Can RC Brushless Motors be used as Spindle Motor ???
I have been trying to design a DIY Spindle for milling aluminum. I came across this DIY Spindle
"http://www.youtube.com/watch?v=fPLdHeRQp_w"]YouTube - DIY 3-Phase Spindle for your cnc
The Designer is using Brushless Motor (used by RC Airplane hobbyists)
Motor Specs (from the Manufacturers Page)
Power 110 Brushless Outrunner Motor, 295Kv
Overview
The Power 110 is designed to deliver clean and quiet power equivalent to or surpassing the power of a 110-size 2-stroke glow engine for sport and scale airplanes weighing 9 to 15 pounds (4 to 6.8 kg), 3D airplanes up to 11 pounds (5 kg), or models requiring up to 2000 watts of power.
Key Features
* Equivalent to or surpassing the power of a 110-size 2-stroke glow engine for 9–15 lb (4–6.8 kg) airplanes
* Ideal for 3D airplanes up to 11 lb (5 kg)
* High-torque, direct-drive alternative to inrunner brushless motors
* Includes mount and mounting hardware
* High-quality construction with ball bearings and hardened 8mm steel shaft
* Includes two 12mm prop shaft adapters tapped out for 10–32 threads
* Ideal for models requiring up to 2000 watts of power
* External rotor design for better cooling
The motors are pretty compact and can do High RPMs. Also we could hook up an encoder to the shaft for RPM control. Everything looks promising but I am not sure about the CONTINUIOUS OPERATION CAPABILITY of these motors since most RC Planes only fly for around 15-20 mins.
- I was wondering if such motors can be used as spindle motors?
- If anyone has experience using these motors please share your experiences/Ideas.
- Also please share your ideas on other suitable types of Motors for a DIY Milling spindle.
Thank You
Joe
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thats a very interesting question man they make a rc car brushless motor that put out 1hp i dont know how to control the speed control without the remote. Probably a reohstat would do. Oh email novak and ask them about duty cycle and tell them your end use. Theyll probably be able to tell you. being about to do the Horsepower calculation for the make tool diameter you intend to use would be great to know too. Let me knowwhat you find out.
later
1. Does it spin?Originally Posted by joprinz
I was wondering if such motors can be used as spindle motors?
Thank You
Joe
2. It has all the power do you need?
PS: Search for a "heli" controller. These ones try to keep rpm constant at load variations.
Ofcourse it does spin...n its rated 2000Watts and can do around 10K rpm. I guess that should be sufficient for light milling work... But I do not know if these Outrunner type Brushless Motors are designed to work continuously for hours. Not to forget the fact that in a RC plane they have the propeller blowing air onto it inturn cooling it.
n Yes Heli Controller idea is good to keep the rpm constant...
The biggest Question is the Continuous Operation capability... Hope someone can share their experience working with these kind of motors...
Joe!
- 2kW?!I want one too!
- I will try soon, with a 250-300W one. I need just the time to put all components together (I just mill PCB for now)
- there are fans (very efficient) that can be mounted on the outrunner
- what do you think that will fail?
copper wirings?! (I don't think so)
magnets?! (maybe glue that hold magnets in place, but I doubt)
bearings?! may-be, but it will fail because of dust that get there, not because of 10 hours of run.
I have not used these motors, but I did check out some of the sites that show DIY versions, wind-your-own etc.
There appears to be two types, Inner rotor or outer rotor.
They did not appear to me to have suitable characteristics for variable speed and torque spindle or servo.
They appear to run extremely hot, 2kw in a very small frame!
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Usually your motors of that style is going to come, and only come in outrunner versions. Inrunners are for cars and buggys, the outrunners like that are for airplanes. Low torque high RPM. Check this place out, i get a lot of my RC stuff from them.
www.hobbypartz.com
Here is a large outrunner like the one in the video, and its cheeeeeep!
http://www.hobbypartz.com/mo1602brmo.html
and your speed controler
http://www.hobbypartz.com/vose80aopbre.html
I was wanting to do this on my DIY router, but i couldn't figure out how to turn the speed controller without a RC receiver and controller.
The one with inner rotor is named "inrunner” and the other "outrunner" (obvious why).
- Inrunners have no air circulations inside; usually are water cooled with a pipe of copper wounded around motor. This type of motors usually have high rpm - at 12V you may get 50-80k, but not more torque (it-s enough for PCB milling)
- Outrunners are true 3phase motors, driven with low voltage. The small controller always used to drive motor is a DC/3~ converter, with variable frequency. Output of the controller is not sinusoid, but square wave.
- Controller uses MOSFET transistors to drive motors, and this type of transistors are largely available in SMD capsule (40V/100A with 0.01ohm when ON). This is the reason controllers are so small.
- Motor presented, as any from this family has a really low windings resistance (0.3 ohm for example) so the heat dissipated is small.
For example: I use for milling a Proxon like tool, rated at max 150W. Let's suppose I will change the motor with an outrunner rated "2700W". I will still use just my 150W, so:
- with no load, motor will "eat" ~1,5A = 0.06W dissipated as heat = absolutely insignificant
- with 150W load: efficiency of the motor is >90% so it will dissipate heat... max 15W (150W from 25V means 6A => P_heat=36*0.03=1W !!!!)
Only one problem remains: to find a power source that can delivery energy as low voltage high current - only switching power supply can do this.
Motor is awesome, but the controller is not 100% compatible.
