Ivatt N1 0-6-2T, British Railways Era

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Instructions for modifying the N2 donor chassis, surface preparation, detailing and decoration

Modifying the N2 donor chassis

NB: These instructions are based on the earlier analogue Hornby N2. They should also apply to the Mainline/Aifi x/Dapol versions. The latest DCC ready version (1948 Olympic Train Pack onwards) features a different weight which is cut down to accommodate the chip. Method 2 is recommended with this version.

Method 1: Modifying the weight

Looking at the chassis we can see that the motor is screwed to the chassis and the weight sits around it. Taking the weight off reveals a small spring contact beneath to the wiper strip (fi g. 1 in red). Power is transferred through the weight to the contact at the top. The weight needs cutting as shown by the masking tape (fi g. 2).The front part of the weight will also foul the base of the smoke box so it’s easiest just to cut right through with a hack saw and discard the front (fi g. 3). Finally you will need to remove some material from the top of the weight in order to get the body to sit lower. If required, you can add additional weight in the front of the boiler. This is also an ideal place for a DCC chip if you are using one.

Next the locating lugs need to be removed from the back and the back corners chamfered (fi g. 4, shown in red). Some material needs to be fi led away on the sides between the radial wheel the and driving wheel (fi g. 5) - this is to allow space for the tank connecting pipes. If you prefer, you can fi le the back of the tank pipes on the body to half profi le (as on the Hornby N2 body) to make this an easier fi t. Next the front coupling is removed and the front of the chassis needs to be cut off immediately forward of the guard irons (fi g. 6). If you are retaining a tension lock coupling retain the base of the coupling and re-fi t after cutting as a fi xing/gluing position (fi g. 7), otherwise remove and discard it.

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Method 1: Modifying the weight (cont.)

Your body should now loosely fi t. The back of the cab has a cut out to accept the Hornby motor (fi g. 8). This is a snug fi t so may need some fi ling. Check that the height is correct over the buffers, fi ling more material if too high or gluing thin plasticard strips on the chassis above the front guard rail or around the motor if too low. To hold in position re-use the Hornby screw at the front and fashion a plasticard lip behind the rear buffer, between the radial wheel underframe.

Method 2: Replacing the weight

Completely discard the weight and re-solder the motor (or DCC chip if using) to the wiper strip. Replace the weight with liquid lead or other small weights. These can be placed in the front of the boiler or fi xed to the underside of the boiler and tanks. Another method is to fashion a container from plasticard and fi ll with liquid lead (fi g. 9). Site this on the chassis where the original weight would have sat (fi g.10).Otherwise as Method 1.

Modifying the N2 donor chassis

NB: These instructions are based on the earlier analogue Hornby N2. They should also apply to the Mainline/Aifi x/Dapol versions. The latest DCC ready version (1948 Olympic Train Pack onwards) features a different weight which is cut down to accommodate the chip. Method 2 is recommended with this version.

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modifi ed chassis with tension lock holder

original N2 chassis

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Copyright © 2013 AJModels - Figures 7 & 8 © 2013 SAC Martin, used with permission.

Surface Preparation

Checking and Cleaning

Check that the model has printed correctly. It should have slight fi ne ridges top to bottom like fi gure 11 (left). There may also be varying amounts of a thin waxy residue covering the model. This is normal and part of the printing process but will need cleaning off.In the unlikely event that it has printed more like fi gure 12 (below left) with additional strongly defi ned banding there has been a problem with the printer. If so please photograph the model and contact Shapeways’ customer services who will send you a re-print free of charge. You will not need to return the faulty print.Gently clean the model to remove the wax. I would recommend an old soft toothbrush and lukewarm soapy water for this. Do not leave immersed. There is no need to use aggressive chemicals or alcohol. Rinse and dab dry with a cloth once cleaned.

Surface Preparation

For best results it will be necessary to lightly sand the model to remove the ridges that are inherent in the printing process. It is recommended to prime the model fi rst with an acrylic primer (Halfords Plastic Primer gives good results). Do not use enamel paints at this point. Once dry rub down with fi ne sandpaper. The tanks seem to sand best along the grain and the boiler across the grain. You can fashion a piece of a rubber to make a small fl exible sanding block to fi t awkward areas such as around the splashers. Also jeweller’s screwdrivers are useful to get into hard to reach nooks and crannies.Prime the model again and repeat the sanding process if required – I have found that 2-3 times is about right before fi nal priming.

