When your projects are just floating off your machine in perfect condition, it is a true joy to embroider. When things are going less than ideal, there are so many things to consider. Computer aided embroidery is no different than any other computer related issue, all the experts have an opinion, and some of those won't work at all for your situation.
Among those issues is the question of thread type. I have said this before, but - be cautious when someone tells you that "only" X brand can solve this issue.
This is the same person who made the statement "one size fits all."
Polyester (Poly) and Rayon/Viscose (Ray) threads have a very interesting relationship. They work together but they can be very competitive and not work well together at all, sort of like a two-year-old throwing a fit.
Projects are better when you are consistent with the thread type that you use. Tension can be differing as your own tests will show. Who needs more issues to deal with?
As you prepare to do a tension test for your threads and machine, select among the most used threads in your stash. Keep track of which threads you are using and eventually you will have an excellent working knowledge of your settings on your machine.
My test took about 15 minutes including saving the files to a common place for recall and review. The underside of your stitching should show approximately 1/3 to 1/2 bobbin thread. The Madeira Metallic and Mettler #40 are approximately correct. The others are just a little tight on the upper thread tension. Always adjust the top tension first. Only adjust the bobbin tension if really
necessary. tension tests.zip (7.8KB)
Tension tests should be completed on a regular basis. If you are embarking on a tricky or detailed project, this test will make the outcome more professional. After all, the back side of your design should be nearly as lovely as the front.