Anybody ever do this? I have a friend that has 28 acres of mountain land that has deer, turkey and bear that come through. Only thing is it's too open, no underbrush. He was thinking of hinge cutting the trees to make it thick plus having good cover.

Where I'm talking about is on the sunny side of the mountain, the top is thick laurel with oak trees and June berry trees.

Yes, a very useful habitat technique given some forethought, proper conditions, and safety precautions.

There are a few threads in this forum on the subject...and some of the guys have some good pictures of what they have done in their threads.

If possible, post up some pics of the project area please.

Yes, I have done it and have been really happy with how my areas are turning out. As O stated, some forethought into what you want to accomplish is key. You can use it to dictate where you want deer to travel, bed, etc.
Some trees hinge better than others, do not try to hinge trees greater than say 6-7 inches diameter. I use a hook to either push or pull tree over. This allows me to only cut thru tree minimum amount that i have to and then I can push it over or pull it over. This leads to a better chance hinge staying intact and tree staying alive for several more years.
Good luck if you decide to do it.

The one section has pole timber in it, it was cleared a while back. That's where he wants to start. As soon as I can get up there I'll take some pics

You Commented "NO UNDERBRUSH" that is a direct result of no sunlight hitting the ground. Do a small clearcut.
let the sun in. it works excellent.

Totally agree with this

Is it ok to start hinge cutting now?

You can hinge cut now but if it is cold the trees are more likely to snap off rather then hinge. I like it to be above 50 degrees.

Our place is likely to see some hinge cuts every time I have the saw in my hand - ha. I'm not afraid to hinge any time of year....especially when the tree I'm hinging has no value standing up - read MAPLE.