answer:What is the pitch of the screw it’s turning? That link you gave shows one with a 3/8”-24 thread. Take the 8000 RPM, pass it through the 9.5:1 box, and you’ll get a hair over 842 RPM. 8000 / 9.5 = 842.105… Turning a nut in a 24 thread-per-inch (like a 3/8”-24) screw will get you 1” per 24 revolutions. That particular model will move at just over 35”/minute 842 / 24 = 35.087 That’s ~891mm/min, which is ~14.8mm/second. 35.087” * 25.4mm/” = 891.2098mm per minute 891.2098 / 60 = 14.853… mm per second Using the 19:1 instead of the 9.5:1 will halve the output RPM to ~421 RPM and halve all the speeds, but still be far faster than you want. As for what gear ratio, that really depends on the pitch of the screw and the RPM of the drive motor. And lastly, suppliers…. I don’t think there are any off the shelf that slow. If you want something at 0.1mm/second, you’re wanting something REALLY slow, probably a custom job. I can say that the higher the weight limit, the slower they will go; they mostly use the same motor, but the higher weight-limit ones trade speed for force. Still, the slowest I’ve seen so far is 0.16”(~4mm)/second for one with a 1500-pound max and a 52:1 gearbox. With the same pitch screw and motor RPM, you would need a gear ratio closer to 2000:1…. or a 40:1 feeding a 50:1 (40*50=2000) if you wanted to keep size manageable. What you need is a stepper motor which is kind of the same, but adds controls that regulate it’s speed and travel better than a simple linear motor…. though at increased cost. At the very least, you need more than simple “on/off” unless you are going to go the custom route that will likely involve a two-stage gearbox.