Homemade Roots Blower: Second revision of the rotor profiles

Hopefully This will be the final designs of the Roots lobes before I start making it.

I decided to design a 3 lobe and 2 lobe rotor that would be compatible with supercharger case I designed, I will see which works out best by testing it in use. I will most likely make the 3 lobe first since I feel that the 3 lobe design is better.

I do not have any keyway broaches, for now I will just have drilled holes for the keyways. I plan on using a 1/8 round nose endmill to cut grooves into the shaft so that i can insert a 1/8 inch metal rod to lock together the rotor and the drive shaft. No idea how well that would work out though.

This 3 lobe is significantly smaller than what I had originally planned mostly due to the size restrictions of my small mill. The entire assembly is much smaller too.

Some advantages I see with the 2 lobe rotors is using less raw materials to make one and less machining required. Unlike the 3 lobe above, the centers of radii is different between the male and female lobes. I designed it this way because when they are equal, the center section becomes too thin to properly support the rotor.


I also made a rotor profile that just looked like an oval blob, was surprised that it actually works but the swept volume was very low so it's not very practical.

Next I will probably try to make a lysholm style rotor.