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Looking to build a DIY conveyor belt powered by a furnace blower motor that I have kicking around using a series of pulleys to significantly step down the speed.

My 3 speed Century DL1076 has an rpm of 1075 but I'm wondering if someone can

A. Confirm that 1075 RPM is its speed on the High setting.

B. Let me know if there's a general rule of thumb for calculating the speeds for Low and Medium in terms of percentages?

Dave

  • I would be a lot more worried about the torque your motor can generate. Blower motors aren't designed to work under significant load. So, first calculate the amount of mass you expect the conveyor belt to handle, then calculate the torque necessary to get it going. Fortunately, those step-down pulleys have the advantage of reducing the torque at the motor proportionally. – Carl Witthoft Feb 20 at 20:57
  • "A motor you have lying around" is probably the most expensive kind of motor... because of the cubic effort needed to adapt it to purpose, as opposed to just getting something built for purpose. Think about the "Do you want fries with that?" test. If it takes 100 hours of tinkering to adapt it, but 50 hours of minimum wage work would let you buy exactly the right part for the job, then you gotta ask yourself... – Harper - Reinstate Monica Feb 20 at 22:24
  • @Harper: Good point taken about cubing with the motor lying around! Think I'll mitigate that by getting an 80:1 worm gear box :) – bushrat Feb 20 at 23:02
  • @Carl: Another very good point there, I'm actually looking to move earth with the conveyor belt up into a truck and am hopeful that its 3/4 hp will be up for the task but if not, maybe I'll pull one out of an old clothes washer or something (knew I hung onto one of those for a reason!). – bushrat Feb 20 at 23:13
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Multi-speed motors are rated at their speed on high, so high will be around 1075. The other speeds will typically be around 100 rpm lower than the next speed, so you don't get a lot of range in that speed. The speeds are also designed so that with the same load applied to the motor (like a fan blade), the different speeds give less power to the motor, so it naturally slows down.

If the motor is loaded more or less than it was designed for the change in speeds will vary. I've never tried this, but I suspect the no-load speed on low will be very close to the high speed, and you will get more separation in the speeds the more the motor is loaded.

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  • Thanks! Exactly what I was after. I'll do my figuring using that max value as I'll definitely want to ensure I'm using all available power. – bushrat Feb 20 at 23:00

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