Well, rolling and laminating 0.4mm ply I have done before... but not so far on such a long, thin core, so I confess to having been somewhat over confident and blissfully unaware of the tribulations to come! Just managing to hold the first sheet in place while the second was glued up and clamped with cable ties turned out to be a nightmare task.
Eventually, and after expending rather too many expletives; three layers were set and left to cure:
After removing the core I found weak spot near the top, where it appeared that the glue had not quite grabbed at the joint, probably as a result of all the grappling involved?!
Carefully prizing the the offending area apart with a scalpel and then working in some fresh glue finally did the trick I'm relieved to say.
Seeing the setting chimney thus parked in situ rather put me in mind of the familiar old Gaselee tugs, seen so often moored on buoys, with some in light steam on Sunday afternoons around Tower Pier... A regular haunt so very many moons ago!
Back when I was fitting the tank filler rim I picked up an extra length of larger, D shape styrene strip to form the stovepipe cap. as per this:-
The original chimney wrapper and rim was fully flush riveted, but "Wren" clearly now carries a replacement, (and in places rather crudely) welded affair - that appears to have been rigged up in the early 1950's (?)
While the skinnier tank filler version had proved to be a task, forming the heavier D shape by gently heating without completely distorting it was almost impossible this time... but after sleeping on the problem, (no... not literally!) it did come out round (ish!) in the end.
The flatness at the back of the strip was mostly lost in the heating and bending process, but after using some brass rod to form a set of rivets, the rim was locked sufficiently firm in place and unable to shift. Awkwardly though, while I would like that lip to assist in maintaining the integrity of the laminated tube, the wrangled, and slightly mangled strip was not perfectly in contact all the way around!
Thank goodness for that lovely, durable Milliput stuff! As the rivets were hammered reasonably flush on the interior, I was able to slide the chimney tight back onto the former for rigidity, and force the epoxy putty well down into all the gaps, top and bottom. When set, the whole thing became extremely solid, close to circular, and a little bit prettier into the bargain!
What was not so pretty was the effect, and entirely a result of using cable ties to clamp the long, vertical seam during setting.
I had considered tightening the ties over a narrow strip of wood to apply even pressure along the full length of the tube, but then feared loss of firm contact at other points of the circumference, so decided not to take that chance. Despite the ties being closely spaced, the otherwise superbly pliable 0.4mm material surprisingly still bowed slightly in the spaces between. The veneers are however so fine that when rubbing back to level there appeared to be far more material removed than in reality?!
Another saving grace, strength wise, is that the original chimney seams were butt jointed and countersunk riveted to a broad strip down the inside. Thankfully, an Horwich draughtsman responsible for one of the General Arrangement drawings decided (unusually) to reveal the precise number and locations of those rivets in one of the elevations, so at least I had something positive to work from! Less fortunately, I had insufficient remaining brass rod of an appropriate size to make those rivets - and I was unable to acquire any fine brass panel pins locally either, so set about searching for any alternative.
The result caused some justifiably quizzical looks here at home...
It did seem to be a strange solution, but after trialling the lower four, and being quite satisfied with the effect, I went ahead and screwed the remainder in place. I did feel that there was actually a distinct advantage in using something that threaded through, and assisted with binding the individual layers of wood - even before the ends were fully burred over.
I would have preferred the eyelets to have been genuine, and slightly more malleable brass, rather than a harder, plated steel, but using a heavy section of bar clamped in the bench vice as an extended anvil, the screws still worked quite adequately:
Taking my usual "belt and braces" approach, I covered the area around the finished "rivets" in cyano, relying on the adhesive to thoroughly soak into the grain all around the threads! Barring any unforeseen disaster; I trust that the little chimney might now at least have a half decent chance of retaining it's shape for a fair while yet?!
Not too much rubbing down was necessary, as the chimney will eventually require a coat of some very thickly applied, gooey paint - almost slapped and stippled on, to go some way towards replicating a working prototype rather than an exuberantly overdone museum exhibit!
The observant might note that the drawing that can be seen hanging over the roundel in so many previous images has been taken down?
Now that the chimney is at last fitted, there is no further need for such a feature of our lives... and that unbelievably hereabouts anyway, has been continuously displayed on the wall for just over nine years!
Pete.
