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1 hour ago, hayfield said:

For years coreless motors have been seen to be the gold standard for locos, especially where slow smooth operation is required, why now are they being questioned

 

I accept there has been this perception - but I was looking for hard evidence that they are invariably better than an iron-cored motor.

 

My suspicion is that the trend towards coreless is based on production costs.

 

John Isherwood.

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John

 

Above my pay grade, a well made chassis is the ideal objective, I have a Wills 94xx with a RG4 and its superb

 

Equally I have a Bachman 57xx with an etched chassis, a Hanazono 1024 open frame motor and flywheel again a faultless runner

 

Both have well made gearboxes/motor mounts

 

I still think for slow running coreless has the edge. some manufacturers seem to be using them now. But a chassis will only be as good as its weakest link.

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Coreless motors have several advantages over their iron cored cousins:

No cogging - smoother rotation at lower speeds

Better power to volume ratio (i.e. more powerful motor for a given size)

Lower inductance of motor windings meaning less arcing on the brushes, meaning longer life.

 

Iron core motors are still less expensive to make and can take more abuse, electrically and mechanically.

 

I've yet to have any problems with any of my N Gauge models, but then I use DCC or a pure DC controller. Perhaps anyone who has repeated problems should also consider if their controller is as much to blame as the motor?

 

 

Steven B.

 

Edited by Steven B
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1 hour ago, Steven B said:

 

No cogging - smoother rotation at lower speeds

 

Steven B.

 

That was the case when RG4s came out against the X04 and motors of the time, but iron cored motors have vastly improved and the best of them can surpass coreless motors.

Oxfords Janus without cogging.

 

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4 hours ago, cctransuk said:

 

I accept there has been this perception - but I was looking for hard evidence that they are invariably better than an iron-cored motor.

 

My suspicion is that the trend towards coreless is based on production costs.

 

John Isherwood.

 

And availability

 

 

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On 12/08/2020 at 16:09, Jeff Smith said:

Can the High Level motors have extended shafts for flywheels?I

 

I heard that coreless motors are best with pure dc controllers and can have problems with feedback type controllers.  I assume dcc chips put out pure dc to the motor but not sure.

DCC decoders output PWM with either Low or High Frequency feedback. All modern ones are either HF only or switchable with HF being the default

 

Coreless motors generally don't like LF feedback controllers due to the lack of iron core which has 2 effects 1) less material to sink any heat generated 2) less feedback which means the back EMF doesn't work properly

Together these two properties can cause a coreless motor to overheat more easily than an iron cored one.

 

Coreless motors have features which can be either beneficial or undesirable for model railway use.

Low mass and small size. The lack of mass is undesirable but the small size is beneficial

Low inertia. Definitely undesirable.

Cost. Portescaps et al can be horribly expensive, conversely coreless motors can be cheap as chips, now the Chinese mass produce them for other uses.

 

IMHO the days of unchallenged superiority of Portescaps is long over, their heyday was when the best elsewhere was nowhere near as good as nowadays.

Their are plenty of good iron-cored motors around.

 

The Coreless motor used by Oxford Rail is IMHO rubbish. it's underpowered, my Dean Goods slow down too much on load, one motor has already been replaced by Oxford due to failure.

Edited by melmerby
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1 hour ago, bigherb said:

That was the case when RG4s came out against the X04 and motors of the time, but iron cored motors have vastly improved and the best of them can surpass coreless motors.

Oxfords Janus without cogging.

 

That's a coreless motor

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54 minutes ago, melmerby said:

DCC decoders output PWM with either Low or High Frequency feedback. All modern ones are either HF only or switchable with HF being the default

 

Coreless motors generally don't like LF feedback controllers due to the lack of iron core which has 2 effects 1) less material to sink any heat generated 2) less feedback which means the back EMF doesn't work properly

Together these two properties can cause a coreless motor to overheat more easily than an iron cored one.

 

Coreless motors have features which can be either beneficial or undesirable for model railway use.

Low mass and small size. The lack of mass is undesirable but the small size is beneficial

Low inertia. Definitely undesirable.

Cost. Portescaps et al can be horribly expensive, conversely coreless motors can be cheap as chips, now the Chinese mass produce them for other uses.

 

IMHO the days of unchallenged superiority of Portescaps is long over, their heyday was when the best elsewhere was nowhere near as good as nowadays.

Their are plenty of good iron-cored motors around.

 

The Coreless motor used by Oxford Rail is IMHO rubbish. it's underpowered, my Dean Goods slow down too much on load, one motor has already been replaced by Oxford due to failure.

Hi,

 

There is a third reason why coreless motors don't like low repetition rate PWM. Their inductance is lower than iron cored motors leading to high rates of current rise, more energy deposited in the windings and more time at max current.

 

By using a high repetition rate the windings spend less time at max current.

 

Regards

 

Nick

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The range of quality coreless motor designs made by  Faulhaber, Maxon and Portescap is vast. They are all much more expensive than no name Chinese stuff.

