FAQ
TL;DR: Need 1–24 rpm? “Rotational speed … must be adjustable between 1 and 24 rpm.” Use a geared drive plus either a VFD on a 3‑phase motor or a proper AC/DC controller, not a lamp dimmer. [Elektroda, hadi makoui, post #21666712]
Why it matters: This FAQ helps makers choose a safe, torque‑capable, low‑speed drive for clay mixers.
Quick Facts
- Target: 1–24 rpm from a 1.5 hp, ~1420 rpm motor requires heavy reduction and electronic control. [Elektroda, hadi makoui, post #21666712]
- 3‑phase motor + VFD: “full torque … within reason,” ideal for low‑speed mixing. [Elektroda, David Adams, post #21666715]
- Single‑phase AC: use a triac motor speed controller; tool‑type modules are common and low‑cost. [Elektroda, Frank Bushnell, post #21666716]
- Example single‑phase controllers exist up to about 2 kW for simple retrofits. [Elektroda, Frank Bushnell, post #21666718]
- Safety: water and electricity don’t mix—use proper enclosures and keep circuits dry. [Elektroda, Peter Evenhuis, post #21666714]
What motor type works best for a clay mixer at 1–24 rpm?
Use a 3‑phase induction motor with a VFD plus a gearbox. The VFD gives controllable speed and strong low‑speed torque. Add mechanical reduction to hit 1–24 rpm without stalling. “VFD will give you full torque … within reason.” [Elektroda, David Adams, post #21666715]
Can I slow an AC motor with a light dimmer?
Do not use a household lamp dimmer. It is not designed for motor loads, has poor control, and creates safety risks. Use a purpose‑built motor controller instead. “A light dimmer is for light not for speed control.” [Elektroda, Peter Evenhuis, post #21666714]
How do I control speed on a single‑phase AC motor?
Use a triac‑based AC motor speed controller. These phase‑angle controllers are common in power tools and available as plug‑in modules, offering simple, low‑cost adjustment. [Elektroda, Frank Bushnell, post #21666716]
How do I control speed on a DC motor?
Use a PWM DC motor speed controller. PWM varies the average voltage while keeping efficiency high, giving smooth, wide‑range speed control and good torque. [Elektroda, Frank Bushnell, post #21666716]
What is a VFD and why choose one here?
A Variable Frequency Drive changes the frequency and voltage to a 3‑phase motor, letting you dial speed and maintain torque. It’s well‑suited to mixers needing low, adjustable rpm. “Full torque … within reason.” [Elektroda, David Adams, post #21666715]
Will a triac controller keep torque at 1 rpm on an induction motor?
Not reliably. Phase‑angle control reduces voltage and torque, which can cause stalling at very low speeds. For strong torque near 1 rpm, use gearbox reduction plus a VFD. “Within reason” applies at very low rpm. [Elektroda, David Adams, post #21666715]
Is PWM the same idea as chopping AC with a triac?
Yes, in principle. A triac controller “chops” the AC waveform similar to PWM on DC, altering effective voltage to change speed. [Elektroda, Frank Bushnell, post #21666718]
What gearbox ratio do I need from 1420 rpm to 24 rpm?
Approx. 59:1 (1420 ÷ 24 ≈ 59). Add more reduction for a 1 rpm minimum while keeping the motor in an efficient speed range. [Elektroda, hadi makoui, post #21666712]
What mains supply should I plan around?
Design for single‑phase 220 V, 50 Hz if that’s your available supply. You can also consider a 3‑phase motor with appropriate control hardware. [Elektroda, hadi makoui, post #21666717]
Are off‑the‑shelf single‑phase speed controllers available for retrofits?
Yes. Example tool‑style controllers exist for single‑phase AC motors up to about 2 kW and can be used in simple builds. [Elektroda, Frank Bushnell, post #21666718]
What’s the cheapest path to variable speed right now?
For simplicity and low cost, use a triac AC controller for single‑phase motors or a PWM controller for DC motors. Both are widely available and inexpensive. [Elektroda, Frank Bushnell, post #21666716]
How should I approach safety around wet clay and electrics?
Keep all electrical parts dry and sealed. Use proper enclosures, strain relief, and ground fault protection. Water and electricity together can kill. [Elektroda, Peter Evenhuis, post #21666714]
Can I adapt a power‑tool style controller to my mixer motor?
Yes, many power tools use similar triac speed controls. A compatible module can provide knob‑type adjustment for AC motors. Ensure current rating matches your motor. [Elektroda, Frank Bushnell, post #21666718]
Which controller should I avoid for induction motors?
Avoid plain lamp dimmers. Use controllers designed for motor loads. Dedicated triac motor controllers address phase control, surge, and protection. [Elektroda, Mark Harrington, post #21666720]
How do I set up a simple AC speed control safely? (3‑step How‑To)
- Choose a triac motor controller rated at or above your motor’s current.
- Mount it in a ventilated, splash‑proof enclosure with strain relief.
- Wire line‑in and motor‑out per the module diagram; test at no‑load, then under clay load. [Elektroda, Frank Bushnell, post #21666718]
What power level am I dealing with at 1.5 hp?
About 1.12 kW (1 hp ≈ 0.746 kW). Ensure controller and wiring comfortably exceed this rating plus startup surge current. [Elektroda, hadi makoui, post #21666712]
