Fixing coach roofs

[Torper]

Over the last few years I have built, but as all too often in my case never got round to finishing, a number of 4mm etched brass coach kits.  I've now bitten the bullet and decided that they must now be finished and so I've painted them, completed the interiors, and started to instal glazing.  My major problem now is how to fit the roofs (or rooves, for those who prefer the older spelling).  All would be well if the finished coach sides were dead straight, but they're not.  It would also be fine if they bowed inwards to some extent so as to make a tight fit with the roofs, but they don't - on the contrary, most bulge out just a little bit in the middle.  And therein is the problem.  The sides should fit flush with the roofs, and it seems to me are obviously going to have to be glued on, but how do I manage to hold both sides securely flush with the roof evenly along their length without at the same time getting glue over my rather nice paintwork?  (This is perhaps one of those instances where I'm frightened to try anything because I'm worried it'll spoil what I've made).

 

Any help would be much appreciated.

 

DT

Edited November 19, 2017 by Torper

[Dunsignalling]

I've not tackled any brass coaches yet but have completed a number of plastic ones, mainly of Ian Kirk origin, and consider the two media are likely to behave similarly in most respects..

 

I long ago decided that building the body up on the underframe and attaching the roof as the final stage (as the instructions usually stipulate) almost never resulted in a perfect union. The problem is that, in order to ensure the sides and roof mate properly, it is necessary to be able to push/support the former from inside whilst the latter is attached. If the sides are already fixed to the underframe, this is impossible. 

 

Therefore, from the second attempt onwards, I adopted the assembly method normally found on r-t-r coaches, namely to make the bodyshell (sides, ends and roof) as one assembly and the underframe as a separate unit. This facilitates manipulation of the sides and roof to ensure neat assembly, with the natural tendency of the sides to bow inwards ceasing to be a problem. Once the roof is fixed, it is quite easy to ease the lower edges apart to fit over the completed underframe.

 

This method also allows the glazing to be added as the very last operation, avoiding any possible damage caused by solder, glue, and paint.

 

Attachment of the body unit to the chassis unit is achieved by shaping (usually two) blocks laminated from plastic sheet to fit the internal contours of the roof. these are drilled and tapped to take lengths of M2 studding (8BA has become ludicrously expensive, if one can find it at all) and glued into place, dividing the length of the vehicle roughly into thirds. This won't be precise as they will have to be juggled to miss obstructions on the underframe and/or interior (I build the latter up as an integral part of the underframe rather than separately).

 

Having made the necessary holes in the interior/underframe unit for the studs to pass through, I add and adjust a nut and washer which will sit on the floor. The coach is then assembled and further nuts and washers added beneath the underframe to secure it. The whole thing is then "played with" until I'm satisfied that any tendency for the underframe to bow upwards or downwards has been "tuned-out". I then detach the chassis and lock the internal nuts with a drop of superglue. Final reassembly has to wait until the superglue is fully cured to prevent the fumes frosting the glazing.

 

This also ensures future access to the interior to re-affix any glazing that becomes detached.

 

John.   

Edited November 19, 2017 by Dunsignalling

[DCB]

Getting the roof straight is always a challenge, Its a bit late now but you needed to solder a brace or three between the top of the sides to stop bowing or even solder the roof in place at an early stage to make a strong rigid monocoque into which you insert the glazing and interior at a later stage.

 

At this stage of the game I fear a jig of a couple of pieces of ply end on to hold the sides straight while the glue sets is the temporary answer but the glue will eventually let go and ruin the model.  The only really successful "Glue" for brass in my experience is solder. 

[Rowsley17D]

The great coachbuilder par excellence, Larry Goddard, I understand glues his roofs on with Evostik. He also solders a strip of brass to strengthen the tops of the sides.

[Torper]

At this stage of the game I fear a jig of a couple of pieces of ply end on to hold the sides straight while the glue sets is the temporary answer but the glue will eventually let go and ruin the model.  The only really successful "Glue" for brass in my experience is solder. 

 

As the roof in this instance is aluminium, solder has never been an option.  For the last few days I've left the roofless coach enclosed by a number of tight elastric bands and they seem to have succeeded in pulling the sides fairly straight.  My most trusted glue at the moment is Deluxe Materials 60-minute epoxy so i think I'll try that together with thin ply strips along the tops of the sides and elastic bands.  I'm reasonably confident......

 

DT

[Guy Rixon]

As the roof in this instance is aluminium, solder has never been an option.  For the last few days I've left the roofless coach enclosed by a number of tight elastric bands and they seem to have succeeded in pulling the sides fairly straight.  My most trusted glue at the moment is Deluxe Materials 60-minute epoxy so i think I'll try that together with thin ply strips along the tops of the sides and elastic bands.  I'm reasonably confident......

 

DT

 

 

Best of luck; I hope this works out for you. Being somewhat paranoid of roofs, I personally would fit cross-members at cantrail level to resist the bowing before fixing the roof. If the aluminium roof has a flange that fits inside the top of the sides, then this needs to be notched to fit over the cross-braces. I would therefore make my cross-braces as vertical plates aligned with the corridor partitions, and would reduce the height of the (removable, cosmetic) partitions to leave space.