I like to add the hanger to the back of my intarsia piece before I glue it to the backer board, but sometimes I forget. It is difficult to hammer those little nails into the backer while trying to protect your intarsia. I have split pieces of my intarsia and have knocked some loose while hammering in those little nails that come with the hangers. I discovered using little screws instead of the nails works very well. The only problem is the little screws are too big to fit into the predrilled holes of the saw toothed hangers. But, if you use a 3/32 drill bit you can enlarge the holes just enough to allow the screws to fit. So if you forget to add your hanger before you glue then try this!
Woodpile Fun! 8mm mini screws at Hobby Lobby
Cy's Corner 
I have just recently taken an interest in intarsia. I have always loved working with wood ( there is no such thing as an ugly piece of wood). I have watched your videos over and over! I am presently in the middle of my first intarsia project and I have made a lot of mistakes but I am also learning. By the way, I was born in McMinnville and all but very few of my relatives live there. Those that don’t live in McMinnville live in Redman or Prineville. Keep making videos!
Barbara
So good to meet you Barbara! I am excited you are making intarsias! I would love to see what you do. If you have any questions just send me an email. I don’t know everything, and am still learning, but it is always fun to talk with other woodworkers 🙂 If you are ever over this way visiting family we should meet up!