I've loaned my favorite mechanical sewing machine once - to a good friend I completely trusted. She liked it so much, she asked me to find her one just like it to buy, which I did. It was a great machine, and before she passed away she gave it back to me. I, in turn, gave it to a young lady who wanted to learn how to sew on a machine and her mother (another good friend) couldn't afford to purchase one.
That was the one and only time I ever loaned out my machine. If another friend really needs to borrow one, I would probably offer it for use at my home, but I probably wouldn't lend it out.