Warbirds in my Workshop

David Glen BSc (Hons) MSc, Model Maker, Journalist and Author

Formerly Spitfire in my Workshop

Fitting out the port sidewall

Saturday, 30th August, 2014

In this and my next web logs I shift the focus to fitting out the port sidewall of the cockpit, with a series of brief sketches to illustrate methods and materials I have used. Some are identical to features of my Mk I model, nonetheless the Mk IX cockpit is sufficiently different to spice the work with variety.


My starting point is the elevator trimmer wheel and its smaller companion, the rudder trimmer, along with the rectangular covers that shield the control cables and chains.


It is curious that rather than carry over solutions, I have tended almost unconsciously to adopt new or revised pathways to the same result. For example, I turned the elevator trimmer wheel of my first Spitfire in brass, yet used resin this time and a very different technique for representing the tricky ridges around its circumference. It will make for some interesting, and perhaps not always positive, comparisons.


When making castings, I always keep any left over resin, since the hardened material is lovely to work, particularly with machine tools. The resin blank of the hand-wheel shown in the first picture is the result of a few minutes work on the lathe. It has been removed on its mandrel from the chuck and re-chucked vertically on the rotary table of my milling machine for the rather more tricky operation of routing with a small side cutter the 20 equally spaced semi-circular grooves around its circumference.


That done, I chopped up a piece of styrene rod of matching diameter into twenty little pieces and glued these in place, taking special care to avoid excess glue from squeezing out around the edges, which would seriously disfigure the job.


Since there is a clear break of angle near the centre of the wheel, I chose to turn the hub separately from alloy, including a short spindle on the reverse side. This is shown glued in place in the third and fourth pictures.


Finally, a working over with fine steel wool very effectively turns the flat ends of the styrene implants realistically dome shaped, a deception consolidated by repeated heavy spray coats of automotive primer, which serve to soften edges and blend the many separate pieces into a single simulated moulding.


As to the rudder trimmer wheel, there is not a lot to say: It is turned from aluminium bar, domed slightly on the front and ornamented at regular intervals around its periphery with the help of a milling cutter and the rotary table, much as descried above.



The cable covers

The challenge when making the control cable covers is to stamp the stiffening flutes into litho plate, and to do this I made two crude but effective punch and die sets. The single-fluted version is shown here. It consists of two pieces of six-ply, one slotted on the milling table; the other bearing a matching length of half-round aluminium rod glued on with cyanoacrylate. With the male and female sides mated up, the ply is drilled through for two guide pegs and the tool is ready for use.


It works best with the thickest printers plate, around 11 to 15 thou, although this does require annealing or it splits under pressure of the bench vice. While it took three or four attempts to get an acceptable result, the task proved easier than anticipated.


With the flutes formed, the outline of each cover is marked around them and the corners drilled and cut away as in full-size practise. The next stage requires that a copy of each cover be cut from sheet brass or steel of exactly the depth of the flanges. This template is then offered up to the work piece, with each corner accurately aligned with its drilled hole, and clamped in the vice while, one by one, the flanges are folded over it.


Still in place, the metal template then serves as a guide while, first, each flange is scored heavily with a scalpel and excess material broken off and, second, while the cut edges are cleaned and trued up with a fine flat file.


Finally, with the template removed, the entire job is rubbed down with fine steel wool to remove burs or hard edges (always very important when working with litho plate for the realism of the finished piece!).

Back to Spitfire Mk IX Diary

The basic shape of the Spitfire's elevator trimmer tab control wheel emerges, having been turned on the lathe from a scrap of left over casting resin.
Slots have been cut round the circumference on the milling machine. A rotary table is almost a must to get the geometry right in a job such as this.
The aluminium boss has been glued in place, along with the ridged finger grips which are represented by short lengths of styrene rod. Note the rather less demanding rudder trimmer wheel, machined in a similar manner to its larger counterpart.
Both pieces after priming and painting.
The two finished control cable covers and the make shift punch and die tool used to form the stiffening flute on the smaller one.
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