https://www.makesea.com/web/cla/~/5...t&_101_INSTANCE_Rl6cqGtVw4Vb_languageId=en_US

so the link above shows a guy that made a brushless motor at home. he states its 600watts at 80% efficiency
so the questions I have
1) what the heck does 80% efficiency mean? is it relating to power or the other motors on the market?
2) If I were to "upgrade the motor how would I get more RPM out of it (I am assuming more magnetic poles or less.... that way it moves to a pole quicker)
2a) how would I get more torque? (I am assuming more or thicker wires per coil to allow more current)
3) can I use this little sucker to make a variation of a stepper motor? with some degree of accuracy and a decent holding force or would turning it into a servo be better? still need that holding force though as a type of electronic brake

as always your input is appreciated and valued

 

Motor output is mechanical power ... in watts.
The motor input power is in electrical watts.
Heat produced by the motor causes the output mechanical power to always be less than the electrical input power.

How about using a large gear ratio ... increased torque, but lower speed?

 

sorry for the late response,
no gear ratio if I can help it. trying to make the 2 parts of the motor to be the base and direct drive to the moving part.
now here is the sad part, the total speed will be at most 240rpm, 4 rotations per second is TOTAL over kill for this project. so I am trying to make a motor that is able to stop at 1 degree increments with a heap of accuracy (was thinking rotary encoder or optical or some such.
the centre shaft will be hollow to allow data cables through it. it will also be earthed to avoid EM interference.
the coil shaft will be mounted on the base to allow controller and such
the magnetic ring will be mounted to the moving part and have data coming through to it.

torque settings are as simple as the higher the better.

 

No need for hollow shaft, the sensors can be mounted on the stator side of the assy.
If you could make a sketch of your idea it would be much easier to understand what problem you are trying to overcome.

 

its ok Kermit. will explain once again.
I am looking to make a motor like in the top link. I wanted to know what would have to be changed to make it slower and more torque.
the design I have does need a hollow shaft as there are no more sensors on the bottom side so I will need to put them on the top.
if I can take the motor linked to and modify it slightly to incorporate these changes I would be ecstatic. this will save me buying an expansive motor

 

The speed of the motor is determined by how quickly the controller cycles power to stator the coils. The torque is determined by the strength and spacing of the stator and rotor magnets and the motor geometry. e.g. A larger diameter motor will provide more torque (i.e. think longer levers) as would a longer motor or several motors mechanically coupled together (i.e. think more force).

 

thanks "blocco a spirale"
so a follow up question, if I use thicker wire/more strands will that help with it holding a greater weight?
also if more stator arms with an extra few coils (so make it a 4 or 5 phase motor instead of 3)and more magnets will that allow more precise movement?
the big idea at the end of this is a bldc/stepper hybrid. also I was thinking about 2-3 motors along the shaft to make the torque very high. so design will take a while but may prove useful

 

so would thicker wire work? this would allow more current to flow through and therefore offer more in the way of magnetic fields.

also if were to use a larger stator for torque I would need bigger magnets or more of them which would affect the spacing of the coils to my understanding.

 

no gear ratio if I can help it. trying to make the 2 parts of the motor to be the base and direct drive to the moving part.
now here is the sad part, the total speed will be at most 240rpm, 4 rotations per second is TOTAL over kill for this project. so I am trying to make a motor that is able to stop at 1 degree increments with a heap of accuracy (was thinking rotary encoder or optical or some such.
the centre shaft will be hollow to allow data cables through it. it will also be earthed to avoid EM interference.

Given the want for 1 degree stepping accuracy with reasonable torque you will be much further ahead to buy a common stepper motor and proper driver for it being building any type of compact direct drive motor that can do 1 degree movement resolution with any repetitive accuracy is not simple or easy.

As for the hollow shaft requirement I would just have the normally solid shaft of the stepper motor drilled out.

 

Given the want for 1 degree stepping accuracy with reasonable torque you will be much further ahead to buy a common stepper motor and proper driver for it being building any type of compact direct drive motor that can do 1 degree movement resolution with any repetitive accuracy is not simple or easy.

As for the hollow shaft requirement I would just have the normally solid shaft of the stepper motor drilled out.

Agreed 100%. no need to reinvent the wheel.

 

Agreed 100%. no need to reinvent the wheel.

Unfortunately far too often people want o reinvent the wheel by trying to take the wrong type of device, like a high speed motor, design and turn it into something it by design is not capable of working as.

The 3D printed motor concept is pretty impressive however given the obvious intended application as the designer shows (30 volt 20 amp input @ ~6500 RPM) it's totally wrong for a high torque extremly low PM precision positioning application. (Like taking a 400 HP sports car and trying to make it work like a 400 HP field tractor because the HP ratings just happened to fit one single part of the overall need and application.)

Now that said, I think a full 3D printed outrunner type high precision stepper motor could be made using the same concept. However, to do so the entire design and layout of the rotor and stator poles and related components would have to be hugely different.
I can't see a design for 1 degree repeatable resolution with plastic 3D printed parts working with anything less than a 90 pole motor design that relies on a multi phase fractional stepping capable driver system being able to do it.

Anything else beyond that is going to need gear reduction to make up for the motor step resolution limits.

 

no gear ratio if I can help it. trying to make the 2 parts of the motor to be the base and direct drive to the moving part.
now here is the sad part, the total speed will be at most 240rpm, 4 rotations per second is TOTAL over kill for this project. so I am trying to make a motor that is able to stop at 1 degree increments with a heap of accuracy (was thinking rotary encoder or optical or some such.

