7mm N2

[52D]

Probably from wartime abbreviation see last post above

[chaz harrison]

I forgive you J P, (but I can't forgive Edward Thompson for what he did to 4470 - barbarian!).

Chaz

[chaz harrison]

I spent some time looking for the tightness in the wheels. I eventually traced the culprits. I had shortened the crank pin bushes to suit the original laminated coupling rods. The machined rods that I replaced them with are a little thicker and consequently the retaining nuts and washers were rubbing on the new coupling rods' fronts. Oops! Easy to miss but also easy to remedy.

Having checked out Brian Clapperton's piece on compensation on his website... http://www.abcgears.co.uk
...I found that by switching the orientation of the motor I could use a fork piece, as he suggests, to restrain it and prevent it rotating on the axle. The snap below shows the fork piece soldered into a slot in the frame space. It engages with a steel pillar which is part of the gearbox.

The motor and gearbox installed on the centre driving axle.

The motor can rock both from side to side and back and forth, allowing the driven axle to move freely in the compensation beams. There is plenty of room inside the side tanks and boiler top for the motor to sit vertically and I won't need to cut off that motor spindle.

Chaz

[chaz harrison]

The loco rolls smoothly along a length of track and the compensation beams allow the wheels to react to a screwdriver blade (!) placed on the railhead.
So the next step is to fit the motor and put the model on the rolling road.

There are no pickups fitted yet so the connecting leads are clipped directly to the motor. Movement is encouragingly smooth with no hint of binding or stiffness. The Phil Atkinson chassis assembly jig justifies its purchase every time it is used.

Chaz

[chaz harrison]

A bit more work on the body this afternoon. I soldered in the sandbox/slashers which had only been tacked in place previously. Also the steam chest front and the coupling rod splashers. there are a few annoying gaps to be filled - I will use my usual method plating over the gap from behind with 5 thou' brass shim and then filling with small pieces of brass dropped in. Any remaining gaps can be flooded with 70 degree solder, which makes excellent filler.

In the picture below the boiler/smokebox unit is just dropped into place to check the fit.

It is irritating that the back of the saddle doesn't line up with the back of the smokebox, as it should. If I cut an overlay (again from 5 thou' sheet) I can correct this and also form a flare at the top to blend in with the smokebox.

Chaz

[chaz harrison]

As I may be a bit critical of this kit on occasion I think I ought to say a few words about kit quality, both of this kit and in general, to put my criticisms into perspective.

This is the seventh O gauge loco kit I have built. Two of them, a J50 and an N7, were a very good fit. I didn't have to make any replacement parts or make modifications to the existing ones. I did some extra work on both sets of frames, but this was because I didn't want them to be rigid, but sprung. Both of these kits were from Jim McGeown's Connoisseur range.
One kit I built, a J52 saddle tank, was a difficult one to build with some tricky problems built into the design of the kit and some mistakes made which made assembly less than straightforward. I was lucky that this kit was not the first one I built as I'm pretty sure it would have defeated me as an inexperienced beginner.
A couple of the kits I built (for a J50/1 and a LSWR 700 0-6-0 for a mate) were pretty dreadful. Bad kit design, a poor fit of parts, dimensional errors and (in the case of the 700) some very soft brass sheet meant that I replaced many parts to make the assembly easier or to correct errors.

The Warren Shepherd N2 kit is sold as "an aid to scratchbuilding". There are four sheets of etchings and a bag of whitmetal details. Most of the brass parts are a good fit and I have not so far had to replace any. At this stage I have some annoying gaps in the footplate around the splashers where the holes have been etched oversize. Undersize is better as it allows the builder to file to a fit. There are some tricky bits, but these are a result of the shape of the prototype. There are a number of parts not included in the kit - smokebox door hinges, brake shoes etc - and these will need to be made or bought in.

I have made substantial changes to the frames, but these are not the fault of the kit, but are due to my wish to fit two-beam compensation (see above).

So would I reccommend this kit? - yes, but not as a first effort by a beginner. I will keep you posted as the build progresses.

Chaz

[chaz harrison]

After a bit of a break the N2 is back on the bench.
The previous GNR designed engines (2 x J50s and a J52) gave me no chance to make the cab roofs removable. A fixed cab roof forces you to paint the interior, fit the crew etc through the side cutouts - what fun! With the N2 a removeable roof may be possible.

The boiler is still not fixed in place but is in position to check the fit of the cab front. The two spectacle plates are temporarily bolted to the body with 12BA nuts and bolts. Two pieces of angle are soldered to the base of the front plate and there is a fixing hole in the base of the tool cupboard on the back. Whilst this is easy enough at this stage, once the roof proper is rolled and soldered on to the spectacle plates access will have to be from underneath. I can forsee nuts or bolts fastened to screwdriver blades or nut spinners with Blutak.

