Most companies allow their employees use of company equipment at their premise to do their side work or a small home improvement job. Some places like Marinas and Construction yards will let employees keep their boats and equipment in the yards for free and let them do their repairs there because it’s a general practice of the business. But remember what your father taught you “NICE GUYS FINISH LAST” and that is true more today than at any other time. . If that employee gets hurt on your premises after or before working hours will your workers compensation policy respond? Will your general liability policy? Their lawyer might say they were on your premises and using your equipment that this is compensation to the employee and you are responsible for their injuries. So either make sure you have high enough limits of insurance and a policy that will respond to this situation or change your current work practices.
It is a shame that business has come to this but if you don’t believe me, ask others as you may find someone who has encountered such a problem and have their own I was just being a nice guy story.