Building a Cambrian Seaham in 3mm/ft scale

[NCB]

Hope you've all survived Christmas.     Mine was tempered by blocked up kitchen sink, dating from the 14th. There's supposed to be a plumber coming, but communication isn't their strong point. He did turn up on the 16th, but using a plunger didn't do it; said he be back the following morning, but nothing since. Grrr!!!

 

Final chassis job; the brake pull rods. Simple soldering job:

 

Then the excess bits on the cross-shafts trimmed off, and a coat of Precision General Purpose undercoat:

 

Due to my dodgy right hand I managed to get a bit of paint on the wheels, but it should be easily dealt with.

 

One thing I've found is that under some circumstance the coupling rods foul the underside of the footplate. The culprit turns out to be the tiny grease glands on top of each coupling rod bearing. Filing back the inside edge of the footplate above the bearings should avoid it; it only needs a bit, in fact I could have catered for it in the first place.

 

Nigel

Edited December 28, 2020 by NCB

[corneliuslundie]

I can get paint on the wheels without the "help" of a dodgy hand. Painting is (one of) my weak points. Soldering is another. Not a good combination for building locos.

Anyway it is coming along very nicely. You are presumably going to have the same problem I did with the motor projecting into the cab. I now have a pair of ModelU crew but they will have to have their legs amputated as I had to put in a raised floor. Hopefully, no-one will be able to see, and I shall ignore their screams.

Jonathan

[NCB]

Yep, Jonathan, the motor does project into the cab. I told myself it won't be visible anyway, and it saves me thinking about the backhead!

 

Finished painting the brake pull rods; here it is:

 

 

Tried a run down the track; wouldn't move. All 4 wheels had paint on the treads in exactly the same position! A bit of scraping with a screwdriver and polishing with a microfibre stick and she ran OK though. I'll take a very close look some other time; my experience is that you can get very small almost invisible bits of paint which still affect the performance.

 

I filed the inside edge of the footplate behind the tank above the wheels, and solved the bearing gland problem; here's the loco as present under test:

 

 

The lump of lead is necessary; eventually there will be plenty in the tanks, and probably in the boiler and bunker as well.

 

So, just need to get back to the body; I'll take a break, probably until late January, as there are other things I want to get sorted.

 

Nigel

Edited December 29, 2020 by NCB

[NCB]

Nudging back towards restarting the project, just a few more things I want to clear. One thing I have been doing though is getting to grips with 3D printing, and the Seaham safety valve seemed a suitably simple place to start. So have been feeling my way around Fusion 360, and ended up with:

 

A surprisingly quick turn around from Shapeways, and I had my first print. Chuffed!

 

 

I used "smoothest fine detail plastic".

 

I'd obtained the chimney and dome some time ago, courtesy of Alan Jones of Coast Line Models.

 

Nigel

[NCB]

Time to get going again!  The final main phase of the body, namely the smokebox/boiler/firebox, is going to be very fiddly, and I've rather been ducking out of it. Coward!

 

Here we go, starting with the firebox. The firebox front is formed from a number of layers of etched formers; the front of these will need to be filed into a curve to represent the brass band between firebox and boiler. The rear two are of slightly reduced diameter and provide something to solder the firebox wrapper onto. Three 0.6mm n/s rods going through the formers keep them in alignment.

 

To start with, I took the front former and placed it onto a flat bit of MDF, then used a drilling stand to drill to 0.6mm holes into the MDF using the former as a template.

 

 

As each hole is drilled I used short bits of 0.6mm rod to align hole in former with the drilled hole.

 

Once done, I replaced the short bite of rod with longer rods, which will eventually extend beyond the firebox wrapper into locating holes in the cab front.

 

 

You can see the firebox wrapper on the left, also more of the formers; two are the same size as the first one, the third, one of two, slightly smaller, will lie underneath the smokebox wrapper. These formers have been pre-tinned, by the way.

 

Next stage is to feed each former onto the rods after sloshing flux on the one underneath and bonding them together using a hot iron and more flux. Here's the final product:

 

 

I used a fine-tipped iron; I wished I'd used a broader one for more heat as in one place things haven't stuck. However, it's easily rectified.

 

I did a test fit of it in the engine body to check it was OK:

 

 

In the next session I managed to curve the smokebox wrapper into the right sort of curve, first by feeding it through rollers then by pressing it with fingers round smaller and smaller diameter brass tube. I also started filing a radius on the front of the former sandwich.

