Everyone knows that industrial machines sew better, last longer, and are more reliable than domestic sewing machines but many sewists are reluctant to acquire one due to the size, weight, speed, and noise. The noise is attributed to the clutch motor that runs all the time and only powers the sewing head when the operator steps on the pedal and energizes the clutch.
This noise problem has been overcome in recent years by the DC servomotor that acts like a domestic foot controlled motor - it does not run (makes no noise) unless the operator steps on the pedal, then the motor spins the sewing machine. While the servomotor solves the noise problem, it still has to be mounted in a power stand so the issues of size and weight are still present.
Many years ago, I obtained a Singer 95-10 tailoring machine. It had a clutch motor but I didn't have a belt to fit and my parts bin had several motors, belts, and foot controls, so I decided to try powering it with a motor off a home machine. To my surprise, the machine worked quite well and sewed everything I put under the presser foot. It was still mounted in a power stand but I had the space so that was not a problem.
When I got my Singer 20U-33, I bought only the head. I saw that there were motor bracket mounting provisions below the balance wheel that looked like those on a home machine so I bolted a motor from an old Brother in place and sewed away.
My internet friend Rich in Tennessee carried things a bit further, he built a wooden box to hold the sewing head and a motor mount and powered a big, honkin' walking foot upholstery machine with a domestic motor. Rich has solved the issues of size, noise, and speed. Don't think that his is a portable though, it probably weighs in the 60-70 pound range.
You would think that a little 1/15 horsepower motor would not spin an industrial machine designed for a 1/4 - 3/4 hp motor but the answer is in the sizes of the pulleys. The pulley on the 1/3 hp clutch motor pictured above is 11 inches in circumference. It drives a balance wheel that is also 11 inches in circumference. The motor pulley on a domestic machine is 3 inches in circumference, so there is almost a 4-1 reduction and the 1/15 hp motor appears to be much more powerful.
This solves another issue of industrial machines - the speed. Many are intimidated by 3500 stitches per minute but with a 4-1 reduction, the machine will only sew about 900 SPM with a domestic motor - the same speed as the average domestic machine. That speed is more easily controlled by the foot control and the operator doesn't need to learn the procedure for operating a clutch motor.
Food for thought