Thursday, 1 October 2015

Clerestory Roof Z Van Construction Tips

The clerestory roof Z van is printed in two sections, representing approx one-third and two-thirds of the van.  Versions are available with end platforms at one or both ends.  These instructions apply to both versions.

At this stage, the Sn3½ and4 mm scale version of the van have been produced.

Removing Support Structures

Carefully remove the support structure from both parts of the guard's van.  It is suggested to use a sharp knife  carefully cut the supports away from the roof, ends, and the underframe.  Take particular care around the running boards, brake hoses, handbrake pillars and the brake gear underneath the floor.

Because of the ribbing on the brake hoses, the 3D printer's automatic software has generated many support points, which may have merged into one.  Carefully cut between the brake hose and the support structure, using repeated cuts with a sharp knife (e.g. Olfa snap-off blade type), to separate the support structure, then carefully trim the remnants from the hose.

Once the majority of the support structure has been removed, carefully go over both parts and cut away the small supports which typically extend from one part to another, for example, around the brake rigging.  An Exacto type hobby knife with a sharp pointed blade (Exacto #11 or similar) is quite useful for getting into the nooks and crannies.

Additional "guards" have been printed, as shown below, to protect the steps during production and shipping.  Once all supports have been removed around the steps, these guards can be cut away from the floor of the van.

Go over the model and smooth off any remnants of the fine supports, especially on the edge of the roof on the open side of the main body section.  A sanding stick or small file can be useful for this.  Be sure to clean up remnants of supports on the clerestory roof windows on the open side of the larger section, as these will be difficult to get to once the two sections are joined.

When finished, test fit the two halves together.  Interlock the square pins on the larger section with the square holes on the smaller section. The square pins will each have a "bump" from the supports on the end, so carefully trim these away.

It may be necessary to sand the edge of the roof of the smaller section where if fits under the clerestory roof on the larger section.

When satisfied with the fit, glue the two sections together, e.g. with super glue.  (Note:  If intending to add weight inside the van (See below.), do it now before gluing the sections together.) It may be necessary to lightly clamp the ends of the roof while gluing to get a tight fit.  To get a smooth finish at the join, particularly on the roof, some filling and sanding will be required.  Tamiya plastic putty works well for the filling.

Tapping Holes

The mounting holes for the couplers and bogies are intended for 2-56 (or 8BA) screws.  The bogie mounting holes should accept screws without tapping.

Note for 4 mm scale version: Because of the thinness of the floor where the couplers are mounted, the holes should be drilled through with a 1.8 mm drill in a pin vice, and tapped.

Note:  Tapping the holes is preferable to using self-tapping screws which may fracture the material.  Although fairly robust, the material is more brittle than styrene or polyurethane.  


Sn3½ version:  Correct bogies are available in kit form from NorthYard in New Zealand - Part No. B1656.  Wheels are included.

4 mm scale version: The VR TT30 bogies from Steam Era Models are a reasonable substitute.  Each bogie fixing on the guards can include two ridges which may need to be ground away to allow the van to sit at the correct height.  The ridges add 0.5 mm to the height.


The ZBA 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 are narrower and have been used because they allow details such as the brake hoses to be positioned the scale distance from the van 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.

Truss Rods

The truss rods can be formed from brass wire.

4 mm Scale Version: From a length of 0.5 or 0.6 mm wire,  64 mm long, form a 18° bend 19 mm in from each end, to leave a horizontal section 26 mm long.

S Scale Version: From a length of 0.8 mm wire, 78 mm long, form a 18° bend 23 mm in from each end, to leave a horizontal section 32 mm long.

The truss rods should fit in the recesses in the bottom of the queen posts and in the grooves provided on the inside of the sideframe members.


Small starter holes have been provided to locate the various handrails, which can be formed from 0.4 mm brass wire.  The starter holes will need to be drilled out, e.g. with a 0.45 mm drill bit in a pin vice.

Handrail Locations
The long handrails on each side curve down at the ends, and starter holes have been provided in the corners of the body, which are angled at 45┬║ to the sides and ends.  Turned brass handrail knobs are available in various lengths (e.g. from Markits), to allow for the thickness of the doors (0.8 mm), so that the handrails remain parallel to the sides.  Note that there should be a gap in the handrail on the opening side of the door (closest to the guard's lookout).

The starter holes for the vertical railings at the end go right through the end beams. Take care when drilling these out to keep the hole vertical.  The vertical railings can be inserted from above into the holes in the end beams, then pushed up into the holes in the end of the roof.  If replicating the horizontal rails at the ends, these can be soldered between the vertical railing prior to installation.

4 mm Scale Version:  The horizontal rail should be 12.7 mm above the floor level.  The vertical railings should be 8.5 mm apart (centre to centre).

S Scale Version:  The horizontal rail should be 12.7 mm above the floor level.  The vertical railings should be 8.5 mm apart (centre to centre).

Brake Stands 

The brake stands should have an L-shaped handle, as per the diagram below.  One option is to simply bend a piece of 0.4 mm brass wire and glue it to the top of the brake stand.

A slightly more complex option is to solder a vertical wire to the L-shaped handle, for fixing into the brake stand.  If using this option, the inside of the brake stand is hollow but the upper section would need to be drilled out (0.45 mm) from below to accommodate the vertical wire.

4 mm Scale:  The horizontal part of the handle should be approx. 6.3 mm long and the vertical part approx. 1.8 mm.

S Scale:  The horizontal part of the handle should be approx. 7 mm long and the vertical part approx. 2 mm.


If required, additional weight can be added inside the van or, alternatively, by gluing lead shot or sheet lead between the various frame members of the underframe, where it would not be seen in normal operation.  If adding weight inside the van, ensure it is fixed securely (e.g. screwed) so that it can't come loose at a later time, and that the weight is symmetrical about the longitudinal centre line of the van..

For the S scale model, the desired weight is about 95 grams.  (Refer to Sn3½ blog article.)  Using the suggested North Yard bogies, the weight of the van is about 68 grams, so about 27 grams if additional weight is required.


Either enamel or acrylic hobby paints can be used to paint the finished model.