 

So far my nerves have held up, but it is fiddly, not helped by my dodgy right hand. I'm thinking of coating the formers with a bit more solder to hid the layers, but it may not be necessary. Also, I need an extra former on the front to locate the boiler.

 

The thought strikes me that the firebox front could actually be made by 3D printing in say brass, but that's one for the future.

 

Nigel

 

 

Edited April 8, 2021 by NCB

[NCB]

At this point there was one of those accidents with which us modellers are familiar. I dropped the firebox front on the floor, and it proved difficult to see. In standing up to get a better view I trod on it, which resulted in the rods becoming somewhat bent. However, with small pliers and a lot of patience I managed to restore it to more or less its original shape.

 

Before adding the firebox wrapper, I soldered the final former to the rods just in front of where the rear of the firebox would be. It was then fairly easy to attach the wrapper, using that former and the firebox front. A few dabs of solder run between formers and wrapper on the underside, and the firebox was complete. Here it is:

 

 

Not perfect, but near enough. I shoved it in position on the body to see how it looks:

 

 

The next stage is to add the boiler. A problem; my calculations seem to have gone slightly astray. The intention was to wrap a boiler wrapper around a piece of K&S thin walled brass tubing, and attach the lot to the firebox front. However, it turns out the result would be almost the same diameter as the firebox, and it needs to be smaller. I found that the tubing itself would be the right diameter for the boiler, so I'll use just that and discard the wrapper, at the expense of losing the nicely etched boiler bands.

 

I haven't any of the right diameter tube in stock anyway, so I'll have to order some.

 

Nigel

Edited April 17, 2021 by NCB

[NCB]

Got the tube for the boiler. Cut it to length so that it would project a bit into the smokebox, and soldered it to the firebox. The rods I used to construct the firebox proved just right to locate the boiler. Nevertheless, it's not one of my best efforts! Things are slightly skewed. But it will have to do. I tell myself that when finished nobody will notice.  Whatever, it's too much effort to try to redo it; probably a different approach might have been better. Indeed, I'm wondering how a 3D printed brass firebox would work out. Here's the assembly temporarily attached to the cab front:

 

 

Next stage will be the smokebox, which will be a separate assembly built around the next size tube so that it's a sliding fit on the boiler. That way I can juggle things so that they fit. I hope!

 

Nigel

Edited May 9, 2021 by NCB

[NCB]

To the smokebox. I cut a bit of brass tube of size next one up from the boiler, of length so that it projected slightly out of the smokebox wrapper. The cutting process tends to shrink the tube around the cut, so the outside is nicely bevelled which is what I want, but the inside will not fit over the boiler tube. So I did a fair amount of filing of the inside until it did fit.

 

Here's the tube, with smokebox front, saddle and half-etched wrapper:

 

 

Now to stick this lot together!

 

Nigel

[NCB]

Soldered tube to smokebox front. A bit fiddly, with nothing positive to locate things, and it took several goes to get it reasonably right. Then added the saddle.

 

 

The smokebox front is slightly deeper than the saddle; it's probably the latter which is slightly too shallow. Doesn't really matter as the saddle is primarily to help locate the wrapper.

 

Now for the joys of adding the wrapper!

 

Nigel

[NCB]

Getting the wrapper soldered on proved very, very fiddly. In the process I found one way of reducing burnt fingers when holding parts together with one hand is to stick plasters on the fingers. That way you can afford to let the solder cool a little longer before screaming and dropping the part. Here's the result:

 

 

Pretty messy, not perfect, but I think after cleaning up it will do. The wrapper isn't quite long enough so a bit of filling will be required around the base when it is finally in place.

 

This is probably the last bit of really fiddly soldering to do. After I've cleaned it up I think I'll take a look at adding boiler and smokebox handrails, as these are probably easier to do before assembling these pieces to the main model.

 

Nigel

Edited June 6, 2021 by NCB

[NCB]

Cleaned up the smokebox; think it'll do. Here's another test fitting of the parts:

 

 

Now for the joys of trying to drill holes for handrail knobs in the boiler tube!

 

Nigel

 

[Ian Smith]

58 minutes ago, NCB said:

Now for the joys of trying to drill holes for handrail knobs in the boiler tube!

 

Nigel

 

Nigel, I always use a sharpened gramophone needle to mark a pilot dimple for drilling small holes. I sharpen the needle to to be 3 square so that it has 3 facets and 3 cutting edges. I even use them when drilling small holes on the lathe.

