Richard Hall

Expensive, yes, but that's a Rolls-Royce specification for micro motors. If these things aren't made of cheese they will be ideal for large (class 8 or 9) locomotives of the kind that, er, I have no requirement for. Never mind, I'm sure they'll be useful one day.

And another - skew wound 5 pole open frame, 9.3mm wide Tenshodo-esque motors, £2.50 for two... http://www.ebay.co.uk/itm/262361938230

Yes, I have 20 of the 37 pence cans and 16 of the 63 pence coreless. But pity the poor souls who come after us.

My latest thinking is to put the resistor in the loco rather than have it on the controller output, so that I get the benefit of the higher track voltage. As you say 18ma should not get too hot, I'll put a 100ma polyfuse in there to stop the loco catching fire if the motor develops a short. I still need to establish the best resistance for the small 8 x 15 can motors which are half way between conventional and coreless motors in their characteristics. So I might end up with a switchable resistor on the controller output for the small cans, and a loco mounted one for the coreless motors. I haven't found the coreless motor at all noisy with the controller I am using (Gaugemaster HH) but other feedback controllers may differ in this respect. I'm also a bit dubious about whether resistors will work on large passenger engines with coreless motors. The top speed of my 2MT is fine for my needs, but I suspect a Duchess on a 15 coach train might struggle with a 330 ohm resistor stuck in the motor circuit. Not my problem, I only model small branch lines. Those Chinese cans are the ones I have been testing. We live in a Golden Age for small motors at silly prices. My only fear is that at the end of all this the Japanese manufacturers (Mashima, Hanazono etc) will have given up, the Chinese will have moved on to other things and we'll be stuffed. From what I understand the latest consumer electronics tend to use linear motors which aren't much use unless you are modelling the Listowel and Ballybunion railway. (Is there a 2mm FS standard for monorails?)

I found a photo taken when I did the J39 coil springs. I also enlarged the centre and rear axle slots vertically and fitted a Flexichas style compensating beam which you can just see in the photo, but with rigid rods it didn't allow a lot of movement, so I'm not sure if it really made any difference. My thinking was that only a very tiny amount of movement is actually needed to keep the weight on all six wheels on level track.

Interesting discovery this evening. Titting about with small motors as usual, I put a variable pot in series with the coreless motor in a Farish 2MT. This one has always struck me as a bit too lively for its own good. By experimentation I found that at around 400 ohms resistance I get - starting voltage 2.5V, top speed in keeping with prototype, current draw around 18ma flat out, and perfectly smooth running throughout the speed range on a feedback controller. It doesn't seem short on poke, will happily spin its wheels even on a fairly low power setting if I stick my finger in its way. Surely it can't be that simple? I'm guessing that the same trick, with a lower resistance, will tame the small (8 x 15) can motors as well, in which case all my controller problems are over - three way switch and a couple of 10 watt resistors will give me a controller that will work with anything.

Thanks for posting that, very interesting. Current production Farish chassis are a combination of ingenious design and dreadful execution: I can't believe just how much slop there is in the bearings even on a brand new chassis. Given that coreless motors have a starting voltage of around 0.8v it doesn't make for reliable running unless you enjoy cleaning wheels and track a lot. I drilled the chassis on a J39 above the bearings and fitted small coil springs (Microtrains knuckle coupler springs) to improve conductivity. It seems to have worked.

That is exquisite. There is no other word to describe it. It's a shame so few people model early railways now. Even pre-Nationalisation modelling seems to be in decline. Something to think about if I ever get round to actually building something in 2mm.

At least it's not a well tank. Then you'd really be struggling.

I have one of those Bachmann controllers and it is better than it has any right to be, especially since it looks and feels as though it fell out of a Christmas cracker, but as you say slow speed control is not 100%. The Mashima M16K is the odd one out in their range, being open frame like the Tenshodo / Hanazono motors but with a better standard of finish. Not very common, but undoubtedly the best motor I have yet come across with enough torque to pull the side off a 2mm house. It just loves feedback and "rough" DC, the harsher the better. In fact I don't know why I'm bothering with these Chinese motors, I should just fit M16Ks to everything.

