Chinese motor test

[Nig H]

The fears about problems with end thrust on these small coreless motors is overstated in 2mm. I have over a dozen locos running with Nigel Lawton or similar motors, John Greenwood also uses them as standard. All the tank locos have the worm mounted directly on the motor and all have run many hundreds of hours. I've never had a problem or a failure yet.

 

I've bought a load of the little 7mm coreless motors, they are all but identical to the latest Farish motor and may well be the same. I've attached some pictures, the Farish on has the F on it so I could tell them apart!

 

 

 

 

Edit to apologise for poor pictures - will snap some better ones later

 

Jerry

The Farish ones have the worm mounted on the motor shaft so they don't seem too bothered about end thrust issues. I've never had any problems with motors having the worm on the shaft either.

 

Nig H

[bertiedog]

The Problem with thrust is that in most three or five pole motors there is a solid chunk of steel, the armature, with washers against this and the bearings that that the thrust from worm gears.

 

However in the coreless, it is just that, there is no core, just the shaft, with the "cup" of resin supported wires surrounding the shaft, just inside the magnets. The commutator, usually a face type, is the only attachment to the shaft, and has to bear the thrust, via the face in one way and a tube around the shaft in the other.

Now a steel armature will not shift, but a plastic or ceramic commutator well might, under the pressure from the end thrust of the worm.

 

Makers know this, and better makers spline the shaft, or do away with the collar inside the coils on the shaft, and mould an extension from the commutator to the other end.  This increases the grip on the shaft, but it is still less grip than a conventional motor.

 

Some designs go further since they are single ended, the armature runs on a shaft as an internal bearing, and the thrust is taken by the shaft ends, this is confined to more expensive coreless motors.

 

Stephen

Edited June 2, 2016 by bertiedog

[Richard Hall]

The Farish ones have the worm mounted on the motor shaft so they don't seem too bothered about end thrust issues. I've never had any problems with motors having the worm on the shaft either.

 

Nig H

I suspect the concerns about end thrust go back to the Portescap days.  I remember reading that those motors should never be fitted with worm gears as the bearings could not handle the end loads. I've now heard from someone who has fitted one of these cheap 716 motors to a Farish model as a replacement for a dead coreless motor - apparently it runs just as well as it did before.

[Izzy]

Here are some shots of one of Nigel Lawtons 8x16 coreless motors. You will see that the construction involves a long central bearing surrounded by the magnet core and the commutator is 5-slotted and sits on the end of the shaft. The rear end cap containing the finger brushes has a reccess for the commutator but no end thrust capability. It's a common design with coreless motors, which are often combined/produced with integral spur gear heads and not intended for end thrust use.

 

 

 

 

 

 

So long as excessive end thrust beyond what the interface between the end cap and commutator can cope with doesn't occur then there isn't usually a problem. And if a travel restriction/thrust washer is fitted on the outer end of the shaft - as is often fitted on some coreless designs (a simple circlip), but can easily be arranged by the user if needed, then it isn't an issue.

 

 

Problems mostly happen when these type of motors are used without an appreciation of their construction i.e forcing tight worms on the shafts with some force which then damages the end cap and commutator. Otherwise they are quite robust. The Nigel Lawton 8x16 was re-assembled and has run since in my Class 15.

 

 

Izzy

Edited June 2, 2016 by Izzy

[2mmMark]

The point about pressing worms onto the shaft is well made. The moulded Association worms (presumably the Micro-Antrieb products) I have fit very tightly onto 1mm and 1.5mm shafts. It might be better to fit the worm onto a brass sleeve which then fits onto the motor shaft, secured with a drop of loctite. The Association can motor comes with just such a turned sleeve with a shoulder which is useful.

 

With a double ended motor, at least the other end of the motor shaft can be held in a pin vice when fitting the worm.

 

Mark

[bertiedog]

It's only that when we used them in a project at work we got the main spec sheets from Maxon and Faulhaber,and discussed this with them, it was always mentioned that no end thrust was the rule, a worm drive was to be isolated from a thrust block by a universal joint. In the equipment built the worm drive was isolated by a 4 claw universal about 3.5mm across. The thrust block was moulded Delrin, and had collars each side to take the thrust.

Maxon seemed to imply that it was the sudden take up of the play that could harm the commutator to shaft joint. The motors were 8mm Maxon but longer in length.