Ian

[NCB]

29 minutes ago, Ian Smith said:

Nigel, I always use a sharpened gramophone needle to mark a pilot dimple for drilling small holes. I sharpen the needle to to be 3 square so that it has 3 facets and 3 cutting edges. I even use them when drilling small holes on the lathe.

Ian

 

Thanks for that. I've been playing around with the points of broaches. The problem is I have a dodgy right hand and its both hard to hold one firmly and to apply any serious force. I wonder if the left hand could manage it. But the broaches aren't that sharp.

 

I have drilled one hole in the smokebox; it's visible in the pic. I shoved the drill in a drill stand and brought it down very slowly in the hope the drill wouldn't fly off target. It worked. Not sure if it would work on the boiler, where I'm using 0.4mm drills. Maybe worth a go.

 

Nigel

[TT-Pete]

Nigel, I stick a bit of masking tape over where the hole is to go, it helps keep the drill bit on target and stops it wandering during the first critical moments.

[corneliuslundie]

Thanks for that tip. I have been getting through rather too many 0.5 mm drills fitting steel heads to white metal buffer housings. I'll try it for the last few buffers. I don't really want to be sending an order to Eileen's just for 10 0.5 mm drills.

And that loco is coming along nicely. It'll knock spots off my 4 mm white metal version.

Jonathan

[NCB]

Just tried drilling the holes in the boiler using my drill stand method. It worked! Only had a quick look to check but it looks as though the holes on one side are level and on the other very slightly sloping, but I think there's enough wiggle room with the handrail knobs to correct this fairly easily. Generally I use either 3mm Society handrail knobs or Markits N scale ones, which are virtually identical; in this case I'm using the latter. I marked the spot for each hole with a fine black marker pen, as seeing the right spot isn't easy, having initially marked them using a scribe.

[NCB]

Went back and checked the handrail knob holes. Found on one side I'd got them too far forwards so drilled some more. Think it's now OK.

 

Off on Friday to sample the delights of Prince Philip Hospital, Llanelli, for a routine op (bladder and kidney stones), so that's probably the last bit of modelling I can manage for a week or so.

 

[ChrisN]

Hope everything goes well.

[NCB]

Battered but survived! Was only in one night, which surprised me; they normally look at me and think decrepit old git, maybe don't let him out too early!

 

Started on the handrails. The holes in the knobs need clearing out and enlarging. I found this very fiddly and several knobs shot off into space, to the point I was in danger of running out. Finally I hit on sticking the knob in a pin vice, and putting that in turn in a bench vice, so that the knob was rock steady. I intended to use 0.4mm nickel silver rod for the handrails, so used a 0.45mm rod held in another pin vice to open up the hole.

 

Similar problem feeding handrail rod through the knobs, until I hit on the idea of using the above technique for that. I cut some over-length rod and put a right angled bend in one end to stop the knobs sliding off, then fed the rod through the knob held in the pin vice, with the same again for the second knob. Another bend on the other end secured the knobs on the rod.

 

I was hoping to use my fine-tipped soldering iron to solder the knobs into the boiler holes, but the heat in the boiler tube dispersed too rapidly, so I used my new medium-tipped iron. This did the job but with rather a lot of solder scattered around, which had to be cleaned off. Also, Antex irons now seem to come with the tips ready tinned; I don't know what they use, but it has a nasty smell and produces a black crud when in use. I used a U shaped bit of 0.7mm rod to act as a spacer between handrails and boiler when soldering.

 

Finally, I trimmed the handrails to length and cleaned up the boiler. Here it is with another test assembly of it on the locomotive.

 

 

Before fixing the boiler I need to add the smokebox front handrail, and also remove a bit from the underside of the boiler to make space for the motor and gearbox.

 

Nigel

[NCB]

Latest stage:

 

 

No difference? Not really. But now everything is soldered in place. I had intended to add the smokebox handrail first, but after bending a boiler handrail decided it would be too vulnerable to my ham-fisted methods! The soldering went quite easily, first the prongs in the cab from the firebox, then the smokebox front base, then the firebox cab join, finally the boiler-smokebox join. Some cleaning up is needed.

 

I now need to add the smokebox - cab pipe and the cab handrails, at which point all the soldering will be complete. However, I'll be leaving this for 2-3 weeks, as I have a laser-cut signal box kit I've promised to do the test build of.