I dug out some Chinese PWM controllers that I bought a couple of years ago and briefly tested before sticking them in a box - disregarding the one that only throttles down to 10% I have two, one around 500hz the other 16khz or so. Guinea pigs (all coarse scale, sorry): Dapol Class 26 diesel (unmodified), Farish Pannier (Chinese 1015 can), Farish J39 (tender drive, Mashima M16K), Farish 2MT (Chinese 7mm coreless), Farish 4F (Chinese 1015 can, shaft drive from tender). Results - the 500hz controller gave better starting and slow speed performance than the 16khz which is exactly what you would expect, but neither of them were really impressive on anything except the Class 26, which would run perfectly on a Triang train set controller. It really is a remarkable mechanism and tells you nothing at all about whether a controller is any good. Maybe I should give up on steam and build a model of Kyle of Lochalsh circa 1980 - I have photos... I suspect that for steam locomotives, with the inevitable varying degrees of friction caused by conrods and valve gear, slightly imperfect quartering, axles moving fractionally in their bearings etc, some kind of feedback control is needed unless you can build mechanisms to Swiss watch standards. I found that the J39 in particular ran slightly better at slow speeds if I "pulsed" the controller by rapidly twitching the control knob back and forth a few degrees, but that quickly gets tedious. Someone recommended an old AGW controller to me and it is on its way courtesy of Ebay, but I have my doubts as to whether it will work with the coreless motors. These little trains are going to see me having an extended stay at Fulbourn Hospital if I don't find a controller soon that does what I want it to do. Benchmark remains the J39 on a Gaugemaster HH (two minutes 15 seconds per driving wheel revolution) but I can't survive on J39s alone.

Yes, that was my understanding. The performance of this motor in the J39 was misleading. Instead of going to bed at a sensible time I put one in the 2MT (it is indeed a direct replacement for the Farish one) and found the new motor behaved exactly the same way as the Farish one, i.e on the HH controller it skipped, stuttered and generally didn't want to know. I think the difference between the two is that the 2MT is very light and free-running whereas the J39 tender has a lot more mass and a good deal of friction from all those little badly formed gears. So the motor is working much harder in the J39. Controllers are vexing me. The coreless motors and the very small (8 x 15) cans have totally different characteristics to the older and larger motors, and I haven't yet found a controller that will suit both. DCC would get round the problem, but it's a big investment when I don't need any of the features that it offers.

An evening of coreless fun and frolics, and not really sure what I have learned. I managed to bodge one of the Chinese coreless motors into the Farish J39 tender drive and tried it with a basic DC controller. It ran but not especially well. So (and disregarding all the warnings that have been published over the years) I hooked up my HH feedback controller. My only previous experience of coreless motors has been the ones that Farish use in their recent models, and those won't run on feedback at all. So I was surprised when the J39 ran beautifully, with good slow speed control and no juddering. It did this for about thirty seconds, then stopped dead and could not be persuaded back into life. The multimeter showed an open circuit across the motor wires. I pulled the dead motor to bits but couldn't see anything obvious. So I fitted another motor to see if I could kill that one the same way. It has now run on the HH at varying speeds for about an hour with a moderate load (four coaches) and still works. However I'm not yet convinced that it has any advantages over the cheap 1015 cans apart from its size. Low speed torque seems pretty feeble. Having said which the Farish tender drive is possibly the worst piece of model railway engineering seen since Lima went bust: this one occasionally locks up randomly for no apparent reason, which may have been what caused the demise of the first motor. I'm tempted to try one in a Farish 2MT (the motor dimensions are identical) and give it a bit more of a fair trial.

The 7mm coreless motors open up the possibility of a self-contained tender drive which intrigues me. I remotored a couple of Farish J39 tender drives with Mashima motors, but the extra bulk of the motor meant I could never get enough weight in them for good traction. The more hopeless of the two is now in bits while I try to rework it for the coreless motor, and persuade all the wheels to go round without sticking. I might have to replace the wobbly Farish gears between the axles with nice Polish ones. If it works it might end up as my first 9.42 gauge loco - reprofiled tender wheels and an unpowered 2mm Assoc loco chassis. I might even be able to get enough lead in the tender to bin the horrible traction tyres. Rubber tyres belong on motor cars, not railway locomotives.

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.

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.

I'm sure you are right, at this price they are either surplus stock or (if we are unlucky) QA rejects fished out of a bin at the back of the Red Flag People's Liberation Micro Motor and Bicycle Factory. A couple of years from now we will all be wishing we had bought more while we could. I have 20 (less the one that I wrecked) - I think that's enough but maybe I should order another ten just to be safe.

Oddly the dead spot went away with a bit more running. It was definitely dead, not just binding. My best guess is a small bit of stray insulating material in one of the commutator slots, right at the edge of the area contacted by the brushes and just enough to occasionally lift one of them clear of the commutator. But what do you expect for the price of half a Mars bar?

