead to some acceptable results, but I'm sure it will pay off, if I can make it. Yet, learning about the methods used in the project are really helpful for my PhD project as well. The problem comes where most professors want concentration from their students and this might not be Ok with working with another researchers. Besides, my collaboration in the side project seems not to be very efficient since it is a side project for my collaborators as well.
The question is should I discuss this with my professor even if I want to dedicate some of my free time to that? Should I risk my relationship with him in the early stages of my PhD studies (in case he is not Ok with that?)? Do I look like some trouble maker if I ask him about this? Do you think I should continue this project or just simply drop it and concentrate on my PhD project?