How to attach an impeller to a CIM motor

[Lowfategg]

We have threaded the shaft of a cim motor before. You need a 8mm die (or 5/16), and a good way of holding the motor shaft to keep it from turning when doing so. Its tricky but we got it to work on our 09 bot's fan.

[martin417]

It is very unlikely that you will get enough suction (delta P) by direct driving an impeller with a CIM. We geared our impeller up 3:1 (the impeller turns 3 times as fast as the CIM motor) to get the necessary rpm. Also, you might look for a different impeller than the one pictured. That is a mixed flow (both axial and radial flow) impeller like what you might see in a turbocharger. This design is a compromise between flow and pressure. What you want is a pure radial flow impeller like you would find in a shop vac. Volume flow rate is not very important, you want to maximize pressure change. A large diameter, narrow cross section impeller will give you that. If you can find a 2-stage impeller, so much the better.

[Dad1279]

We used a shop vac. Removed everything but the impeller, housing, and motor. Then we removed the armature from the motor shaft with a press and mounted a toothed belt pulley on the motor shaft, another on the CIM, with a 3:1 increase in speed.

Tried gears first, but it was very loud.