That's encouraging, presumably these gears are of good quality then. They do a very compact 15:1 gearbox which looks nice. http://shop.kkpmo.com/product_info.php?info=p838_gearbox-with-wormgearratio-15-1.html

Hmmm... I thought my Gaugemaster HH feedback controller had died, but it was just a bad connection in the DIN plug. In the interests of science I tried it with the Chinese motors and it turns out that the one in the Pannier has a very small dead spot on it: at very low speeds (and I mean 1 wheel revolution every 5 seconds) it sometimes stops dead and needs a shove to get it moving. Not a pickup issue, it's actually the motor itself. The one in the 4F has no such problem, and actually runs slightly better at ridiculously slow speeds than my Mashima M16K-motored J39. If you are using these motors, better test them before you fit them to anything. For those with too much time on their hands, here is possibly the most boring video ever uploaded to YouTube - J39 and 4F. They aren't actually coupled together, but speed is near enough the same on both for a given controller setting. https://youtu.be/J-2NLbInWMQ

Small spur gears seem to be hard to find, but these look interesting. http://shop.kkpmo.com/index.php?cat=c21_Spurgear---Pinions-Spurgear--Gearwheel--Pinions.html

Motor test no 2 - another Poole relic, but possibly of interest to 2mm modellers as I have put the motor in the tender, driving via a ball and socket shaft. This one still needs work: my home-made driveshaft doesn't give enough movement on sharp curves, especially in reverse. In fact the whole installation is a bit of a lash-up, with about a ten degree angle between the two driveshafts due to extreme laziness on my part. And the wiring is horrible. But in a straight line it's lovely, absolutely dead smooth constant speed even with the wheels turning at around one revolution every three seconds. These motors are the bargain of the century. I managed to bend the shaft on one, trying to press on a brass sleeve with the world's worst vice. That gave me the opportunity to pull it to bits and see what it's made of. The armature is a bit crudely finished, but it has pretty substantial phosphor bronze bearings, with what look like nylon thrust washers. Brushgear is metal on metal which will kill it in the end, but I suspect most can motors are like that - "sealed for life" with non-replaceable brushes.

The first parcel of Chinese motors arrived last week. These are 3 pole 1015 flat cans, costing 37 pence each. In the spirit of the old Iain Rice motor surveys I stuffed one into the first chassis that came to hand (an old Farish Pannier) to see what it would do. The answer is a lot better than I expected for the money. It isn't as sweet as a Mashima, and rather noisier, but slow speed running is very good even on a cheap and nasty controller. I hung three coaches and 35 wagons on the back of the Pannier and it seemed perfectly happy with that for 30 minutes or so continuous running at moderate speed. It didn't overheat, or catch fire, or just go "fzzzzt" and stop working which I half expected. Motor is 15 x 12 x 10 with a 1mm diameter shaft, and the brushgear at the shaft end. At the back there are three threaded holes for mounting, two large and one small. At the front is this plastic lug: I suspect that with proper gearing rather than the Farish toy train 30:1 or so, and a better controller (mine is actually a toy train controller, it is from a Farish train set and the only working controller I have at the moment) these little motors should do very well. The only reservation I have is build quality: there's a fair amount of endfloat on the motor shaft, and I don't know how well the thrust washers inside will cope with the end load from a worm gear. Ideally I'd use spur gear primary drive, maybe 2:1 or so. But overall I'm impressed, especially for 37 pence... Richard

Thanks very much for that, it all sounds very promising. I'm not in a position to do any modelling right now, but I might buy a loco kit and a few bits so I can sit and look at them. I see there is a whitemetal J72 available, designed to fit the Triang Jinty chassis which makes me wonder if the dimensions have been messed around with. Could be a good starting point even so.

Having sold my N gauge layout I'm thinking of taking the plunge into 3mm. The one thing that is putting me off at the moment is wheels. Before I send off a cheque to the 3mm Society, can anyone tell me what the current position is with the availability of finescale loco driving wheels? It would be nice to know what sizes are currently available and how good they are. I was thinking of starting with a rewheeled Triang Jinty chassis and a cast metal body kit, just to get something up and running fairly quickly - still trying to decide whether to go for 13.5 or 14.2 gauge, I can see the arguments for both. Track building is no problem, I built an EM layout a long time ago and I don't think my soldering skills have got any worse since then. I just like the idea of a scale where you can't buy perfect museum quality models off the shelf for less than it would cost to make them yourself. I'm awkward like that.