My machine using loose, tight and "good" tension. Interestingly, this is very hard to replicate on newer digital machines, as they seem to self-correct unless the machine is threaded wrong, like no bobbin tension at all or the top thread not going through all components. This happens when I teach my year 10 textiles class. This is sometimes a drawback as I use the tight tension to pre-gather ruffles etc. This can't happen with the new machines; I need to use the special gathering foot.