 

On fitting the worms to shafts, (if you do), they must never be pressed home, the force is amazingly high, the worm should be reamed out with a fine taper reamer, the long tapered clockmakers broach type will do it. A tiny spot of Loctite will hold it to the shaft.

 

Stephen

[2mmMark]

It's a far cry from the small open frame Tenshodo motors which I,  er...  "a friend" modified from double ended to long single ended by gently tapping the shaft through the motor & armature to suit a particular tank loco chassis design. 

 

I still like those motors. Rugged, reliable and smooth running, not too high revving.  Bit like a BMC A series engine.

 

Mark

[bécasse]

 

On fitting the worms to shafts, (if you do), they must never be pressed home, the force is amazingly high, the worm should be reamed out with a fine taper reamer, the long tapered clockmakers broach type will do it. A tiny spot of Loctite will hold it to the shaft.

 

 

And if you need to remove the worm subsequently, just dip it (the worm, not the whole motor) into a plastic cup of boiling water, the heat of which is quite sufficient to break the loctite bond.

 

I should add that this tip isn't original - I was once very puzzled at an exhibition to see someone seemingly dipping a motor into a plastic cup of tea, so puzzled, in fact, that I asked why and all was explained to me. I use the trick (without the tea or coffee flavouring - except in extremis) myself now, it works a treat in freeing loctite bonds not only on worms but on flywheels - and on gear wheels mounted on axles. It is also very useful if you should manage to get a trace of loctite between an axle and a bearing.

[bertiedog]

http://www.ebay.co.uk/itm/Citizen-Micro-Coreless-Electric-Motor-with-Pinion-Gear-Job-Lots-5-Pieces-/191883192173?hash=item2cad21276d:g:BIsAAOxyf1dTJaN4

 

Try UK supplier on Ebay, 5 for £10, 10mm dia 9 volt coreless, made in Japan, by Citizen. Some coming, will report. Previous Citizen motors were top quality.

Stephen

[Chris Higgs]

http://www.ebay.co.uk/itm/Citizen-Micro-Coreless-Electric-Motor-with-Pinion-Gear-Job-Lots-5-Pieces-/191883192173?hash=item2cad21276d:g:BIsAAOxyf1dTJaN4

 

Try UK supplier on Ebay, 5 for £10, 10mm dia 9 volt coreless, made in Japan, by Citizen. Some coming, will report. Previous Citizen motors were top quality.

Stephen

 

 A bit long mind, and let's hope you can get the pinion off!

 

Will be intersted to hear

 

Chris

[Richard Hall]

I just had one of the Chinese coreless motors to bits out of idle curiosity and it's basically a three-pole version of the Nigel Lawton one, with a complete lack of anything resembling thrust bearings to take an end load. I put it back together and it still goes round but makes unhappy noises, so that's 62.5 pence down the drain. But I still have another fifteen of the little things.

[bertiedog]

UK supplier, so by return post, 5 of the Citizen Motor company Japanese made coreless motors mentioned a couple of posts earlier. They are small diameter, but longer than some, and top quality. They were intended to screw onto a gearbox, and the pinion is very small, on a 1mm shaft.

 

Completely silent in operation, dead smooth, would suit a tender mounted motor driving a universal drive shaft to the loco in 2mm scale.

 

The gear Mod pitch is very small, so best remove and attach sleeve to the shaft to use. Very low current, but quite powerful, enough for a 4mm loco of modest size.

 

As the pinion is precision made in steel, it could be left and the sleeve added over the teeth.

Or a pulley added to the shaft, with a belt drive as per Nigel Lawton method, no end thrust to worry about.

I have some micro gearboxes from Ebay with micro motors and the pitch of the micro gears may be the same as the pinion, I will check.

Stephen

[queensquare]

P1019079 Citizen motors.JPG

UK supplier, so by return post, 5 of the Citizen Motor company Japanese made coreless motors mentioned a couple of posts earlier. They are small diameter, but longer than some, and top quality. They were intended to screw onto a gearbox, and the pinion is very small, on a 1mm shaft.

 

Completely silent in operation, dead smooth, would suit a tender mounted motor driving a universal drive shaft to the loco in 2mm scale.

