Building a Cambrian Seaham in 3mm/ft scale

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11 hours ago, Furness Wagon said:

It's coming along very nicely. 

Marc

Thanks! Happy that there's no major errors in the etches so far.

 

Nigel

[03060]

Hello Nigel,

 

I'm thoroughly enjoying following the build.

Are you still intending making the etches available at some point, please ? I am the custodian of Mark Haynes old Hemyock Road layout so I could genuinely find a home for one of these little tanks.

 

Regards,

Ian. 

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On 09/07/2020 at 14:43, 03060 said:

Hello Nigel,

 

I'm thoroughly enjoying following the build.

Are you still intending making the etches available at some point, please ? I am the custodian of Mark Haynes old Hemyock Road layout so I could genuinely find a home for one of these little tanks.

 

Regards,

Ian. 

 

Hi Ian

 

Want to see how it turns out first. I'm keeping notes of things I've encountered with the idea of updating the CAD at some point, after I've finished the model. Will start thinking of options then.

 

Cheers

Nigel

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Not had time to do much of late; covid-19 restrictions easing have brought a list of things which need doing, damn it!

 

However, the next stage is motorising the chassis, which needs the compensation beams assembling:

 

 

There's a 1/8" axle bearing at each end (Branchline straw hat), and a 1.5mm bearing for the pivot in the middle. Each beam uses 2 thicknesses of etch. Simply shove the bearings flange down on the surface, and fit both etches on top. A bit of solder run around the edges of the bearings stops the assembly falling apart. It can then be turned over, a bit more solder run around the edges of the flanges, and then more solder run all the way around the edges of the assembly. After washing and cleaning up they appear as above.

 

It's possible that I don't need 2 thicknesses of etch, but it does make a nice rigid beam. Using 1 thickness would give a thinner beam, which might make it possible to use this form of suspension on 12mm gauge chasses; this is something I'd like to find out, but haven't tried it yet. Space would be very limited.

 

Ever been assembling something, and suddenly realising you've got a problem? Happened with the chassis:

 

 

I suddenly realised the middle cross shaft, which is attached to the rear set of brakes, has a couple of problems! One is that it sits partly over the central attachment hole for the pickup assembly, so that the 12 BA screw which should screw into the nut soldered behind the attachment hole is unable to do so. The other is that the rear brakes partly block the holes in the chassis sides which take the 1.5mm rod used as a pivot for the compensation beams; this can be seen in the pic.

 

Still thinking about the solutions, but for the first problem I think I can solder a nut behind the rear hole in the pickup mount (there are 3 holes to allow for this sort of thing), and for the second I think there's enough flexibility in the brake assembly to squeeze the pivot shaft past the brakes.

 

Nigel

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I solved the pickup problem by successfully soldering a nut under the rearmost pickup platform hole, managing not to solder up anything I didn't want to!

 

Seemed a good idea to try out the compensation beams, in case of possible errors. A short (about 4mm) of brass tube, ID 1.5mm, was cut to act as a spacer between the beams. Getting these set up in a confined space is always a bit fiddly, but I managed it with no major problems:

 

 

I might try a slightly longer spacer; as this one allows about 1mm of play, quite a lot, but it'll do for now.

 

Next is to try the wheels and so how it runs on the track:

 

 

All fine, runs smoothly under finger power! I had to reduce sideplay on the driving axles, as anticipated, to stop the wheel flanges coming into contact with the brakes thereby giving rise to a short. Clearance is still fairly fine, but I think it'll be OK.

 

Finally, couldn't resist trying it with the body:

 

 

The crank pins bash the valance, but should be OK when cut to length. Next thing will be to sort out motor and gearbox.

 

Nigel

Edited July 25, 2020 by NCB

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Motor & gearbox; these are basically variants on a High Level Slimliner Compact+ gearbox, plus a Tramfabriek 8x16.9 coreless can motor:

 

 

The gearbox is a two stage one with the second stage being flexible, to allow for different physical positioning. The first stage was designed for Mashima motors and has screw holes for attaching them. The Tramfabriek motor doesn't have that sort of fixing, so I designed and had etched my own first stage. It enables the motor to be glued in place; I use Araldite Rapid, which is strong enough to hold the motor in place, but if necessary can be easily detached by sliding a Stanley knife blade or similar between stage and motor. This is the second prototype first stage, and has windows in the sides to make it easy to check the mesh of the worm and gear. I had to chop some of the bottom of the sides off to avoid contact with the axle, and the next prototype will encorporate this; I will get it right one day!

