Tuesday, 21 June 2016

WO Assembly Tips

Parts List

  • Bogies: e.g. "100-ton roller bearing" by Kadee part no 569 or 1569 (see below) or Tichy #3009 (1 pair) or #3036 (10 pairs)
  • Couplers: Kadee #148 or #158 or Glatzl rotary & dummy couplers (see below)
  • Replacement Metal Wheelsets 36" diameter - if using Tichy bogies, e.g. Intermountain #40051 (4 per wagon).
  • Coupler boxes: Kadee #262 (supplied)
  • Air Brake Hoses, e.g. Detail Associates #6206
  • Brass wire: 0.4 mm for handrails, etc. (approx. 1.5 x 300 mm lengths required per wagon)
  • Fixing screws: (see below)
  • Glue, paint, decals
Marbelup Models can a supply "Parts Kit" containing all of the above items, with the exception of glue, paint and decals, with a choice of Kadee or Tichy bogies.

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 and delicate parts.  Take particular care around the bottom of the ladders, and the various items of brake gear on the bottom of the wagon.

The following images highlight the more delicate parts, some of which are only visible once the outer layers of supports have been cut away.

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 including, for example, on the end ribs and bogies bolsters.  An Exacto type hobby knife with a sharp pointed blade (Exacto #11 or similar) is quite useful for getting into the nooks and crannies.  

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.

Bogie and Coupler Mounting Holes

The mounting holes for the couplers and bogies have been printed at 1.8 mm diameter to suit 2-56 screws.  

Due to the difficulty of tapping the blind holes for the bogies, 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.  Note that the depth of the blind holes is 4.4 mm.  If using Kadee bogies, the supplied screws may need trimming to avoid damaging the floor of the wagon.

The holes for mounting the couplers are also blind, but should be drilled right through the floor with a 1.8 mm drill to obtain a strong fixing.  These holes should be tapped 2-56.  Note that one end of the wagon has two blind holes for couplers.  The one closest to the end of the wagon is for a Kadee coupler and the hole closest to the bogie fixing holes is for the rotary coupler option.

Note: An economical source of steel 2-56 screws in various lengths is Little Bird Electronics.  


The suggested bogies are Kadee #569 or #1569, the only difference being the width of the wheels.  Atlas and Athearn and others make similar bogies, but the advantage of the Kadee ones is that they add some weight to the wagon due to the use of a relatively heavy plastic material.

Tichy Train Group also makes an economical 1-piece plastic bogie #3009 (1 pair) or #3036 (10 pairs), however these are supplied with relatively low quality plastic wheelsets which are also too small in diameter (33").  Intermountain Railway Company sell high quality all-brass wheelsets which fit well in the Tichy bogies and are the correct size, i.e. 36".

Note that Intermountain do also sell complete roller bearing bogies but these are supplied with 33" wheelsets only.  Be wary of other brands of bogies as well.  In general, US roller bearing bogie (trucks) described as "100-ton" have 36" wheelsets and "70-ton" have 33" wheelsets.

Note that the depth of the blind holes for the bogies is 4.4 mm.  If using Kadee bogies, the supplied screws will need trimming to a length of 7.5 - 8 mm to avoid damaging the wagon (or shorter screws substituted).  Do not drill the bogie mounting holes right through, as they will be visible on the finished model.

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


Option 1 - Kadees

The WOB 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 couplers do not fit as they have a different mounting hole position.  The #262 draft gear boxes (supplied) 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.

Ideally, the coupler fixing screws should be trimmed to exact length so that the end of the screw is flush with the inside of the floor.  Nylon screws (e.g. Kadee #256) can be used, as they are much easier to cut to the desired length.

Kadee nylon 2-56 screws are available from good hobby shops.

Option 2 - Glatzl (Sergent) Rotary Couplers

If desired, the wagons can be fitted with a rotary coupler at one end, as per the prototype, to facilitate unloading in a rotary car dumper (tippler).  Glatzl sell working rotary couplers and matching dummy couplers which are available from Sergent Engineering in the US.  The Glatzl couplers will couple with "scale" size Kadees but not with "standard" size Kadees.

Note that it is preferable to use Glatzl dummy couplers rather than a "scale" size Kadee for the "fixed" coupler as the relatively tight fight between the Glatzl rotary and dummy couplers results in better operation with a rotary car dumper.  On the Sergent web site, the dummy couplers are listed under the "economy" tab.

