Tips/Techniques Manual speed control for brushless spindle

[PeterT]

These brushless motor kits come in a variety of flavors between 500-900? watts. I think some of you might even be running one? I'm starting to think they are not created equal. My question is if I want to vary speed with a manual knob (vs driven through software in CNC application) what am I looking at here? Many don't include it. Some call it potentiometer, some call it speed controller, some call it PWM controller. I see 3 wires on a little board looking thing. Would it be dedicated to the unit or something more generic?

Amazon.ca

www.amazon.ca

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www.aliexpress.com

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www.aliexpress.com

 

[whydontu]

The manual speed control is a standard 5k potentiometer (variable resistor). The Amazon kit comes with everything you need to set up a manual speed control, except the wire from the power supply to the wall outlet. Would you like a wiring diagram for the manual configuration?

 

[Susquatch]

^ what @whydontu said.

The three wires on the pot board are required for voltage division. One is positive, one is negative, and the third is the wiper voltage that is used to set speed.

I have two of these motors with controllers. They are called lots of things just like you say.

My impression is that the power supply for both of mine does not provide sufficient current at the target voltage to reach the power rating.

I have put a scope on mine to figure out how it works.

My two motors (500 & 750 watts) are both pure variable voltage DC speed control. One came with a PWM controller, and the other came with a variable voltage power supply. Both controllers will run either motor. Both are current limited which limits performance.

My current plan is to find or make a bigger supply and probably go PWM.

As you should expect, reversing the motor wires reverses its direction.

Can't speak for other motors but that is how mine work and its the best info I could find on other motors too.

 

[whydontu]

The Amazon version is a brushless dc motor and uses a logic controller for direction, so a simple on-off switch changes direction. And as @Susquatch says, the wattage rating of the motor is wildly optimistic. I have a 48v 10a power supply on mine (450 watt), and under load the motor pulls about 2.5a, roughly 120 watt).

 

[PeterT]

Yes just to be clear, I am only considering the brushless motors. So the pot is a standard DC pot with 3 wires & it talks to the black control box ? The 3 wires have nothing todo with brushless controllers like speed controls with 3 wires for phase control like ESC's - that happens inside the black box itself? The little board the pot is mounted to is maybe just that - a board, so other components containing magic smoke? From what you guys have seen of these (generically similar on Amazon, Ali, Ebay...) does the aforementioned manual speed control pot/knob tie into the box & function the same across the line of increasing power outputs?

Yes, I'm suspicious of wattage too which s probably why I'd opt for bigger one & divide by some reality factor & cross my fingers.

 

[PeterT]

I have two of these motors with controllers. They are called lots of things just like you say.

I thought yours was brushed but maybe I'm remembering incorrectly or you have more

 

[Susquatch]

Yes just to be clear, I am only considering the brushless motors. So the pot is a standard DC pot with 3 wires & it talks to the black control box ?

Yes.

The 3 wires have nothing todo with brushless controllers like speed controls with 3 wires for phase control like ESC's - that happens inside the black box itself?

Yes, not a three phase motor. Yes, it's just a magic voltage applied to the controller to tell it how fast to drive the motor.

The little board the pot is mounted to is maybe just that - a board, so other components containing magic smoke?

Yup.

From what you guys have seen of these (generically similar on Amazon, Ali, Ebay...) does the aforementioned manual speed control pot/knob tie into the box & function the same across the line of increasing power outputs?

Ya, that's pretty much what I have seen. The only reason for the cable on the pot is so it can be mounted remote from the speed control box.

Yes, I'm suspicious of wattage too which s probably why I'd opt for bigger one & divide by some reality factor & cross my fingers.

Yup. Pretty much how we all feel. But my suspicion is that both the motor AND THE CONTROL BOX are over rated. To get the most possible out of the motor I am using a bigger controller. It's still underwhelming.

 

[Susquatch]

I thought yours was brushed but maybe I'm remembering incorrectly or you have more

You remember correctly. The first one fried when some idiot shorted the 115 input to a metal part on the board with a wire that was longer than the attachment lug. So I got 2 more.