 

The motor just needs a bit of brass tube, 1.5mm OD 1.0mm ID, on the spindle so the worm can be fixed. The other change to the gearbox is that High Level currently are unable to supply the complete kit due to problems obtaining the final gear. However, they sold me some boxes without the final gear  and I managed to get some gears manufactured to special order by KKPMO in Poland, who aren't cheap but provide a good service:

https://shop.kkpmo.com/product_info.php?info=p614_gearwheel-pinion-m0-4---20teeth.html

The Compact+ gearbox is a boon in 3mm, and I'm glad I had that sorted, at least in the short term.

 

Here's the gearbox loosely assembled, with the motor glued in place:

 

 

That's roughly the shape I need: I want the motor as far forward as possible to minimise the amount in the cab. When the shape is finalised I'll put a droplet of Loctite Retainer between the two stages to lock it in place.

 

Nigel

Edited August 3, 2020 by NCB

[NCB]

To fix the shape of the gearbox, I slipped a bit of Retainer between the overlapping bits of the two halves of the gearbox then quickly placed it in the chassis. The idea is to allow a bit of movement, enough so that the compensation isn't compromised, but not so much as to put a strain on the rather delicate motor leads. So I pushed the motor forwards until the gearbox front made contact with the chassis cross-member, then slipped a 1.5mm deep bit of Plastruct under the motor rear. This allows a bit of movement; eventually I'll probably replace the Plastruct by something around 1mm deep, to give just a bit more.

 

I reckon Retainer gives you about 2-3 minutes before it starts to grip, a few more minutes before it's effectively set (although moveable with a bit of brute force). I always leave it 24 hours to fully set.

 

 

On testing the chassis against the body, I found that, as I suspected, the motor needs to project about 4.5mm into the cab. There was no way I could maneouvre the motor into the cab because the cab floor was in the way, so I removed the front 6mm of the cab floor with a cutting disc. The chassis then slipped up under the body quite easily:

 

 

Nigel

Edited August 10, 2020 by NCB

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With the wheels still on the chassis, I thought this was a good idea to sort out the pickups, so cut a piece of PCB to fit the tray on the underside of the chassis. Here's a test fit:

 

 

A problem! I hadn't recessed the tray enough, so there's very little clearance between PCB and brake cross-shaft, and not enough for the phosphor bronze wire which gets soldered to the pcb.

 

Nothing for it but to move the tray. I removed the PCB, heated up my iron with the larger bit until it was thoroughly hot, whacked it on the tray and pressed down. In fact I ended up with the whole lot coming free. It was fairly easy to move it down a tad, heat it up again and have it in a more suitable position. Problem solved! I think in future I'll take more care in the design of these trays so that they are precisely located where they need to be in the chassis.

 

After that I dug out some PB (Phosphor Bronze) wire for the pickups. As is normal this comes as a fairly tightly wound coil, and straightening a bit of this out I find a pain. You can now get nickel silver wire in straight lengths of various thicknesses, also brass wire, why not PB? Then a thought struck me and I had a look at Eileen's Emporium website which is good for wire and other things; they now do straight PB wire in 0.35mm and 0.5mm thicknesses! Great! Ordered a pack of each. The 0.35mm is around what I use in this scale.

 

One other problem attacked. The final bit of work needed on the main part of the chassis is the guard irons at either end. Unfortunately... I forgot to shove any on the etchings. However, I was working on another sheet of artwork for etching by PPD, so drew up the guard irons and added them to the sheet, which is about to go off.

 

Nigel

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PB wire arrived from Eileen's Emporium; excellent service. Cut a couple of bits slightly overlength, put a couple of bends in each so that they reached out to the wheel rims, then soldered them to the PCB, which I'd gapped with a cutting disc:

 

 

It was fairly easy to hold them in place on the PCB with a screwdriver, with the wire firmly touching the wheels, then applying some solder.  I trimmed the pickups to length and gave the ends a slight bend to form a knuckle, which becomes the main contact with the wheel; for some reason this seems to work better.

 

After that I wiggled the wheels around a bit looking for gaps between wheel and pickup; found one on just one wheel at an extreme setting. To deal with that, and make sure all were working properly, I took off the wheels and gave the pickups just a bit of an extra bend:

 

 

They should now make reliable contact. The nice thing about using this sort of PB wire is that it is springy enough to make good contact without giving unnecessary drag.

