Stitches Per Minute
Being increasingly drawn to industrial machines, I'm interested in SPM as a comparison between machines and manufacturers. I have a modern Janome domestic (6500P) whose literature claims it is "blazingly fast" at 1000 SPM. Even running it at top speed, I don't find it particularly fast at all. My other domestics run similarly, some slower, some about the same speed. I have a Pfaff 30 that is fairly quick but I haven't tested it.
I'm currently considering a modern industrial that runs 5500 SPM. Others approach 6500 - 7000 SPM and changing the diameter of the motor's pulley (connected to the belt, controlling the speed of the drive shaft) can increase the speed further (or decrease; larger diameter == faster, smaller == slower).
When measuring SPM, does a manufacturer measure straight stitch only? Is the length of the stitch reduced from, say, 3 mm in order to perform a speed test? (I would imagine length would have a negligible effect on speed as long as the material can be fed accordingly -- if that is how the test is being performed).
In the little investigating I've done, both modern and vintage industrial machines are/were made to run above 6000 SPM and less than 2000. It depends upon the model and its intended purpose.
Is speed a meaningful measurement to you?