Look at the motor: "Cells Li-Po: 9-10" = 40V_max, and the controller: "Li-ion/Li-poly: 2-6" = 24V_max. So you will use motor at maximum half its power. (personally I think that it's enough even so)
-without controller (DC/3~ inverter) is impossible
-but as RC receiver search for a "servo tester" circuit (IC 555 as astabile). there are many circuits.
An Astro Flight servo tester would work well in place of transmitter/receiver and has a knob for variable speed.
It should be enough to get started. Just plug it into the "servo" lead of the ESC. You may need an external 4.8v depending on your ESC. There are devices that will turn the knob via the CNC controller but I can remember who makes it right now.
I have several motors both inrunner and outrunner and will test when the time is available. I would make sure there is plenty of cooling if running the motor near its max power input. A watt meter will tell you what the power consumption is and could be left in the circuit while cutting to monitor it for quite awhile. My plan is to make a spindle and then drive the spindle with the brushless motor.
If you use a castle creations esc they have helicopter function built in and are easily accessible through the castle link.
Mike
Warning: DIY CNC may cause extreme hair loss due to you pulling your hair out.
Usually you can throw more than 24v at a motor that size, you can run barely 24v on a standard 550-540 size motor which is like 1.5" in diameter. But here, I think that torque is needed a little more than RPM's. So amperage would be the key here.
That is a Sweet idea! never thought of that....I suppose you can put a 20-24v power supply to the motor leads with the servo tester and see how it goes. I might try this in the future.
I use the servo tester to spin up all of my motors when first setting up the power system in my planes. When I did the 10 cell lipo power for my large chipmunk I moved all the dust around in the shop(not to mention the smaller handtools). It makes it easier than trying to hold the plane and transmitter at the same time.
I have been looking at this for some time as an option on my router or for a new pcb router that I may build.
Mike
Warning: DIY CNC may cause extreme hair loss due to you pulling your hair out.
I haven't done this myself, but there is a nice example at this link:
http://www.recumbents.com/wisil/shumaker/default.htm
You will have to scroll down a ways for the actual descriptions, but I find the whole link to be interesting, personally.
Regards,
Raymond
Controlling a servo or in this case and ESC with a small MCU is trivial.
"http://www.youtube.com/watch?v=omC6sVKlZhM"]YouTube - Final version of my gripper with controller
That's a $2 Atmel Tiny13 running two servos and reading an IR sensor on an A2D channel. What you need to know is that an RC signal frame is 30ms long. To turn all the way CCW (or for airplane throttle all the way off) you send a pulse 1ms wide at the beginning of each frame. You increase the pulse width to 2ms for full CW or full throttle.
If you need the code I have some. Ideal would be to have the board interface to Mach or the Linux solutions. I could try to throw a board together that uses a POT for speed control. I'm always looking for fun little projects.
Jay
Jay, Thank you for your Explanation on the Pulse sequence for RC Signaling. However I have one doubt. You said a Frame is 30ms and for Full Throttle you Send a 2ms pulse at the beginning of a Frame. So if I want the Motor to speed up, will it be ok if I send 2ms pulses continuously??? or should I send the 2ms pulse ONLY every 30ms???
Can you post a simple circuit to generate variable throttle control signals for an ESC? It would be a great help since I am new to RC Motors and controls...
Also plz do share if you have some ideas on how to directly interface the ESC to Mach3 or EMC2???
Joe
servo signal = 1 pulse between 1 and 2ms, every 20ms.So if I want the Motor to speed up, will it be ok if I send 2ms pulses continuously??? or should I send the 2ms pulse ONLY every 30ms???
Joe
from ESC that I've tried by now, 1.5ms means speed=0 for motor, 2ms means maximum speed.
but you will need to send that pulse every ~20ms
I doubt that motor will start with maximum speed so it's wise to accelerate-it (a few pulses with 1.5ms, then 1.6ms, ... until 2ms).
RC toys use a potentiometer to set speed of the motor, so it can't jump instant to the maximum speed
http://www.rc-cam.com/servotst.htm
http://web2.murraystate.edu/andy.bat...mpledriver.htm
eSilviu, Thank you for the clarification n the circuits. Highly appreciate it
BTW since this is a 5v Pulse I believe we cud somehow use EMC2 to generate this pulse and control the motor RPM from the program itself. If we were to connect an encoder to the shaft we cud return the rpm to EMC2 too. Is it not possible??? Has anyone tried this setup???
Joe
I doubt that windows is so precise that will allow you to generate a pulse of 1.75ms, every 20ms, for 2 hours....eSilviu, Thank you for the clarification n the circuits. Highly appreciate it
BTW since this is a 5v Pulse I believe we cud somehow use EMC2 to generate this pulse and control the motor RPM from the program itself. If we were to connect an encoder to the shaft we cud return the rpm to EMC2 too. Is it not possible??? Has anyone tried this setup???
Joe
Yes Ur probably right... With Windows it could be hard as I have read so many posts relating to the inability of Windows to provide Perfect Timing.
But EMC2 runs on Ubuntu Linux with RTC extensions... I have read timing on Linux RT is highly accurate... If we could somehow find a way to make EMC2 send the pulse based on the RPM requirement in the G-Code, we got ourselves a Computer controlled Spindle. I know what I am suggesting is probably TOO Much for me right now... But I'm just suggesting a possibility... n I'm sure this idea is definitely not new... There has to be someone who has tried this route... Jus hoping someone cud share their experience with us...
Joe
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