[chaz harrison]

HELP PLEASE

Anybody got any advice about forming the corners of the flare on the back of the bunker? The flare is easy enough but that curve at the corners where it blends round into the flat sides is tricky. I would rather not have to do too much filling with solder, although I suspect some is inevitable.

Also does anybody have a close-up photo or two of the smokebox saddle on the Prototype N2? I am particular interested in the way the saddle goes behind the splasher/sandbox unit. This area will need to be compromised because of the frames and wheel standards but I do prefer to start with reference to the real thing.

Chaz

[Bill Bedford]

Also does anybody have a close-up photo or two of the smokebox saddle on the Prototype N2? I am particular interested in the way the saddle goes behind the splasher/sandbox unit. This area will need to be compromised because of the frames and wheel standards but I do prefer to start with reference to the real thing.

You need a GA or similar drawing for the outline of this part of the frames. The frames were bolted to the outside of the saddle and the sandboxes and splashers fitted to the outside of the of the frames. Often the tops of the frames did not follow the tops of the splashers so there was a gap between the two.

[rob]

Chaz-
I've done this type of "wide" flare in 4mm but did not take photos-should have,sorry.This worked for me in 4 but might not be so easy in 7,and a written outline might not be too useful either but here goes....
Take some scrap etch and cut it as a tri-angle,over length for the gap-the top will be used to hold the piece.
Trial fit a few times,roughly curving and possibly flaring until its a fair fit.In 4mm I left the piece flat but curved if that makes sense,the gap being much smaller.
Hold it in place,solder the point into the gap securely.
Bend and shape the upper section a bit more if possible/necessary.
Flood the rest with solder.
Now cut the excess at the top off,resolder the top area if needed.
Shape etc.
I'm sure I've seen this in detail somewhere like MRJ,a GWR tank IIRC.
In 4mm I didn't need filler but I've found Milliput reliable,you may not like it.
Probably not much help but if I come across the original article I'll let you know.
Cheers,
Rob

[chaz harrison]

Bill,

Thanks for the advice.
I do have a copy of a GA drawing, numbered Q - 89N (It was originally numbered 9530B but this has been crossed out). I think it's a Doncaster drawing - it is very detailed and carries lots of dimensions.
This does show most of what I want. It does for instance show that gap you refer to between the back of the splashers and the outside surface of the frames. However there are lots of hidden detail lines in this area, which show the cylinders, steam chest etc. Interpretation of this drawing would be easier if I had some photographs to hand.

Chaz

[rob]

Apologies,did take photos later when using this technique on the Q10;

As you can see I didn't do much shaping here,the origins of the scrap etch are fairly obvious! In this case though the gap was quite small.

Ahem!But I hope it is some backup to the written stuff above!
In fact I had overdone the flare on this tender and was not happy with it-but I stubbornly went ahead,had coal rails and all attached and then had to unsolder,reshape and do the whole lot again ,
Rob

[chaz harrison]

Rob,

thanks for the details of your solution. If you look at my posted snap (#17) you will set that the side sheets (which are the plating behind the coal rails) are partly flared already. As you might guess by the solder traces I have already had one go, trying to form a rolled bend at each end of the straight cross piece. Very tricky to get a nice flare, even with the brass annealed. I think your suggestion of a triangular fillet might well be an easier option. I prefer to avoid the need for plastic fillers. In the past I have resorted to very thin brass shim as a support for solder. Now that you have nudged my memory I remember some stuff about this in MRJ, must get looking through my set (I have an index).
Your photographs are helpful Although on this tender you have two flares meeting at the corner, as distinct from a flared top merging into a vertical flat sheet. Still the priniciple is sound. Watch this space.

I also sympathise with the need to dismantle a mistake and rebuild. When i was at Art College (a long time ago) one of the lecturers had two sayings which can be applied to models just as easily as he did to graphic design.

1) "If in doubt, chuck it out."

2) "If you have to ask 'Does this look straight to you?', it isn't."

Chaz

[chaz harrison]

Rob,

I have looked again and my task is a bit more challenging. Your Q10 has square corners. The N2s bunker back has radiussed corners so my triangular fillet pieces will need to be trapezium shaped (or truncated triangles!). The bottom edge will have to be curved to match the radius and then a flare persuaded in to it (it will definitely have to be annealed). But I do think it's going to be easier to shape a separate small piece.

Chaz

[chaz harrison]

No progress yet but this photograph shows a useful working method.
I always start a loco body by cutting a base block - usually from thick chipboard. I solder the captive nuts to the footplate that will later fix the body to the frames. I counterbore the block and fix the footplate to it with screws into the captive nuts. This keeps everything flat and true whilst the basic structure (valances, tanks, cab etc) are added.

I can put the body back on the block and fix this into a swivel-head vice to get a good working angle. Here I have set it up to work on that tricky bunker flared back.

Chaz