As already mentioned, trying to get those specs with a ESC controller will fail miserably IMO.
It is hard enough to get a BLDC motor to position or run at low rpm without 'cogging'.
I use BLDC motors in motion control applications where the positioning is in μm.
For this I require to use a motion card such as Galil using a encoder feedback together with a trans-conductance drive to eliminate the 'cogging' effect.
Max.

 

Unfortunately far too often people want o reinvent the wheel by trying to take the wrong type of device, like a high speed motor, design and turn it into something it by design is not capable of working as.

The 3D printed motor concept is pretty impressive however given the obvious intended application as the designer shows (30 volt 20 amp input @ ~6500 RPM) it's totally wrong for a high torque extremly low PM precision positioning application. (Like taking a 400 HP sports car and trying to make it work like a 400 HP field tractor because the HP ratings just happened to fit one single part of the overall need and application.)

Now that said, I think a full 3D printed outrunner type high precision stepper motor could be made using the same concept. However, to do so the entire design and layout of the rotor and stator poles and related components would have to be hugely different.
I can't see a design for 1 degree repeatable resolution with plastic 3D printed parts working with anything less than a 90 pole motor design that relies on a multi phase fractional stepping capable driver system being able to do it.

Anything else beyond that is going to need gear reduction to make up for the motor step resolution limits.

so now that I know this is not the best motor for my design, can someone sketch the internals of a stepper so that I can try to make something close to what I want pretty please.
I was thinking of modifying the motor above to go low rpm but the 20amp rating was way too high. this motor would be good for a lathe motor or something but I need something that is smooth(steppers aren't as smooth as I would like) have precision (BLDC don't have any holding torque). So I am thinking of making a low rpm motor with like a ratchet on the end to hold the device in a certain position, the put an encoder on it to detect the position. or even a hybrid BLDC/stepper

 

so now that I know this is not the best motor for my design, can someone sketch the internals of a stepper so that I can try to make something close to what I want pretty please.
I was thinking of modifying the motor above to go low rpm but the 20amp rating was way too high. this motor would be good for a lathe motor or something but I need something that is smooth(steppers aren't as smooth as I would like) have precision (BLDC don't have any holding torque). So I am thinking of making a low rpm motor with like a ratchet on the end to hold the device in a certain position, the put an encoder on it to detect the position. or even a hybrid BLDC/stepper

I promise, you cannot roll your own motor any better or any cheaper (not by a long shot) than the Chinese. Just go on eBay, but a motor and driver, and be done with it.

 

so now that I know this is not the best motor for my design, can someone sketch the internals of a stepper so that I can try to make something close to what I want pretty please.
I was thinking of modifying the motor above to go low rpm but the 20amp rating was way too high. this motor would be good for a lathe motor or something but I need something that is smooth(steppers aren't as smooth as I would like) have precision (BLDC don't have any holding torque). So I am thinking of making a low rpm motor with like a ratchet on the end to hold the device in a certain position, the put an encoder on it to detect the position. or even a hybrid BLDC/stepper

The unfortunate reality is any motor you make from 3D printed plastic is going to be very low average powered simply due to plastic having such inherently a poor thermal conductivity and low melting point. Simply put, putting any power to it that an all metal motor of equal size can handle for any length of time will simply cause it to meltdown.

If you need positioning power plus precision you are rather stuck with having to buy a proper application specific unit like a high step count stepper motor with an appropriate controller that give you the necessary function you want.

I was just talking with my brother earlier who is into CNC stuff big time and he commented about using normal stepper motors in fractional stepping applications and his comments were that they run crazy hot to the point of frequent burnout when doing it. Which if an all metal purpose built motor burns out from overheating an all plastic one won't stand a chance doing the same work.

 

I promise, you cannot roll your own motor any better or any cheaper (not by a long shot) than the Chinese. Just go on eBay, but a motor and driver, and be done with it.

I agree that it won't be cheaper.... but I will learn something from this

The unfortunate reality is any motor you make from 3D printed plastic is going to be very low average powered simply due to plastic having such inherently a poor thermal conductivity and low melting point. Simply put, putting any power to it that an all metal motor of equal size can handle for any length of time will simply cause it to meltdown.

If you need positioning power plus precision you are rather stuck with having to buy a proper application specific unit like a high step count stepper motor with an appropriate controller that give you the necessary function you want.

I was just talking with my brother earlier who is into CNC stuff big time and he commented about using normal stepper motors in fractional stepping applications and his comments were that they run crazy hot to the point of frequent burnout when doing it. Which if an all metal purpose built motor burns out from overheating an all plastic one won't stand a chance doing the same work.

I agree with this, but the idea is to make a motor to specifications. the housing can be made differently, the coils can be made differently, more or less magnets. make a controller to suit then too.

the overall process of making this motor is to learn about motors and understand some fundamental ideas so that a specific motor can be made. hybrid motors are also possible from this (going to be inefficient, costly and hair pulingly frustrating, but still good for learning).

 

(BLDC don't have any holding torque).

That does not make any sense, the motor is only part of the equation, With the proper controller, encoder and PID loop it will perform whatever you want within the torque range of the motor.
Max.

 

That does not make any sense, the motor is only part of the equation, With the proper controller, encoder and PID loop it will perform whatever you want within the torque range of the motor.

Until it burns down.

 

Until it burns down.

That is why I do not exceed the continuous torque rating for the motor.
The drive takes care of the limit.
Most of the CNC/positioning systems I have built in the recent past are BLDC.
CNC systems would be useless using BLDC if you could not hold position.
Max.