But it may take some practice to get used to lifting with free weights, and it's essential to use proper technique. Machine weights also can be effective weight training tools, as long as you use machines that adjust to your body dimensions and allow your joints to move through their natural motion paths.Machine weights are generally safe when used with the proper technique. Many people can learn to use them quickly.he choice of using free weights or machine weights is based on your personal preference, your physical fitness level, your fitness goals and your access to equipment. Free weights are versatile and inexpensive. They also simulate real-life lifting situations and promote whole-body stabilization.