I have found that the reg. coats & clark thread does not hold up very good , I did mine on a kenmore serger back in the late 90's, did not last, the thread just didnt hold { resewn the blocks } .Then son was using it and was stolen from his truck. I used all differnt colors of threads My singer 101 sews with the heavier thread ,guess its time to do another one? DottieBug Ohhhh I use the jeans thread the off colored orange one