 

Meanwhile, the etch containing the guard irons has gone off to PPD. Turns out delivery time is about 6 weeks; either Covid-19 has delayed things, or because of the lockdown they've been inundated with orders! Whatever, think I'll use this for a bit of a break, although might do the odd bit on the body if I'm in the mood.

 

Nigel

 

Edited August 23, 2020 by NCB

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While waiting for the guard irons I finished work on a Cambrian Albion chassis. This was intended for an SCC 3D printed body; the body has sustained a bit of damage (front steps broken, splashers chipped) so when I can get around to it I'll order another one.

 

 

This is very similar to the Seaham chassis, differing mainly in wheelbase and wheel sizes. The motor will fit, just, inside the firebox.

 

The work just done was completing the painting of the wheels, trimming the crankpins and checking the coupling rods weren't too tight, fixing the crankpin nuts with Nutlock, then oiling everything and testing it. The painting was the annoying bit; I have trouble finding black paint which I'm happy with. I used to use Polly Scale Steam Engine Black which covered superbly and dried to an even smooth matt finish, but it's no longer available. I tried Precision and Railmatch blacks, but they went on like tar. Eventually I shoved some Precision Matt Varnish on top, which at least improved the finish. Do others get problems with black? The other Precision and Railmatch paints I'm fine with.

 

Here it is with basic body in place:

 

 

I did it partly to see how 3D printed bodies compared with using etched parts.

 

The advantage is that SCC has done a very good job on the design, and you have a nice body ready to use. On balance, I think I prefer the etched approach, especially in 3mm/ft, for the following reasons.

1) the thickness of the material means some compromises are needed. So, the tender wheelbase is a tad short; this doesn't bother me too much. But to get the driving wheels to clear the body I used 15.75mm diameter wheels not the correct 16.5mm diameter, and even then I had to raise the body by 1mm (the bits of plasticard on top of the chassis) to stop the coupling rods fouling the underside of the footplate.

2) the thickness also means there's a bit less room for cramming weight inside the body, indeed the boiler is the only place.

3) it's less easy to attach bits and pieces. So the tender handrails are superglued in place, I found it difficult to make them straight, and I'm not sure how robust they are.

 

Still, I'll get another body and complete it, and see how it does, which is the point of the exercise. If it pulls anything I'll be pleased, but the same question would arise if I'd used etched bits; a prototype like this is always going to be challenging in 3mm/ft. Thinking about it, using one of Tramfabriek's 6x15 motors might be the way to go on this sort of thing, as it might make room for some weight in the top of the firebox.

 

The same problem doesn't arise in the Seaham, because it has useful tanks and a bunker which can be crammed with lead!

 

Nigel

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The PPD etch has arrived, earlier than I expected. In the meantime a couple of Cambrian wagons have migrated to the workbench and I'll finish these off before returning to the fray with the Seaham.

 

However, in the meantime one problem has reared its head, which they tend to do :-(  While looking at the chassis I suddenly noticed some rust on an exposed bit of the cross rod on which the compensation beams rock. A close look confirmed my worst fears. The beams had rusted solid with the rod. The rod itself hadn't yet been glued in place so could turn, but what it meant was that both beams moved together. For and aft movement was OK but the axles couldn't tilt.

 

The reason was probably that when I was soldering the pickup wires in place a drop of flux must have seeped through to the rod. What I should have done was dismantled the beams and pickups and thoroughly cleaned them and the chassis. What I actually did was simply wiped around the pickup area with a meths-soaked cotton bud, which works OK for small areas but not if the flux has moved elsewhere.

 

Lesson learnt! Lucky that I discovered this now, not when the chassis was fully assembled. It wasn't too difficult to fix. The beams refused my attempts to move them while in place. So I removed the redundant bit of the brake hanger rods which lay between the frames, and could then get a cutting disc on the rod. Once it was in two pieces both halves, with beams attached, were removed quite easily, and the bits of rod were persuaded to exit from the beams. All it needs now is a new steel rod. Phew!

Edited September 29, 2020 by NCB

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Wagons built. Here they are in their unpainted state, Cambrian 2-plank fixed side open and 6 ton 9' 4 1/2" wheelbase van:

 

Coast Line Models (Alan Jones) 3D printed bodies, buffers and oil axleboxes / springs, 3mm Society buffer heads, wheels and bearings, my etched chasses. The bodies are very nicely detailed and really need painting to do them justice. The brake handles are very delicate but luckily a spot of solder strengthens them up.

