Query Related To Sewing Machines

Q. With same brand and same model of machine while the stitch regulator is set at a particular reading all the machines don't give same SPI, why? Do'nt you think a machine manufacturer should look into the problem which will make life easy for sewing supervisers and operators?

Ans. It should be cased by difference of feed dog adjustment. If you maintain the machines with exact adjustment for feeding, stitch length will be the same.