[NCB]

Took some time off the signal box and cracked on with this. Fitted the handrail on the smokebox front; hope it clears the door but can't check as I'm not sure where I put the door casting! Also fitted the pipe from the cab to the smokebox. Here's the result:

 

 

Then had a go at fitting the cab handrails. These are meant to be 0.5mm nickel silver soldered to thin fingers which project into the cab opening from the tank and bunker sides. No joy! I tried a number of approaches, but my dodgy right hand meant I couldn't position them and solder them up accurately; with two good hands it would have been fairly simple. Think I'm giving up on this. Being in the cab opening rather than stuck onto the sides they aren't too obvious anyway.

 

Unless I change my mind, that's all the soldering down. Yipee! I've a bit of filling to do, mainly the corner of the flanges at the tops of the tanks, and gaps at the base of the smokebox; thinking of using Milliput. And I need to add lead to the tanks and check balancing and running. Not sure which I'll do first.

 

Nigel

Edited August 5, 2021 by NCB

[NCB]

No pics this time. Glued a slab of lead in each tank. There was rather less room than I thought, so not sure yet if it's enough.

 

Decided to test it. Found the gearbox jammed in the slot on the bottom of the boiler; thought I'd checked this but obviously not. Out with the Proxxon drill and a grinding bit, enlarged the slot. Chassis now fitted, running not bad but with the occasional stop. Checked again and decided the gearbox was still touching the boiler, enough to affect the compensation. Bit more grinding and it now runs fine. Tested it with 3 wagons, and then with a D&S Cambrian bogie coach. Handled them OK. Test track too short to try more, so I'll try it on my GWR layout, which needs connecting up.

 

Nigel

[NCB]

More tests of the engine under power, this time on my GWR layout. A bit of lead squeezed into the smokebox / front of boiler improved things. Decided I needed some more weight, and managed to glue another layer of (thin) lead sheet inside the tanks. OK, but the centre of gravity was behind the leading drivers and I reckoned over those drivers would be better, so tested fitted another bit on top of the first in the boiler which produced the balance I was looking for; with the c of g over the leading drivers all wheels are carrying roughly the same weight, which I feel is a good thing.

 

That did it. Now very smooth even running, and the coreless motor is a gem. Tried it with 6 weighted GWR wagons on the layout and it didn't even notice them. There was the odd bump but that was due to track issues which need to be fixed. Here's a pic:

 

 

So, now to do a bit of filling on the body and add the fittings. Getting there... slowly!

 

Nigel

 

P.S. I notice that one of the platform benches has flown into the bay. Wonder how that happened!

Edited August 30, 2021 by NCB

[NCB]

Another small step, one I wasn't sure how it would work out. I mixed a small amount of Milliput (fine) and used it to build up the awkward corner between the flanges on the sides of the tank tops. And also filled small gaps at the base of the smokebox.

 

 

Not perfect, but as good as I hoped.

 

All that's now needed is to add all the various fittings. If I can find them! Can't actually remember if I'd sorted them all, or if there were gaps. I know where the 3D printed chimney, dome and safety valve are. The buffers (GWR Metro) should also be OK, although not sure if I'll have to raid my spare Metro kit or whether I acquired another spare set. I think I did acquire some tank fillers. Not sure about the smokebox door. Here's to looking

[NCB]

So, the search for fittings!

 

Starting with the whitemetal ones, I found my spare set of Metro buffers fairly quickly; thought they looked a bit large, but checking against the plans they seem to be spot on.. The tank fillers drew a blank except for a pair from a GEM pannier tank kit, which frankly aren't that great; I may need to raid the 3mm Society parts list. I found one smokebox door but it is just that bit too large, especially as the handrail has ended up slightly lower than intended. The 3mm Society list has a smokebox door, from a whitemetal small prairie kit, which is more or less right, so may need to opt for that, or consider doing my own 3D print.

 

Can't find the 3D printed chimney and dome Coast Line Models did for me. Thought they were with my recent 3D printed safety valves, in the set of boxes holding all the 3D printed stuff, but they weren't. In the end went through all the 3D bits and did a much needed re-organisation, and ditched all not needed packing. So at least I know what's there, and have matching items grouped together.

 

So the chimney and dome are either somewhere in the mixed mounds on the workbench representing current projects, or have drifted into some other box; the one holding bits for my Rhymney Class M is one possibility.

 

Enough for tonight; the search continues tomorrow!

Edited September 20, 2021 by NCB