Using the Impeller Designer
Design your own impeller with everything you have learned — then download it for a 3D printer.
⏱ 8 min
- Everyday comparisonStep 1 of 6
Your own recipe
A baker changes a recipe to get a lighter cake or a crunchier crust: a little more of this, a little less of that — and knows why.
You now know the “why” of every part of an impeller. Time to write your own recipe.
- Try itStep 2 of 6
The Impeller Designer
Change the dimensions and watch the impeller update in front view and in a side cut. The estimate below shows roughly what it would do at your motor speed.
Switch to 3D to turn your design around, and tick With casing to see the matching volute casing around it.
When you are happy, press Download STL — you get a real, printable 3D model of your design. Download matching casing gives you the snail-shaped body and its cover, sized to fit your impeller.
Challenge: Double the motor speed. What happens to the tip speed, the flow, the head and the power? Does that match the affinity laws from Module 5?
- ExplainedStep 3 of 6
What each dial does
Outer diameter D₂ and motor speed set the tip speed — and head grows with tip speed squared (Euler). Vane height b₂ and the eye mostly set how much water fits through: the flow.
Outlet angle β₂ trades head against a stable curve (backward-curved: 20–30° is typical). The inlet angle β₁ should match the incoming water, usually 15–30°.
- ExplainedStep 4 of 6
Rules of thumb for a first design
Start with 5–7 vanes, β₂ ≈ 25–30°, and an eye about ⅓ of D₂. Keep vanes at least 1.5 mm thick so they print strongly.
Small flow and big head? Narrow b₂ and a bigger D₂. Lots of flow, little head? Wider b₂ and a bigger eye. The designer warns you if the vanes get crowded or the eye is blocked by the hub.
- ExplainedStep 5 of 6
Printing it
Open the in a and print it with the back disc flat on the bed. A semi-open impeller prints without any supports — the best choice for your first one. A closed one needs supports inside the channels, which are hard to remove.
Use (it handles water better than PLA), 0.2 mm layers and plenty of walls. Check the bore fits your motor shaft; print a test piece if unsure.
- The impeller connectionStep 6 of 6
Next: build the pump
An impeller alone just stirs water. In the next lesson you will put it in a casing, give it a motor, and make a working pump.
📌 Remember this
The diameter and speed set the head, the vane height and eye set the flow, and the vane angles shape the curve. Print a semi-open design in PETG for your first prototype.