A while back I bought a leaky air compressor for $50 because it had a good 3HP motor on it that I figured I could use someday for something, probably.
When Mr. Wendel built a small dust collector with a tile saw motor, I knew my old motor had found its destiny.
Little did I know that this would lead to one of the scariest things I have ever built (and I’ve made a good number of catapults and potato cannons in my day).
I needed to make three things: an impeller, a cowl, and a motor mount.
Everything I needed I already had laying around, so I figured this would be a good way to use my tools and my time. At the very least it would be an educational experience.
First: Thing 1 – Impeller
To start, I cut some 1/4″ plywood into two identical discs by taping two squares together with double-sided tape and then spinning them across the blade on a screw I had driven through a thicker board (a rudimentary form of a dedicated circle-cutting jig)
A piece of oak I had in my scrap bin became the impeller fins. I printed out a template and glued it to the piece of wood and then cut out the pieces freehand on my bandsaw.
Since this was a remnant piece of wood, it was not the same thickness all the way through, so I removed some wood from the top of each fin after setting it against the bottom of my milling machine vice to ensure that they were all the same height.
Using 9 fins, the math was easy, I placed a fin every 40-degrees around the bottom disc. The tilt was determined based on what looked best to me, then I just measured the offset from the 40-degree lines and placed the tip of the fin on one line and base of the fin on the other.
After setting everything in place dry and ensuring in all aligned properly, I applied glue to the top and bottom surfaces, set them in their pre-determined places around the bottom disc, and then set the second disc on top.
I didn’t want to mess with clamps, so I set the assembly on a known flat surface (my table saw) and set another known flat surface on top (yes, that’s the table top from the old scroll saw) and piled some heavy metal pieces on that.
After letting the glue set overnight, I took the assembled impeller to the drill press, where I used a 4-inch hole saw to open one side as the air inlet.
Next I set a large ball bearing on top of a metal cylinder in the vise and balanced the impeller on top of it.
I used a forstner bit to remove wood from the heavy side until the impeller stayed level while balanced on the bearing.
So, now I had the impeller… part 1 complete.