I use a table saw with a thin kerf finishing blade (80 tooth). The cutting is done with a segeasy sled. They are easy to make. There are also commericial cross cutting sleds that you can buy. I have had no problem cutting segments less than .25". In my experience it also helps to have the saw blade raised to its full height.
What type of a project are you working on? How many segments & rows? What type of wood?
I have always used my tablesaw with a Freud Ultra fine crosscut blade. Starting out segment edge length can be very small. I will also stack strips together and put a dab of glue on the far end so I can cut more pieces at once.
As an alternative, you might want to consider trying the miter saw to cut your segments. I like it because I'm able to stand up straight and it is easy to stack boards and make 3-5 segments with every cut.
Watch Tutorial #2 at the following link to see how I do mine: Title: Beginner's Project - Open Segment Christmas Ornament