Structure Gauging Train - 3D printed optical car

[The Fatadder]

Last year I started  building a model of the Structure Gauging Train in 1998 Serco condition.  I have previously covered the conversion of a pair of Bachmann Mk1s here:  In short the work involved a little cut and shut activity to get the windows in the right place, filling redundant windows and adding a new cab end.   These are all laid up waiting for paint, the biggest task was still outstanding: building the optical car.

 

A RTR model is (or at least was) available from Britannia Pacific Models, however it is costly and I understand there is a long waiting list.  There is also a 3d printed resin model available, but its utter rubbish and bares only a minimal resemblance to the prototype. 

My plan originally was to follow Mick Bryan’s approach, using a Bachmann VAA as a base, modifying the van to get the full height ends before scratch building the rest.  However with the purchase of the Photon Mono I wanted to see what the printer could achieve.   This started with a plan to print the centre section to fit between the ends that I had already built, however I got a bit carried away and soon had the whole body drawn up.  This was drawn in two halves in order to reduce the print time (and simplify the support structure.)

Speaking of the supports, I overdid the internal supports and they merged together on the print making removal more difficult.  (It also resulted in uncured resin not fully draining from the model in the wash station and a quick stop to wash potential resin off my hands and put on gloves.  Naturally this was the first time that I haven’t worn gloves when touching the parts between coming out of the wash and going back in the machine for curing…)

 

The Bachmann VAA chassis needed some modification, first removing the W Irons (The model was already fitted with Bill Bedford units) along all other underframe parts. The screw towers and metal weight were removed from the top of the wagon (along with cutting off the raised lip that located the original ends).   With that complete the 3d printed bodies were glued into position on the chassis (along with refitting the Bill Bedford units).

I have yet to do any sanding or other finishing to the prints, over than removing the remains of the supports 
 

I have also drawn up new suspension units (which will fit as an overlay to the brass W iron), the box slightly inboard of each wheel and the lower part of the scanning unit on the wagon centre line (including its brackets).    These all need to be printed this evening ready for fitting.  For the ends strangely the corridor connection looks to be of the LMS design, looking a bit odd between two mk1s.  I will use my printed part, along with the Comet etched LMS mounting brackets.  The rectangular vent to the side needs drawing still (but will be added to the same print).

taken before adjusting the top edge of the boxes (as the profile is wrong here)

 

There are other parts I have not yet done, the various jumper cables and sockets will be a useful part for other coach projects and will need drawing eventually once its painted.  I also need to add the small cylinders to the outside of the suspension units, they will probably have to wait until after I have finished the main underframe parts. 

Edited February 13, 2022 by The Fatadder
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[The Fatadder]

A little more progress today, I have printed off the majority of the remaining parts.  Alas one suspension unit broke while

removing the supports so that needs redoing.  I have sketched out the missing actuator to the outboard side of the suspension, and need to adjust the boxes to the inboard to add the missing support legs (as it will be a bit stronger on the print than using plasticard).

 

once that is done I will give it a coat of primer to see what further rework is required, before adding the missing handrails.  After which it will be ready for paint

[The Fatadder]

The optical car’s body has now been given a coat of Halfords red oxide primer, followed by some fettling to get rid of imperfections from the print. 

 

This was followed by fitting a replacement print for the broken suspension unit, the revised print for the boxes and a new print for the actuators (finished with some brass wire).  Holes have also been drilled for the main handrails (which will be fitted post paint)

 

it needs another dusting of primer in the morning to prime the new parts, then hopefully a coat of black at lunch…