I use them all the time. Be careful that you aren't using the prewounds for machine embroidery. The thread on these is a very light weight lingerie thread. I had a really unfortunate experience when I forgot to check what was in my bobbin case before I did my piecing. And, of course, I had an embroidery bobbin in the bobbin case. My seams in completed top actually started to pop apart as I was doing my final press. Bad, bad words fell out of my mouth!!!!