 

I can leave the painting for now, and clear the workbench for a return to the Seaham.

 

Nigel

Edited October 16, 2020 by NCB

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So... guard irons bent to shape and soldered to the main chassis:

 

I hate soldering fiddly bits onto something else like this! Managed to lose one but as I usually do I had two sets etched. Next time I do a chassis I'll definitely make the guard irons integral to the main etch; in this scale there's very little to be had by making them seperate.

 

The chassis is now ready for painting.

 

Nigel

Edited October 20, 2020 by NCB

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The chassis has been painted, first a coat of Precision General Purpose Primer, which I like, then Precision Dull Black. Still not happy with blacks. This was a new tin, and went on better than my attempt with the Albion above, but the finish still not quite as consistent as I'd like, some bits almost gloss. So I'll probably whack some Precision Matt varnish on top.

 

Maybe I should try Precision Matt Black. Or a Humbrol black, which I haven't used for years. I did have a new bottle of Railmatch Black, but like the previous bottle it was like tar; Railmatch have taken to using a plastic grommet in the bottle rather than the silvered cardboard disc they used to use, and I'm wondering if it allows the paint to dry out a bit.

 

I will put up pics in due course. Unfortunately, I am currently semi-mobile. Went for a walk on Friday, about a mile, which currently is about my limit, having dodgy legs due to a spinal cord issue 14 years ago, which lack of practice during lockdown did nothing to help. OK but tired legs at the end of it. In the kitchen in the evening one leg momentarily gave way; it does this at times especially indoors, it usually recovers in an instant but on this occasion didn't. After bouncing off a kitchen cabinet I instinctively tried to recover, not a wise move, and sprained the left leg. Thought it was the knee, but today came round to the view it was a torn calf muscle. Very little pain as such when not walking but useless as regards walking. Crutches make walking possible, or using my wheeled office chair for support, but I'm giving it several days doing nothing hoping it'll recover. So much for all the things at home I intended to get out of the way during Welsh lockdown!

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Managed to stagger to the railway room! Took a pic of the painted chassis. I'd taken a pic of it in its undercoat a few days before:

 

Here it is in the black finish:

Will probably stick some flat varnish on top of it; it doesn't show in the pic, but the Precision "dull" finish seems to vary between a satin and a gloss.

 

Leg being rested but not doing too badly at all. I'll give it another day's rest then ease it back into action

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Sloshed some matt varnish over the chassis, now drying, In the meantime, I've assembled the coupling rods. Each is in two pieces, a solid rear and a half-etched detailed front. I tinned the rear while still on the etch, and then used two discarded wheels with crankpins intact to solder them together:

 

The two bits were placed in turn over the crankpins, some flux applied and then heat applied to the middle part, avoiding the end so the crankpins don't get soldered solid to the coupling rods. The rods are then removed and solder flowed around the edges. Old wheels have all sorts of uses.

 

Nigel

Edited October 29, 2020 by NCB

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Another use for old wheels. 3mm Society fine scale axles are shouldered, with a 1/8th inch main part and a 2mm bit each end which takes the wheels. The latter are extended to allow outside cranks to be fitted, very useful, but it does mean that they have to be trimmed for most uses. Sticking each end through an old wheel means the excess can be easily and fairly accurately cut off using a cutting disc; if the wheel is damaged it doesn't matter. The ends just need finishing with a file. Here an axle through an old wheel about to be trimmed, and a finished axle.

 

Axles can vary in tightness on the wheels slightly so I use Loctite 203 Retainer to fix them. The axle is pushed slightly into the wheel, creating a cup on the outside. A couple of small drops of Retainer on the end of a thin rod are dropped into the cup, the wheel pushed firmly home, and the excess Retainer wiped up with a cotton bud before it does any damage. Here's one wheel done for each axle; I allow 24 hours for the Retainer to set before using them.

 

At this point I refitted the compensating beams to the chassis. If you remember, I had a problem with them previously rusting up. Once I had them in place, I decided to use a small drop of Loctite Nutlock on the outside of the chasses to stop the rod acting as a pivot from sliding out. The idea is to move the rod just slightly to get the Nutlock to seep between rod and chassis, while avoiding going further and gumming up the the beams. That was the idea. Unfortunately, the rod moved too far, and in returning it to the correct place some Nutlock reached a beam, which quickly started to gum up. Doh! Using some brute force I luckily managed to disassemble the beams before it was properly set. Another go will be required!

