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.

Homemade Roots Blower: Almost done with the design

All i need to do now is print out the drawings and cut a prototype out of plastic or some type of hardwood.

I think my next few posts will be the drawings/blueprints of the individual components. 

If I make this out of wood I would probably just print out the drawing, glue it onto a block of wood and jigsaw out the profile of the part.

If I am to use this as a supercharger as originally planned, this would need to be made out of aluminum at least... as I'm sure gasoline and wood does not mix well especially if I am trying to keep close tolerances on the wood.

DIY Roots blower: Blower case and animation

So my previous posts was about blower rotors and how I might make them, now I get to put those rotors into a case. It is a rather simple case, but I am trying to make the construction as simple and straightforward as possible when I start making it out of wood later on. This is a primarily designed as a kind of DIY home made supercharger, not something you would bolt into your car.

And this is how it looks assembled

Since I have it all assembled, might as well make a animation of it...

DIY Roots blower: rotor profile drawing/dimensions

I set up this CAD drawing for spacing the rotors 2 inches apart. But when i actually make it out of wood, I think I will resize the dimensions so I can reuse my hole saws from before. Trying to find .518in radius I.D./O.D. hole saws would be too difficult... With this base drawing I should be able to scale it up to any size i want.

Roots Supercharger Rotor Profile

I wanted something simple so I wanted to see if I could make the classic roots rotor profile in cad. Doing so I discovered why my wooden rotors didn't mesh properly. I totally cut the rotors wrong, but the proper profile also seems rather simple to make.

Now this looks much better, I'll post the actual dimensions and drawing later...

Even though I designed this in a CAD program it still seems like it would be possible for the layman to make a real supercharger.