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Kerr Stuart KS4421 in EM Gauge


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There is a much easier way of dealing with plastic gears slipping on axles. If you roll the axle with a fairly coarse file it will effectively knurl it and provide a grip on the gear wheel - do this in advance, just in the area where the gear will fit - not all across. The same technique works with loose fitting driving wheels, nearly always necessary with Ultrascale ones. Introducing Loctite anywhere near bearings is a lways a bit risky.

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On 23/08/2021 at 09:10, Barclay said:

The plan was to sort out the springing and set up the drivetrain. Springing wasn't too bad - I have used lengths of 0.33mm brass wire, which bear against the top of the hornblocks, and they seem to do the job. I know the CSB enthusiasts seem to use steel wire. Is there a reason for this I wonder? Does brass lose its spring over time? At the moment there is enough spring to hold the back wheels off the ground in this shot but a little weight will have it sat down nicely.

 

 

Brass wire can tend to 'temper' over time so tends to lose it's spring a bit. If you can find small enough gauge piano wire for the spring rate needed this would be better. It's meant not to get a 'memory' and no matter how long held at very tight curvature will always return to the straight when allowed so the springiness remains constant. K&S do fine stuff, and John Dutfields do/did stock a wide range of it in long lengths, 36" etc. 10thou/33swg or finer is probably around what you need.

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Steady progress - the running plate has been attached to the chassis, and the second photo shows the large lead weights that have been fitted into the underside to start the ballasting process. They are removable to facilitate maintenance as they are retained by the same bolts that hold body to chassis. The picture also shows the top acting pickups which can be fully on show because they will be hidden by the outside frames.

 

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As you can see, that weight still isn't enough to let the loco sit down fully onto all its wheels, so extra ballast has been used during testing. I can always ease the springs a little. Running is great at last, with the loco topping out at about 20mph, and running very smoothly down to well below walking pace. I've used quite a few slow revving motors recently but this one has reminded me that a really fast motor, with a flywheel (20th Century stay-alive!) and suitable gearing can really deliver good performance. More than ever I am convinced of the value of flywheels for smooth and unstoppable running, at least for us 12v dc luddites anyway...

 

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The buffer beams were cut from 15 thou brass and the buffers are Gibson industrial, the type with the smaller head. They aren't quite correct but look OK. Drawplates (is that what they are called?) are from an MJT wagon W-iron etch. Then came the outside frames, which are also 15 thou brass. They are due to have a lot of detail added and I thought long and hard about whether to detail them up before they were soldered in. However in the end it seemed more important to get the structure straight and true first. Soldering on details shouldn't worry the frames as the bulk of the running plate should hopefully act as a heatsink.

 

All bolted together and it still runs! I must say every weekend I find the wheels have started to rust again and need cleaning. I  am familiar with this immediately after construction but in my experience steel tyres quickly seem to become impervious to rust and rarely need cleaning. I can't explain this phenomenon but it does occur. Hopefully these will settle down soon.

 

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On 23/08/2021 at 04:10, Barclay said:

 

The plan was to sort out the springing and set up the drivetrain. Springing wasn't too bad - I have used lengths of 0.33mm brass wire, which bear against the top of the hornblocks, and they seem to do the job. I know the CSB enthusiasts seem to use steel wire. Is there a reason for this I wonder?

 


Hi Barclay,

 

CSB users use plain steel guitar strings because they are available in such a wide range of sizes and given the amount used per loco, are dead cheap. They are also widely available at any music shop worth its salt. Ask for the range of different sizes of top E string. For more information on CSBs have a visit to: http://www.clag.org.uk/beam-menu.html

HTH,

 

David

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11 hours ago, davknigh said:

Hi Barclay,

 

CSB users use plain steel guitar strings because they are available in such a wide range of sizes and given the amount used per loco, are dead cheap. They are also widely available at any music shop worth its salt. Ask for the range of different sizes of top E string. For more information on CSBs have a visit to: http://www.clag.org.uk/beam-menu.html

HTH,

 

David

 

9 hours ago, PenrithBeacon said:

Steel wire is much less susceptible to work hardening than brass.

Thanks chaps - steel is probably a better solution, and I probably have some spare guitar string somewhere. My only concern is rust. However if the brass springs lose their temper then they will be replaced !

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20 hours ago, Barclay said:

The buffer beams were cut from 15 thou brass and the buffers are Gibson industrial, the type with the smaller head. They aren't quite correct but look OK. Drawplates (is that what they are called?) are from an MJT wagon W-iron etch. Then came the outside frames, which are also 15 thou brass. They are due to have a lot of detail added and I thought long and hard about whether to detail them up before they were soldered in. However in the end it seemed more important to get the structure straight and true first. Soldering on details shouldn't worry the frames as the bulk of the running plate should hopefully act as a heatsink.

 

All bolted together and it still runs! I must say every weekend I find the wheels have started to rust again and need cleaning. I  am familiar with this immediately after construction but in my experience steel tyres quickly seem to become impervious to rust and rarely need cleaning. I can't explain this phenomenon but it does occur. Hopefully these will settle down soon.