 

https://www.maxongroup.com/maxon/view/content/product-overview

 

https://www.faulhaber.com/en/products/dc-motors/

 

I thought I might have a German Faulhaber in my Trix P10 but it's a Portescap Athlonix 12G88

https://www.portescap.com/en/products/brush-dc-motors/athlonix-motors

 

 

IMG_2873_00001.jpg

Edited by maico
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9 hours ago, bigherb said:

That was the case when RG4s came out against the X04 and motors of the time, but iron cored motors have vastly improved and the best of them can surpass coreless motors.

Oxfords Janus without cogging.

 

 

Any makers name visible on the motor? Looks like a brushed coreless design.

 

Roco-Fleischmann still make their own conventional open frame iron armature motors for some models at their Austrian HQ and main Romanian factory in Arad.

Edited by maico
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1 hour ago, NIK said:

Hi,

 

There is a third reason why coreless motors don't like low repetition rate PWM. Their inductance is lower than iron cored motors leading to high rates of current rise, more energy deposited in the windings and more time at max current.

 

By using a high repetition rate the windings spend less time at max current.

 

Regards

 

Nick

I actually missed the inductance out of reason 2)

As it stands, on it's own it doesn't make sense.

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1 hour ago, maico said:

 

Any makers name visible on the motor? Looks like a brushed coreless design.

 

 

By their nature all coreless motors have brushes.

 

It looks like the one used in the Dean Goods, which is like a no-name Chinese 1021 motor, it is 3 pole with metal (silver?) brushes, the comm also looks like it's silver.

Buy them in bulk from AliBaba for under $2 each.

Edited by melmerby
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9 hours ago, NIK said:

Hi,

 

I understand most PWM/feedback controllers designed since about 1980 use high frequency (see other topics on this on RMWeb).

 

Coreless motors were very expensive when they became more common in kit and scratch built steam locos in the 1970's so I guess there was pressure on DC controller manufacturers to produce PWM controllers that could not burn out coreless motors due to the wrong frequency.

 

I don't think its easy to check if a DC PWM controller is high frequency or not.

 

I've just checked if the Bachmann Class 117 DMU uses coreless motors because of my worry about it being run with too low a frequency drive. Judging by its motors DC resistance and inductance at 1khz it does not have coreless motors.

 

Regards

 

Nick

 

I can't say for certain, but I'm pretty sure this is wrong. Certainly Bachmann (Farish) warn about the issue in their N Gauge locomotives. Gaugemaster are particular about which of their controllers are unsuitable for use with coreless motors and that includes feedback controllers. Fellow modellers have commented on bad experience using feedback with coreless. I have a KPC feedback controller which is a fairly modern design and it definitely isn't suitable.

 

It would be great if there was a DC controller which used high frequency feedback of the sort found in the better DCC chips. But I've never found one.

 

Nigel

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40 minutes ago, melmerby said:

By their nature all coreless motors have brushes.

 

It looks like the one used in the Dean Goods, which is like a no-name Chinese 1021 motor, it is 3 pole with metal (silver?) brushes, the comm also looks like it's silver.

Buy them in bulk from AliBaba for under $2 each.

 

Makers make the distinction. Brushless https://www.faulhaber.com/en/products/brushless-dc-motors/ 

vs brushed with commutation systems of precious metal or graphite brushes on copper

https://www.faulhaber.com/en/products/dc-motors/

Edited by maico
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4 minutes ago, maico said:

 

Makers make the distiction. Brushless https://www.faulhaber.com/en/products/brushless-dc-motors/ 

vs brushed with commutation systems of precious metal or graphite brushes on copper

https://www.faulhaber.com/en/products/dc-motors/

Once again we have the nonsense that is "Brushless DC motor" which is twaddle from an electronics point of view as the motor will not (can not) operate from DC but needs a convertor to change the DC supply to AC or a pulsed signal.

Faulhaber supply these seperately depending on usage required.

 

I know it's now widely used but the term BLDC (Brushless DC) just grates.

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9 minutes ago, maico said:

Portescap have a good exploded diagram here. They state commutation of the brushless DC motor is made electronically not mechanically and is done either by looking at the back-EMF of the motor or by using a position sensor.

 

https://www.portescap.com/en/products/brushless-dc-motors/bldc-motor-design

image2_0.png

The actual motor part still doesn't run on DC (It can't, it's basic electromagnetic theory). There has to be some form of commutation, either by brushes or chopping the supply.

 

 

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1 hour ago, NCB said:

 

I can't say for certain, but I'm pretty sure this is wrong. Certainly Bachmann (Farish) warn about the issue in their N Gauge locomotives. Gaugemaster are particular about which of their controllers are unsuitable for use with coreless motors and that includes feedback controllers. Fellow modellers have commented on bad experience using feedback with coreless. I have a KPC feedback controller which is a fairly modern design and it definitely isn't suitable.

 

It would be great if there was a DC controller which used high frequency feedback of the sort found in the better DCC chips. But I've never found one.

 

Nigel

Hi,

 

That's a shame. It seems odd that RTR manufacturers are putting coreless motors into new designs when there appear to be suppliers of DC controllers that do not work with coreless motors and presumably don't have a warning on the front of the controller.

