I recently purchased a 3 jaw 5" chuck for my LMS 4200 HiTorque Mini Lathe and I love it. But I find that mounting it is more difficult than my 3" chuck because of its size and weight. So I came up with a little trick that helps a lot. When mounting the chuck I place a 1" thick piece of soft wood across the ways to hold the chuck up while I bolt it on. I use the same trick when I dismount the chuck to make sure I don't drop it on the ways.