 

Nigel

Edited November 7, 2020 by NCB

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This time I managed to get the beams in place with no problems. I decided not to use Nutlock, as the rod seemed to be fairly secure anyway and it would have to force itself past the brakes to come adrift. I added some oil, Woodland Scenics Lite Oil which I use for most things, to the rod to guard against future rust, and tested the beams for free operation.

 

Next I put back the pickup assembly and checked the pickups would operate as intended; it's much easier to adjust things at this stage than after the wheels have been added. Then I temporarily mounted the motor/gearbox assembly using a spare axle, and soldered the leads to the pickup assembly PCB board; again, it's easier to check the pickups haven't been disturbed at this point rather than later. Remembering the previous rusting problem I used a droplet of Carr's Red Label rather than Green Label in the soldering, as it's relatively non-corrosive. To make sure I wiped adjacent surfaces with a meths-soaked cotton bod. Finally I attached some controller leads to the pickups to check that power would reach the motor.

 

Here's the chassis with things mounted:

 

and here's a look at the underside of the chassis:

 

Next comes the infinitely more fiddly job of mounting and quartering the wheels.

 

Nigel

Edited November 10, 2020 by NCB

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For the first driving axle, I shoved on a couple of 0.4mm 1/8" washers, and from one side fed it through the first compensation beam, one gearbox bearing, the brass final gear, the other gearbox bearing and the other beam. This is all pretty fiddly, especially getting the brass gear in position and threaded on, but with a lot of patience (which I am not noted for), I managed it.

 

Then it's a question of adding another couple of washers, getting the second wheel partially fitting on the axle end, tweaking it until it's quartered, adding a drop of Retainer, then pushing it home. Simple. Not.

 

The tricky bit is making sure the washers stay on the axle proper rather than drop into the 2mm bit. So one needs to make sure the first wheel is pushed as near to the chassis as possible, leaving the maximum amount of axle protruding on the other side, and while keeping the wheel in position feed on the washers, and then a bit of the wheel, hopefully in roughly the right position for quartering. The actual quartering on the first axle is actually easy; it just needs to be more or less right and can be done by eye. When satisfied a drop of Retainer can be dropped in the cup formed by wheel and axle end, and the wheel pushed home. After that a back-to-back gauge can be used to double check a washer hasn't dropped and the wheel is truly home, the quartering can be rechecked by eye and tweaked if necessary, and the excess Retainer wiped away with a cotton bud.

 

There was one snag to the above. Over the last few months I've been developing some weakness in the right hand, which is being investigated (my guess is Carpal Tunnel syndrome). It means my usual squeeze hard with the fingers method of shoving wheels home wouldn't work. However, I did manage in the end to get the wheel in place. I also did the simple job of adding the pony wheels at the front. Here's a pic:

 

I'll leave the lot to thoroughly dry before dealing with the second axle.

 

Nigel

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On Tuesday I set to with the quartering. The method is this. When quartering is out it tends to be when the cranks are at 45 degrees that things stick. So what I do is stick the coupling rods on, get the cranks at 45 degrees then press home the fourth wheel. As at the moment there's virtually no play in the rods, deliberately, this forces the fourth wheel into the correct position.

 

I did it once without using any Retainer and tested it. Things rotated OK. That's good, because with minimal clearances quite often there'll be a bit of stickiness. I then eased the wheel off slightly, stuck a bit of Retainer in the axle end then pushed the wheel home again, wiping off the excess as with the other wheels. I checked the back-to-back; it was out. Sure enough, one washer had become jammed between wheel and shoulder. So I repeated it and got it correct. Checked again and everything seemed OK. So I left it to set. Here it is:

The blue bits of wire insulation are an easy dodge to fit the rods without fiddling with nuts.

 

Took a look yesterday. I found that twirling the wheels there was now a spot where things caught slightly, not much, but enough to notice. Eventually the holes in the rods will be opened up slightly and I thought that would cure it. However thought some more and took a close look at it today. By looking through the spokes and comparing how opposite wheels lined up I could see that the quartering on the rear wheels was slightly out; the fact that I could see it meant it was too much. So, I broke the seal on the Retainer and rotated the wheel to the correct position, and tested it. It was now OK. It must have got knocked after my previous test before the Retainer had dried.