 

Regards

 

Nick

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2 hours ago, NIK said:

Hi,

 

That's a shame. It seems odd that RTR manufacturers are putting coreless motors into new designs when there appear to be suppliers of DC controllers that do not work with coreless motors and presumably don't have a warning on the front of the controller.

 

Regards

 

Nick

 

It's the other way round, a few cottage industry British companies might still have DC feedback controllers that can cause buzzing with coreless! The World has moved on.

I have a Trix DC controller that I use with the loco shown in this thread. It's based on the Fleischmann unit that has been around for decades. It works fine with coreless.

The black case Guagemaster feedback controllers would not, and the company has moved on and mainly sell the yellow case designs that do work.

Edited by maico
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I think coreless is probably the way the market will go due to the smaller size per horsepower.

It's a pity some makers seem to have taken a race to the bottom to very basic designs, which IMHO are noticeably inferior to iron cored motors.

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3 hours ago, NIK said:

Hi,

 

That's a shame. It seems odd that RTR manufacturers are putting coreless motors into new designs when there appear to be suppliers of DC controllers that do not work with coreless motors and presumably don't have a warning on the front of the controller.

 

Regards

 

Nick

 

When these controllers were designed and built coreless motors in rtr were generally not in use although a few modellers were starting to use Portescap motors in their kit built locomotives.

 

It's a bit like saying why did manufacturers not put a sign on first generation mobile phones that they will not work for internet access.  

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Roco-Fleischmann still have replacement ring type motors available for a fleischmann DB 103 loco I bought in 1978.

Current style can motor production is shown being made here

 

 

Edited by maico
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4 hours ago, Andy Hayter said:

 

When these controllers were designed and built coreless motors in rtr were generally not in use although a few modellers were starting to use Portescap motors in their kit built locomotives.

 

It's a bit like saying why did manufacturers not put a sign on first generation mobile phones that they will not work for internet access.  

Hi,

 

I thought from NCBs post that DC controllers are being built now that don't work with coreless motors. I assume they don't have a warning on the front of them about not using them with coreless motors.

 

Regards

 

Nick

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I think there are some mis-conceptions about what coreless motors are, and aren’t. They have been around a very long time, made by Swiss and German firms as high precision instrument motors. That is what they were originally designed for use in, and thus generally known as such, instrument motors. Made to use minimal current and react quickly and precisely to very small changes in it. Often they come with integral spur drive gear heads of typical watchmaking precision and size and this is where they are able to produce high levels of precision controlled power.

 

As such they are thus very efficient in terms of their power output via the current consumption but, sadly, this is mostly taken to mean they are also more powerful than conventional iron core motors, which they are not. Size for size the latter may consume more current but can generate more power for any given size. New magnet types have in recent times raised the coreless power output to be nearly the same as iron core, but not more.
 

Where the coreless does score for general use today in electronics is that minimal current draw, and that the different design means smaller sized motors with higher voltage ratings can be produced than with iron core types. There is more room in the casing for the windings.

 

A further aspect which helps explain their much greater use today is that on environmental terms the lower current consumption is seen as being ‘green’ so their production is being encouraged as more beneficial than iron core ones. This is a bit like the newer light bulbs, LEDS etc, taking over from previous types. So model makers are following this trend, probably aided by the increasing difficulty in sourcing iron core ones. 
 

Quite obviously the cheaper coreless motors now being produced en-mass in places such as China don’t have the quality that Swiss/German ones do, but then the price difference is in some cases massive. It’s again the adage that you get what you pay for, but even the best quality coreless motors can’t take the abuse that an iron core  type can in terms of over-heating or over-loading.

 

PWM Feedback controllers work by giving full voltage pulses of power at varying intervals. Because of their winding design coreless motors can’t absorb the heat generated by this as easily as iron core ones with their solid core and they react too quickly to the voltage changes the feedback generates. Raising the voltage frequency and reducing the level of both sampling and feedback rate is something that helps offset this and can be done with DCC decoders. Many better ones have settings to specifically use with coreless motors.

 

Sadly most DC Feedback controllers only produce low frequency output and neither can the feedback rates be reduced. When coreless motors such as the Portescap RG’s first became popular the late Len Rich of AMR spent much effort and made several attempts to produce for me a modified AMR feedback controller that was usable with coreless. In the end he had to admit defeat within the constraints of the design he used to produce his controllers. 
 

The Pentroller, a DC controller designed by the late Stuart Hine, is I believe the only one that was specifically made to be able to run coreless motors alongside feedback. A switchable design made for Pendon originally. I think, but am not sure, that a similar version of this is, or was, produced in recent times.

 

Stick to using the standard non-feedback controllers such as those made by Gaugemaster though and it’s fine. Or use DCC. 
 

As with any loco using too small a motor, one that is not powerful enough to cope and not given the correct gear reduction to offset this, will cause problems ( I am thinking of the stupidly small coreless motors used in some recent locos),  and gives the motor design a bad name through no fault of it’s own.

 

Sorry for the length of this post, but I hope it might help the understanding of coreless a little bit.

 

Izzy

 

 

 

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