Old controller with coreless motors.

[melmerby]

8 hours ago, AndyID said:

 

 

 

 

I don't know of any manufacturers who put coreless motors in their products but some might.

Oxford, Hattons (DJ Models) probably others

[kevinlms]

14 hours ago, johnarcher said:

Thanks again to all contributors, I do have the impression that my Compspeed with feedback turned off should be OK?

 

 

If you're concerned about the switch, you could always remove it, or otherwise configure the switch so that if it is changed accidentally, it doesn't do anything - i.e. permanently set to off.

[DCB]

The back EMF theory is really interesting to me.  Thanks

 

However the "Feedback" controller was really about taming the pretty poor mechanical performance of the 1960/70s motors and gearing.   Many of these did not have proper thrust bearings on the armature shafts and any longitudinal load applied to the shaft as when a worm drive meets resistance, led a big increase in mechanical resistance as the thrust was transferred to washers pressed against the front bearing over quite a large surface.      Hornby Dublo used the same 1/2" armature concept but fitted ball bearings to control end float (as did Triang on some power bogies) and H/D used single start worms to reduce the longitudinal loads.  This led to H/D exhibiting much superior starting and slow running than others. 

 

Even back then heating was a problem and blackened armatures and smoke when running slowly on feedback or pulse power were not unusual.

[AndyID]

9 hours ago, DavidCBroad said:

However the "Feedback" controller was really about taming the pretty poor mechanical performance of the 1960/70s motors and gearing.

 

It does help that a bit but even with modern mechanisms it's great for preventing slow trains stalling on tight curves and gradients.

[johnarcher]

1 hour ago, AndyID said:

 

It does help that a bit but even with modern mechanisms it's great for preventing slow trains stalling on tight curves and gradients.

It seems to me that with normal Mashimas a bit of feedback (the 1 setting on that controller) does help get a slow, steady start.

[AndyID]

12 hours ago, melmerby said:

Oxford, Hattons (DJ Models) probably others

 

Oxford Rail just says "Smooth Running 5 Pole motor". That doesn't mean it's not coreless but you'd think they'd feature it if it was.

[melmerby]

1 hour ago, AndyID said:

 

Oxford Rail just says "Smooth Running 5 Pole motor". That doesn't mean it's not coreless but you'd think they'd feature it if it was.

They told me that, in fact I was told it was a quality 5-pole non coreless design but the truth was a crappy 3 pole coreless which expired, the replacement is identical.

This is in the later Dean Goods which also has somewhat limited pulling power, the earlier one has a 5 pole iron cored motor.

 

See another thread starting here:

 

Hattons/DJM 48XX is also coreless,

I believe some other newish models (Dapol?) are also coreless as they are smaller than the equivalent iron cored motor as the magnet is effectively where the iron core would be rather than outside it.

 

[MGR Hooper!]

3 hours ago, melmerby said:

They told me that, in fact I was told it was a quality 5-pole non coreless design but the truth was a crappy 3 pole coreless which expired, the replacement is identical.

This is in the later Dean Goods which also has somewhat limited pulling power, the earlier one has a 5 pole iron cored motor.

 

See another thread starting here:

 

Hattons/DJM 48XX is also coreless,

I believe some other newish models (Dapol?) are also coreless as they are smaller than the equivalent iron cored motor as the magnet is effectively where the iron core would be rather than outside it.

 

Dapol use iron-cored motors.

I'm only aware of DJM and Graham Farish who use coreless motors.

[maico]

The German company sb modellbau re-motor just about any Ho and N loco with quality Faulhaber and Maxon motors and flywheels.

It would need a treasured locomotive though as the prices are elevated. Some of the conversions are straightforward and some a bit nuts

 

https://www.sb-modellbau.com/

 

Edited October 11, 2019 by maico

[DLT]

1 hour ago, maico said:

The German company sb modellbau re-motor just about any Ho and N loco with quality Faulhaber and Maxon motors and flywheels.

 

Very impressive!

[melmerby]

You too could re-motor with a Maxon 12v motor for £3.74:

https://www.aliexpress.com/item/4000212780670.html?spm=a2g0o.productlist.0.0.26376535px6qw6&algo_pvid=adeab137-07e6-4b11-bc83-7ff85cd616c1&algo_expid=adeab137-07e6-4b11-bc83-7ff85cd616c1-0&btsid=f8ae5374-2d57-4f56-9b38-6f3befa262c9&ws_ab_test=searchweb0_0,searchweb201602_1,searchweb201603_55

[cliff park]

It seems to me that a coreless motor is the last thing you need in a locomotive. Now I can see the virtue in small scales as they can be made small and still powerful, but to put a coreless motor in, then put a flywheel on the end is bonkers. A normal electric motor has a built in flywheel, the armature, and with modern magnets, a 5 pole motor is a world away from the early years of model railways.

[sharris]

1 hour ago, cliff park said:

It seems to me that a coreless motor is the last thing you need in a locomotive. 

 

I see your point - for a model locomotive you want some inertia. As Andy said on the previous page coreless motors are good for rapid response - I used to use coreless Maxons and Faulhabers when I was doing robotics research - a situation where rapid speed changes were necessary. 