 

The gear Mod pitch is very small, so best remove and attach sleeve to the shaft to use. Very low current, but quite powerful, enough for a 4mm loco of modest size.

 

As the pinion is precision made in steel, it could be left and the sleeve added over the teeth.

Or a pulley added to the shaft, with a belt drive as per Nigel Lawton method, no end thrust to worry about.

I have some micro gearboxes from Ebay with micro motors and the pitch of the micro gears may be the same as the pinion, I will check.

Stephen

They look interesting Stephen. Could you give us the exact dimensions and also an idea of how easy it would be to get the gear off.

 

Jerry

[alfsboy]

The great thing about these motors is the fact that as long as you buy a few at once you have a few spares laying around for the day one fails which as we all know never happens when you have a spare handy but is a near certainty when you dont .

[Chris Higgs]

They look interesting Stephen. Could you give us the exact dimensions and also an idea of how easy it would be to get the gear off.

 

Jerry

 

Specifications are as found in the listing:

 

Model.....................SCR10-2507

Type.......................Coreless

Diameter.................10mm

Length....................24.6mm

Rated Voltage.........9 volts

No Load Speed.......12200 rpm

Max Output W........1.0 w

 

1.0W is more powerful than a Maxon.

 

Would go well as axle mounted motors on a Gauge 1 diesel. Hmm.....

 

Chris

Edited June 7, 2016 by Chris Higgs

[bertiedog]

The 24.6 mm includes the screwed area at the nose end, designed to screw into an epicyclic gearbox. The gear is about 2mm thick, and would remove by pressure on the side of the gear like a gear splitter, a sharp steel blade pressed into the teeth form in a vice, or file away at one side with a needle file till it comes off, I would not like to use force against the body to pull it off, too delicate a motor.

 

However a miniature gear puller would work, there is just space to get behind the gear with a steel plate with a sharp edge, and rig an arm over the gear, with a tapped hole at say 10 ba, and screw in a 10ba steel screw to bear on the shaft. The end of the 10ba should really be centre drilled, I know this is small, but you can do it with a small .5mm number drill, by eye, and the drill held in a watchmakers chuck. The end is flattened by fine file, then a fine punch makes the centre and drill in a small dimple. the dimple will help centre the bolt on to the rounded shaft end.

 

Looking closely under a glass, the shaft ends are flat on these motors, so no need to drill, but you may need to file down the thread at the end of the steel 10 ba bolt to clear the pinion.

 

It may be best to leave the pinion, and simply drill out a bush till it just fits tightly over the teeth, as it will get a good grip. Glue with dab of epoxy.

 

Heat will sometimes release the pinion, but on a small delicate motor heat could be terminal!

 

Stephen.

Edited June 7, 2016 by bertiedog

[queensquare]

Thanks for the information gents. As Chris said they are a little long for all but the biggest tenders in 2mm but at that price and quality its worth having a few in stock.

 

Jerry 

[dajt]

Re the pulley idea, does that put a lot of lateral force on the shaft? It's a pretty short shaft so there is no room for an external support.

 

Being a bodger I wouldn't bother, plenty of spares if it ever did wear out.

[bertiedog]

They are certainly higher quality than most Chinese at bargain prices, my guess is that they came from Video camera focus systems of about 15 years ago period. Citizen and Casio specialise in making internal parts for other camera makers, especially mechanical parts. Nakami made  coreless motors for Nikon etc., with very much the same screw on format, (might be interchangeable).

 

Too big for 2mm!?!? come on!, 24.6/2 equals about 13 feet, most tenders are bigger than that!

 

A Midland ,(LMS) Kirtley 6 wheel tender is 70mm long internal body space in 4mm, and 35mm in 2mm scale, so the motor would fit the tender with space to spare, and it is a small sized Victorian tender........I cannot think of many tenders that are too cramped to get one of these in the internal space.

 

Stephen.

Edited June 7, 2016 by bertiedog

[bertiedog]

I do not think side force affects these motors as the shaft is long, and properly born by bearings, in the case of the Citizen motors, high quality bearings.

Nigel Lawton uses belts one his designs, and sells them, with pulleys etc, although if you have a lathe you can make your own. The belts are tiny but strong, and operate as a V belt should, the pull tightens the belt into the V, not the pressure or tightness of the belt itself. the belts are just tight by a whisker and the pull grips the V pulley. His belts are cut square, but operate as a V belt. They can be used as a square belt on flat pulleys but the tension must be higher. The belts are high quality and last amazingly well.