Typical steps to fit a Glatzl rotary coupler are:

  1. Cut the rear portion off the Glatzl draft gear box leaving 16 mm of the draft gear box remaining.
  2. Drill a 2.3 mm diameter hole exactly in the centre of the circular mould mark in the coupler box.
  3. Fix the coupler to the end of the wagon opposite the ladder and handbrake wheel using a 2-56 screw.
To fit a Glatzl dummy coupler:
  1. Use a round needle file to slightly enlarge the hole in the shank of the dummy coupler so that it pivots easily in a Kadee #262 draft gear box.
  2. Cut away a small amount of plastic from the rear of the coupler knuckle to allow the coupler to fully swing from side to side in the Kadee #262 draft gear box.
  3. Assemble the couple in the #262 draft gear box and snap on the lid.  Fix the assembled coupler to the end of the wagon with the ladder and handbrake wheel using a 2-56 screw.
Ideally, the coupler fixing screws should be trimmed to exact length so that the end of the screw is flush with the inside of the floor.  Nylon screws (e.g. Kadee #256) can be used, as they are much easier to cut to the desired length.

Kadee nylon 2-56 screws are available from good hobby shops.

The height of the installed Glatzl coupler (rotary and dummy) should match the Kadee coupler height gauge.

Brake Rods

There are 4 brakes rods which can be formed from 0.4 mm brass wire.  The following diagram indicates the locations.

Typically, the holes for the brake rods are printed at 0.4 mm diameter but all will require cleaning out using a pin vice and drill bit, e.g. 0.45 mm.

The two shorter brake rods should be approx. 15.7 mm and 16.2 mm long, with 90-degree bends at both ends.  The bent ends fit into the hole in the brake levers.

The two longer brake rods should be approx. 19.5 mm and 21.5 mm long, with a 90-degree bend at one end, approx. 1 mm long.  The straight end fits in the hole provided near the bogie pivot hole and the bent end fits into the corresponding brake lever.

Handrails and Safety Rails 

The WO has short handrails at each corner, mounted on the side of the rectangular "buffers".  Small starter holes have been provided to locate the handrails, which should be drilled out, e.g. with a 0.45 mm drill bit in a pin vice.

The handrails can be formed from 0.4 mm brass wire.  They are actually semicircular, and are 1.5 mm wide (centre to centre) and 1.75 mm high, which allows for 1 mm to be inserted into the holes.

This great photo from Rail Heritage WA of a WO under construction at
Midland Workshops clearly shows the semicircular handrails.
There are also "safety rails" running along the bottom of each side of the wagon, between the ladders.

The safety rails are approx. 95 mm long - check this measurement on the actual wagon before cutting the wire.  They require a slight bend 10 mm from each end, so that the ends fit behind the vertical members of the ladders.  Small grooves have been provided on the rear of the ladders to locate the ends of the rails.  Along the sides of the wagons, the rails fit into the base of the side ribs, on top of the protruding flange.

Air Brake Hoses

Small brackets are provided next to the couplers on each end of the wagon for air brake hoses.  Cast plastic hoses are available from Detail Associates, part number 6206.  Carefully drill out the starter hole provided in the supporting bracket to suit the diameter of the "pipe" on the air hose.  A suggested drill size is 0.65 mm.

Uncoupling Levers

Notched brackets have been provided at the handbrake end of the wagon for the uncoupling lever, which runs across the full width of the wagon.  Note that there is no uncoupling lever at the other end of the wagon, as this is the rotary coupler end on the prototype.  The uncoupling lever can be shaped from 0.4 mm brass wire.   The diagram below shows the approximate shape to aim for, but feel free to adjust the measurements to suit your model.

Diagram to be added.

After positioning the uncoupling lever, check that the coupler can swing freely and is not obstructed, prior to gluing it into position.

Handbrake Wheel

A 0.5 mm spigot has been provided on the handbrake assembly, to which the wheel can be glued.  If necessary, open out the central hole in the handbrake wheel with a 0.6 or 0.7 mm drill bit to fit over the spigot.


Details to be added.

With the suggested Kadee bogies, the completed WO weighs approx. ?? grams.  For this length wagon, the NMRA recommended weight is ?? grams, although some modellers feel that the NMRA weight recommendations are excessive.  A total weight of somewhere between ?? and ?? grams is probably about right.


Either enamel or acrylic hobby paints can be used to paint the finished model.  The model pictured has been painted with Testors Model Master Enamel colour "Gelb RLM 04".  (Gelb is German for yellow!)  A white undercoat (e.g. Testors Model Master 2748 enamel) is recommended to enhance the yellow colour.