 

So, I now have a wheel to refix!

 

Nigel

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Wheel refixed and tested. Seems OK, revolves with no tight spots or catching. So I'll assume it is OK!

 

I decided that this was a good time to finish any painting of the wheels while I could get at them easily without coupling rods and brake pull rods getting in the way, so removed the coupling rods. First thing was to add the balance weights. These are adjacent to the crank pins but slightly offset. I found a curious thing; the offset on the Mike Morton Lloyd plans is in one direction on the Cambrian locomotive and the other direction on the GWR rebuild. This is born out by photographs. Seems the GWR switched the wheelsets around!

 

I added the weights using ZAP Thick then sloshed a thin coat of Precision General Purpose Primer on the weights, the wheel centres, and the wheel rims; I don't go for shiny wheel rims. Here's the result:

 

Not the easiest with my currently dodgy right hand!

 

Nigel

Edited November 23, 2020 by NCB

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To finish the painting, with no great enthusiasm I picked up the Precision Dull Black I'd used before, when I had an inspiration. I looked on the shelves and found some Humbrol acrylic Matt Black. With nothing to lose I gave it a try. It went on fine, smooth, covered well, not too thick and with a decent finish. Here's the result:

 

Painting done. Now the time to fix the gearwheel, for which I use retainer. I hate this because it can seep into the bearings, and if that happens it probably means a scrapped chassis; some High Level gearboxes have boss with a retaining screw, but on the Compact+ there isn't room for it.

 

I shoved on a drop and waggled the gearwheel slightly so it would seep between axle and gear, and left it. The drop was larger than intended but so far it has stayed where I wanted it to. I propped the chassis up roughly level to discourage it from flowing, and left it. Here's hoping!

 

Nigel

Edited November 24, 2020 by NCB

[NCB]

Took a look at the chassis and at first it looked as though the bearing might have got glued up, but waggling things around seemed to free things up. Tried it with power on the driven axle, and no coupling rods, and it rotated but with a bit of stiffness at one point. This is unusual using High Level gears (I've had it with Romford all-metal gears); I wondered if the final gear was rubbing against the intermediate gear as there's not much room. So I oiled everything up including the side of the final gear and this cleared it. So I then spent some time with the coupling rods on and weights balanced on the chassis. I've got it running pretty smoothly except it sometimes stops at one spot, as though something is catching. All in all the motor seems great; the motor + High Level gearbox plus moderate sized wheels gives spot on performance. I found getting the weight in the right places is critical (normal) and it's difficult to test properly just using the chassis.

 

It was my intention to finish the chassis completely (fix coupling rods permanently, add brake pull rods, etc) before going back to the body, but now I think I need to leave final testing and tweaking until I can do body and chassis together, so I'm leaving the chassis as it is and will pick up the body again.

[NCB]

Success   I changed my mind and decided to have another look at the chassis, and ran it backwards and forwards until it hit the spot where it stops. Turning it over, I found that the bottom of the tread on one wheel had a sort of film over it, as though a drop of some liquid had dried up. Moreover, the adjacent wheel had a spot of dirt in the middle of the bottom of the tread. So at that point one wheel wasn't picking up, and the adjacent wheel wasn't either if the point of contact was the bit of dirt. Quick scrape with a screwdriver, and running was almost perfect. Found a couple more specks of dirt, removed them, and it was now fine. Tackled several bits of track with no problem, and the running is very, very smooth, probably the best I've built.

 

I think I'll carry on and finish the chassis, as I can't see there's anything left to alter. Bit tied up at the moment but I should get it done before Christmas.

 

Nigel

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Coupling rods. Removed the blue bits of wire insulation and checked the coupling rods had a reasonable amount of play between wheel and retaining nut. You don't want too much or the nut might hit the footplate valance. Normally before doing this I'd take off the coupling rods and open up the holes a tad, but I'd already done a bit of this and there appeared to be no binding when the engine was running so decided there was no need.

 

Then it was a question of snipping off the excess crankpin with Xuron sprue cutters, winding each nut half off, sticking a drop of Loctite Nutlock in the cup on the end, winding the nut back to its original position (checking again for play), and wiping off the excess Nutlock. And hoping none had reached the coupling rod holes. Then they were left overnight to properly bond.

 

Tested the chassis again this evening and it seemed fine. As I've yet to oil the coupling rod holes I'm confident this is good enough

 

 

Nigel

 

Edited December 9, 2020 by NCB