Saturday, 27 September 2014

NH ENH QA HA Hopper Wagon Assembly Tips

TT3 (left) and S scale models with supports attached.

Removing Support Structures


Carefully remove the support structure from the wagon.  It is suggested to use a sharp knife to cut the supports away from visible areas.  Take particular care around the end steps and the ends of the hopper doors where there are fine pull rods.

Note:  Sometime, contrary to instructions, i.Materialise remove most of the support structures in the factory.  Marbelup Models prefers that the supports structures are left attached in the factory as they help protect delicate parts of the models during handing and shipping.

Once the majority of the support structure has been removed, carefully go over the wagon and cut away the small supports which typically extend from one part to another, for example, around the door operating mechanism and other detail items.  An Exacto type hobby knife with a sharp pointed blade (Exacto #11 or similar) is quite useful for getting into the nooks and crannies.  For some parts, e.g. around the door actuating mechanism, where even a fine knife blade won't reach, a piece of wire (e.g. 0.8 mm spring steel wire) can be used to push against the support attachments and break them off.  Another option is to sharpen the end of the spring steel wire to a chisel point, and secure the wire in a pin vice to form a tiny chisel.

Go over the model and smooth off any remnants of the fine supports, expecially in the visible areas.  A sanding stick or small file can be useful for this.  A hobby knife with a chisel type blade (Exacto #17 or similar) can also be useful for smoothing flat areas, such as the underside of the underframe,

Bogie and Coupler Mounting Holes


For HO and larger versions, the mounting holes for the couplers and bogies have been printed at 1.8 mm diameter to suit 2-56 or 8BA screws.  Clear out the holes with a 1.8 mm drill in a pin vice, but it is preferable to NOT drill through the floor to avoid the screws being visible on the finished model.

The coupler mounting holes for the HO version do go right through the floor due to the limited material thickness available.  The holes should be tapped for HO versions only.

For S and O scale verions, the mounting holes are "blind".  Due to the difficulty of tapping the blind holes, the 3D print includes vertical grooves in the sides of the holes to help the screws cut their own threads, so tapping the holes is not required nor recommended.

Grooved holes used for S and O scale versions.  Tapping is not required for these holes.
For TT3 versions, the mounting holes for the couplers and bogies have been printed at 1.2 mm diameter to suit the size 0-48 screws typically supplied with Kadee HOn3 couplers.  These holes should be cleaned out with a 1.2 mm drill but don't need to be tapped.

Bogies


Various options are available for bogies for the different scales.  Some packing will most likely be required, depending on the bogies used, to achieve the correct wagon height above rail level.

TT3n½ Scale (10.5 mm gauge)

MicroTrains HOn3 Bettendorf bogies #00502020 were used on the Marbelup Models test model and fit well, although they represent an early 20th century design rather than the more usual mid-20th century Bettendorf style.

Blackstone Models HOn3 Bettendorf Trucks #B370110 are potentially suitable, but have not been tried.

HOn3½ Scale (12 mm gauge)

Marbelup Models used Wuiske Models QRB008 Modern QR bogies on test models.  They fit the NH and ENH models but don't suit the Tasmanian QA.HA version as they are fairly long wheelbase and the inner wheels foul the extra door stop parts.

Caintode Flats produce a range of bogies for QR and Tasmanian models, and the shorter wheelbase Bettendorf style bogies may be suitable, but have not been tested.

Sn3½ Scale (16.5 mm gauge)

The bogie mounting points are designed to be 10 mm above rail level.  Depending on the bogies used and the height of their bolsters, it may be necessary to add washers or similar so that the coupler mounting surface is 11.5 mm above rail level.

Marbelup Models has 3D-printed bogies of the correct design for the WMC/WMD available for sale which are pretty close for this model.  Please refer to the WMC/WMD Assembly Tips for more information on these bogies.

Similar bogies, although of slightly different shape, are available from Black Diamond Models in Queensland.  The Black Diamond bogies are cast in white metal and are supplied fully assembled with wheels.

Marbelup Models WMC/WMD Bogie

On3½ Scale

Marbelup Models is not aware of any specific bogies which are available.  Potentially, On3 or S scale standard gauge bogies could be suitable.  Also, the Marbelup Models 3D-printed bogies for the WMC/WMD hopper wagon could potentially be printed in O scale, depending on the availability of suitable wheelsets.

Couplers


As with bogies, there are various coupler options depending on the scale of the model.  Because the models are 3D-printed "on demand", it is possible to customise the coupler mountings to suit specific requirement of individual modellers.

TT3n½ Scale

The TT3 version is currently designed to suit Kadee #711/#712 HO 3/4 size couplers set at a height of 7.8 mm to match the prototype coupler height.  These couplers are the same as Kadee #713/#714 HOn3 couplers, other than having a longer trip pin to suit HO standard gauge models.  For TTn3½ use, the trip pin on the #711/#712 will need to be shortened by about 2 mm to match the 7.8 mm coupler height.

