|I use a fold-up table that's about 28 inches high for my sewing machine . After a day of sewing hunched over the machine, I had some nasty upper back strain. When I raised my chair height, then my feet couldn't sit flat on the floor.
Then it dawned on me to place some thick large books under the machine for more height. I used two books that are each 1 inch wide at the binding, and the problem is solved. For added security, I used "Miracle Hold" gripper cloth under the books. There is no machine wobbling or vibrating movement, even when using just the free arm.