Originally Posted by DanTwoLakes
Just like Singer and a few others, Union Special has their own numbering system for needles. The first number is the metric size, and the number after the forward slash is the Union Special equivalent. Any good needle supplier will have the needles for your machine. You can use the 125, 140, and 150 with #92 polyester thread.
Compound feed means there are two types of feed being employed at the same time. This usually means needle feed (the needle pulls the fabric through) and drop feed ( the feed dog and walking foot pull the fabric) but it can also mean any two types of feed working together.
Many thanks Dan. I'm sure I'll have more questions when I find a suitable machine. We do have a Bernina machine with a walking foot, but I doubt is has enough "oomph" to handle upholstery.