An antique Singer model 7-31 industrial sewing machine, manufactured at Singer's Elizabethport, NJ plant in 1917! The 7 series encompassed most of Singer's commercial machines made not just for manufacturing use, but for tough work - sails, wagon covers, tarps, and even leather. You may enjoy reading more about the 7 series here.

The 7-31 models were originally designed for use with overhead drivelines on factory production floors, most extant units have since been converted to run on individual v-belt motors (technically making them 7-32s,though they still bear the 7-31 tag), and it has long been a popular machine with hobbyists and leather workers, so there are likely resources to help you complete said conversion with this one. It does not come with a motor, but compatible motors from Singer and other makers are readily available online. This machine will need a good cleanup - personally I found the job of scrubbing through 110 years of grime to clear the serial number quite satisfying, so maybe you'll have fun! It seems to be in a good starting place for restoration, the wheel turns smoothly and the needle shaft moves up and down freely.

These machines are rare, and there are very few documented sales in recent years. As of 4/22/26 there are two 7-31s listed for sale with motors and tables for $1500 and $1800.