 

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This looks really great.
The only wheels I and Coachbogie have had rust problems with, were the later K's steel wheels. I've had gunge buildup on Sharman wheels.
My High Level Armstrong Whitworth DE and Impetus Lewin are absolutely fine.
Best Wishes,
Chris.

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6 hours ago, Barclay said:

 

Thanks chaps - steel is probably a better solution, and I probably have some spare guitar string somewhere. My only concern is rust. However if the brass springs lose their temper then they will be replaced !

Rust should not be a problem as guitar strings are routinely subjected to handling with sweaty fingers and don’t rust. Given that your spring would be inside the body shell the only thing you might  have to be careful of would be exposure to acid flux. 
 

Cheers,

 

David

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2 hours ago, davknigh said:

Rust should not be a problem as guitar strings are routinely subjected to handling with sweaty fingers and don’t rust. 

I can confirm that steel guitar strings do indeed rust, especially if not wiped down between playing or after having been stored for a few months. 

 

Paul A. 

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That's looking very promising, Stuart. For what little my tuppence worth counts - all my pickups are phosphor bronze these days and this seems to work pretty well. That's probably just as well because I've got a couple of metres of the stuff.

 

Adam

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On 29/09/2021 at 10:51, avonside1563 said:

Have you got all the cab interior details? I can get some pics this coming weekend if you need some.

I do have a couple, but if you get the chance that would be great, thank you.

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On 29/09/2021 at 11:48, Adam said:

That's looking very promising, Stuart. For what little my tuppence worth counts - all my pickups are phosphor bronze these days and this seems to work pretty well. That's probably just as well because I've got a couple of metres of the stuff.

 

Adam

I really should try it !

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8 hours ago, avonside1563 said:

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Many thanks and most interesting. Does that flap stay up for a cold start, like the radiator blinds people used to have on cars? Then lower it when working temperature is reached? If that's the case then the cab must be sweltering on a hot day. If I can find the right kind of mesh I would model it open if that's appropriate. Having said that the Dorman branding on the rad (?) suggests this set up dates to when the loco was re-engined and my intention is to depict it in original form with the McLaren-Benz engine. Perhaps I'm obsessing - you won't see much anyway !

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I'm not sure if the radiator would have been in that position with the McLaren-Benz engine in, and also the engine controls may have been different.

 

The two levers on the left of the radiator are the forward reverse selector and the gear shift between low and high gears, and just below is the foot treadle for the clutch. The far left lever on the ratchet is the transmission brake.

 

She also moved under her own power again on Sunday and has now been brought out of the museum for work to return her to traffic which may include some cosmetic work to return the loco to an 'as built' look with the exhaust silencer on the bonnet and the bell.

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  • 4 weeks later...

This is a plain and simple looking engine, but there is a lot of detail on the outside frames which had to be tackled. When I realised just how small most of it is I knew I would be working in the field of impressionism - one thing I just can't cope with is making lots of microscopic bits and then soldering them together. We have the strengthening fillets between frames and buffer beams from riveted 10 thou; the strip along the top of the frames from 5 thou with slightly smaller rivets; supporting brackets for the running plate are from 10 thou and much simplified, as are the cab steps. The springs are Gibson GER loco. type, shortened and flattened, with tiny bits of 2mm brass angle to represent the brackets that support them. These are not all as tidy as I would like. Axle boxes are from copper tube filled with Milliput and the tensioning rods and turnbuckles from brass wire and tube. From the springs onwards, these parts were superglued and Araldited into place on the frames because I didn't trust my ability to solder them without everything dropping to bits again.

 

After that the 2 bonnet sides I had made some weeks ago from 15 thou brass had door apertures scribed on and holes drilled for grab rails before the bonnet top was made from 10 thou and soldered on. Simple and pleasurable work after all the fiddly stuff. I have some very small brass angle to go around its base.

 

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And it still works - but curse those wheels - they went rusty again!

 

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  • 3 weeks later...

The bonnet received a door on the front from a piece of 5 thou brass shim, and was soldered to the running plate with some 0.5mm brass angle around its base. That was so small that I struggled to work out what way up it was - I think I've reached the age when I need an Optivisor...

 

The cab was made from 10 thou with beading from brass wire, and has been soldered in place. Thanks to pictures kindly supplied by Avonside 1563 and Sir Douglas I can now make a reasonable stab at a cab interior. Looking at drawings I think the basic layout was the same when it had the McClaren-Benz engine (Not Mercedes-Benz as suggested on one website !!) so I will make it look more or less as it does today. Room for a little lead in front of the cab and in the radiator assembly in the cab, plus a small piece inside the cab roof, which should balance the loco. With the bonnet on I found the flywheel was catching the front body mounting bolt. No room to move it upwards as clearance under the bonnet is very limited so part of the nut was ground down.

 

The bottom front left corner of the cab looks a little awry in the pictures and inspection revealed that the cab side had slightly relocated itself, presumably when I soldered the cab to the running plate, so this has now been corrected. Photography can be a useful tool when building models.

 

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