[melmerby]

2 hours ago, cliff park said:

It seems to me that a coreless motor is the last thing you need in a locomotive. Now I can see the virtue in small scales as they can be made small and still powerful, but to put a coreless motor in, then put a flywheel on the end is bonkers. A normal electric motor has a built in flywheel, the armature, and with modern magnets, a 5 pole motor is a world away from the early years of model railways.

I used to service equipment where coreless motors were essential, these were mechanical plotters where rapid response was crucial, I actually built up a small stock of 16mm Canon coreless motors in my spares box.

As I assumed, due to their charactersistics, they were no use in modelling I junked them when I retired!

 

I think the "desire" for coreless motors came from the days of Portescaps when the alternatives were not particularly good, these days (IMHO) a decent 5 pole motor and a good gearbox will produce a smooth powerful drive unit.

Coreless motors should only be used where the size is important.

With Oxford Rail the change from the original 5 (?) pole iron cored motor with two flywheels to a 3 pole coreless one with one flywheel was a definite "own goal" producing an inferior running machine to that originally on sale.

[johnarcher]

With reference to the last two posts, how do you more electronically-knowledgeable people reckon I would be better off, in a space-limited prototype where the biggest practical motor would be approx 1020 size with a single-stage 40:1 or 50:1 gear mount or 1015 with a higher reduction, like a Loadhauler.

The 1020 option could be a Mashima 1020, if I can still find one, or this 1219 coreless that High Level now have.

The 1015 options are the Mashima maybe (but some people seem to have reservations about it), or 3 pole ones like the N-drive or the Chinese N20?

[melmerby]

Mashima 1020 still in stock here:

https://www.scalelink.co.uk/cgi-bin/sh000002.pl?WD=mashima&PN=Sundry_Items__Lead_Foil__Chain_Etc_.html#aSM_2dMHK1020

[johnarcher]

Thank you, do you reckon that would be better than the coreless, with probably 39:1 gearing? The price is not much different. and the no-load speed pretty simlar.

Edited October 11, 2019 by johnarcher

[Denbridge]

My concern with using switched feedback controllers is forgetting to flick the switch. It doesn't take much to irreparably damage a coreless motor. 

Personally I'd plump for more suitable controllers.

[maico]

5 hours ago, melmerby said:

You too could re-motor with a Maxon 12v motor for £3.74:

https://www.aliexpress.com/item/4000212780670.html?spm=a2g0o.productlist.0.0.26376535px6qw6&algo_pvid=adeab137-07e6-4b11-bc83-7ff85cd616c1&algo_expid=adeab137-07e6-4b11-bc83-7ff85cd616c1-0&btsid=f8ae5374-2d57-4f56-9b38-6f3befa262c9&ws_ab_test=searchweb0_0,searchweb201602_1,searchweb201603_55

 

You could do but aliaexpress is full of fake and used stuff. These are fakes for example. It takes a close examination with the real thing but they are knock offs. https://www.aliexpress.com/item/10000000472623.html?spm=a2g0o.productlist.0.0.388c645bYki5AD&algo_pvid=ab70e6ff-2632-4142-b7c7-ed164d45d572&algo_expid=ab70e6ff-2632-4142-b7c7-ed164d45d572-37&btsid=48a145ea-5f9d-49b2-a00f-e5465a78ae81&ws_ab_test=searchweb0_0,searchweb201602_1,searchweb201603_52

Edited October 11, 2019 by maico

[melmerby]

27 minutes ago, johnarcher said:

Thank you, do you reckon that would be better than the coreless, with probably 39:1 gearing? The price is not much different. and the no-load speed pretty simlar.

I was put off coreless by the Oxford fiasco so maybe I'm biased!

Mashima at least have a good reputation for quality.

[maico]

Roco, now Roco-Fleischmann have been making their own reliable motors in Europe for years. A completely different mindset to Hornby who fit things like 66 cent Chinese 3-pole motors to the P2 class !

See 5.20min in the Roco factory tour

 

 

[Mike Buckner]

Perhaps someone can enlighten me. In the case of coreless motors, is there an equivalent concept to 3-pole / 5-pole / etc?

[melmerby]

1 hour ago, Mike Buckner said:

Perhaps someone can enlighten me. In the case of coreless motors, is there an equivalent concept to 3-pole / 5-pole / etc?

Yes, they still have 3 or 5 (or more) sections to the commutator with brushes and the windings produce a magnetic field in a similar way to iron cored motors.

The shape of the windings is by nature somewhat different.

You can see the windings on the left are like a cylindrical basket and the case on the right has the cylindrical magnet in the centre with the motor shaft running through it.

The winding rotates between the magnet and the steel case, which completes the magnetic circuit.

 

EDIT

Another view of the rotor, the commutator is on the right:

Edited October 11, 2019 by melmerby

[AndyID]

4 hours ago, Denbridge said:

My concern with using switched feedback controllers is forgetting to flick the switch. It doesn't take much to irreparably damage a coreless motor. 

Personally I'd plump for more suitable controllers.

 

and even then if you run the poor thing into the buffers and it stalls it's likely to overheat. Ideally you want a controller with sensitive over-current protection.

[maico]

Maxon have produced a pretty good pdf. guide to coreless motors

https://www.maxongroup.com/medias/sys_master/8803450421278.pdf