Kadee #713/#714 couplers can also be used at the intended HOn3 height, which requires a shim of approx. 0.6-0.7 mm to bring the couplers down to the HOn3 height (7.14 mm).

HOn3½ Scale

The HO models are designed for Kadee HO "whisker" couplers at the HO standard gauge height (9.9 mm).  Either the #158 (scale size) or #148 (normal size) couplers can be used, with #262 draft gear boxes.

The draft gear boxes supplied with the couplers do not fit as they have a different mounting hole position.  The #262 draft gear boxes are narrower and have been used because they provide more clearance for narrow gauge wheelsets.  Also, the #262 draft gear boxes are easier to use as the lid snaps into position.

Note that the height from rail level to the coupler mounting surface should be 11.5 mm, the standard for Kadee HO couplers.

Sn3½ Scale

The S models are designed for Kadee HO "whisker" couplers at the HO standard gauge height (9.9 mm).  Either the #158 (scale size) or #148 (normal size) couplers can be used, with #242 draft gear boxes which are the ones normally supplied with the whisker couplers.  The reason for using the #242 draft gear boxes is that the mounting screws are closer to the end of the wagon (compared to #262 boxes) to avoid a clash with the outer axles.

Note that the height from rail level to the coupler mounting surface should be 11.5 mm, the standard for Kadee HO couplers.  The 2-56 6.35 mm (1/4") long screws commonly used for couplers are slightly too long for the blind holes.  Options are to shorten the screws by 0.5 to 1 mm, or to add a flat washer between the head of the screw and the coupler.  Railwest Models sells suitable washers with a 2.2 mm hole diameter.

On3½ Scale (1:48 and 7 mm scale)

The 7 mm scale model is design for the Kadee #805 O Scale couplers or other Kadee couplers with the same mounting holes.  If requested, the 1:48 scale model can also be configured for these couplers.

Handrails and Brake Handle


Small starter holes have been provided to locate the L-shaped handrails on each end.  One end also has a brake handle.  These parts can be formed from brass wire and fixed in position with superglue.  The hole for the vertical leg of the handrail is located near the corner of the underframe, and the hole for the horizontal leg is located just above the second rung of the ladder.  Carefully drill out the starter holes - see below for drill sizes.

The suggested wire sizes and dimensions for the handrails for each scale are as follows:

TT3: 0.4 mm wire, 0.45 mm drill, horizontal: 4.5 mm, vertical: 8.5 mm
HO: 0.4 mm wire, 0.45 mm drill, horizontal: 5.5 mm, vertical: 9.5 mm
S: 0.6 mm wire, 0.65 mm drill, horizontal: 7.5 mm, vertical: 12.5 mm
O 1:48: 0.8 mm wire, 0.85 mm drill, horizontal: 10 mm, vertical: 16.5 mm
O 7 mm: 0.8 mm wire, 0.85 mm drill, horizontal: 11 mm, vertical: 18.5 mm

Note:  The above measurements are a suggested starting point.  Feel free to make adjustments as required.

Handrail and Brake Handle

The brake handle is also an L-shape, with the shorter, horizontal portion fitting in a hole just above the centre of the handbrake mechanism.  The suggested wire and drill sizes and dimensions for each scale are as follows:

TT3: 0.4 mm wire, 0.45 mm drill, horizontal: 1.5 mm, vertical: 6 mm
HO: 0.4 mm wire, 0.45 mm drill, horizontal: 2 mm, vertical: 7 mm
S: 0.4 mm wire, 0.45 mm drill, horizontal: 2 mm, vertical: 9 mm
O 1:48: 0.4 mm wire, 0.45 mm drill, horizontal: 2.5 mm, vertical: 12 mm
O 7 mm: 0.4 mm wire, 0.45 mm drill, horizontal: 2.5 mm, vertical: 13 mm

Painting


Either enamel or acrylic hobby paints can be used to paint the finished model.  The test models have been painted with Revell Hobby Enamel No.83 "rust" which seemed a good match for the faded red/brown of the original NAR NH hoppers.

Monday, 15 September 2014

NH ENH QA HA AHAF Hopper Wagons

NH Hopper S Scale after Painting
The latest 3D design from Marbelup Models is a little different, in that it is of a wagon which didn't originate from WA although some did find their way to WA in 2003.

These wagons were originally built in 1966 and 1968 to carry iron ore on the North Australia Railway from the Mount Bundey and Frances Creek mines to Darwin.  In the late 1970's, they were relocated to Port Lincoln in South Australia for use on the Eyre Peninsular Railway, carrying superphosphate, ballast and, later, Gypsum.  Some were relocated to Tasmania to carry coal and superphosphate.  Then, in 2003, approx 20 were shipped across to WA and refurbished for use on the Mt Gibson iron ore trains to Geraldton.

So, it seemed a good opportunity to build a model of these wagons which have served in 4 states/territories for well over 30 years, all on the 3' 6" (1067 mm) narrow gauge.  At this stage, Marbelup Models has done the 3D design for the original NT, SA and Tasmanian versions.  We will consider the WA AHAF version is there is any interest from modern image modellers.