 

However I use them doubled, two side by side just to be sure, so a double grooved pulley must be fitted to the pinion or shaft on the Citizen motor.

Stephen.

[bertiedog]

Ebay at present is full of Micro mini motors from Digital camera focus systems, a small or very small motor connected via worm drive to a chain of gears to about 150:1. The motor can be removed and the worm and first gear etc., used to create a 40:1 box etc.

 

 

The gears are first class nylon in most cases, and float on shafts as bearings, easy to make a new support frame in brass. The worms seem generally to be two start type, very smooth in operation. The motors are not coreless, but three or five pole types.

 

The complete plastic unit can be used for point motors, level crossing gates or powering a turntable as with the high ratios they are powerful.

 

The down side is that they are 5 volt rating generally, so operation on 12 volts will cramp the range on the controller dial. They will stand more voltage, and start at very low voltage and current.The smallest motor size would fit Z gauge locos,

 

Most are being offered at about £2/£3/£4 etc., per 10 units! post free from Hong Kong.

 

Very much an experimenters delight, not mainstream traction motors, but you will not get smaller motors, or with a gearbox of this quality thrown in easily. I suspect that they are surplus to requirements sales, as digital cameras are moving on to linear motors for focus and aperture nowadays.

 

Stephen.

 

[queensquare]

 

Too big for 2mm!?!? come on!, 24.6/2 equals about 13 feet, most tenders are bigger than that!

 

A Midland ,(LMS) Kirtley 6 wheel tender is 70mm long internal body space in 4mm, and 35mm in 2mm scale, so the motor would fit the tender with space to spare, and it is a small sized Victorian tender........I cannot think of many tenders that are too cramped to get one of these in the internal space.

 

Stephen.

It's not simply a question of fitting the motor in the tender, it needs to be far enough back so that the UJ is within the tender wheelbase, otherwise it can cause problems on curves.

 

Jerry

[bertiedog]

A small tip then for 2mm tender mounted motors, do not fit them front facing, but backwards, with pulley or gear at the back end, to a layshaft under the motor, which leaves the entire length of the tender under side for the universal joints. It works very well indeed, no space problems. I use 1mm ground stainless steel for the layshafts, with a 2mm U/J on 1.3mm square sliding section.

The weight of the tender is taken by the loco rear, the front axles of the tender do not bear weight at all. This transfers the motor weight to traction weight.

I tried desperately to keep a straight face at an association meeting in the 70's, where a member complained that reversal of the motor would make the loco go the wrong way...........you can't help some people!

 

Stephen.

[queensquare]

A small tip then for 2mm tender mounted motors, do not fit them front facing, but backwards, with pulley or gear at the back end, to a layshaft under the motor, which leaves the entire length of the tender under side for the universal joints. It works very well indeed, no space problems. I use 1mm ground stainless steel for the layshafts, with a 2mm U/J on 1.3mm square sliding section.

The weight of the tender is taken by the loco rear, the front axles of the tender do not bear weight at all. This transfers the motor weight to traction weight.

I tried desperately to keep a straight face at an association meeting in the 70's, where a member complained that reversal of the motor would make the loco go the wrong way...........you can't help some people!

 

Stephen.

 

This sounds incredibly complex compared to the way I, and most other 2mm modellers do it. You have the rear mounting of a coupling on the tender to consider which the pulley arrangement will need to clear. The motor wont be able sit very low as the lay shaft will need to clear the tender axles - the split axle with muff arrangement of 2mm wheels means there's not much room below the axles so it would probably have to go above. You would then have to have more gears/pulleys to get the drive back up again in the loco. Overall I cant see this as a practical proposition and even if it did work all those gears, shafts and pulleys would make it noisy. That said, I'm all for being proved wrong, Id be very interested to see this, could you post some pictures of the ones you have done.

 

Jerry 

Edited June 8, 2016 by queensquare

[bertiedog]

 

Outline for 2mm compact tender motor mounting. I have a 3F with this arrangement, pulls well, as loco is solid brass, with transfer weight as well.

If my hands and eyesight can take it I may do some more 2mm, the layout is still functioning at nearly 50 years old.

Stephen.