I watched a youTube video on some sewing tips a few months ago, primarily for using vintage machines. One of the tips in it was to cut the thread on a diagonal for threading a needle. I was having a hard time threading my machines since they are both vintage Singers and don't have an automatic threader (my reading vision is also not the best). I was skeptical at first, but it does work for me, not only for threading a machine but also a sewing needle. Sometimes I have to cut the thread several times because the thread frays a bit, but eventually I get the machine threaded.
Shari