Surface Preparation

fi g.11 - correctly printed

fi g.12 - faulty print

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Condensing equipment (saturated boiler version only) some ex-London N1s retained the vertical vent pipes in front of the cab on the tanks – remove these as necessary for your chosen prototype.

Handrail knob positions have been included and these may need to be hand drilled out with a suitable bit. Form the smaller handholds from brass wire. The knobs can also be used for the smokebox door handle and the valve chest handles.

If using the included buffer shanks (fi g.13), carefully remove these from the sprue inside the body and fi t in the recesses on the buffer beams. The recesses have been designed to fi t Alan Gibson GNR-type sprung buffer shanks and these can be used if so desired.

Smoke box handle and safety valves – 3rd party sourced such as Romford. Alternatively the Hornby N2 safety valves can be reused.

Whistle - re-use the Hornby N2 whistle, cut down and glue to brass wire, feed through the pre-formed hole in the cab front.

Lamp brackets – the base plate of the bracket is part of the print – a hole is provided for the iron which can be fashioned from a staple, brass wire or brass strip.

Pipework – the vacuum and steam pipes along the bottom of the body are deliberately cut short of the buffer beams to allow the different shape end parts to be modelled in brass wire. Some were curved and some at right angles. Refer to a photograph of your chosen prototype. The small and large vacuum ejector pipes on the right side of the boiler also need to be added. The large pipe (bottom) bends into the hole in the smoke box and the small pipe (top) fi ts into the printed end part. The valves on the smoke box sides can be formed with a small bead and wire.

Mechanical lubricator hand wheel (superheated boiler version only) – this part is actually below the specifi ed limit of the printers’ resolution and so may not have printed well and may be very delicate. If so replace it with a brass version.

Steps – these are too thin to be done as part of the 3d print so will need to be created from plasticard or brass sheet. Use the included template as a guide. Alternatively you may be able to reuse the Hornby N2 steps. The small steps on the left side bunker and the tank fronts can be formed from thin plasticard and have a ready made slot.

Detailing

To complete the model you will need to add additional 3rd party details. These are best fi xed in place with superglue. Refer to fi gures 13 - 20.

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fi g. 15Copyright © 2013 AJModels - Figure 13 © 2013 SAC Martin, used with permission.

Bunker – Form the three coal rails from brass wire and glue in place. You can use the included template to make a jig from plasticard to aid you with this if desired. Create a cover over the motor in card or plasticard and fi ll with coal.

Form the smokebox cocks from brass wire and a small bead or similar.

There are slots on the rear bunker for the destination board. If these are on your prototype add these with small strips of plasticard. Otherwise fi ll them in.

Etched brass 7 or 5 bar spectacle grills – 3rd party sourced such as Mainly Trains.

Form the tank fi ller stays from a staple or brass strip

Finally add cosmetic coupling hooks, screw link coulings, vacuum and steam pipe fi ttings as desired. Additional detailing can be added to improve the Hornby chassis, such as brass wire brake rigging, replacement guard irons, sand pipes, etc.

Detailing

To complete the model you will need to add additional 3rd party details. These are best fi xed in place with superglue. Refer to fi gures 13 - 20.

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Decorating

Acrylic paints are recommended but it should be possible to use enamels over a sound acrylic primed fi nish. In the BR-era most N1s were plain black but some were lined for periods. Refer to Yeadon’s or a photograph. In very early BR days a mix of numbering and lettering sizes could be seen, again refer to photographs. From around 1949-50 the BR ‘cycling lion’ logo was used on the tank sides with 10” Gill Sans numbers on the bunker. Apply with your chosen method - a template is provided to aid in lining up the numbers if required (fi g. 17). This can be held in place with low tack masking tape.

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fi g. 18Copyright © 2013 AJModels

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Copyright © 2013 AJModels

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Coal Rail Jig

Print this sheet at A4 and cut the three coal rail layers in 0.5mm plasticard, glue into a sandwich with the central layer forming a recess. Bend handrail wire along groove.

Step Templates

Print this sheet at A4 and use these to aid in the construction of plasticard/brass steps

Bunker Number Templates

Print this sheet at A4 and use these to aid in the positioning of 10” BR bunker numbers

Construction Aid Template (Print at A4 Actual Size)

AJModels

Copyright © 2013 AJModels

Ivatt N1 0-6-2T, British Railways Era

AJModels

Copyright © 2013 AJModelsCopyright © 2013 AJModels