NH Hopper TT Scale after Painting
A further difference is that the model can be 3D printed in various scales, including TT3n3½ (1:101.6), HOn3 or HOn3½ (1:87), OO (1:76.2), Sn3½ (1:64) and On3½ (both 1:48 and 7 mm scales), to cater for the various scales used by Australian narrow gauge modellers.  Bogie and coupler mounts can also be customised for the various scales.  The model can also potentially be used for HO standard gauge, although it is quite a small wagon compared to most HO wagons.

The photos, below, of the unpainted models include added handrails and brake handles formed from brass wire.  Starter holes are included in the 3D print for the wire details.  See assembly tips for more information on finishing and detailing.

NH S Scale, Unpainted, A End

NH S Scale, Unpainted, B End
Original NH/NHA as running in Northern Territory 
NH/NHA "late" version as running in Northern Territory and also in
South Australia circa 1978-1984, prior to entering gypsum traffic.
QA and later HA as running in Tasmania
ENH/ENHA as running in gypsum traffic in South Australia.
The ENH/ENHA is also available with brackets for hungry boards, but without hungry boards.
AHAF as running to Geraldton, WA
The approximate cost for this wagon (body only) will be approx. $30 in TT3 scale, $40 in HO and $80 in S scale.  The cost will vary slightly for the different versions, and is subject to the usual exchange rate variations.

RB Open Wagon Construction Tips

Removal of Support Structure


In general, it is best to first cut away the supports from the areas which have small details, and the areas which will be visible on the the finished model with a sharp hobby knife.  (An X-Acto style knife with a #11 fine blade can be useful for the fiddly bits.) Take particular care removing the supports from the brake handles, queen posts, door bumper strips, vacuum hoses and underfloor brake gear.

The brake handles have "sacrificial" guards around them to provide some protection against breakage during production and shipping of the 3D printed model.  It is suggested to leave these in place until most of the other work has been done to minimise the risk of breakage to these delicate parts.

Once the supports have been cut away from the delicate areas, the remaining supports can be broken away by wiggling them or applying pressure to break the small attachment points.

Non-Tapping Holes


The holes for the couplers and bogies are designed to accommodate 2-56 or 8BA screws without tapping.  This also has the advantage that the screws remain tight, so they won't accidentally work loose (especially for the bogies).

Note:  Tapping the holes is not recommended as it will remove more material and potentially lead to stripped threads.

Bogies


Railwest Models sells suitable arch-bar bogies.

If necessary, adjust the height of the wagon on the bogies so that the coupler mounting surface is 11.5 mm above rail level.

Couplers


The VG is designed for Kadee "whisker" couplers.  Either the #158 (scale size) or #148 (normal size) couplers can be used, with #262 draft gear boxes.

The draft gear boxes supplied with the #148 and #158 couplers do not fit as they have a different mounting hole position.  The #262 draft gear boxes are narrower and have been used because they allow details such as the brake hoses to be positioned the scale distance from the wagon centre line.  Also, the #262 draft gear boxes are easier to use as the lid snaps into position.

Note that the height from rail level to the coupler mounting surface should be 11.5 mm, the standard for Kadee couplers.

Handrails


Handrails can be formed from 0.4 mm brass wire.  Starter holes are provided on the ends, which should be opened out with a 0.45 mm or 0.5 mm drill bit.

The lengths of the end handrails (centre to centre) is 4.5 mm.  Once in position, the handrails and other brass details can be secured with Super Glue.

Truss Rods

The RB has four truss rods which can be formed from 0.6 mm brass wire.  The diagram below gives the dimensions for bending the truss rods.  The longer truss rods are on the outside of the wagon.

The anchor points on the underframe for the ends of the truss rods have preformed holes which should be drilled out with a 0.65 or 0.7 mm drill bit.



Brake Rods


There are a total of 5 brake rods which can be formed from 0.4 mm brass wire.  Starter holes are provided which should be opened out with a 0.45 mm or 0.5 mm drill bit.

Two long brake rods go from the handbrake lever at each end to the main brake shaft near the centre of the wagon.  Because the main brake shaft is offset slightly from the wagon centre line, the length of these rods is 63 mm and 58.6 mm, not including a right angle bend of approx. 1 mm at each end.  The bogie bolsters include holes though which these long brake rods can be threaded.

The other three brake rods are near the wagon centre line and represent the rods which, in real life, connect to the brake rigging on the bogies.  At the left end, as pictured above, the brake rod should be 49.5 mm long, not including a right angle bend of approx. 1 mm at one end only.  The other end attaches to a hole near the bogie pivot point.

At the right end, there are two rods which are connected via an intermediate lever.  The first is 29.2 mm long not including right angle bends of approx. 1 mm at each end.  The second rod is 26 mm long with a right angle bend at one end only, the other end attaching to a hole near the bogie pivot point.