I have a Viking D1 and it sews with jean thread, cotton 30 wt for my piecing, to 40-50 wt. polyester for embroidery. I just make sure the needle is right. That is what has caused me the most problems in the past; wrong size or dull needle... the machine doesn't seem to mind. It's kinda like horseback riding: the horse will usually go Western or English because they all walk, trot, canter, gallop. The rider usually decides on the type saddle/bits they like and feel comfortable riding with... to me, that's how sewing is, each to his own likes and dislikes... unless you just get a funky machine and I have a couple of those! LOL