We had one in our shop. I found that the Aurifil 50 wt plain colors worked best. Usually used a 100 topstitch needle. Some of Sulky 30 wt did OK, but only if they were plain or the variegated did not change color much. For example, the varigated pastels did OK, but varigated black to white was MISERABLE!!! Too much color change was hard to work with. Even the Sulky reps didn't know why. Don't go too fast - that made the thread break. Good luck - when you find the right combination for you it'll be great!