Page created on 24/09/2024; updated on 2nd/11/2024.
Work on the body
This mainly involves preparing the roof to receive Pennati pantos and a roofline worthy of the name. There are a number of mouldings to be levelled and holes to be filled or drilled:
- Drilling ⌀ 0.8 for new horn supports.
- Plugging of old horn supports.
- Plugging then drilling ⌀ 0.8 of pantograph insulator locations.
- Levelling and then plugging the central fixing of the pantographs.
- Plugging of the fanciful termination of the roofline.
- Location of panto servos (unmodified).
- Plugging up the location of the old roofline insulators.
- Drilling ⌀ 1 of new roofline insulator location.
- Drilling ⌀ 1.5 for roof feed-through insulator.
- Drilling ⌀ 1 for the DJM circuit breaker.
- Plugging then drilling ⌀ 1 for the TFQ transformer insulator.
Filling is made with Evergreen polystyrene rod. If the diameter of the hole doesn’t match an available rod, it is enlarged.
The plug is levelled with a flush cutter, followed if necessary by light milling. The plug is reinforced on the inside with Faller Super Expert plastic adhesive.
Notes
- Horns, points ① and ②: here’s a comparison between a Lima part and one I made fifty years ago for my 17009 Lima. So I’m going to use this one, even though I’ve swapped the large and small horns (but there are exceptions: 17086, 17087, 17097, proven from photos). So new holes have to be drilled.
Nevertheless, I will refine the horn support.
- Panto insulators, point ③: the Pennati pantos have ⌀ 0.4 fixing pins.
I drilled at ⌀ 0.8 to keep some positioning clearance. Please note: the locations
are not symmetrical, in accordance with reality.
Lima respected this point, and so did Pennati, of course. Not Piko.
Panto insulator layout.
Actual dimensions in brackets.
Example of filling a hole: this is the hole through which the panto fixing screw passed. There was a very ugly boss here that was first cut away.
Levelling.
Testing the panto assembly
The Pennati insulators need to be shortened, for they are too high. To do this, I cut off their top end. But this is not suffiscient. So I dig out their location on the roof, by a very small amount, about 1 or 2/10 mm deep, with a ⌀ 2,5 mill bit, to slightly ‘bury’ their base.
Pennati insulators,
before / after shortening.
Click on the image for a closer view of a pantograph.
For the trial, I installed the roofline I made fifty years ago for the 17009 Lima. It’s not perfect, but it’s still much better than the original (modesty aside)!
Another example is for the horns.
- Non-through drilling of the original locations ⌀ 2;
- placement of a small EVG pellet ⌀ 2 ②;
- drilling ⌀ 0.8 for fixing the horn bracket ①;
- drilling ⌀ 0.3 for the horn supply inlets ③ (Note: on the R37 “dancers” (nickname of the BB Alsthom: 8500, 17000, 25500, etc.), these parts are far too large and in my opinion would have benefited from being engraved on the body rather than inserted).
Painting
Repainting was carried out using Decapod 8091 dark bluish green (1978 version), using an Aztek airbrush, 0.5 beige nozzle, pressure 1 bar, after masking the roof vent and all sides of the body.
Milling the light guides
As the light guides for the white lights are very firmly glued in place, it is impossible to replace them. However, they protrude into the body and prevent the future lamp circuits from being positioned correctly. So they must milled flush.
Ideally, the minimum interior distance between the ends should be 152 mm.
Value to be compared with that between the ends of the chassis fitted with its new lamp circuits, which we will see later.
Improving the roof
Roof access handrails
Although it’s quite rough, I’ll keep the original decking, but replace the handrails with 0.25 mm steel wire. Shaping is carried out on a template, the dimensions of which follow.
Installation
I drill the 0.4 mm diameter holes in the floorboards installed in their place on the body. This method prevents the drill from deviating, but makes positioning a little more difficult, as the flooring is installed at an angle to the locomotive axis.
To glue the railings at the right height, I made an installation template: a 2.9 mm high, 2.5 mm wide square that fits under the railings. I milled it out of a 3 × 3 mm square brass tube.
I notice in this photo that the railing in the foreground is not pushed in far enough.
Roofline
First, here is a partial view of the actual roofline of a BB 17000.
Photo F. Pejon on DocRail.
- Pantograph servo-motor.
- Circuit-breaker, disconnector.
- Earthing switch.
- Circuit-breaker, auxiliary arc extinguishing chamber.
- Circuit-breaker, arcing chamber.
- Roof feed-through with spark gap
- Line insulator.
- Voltage measurement transformer.
- Pantograph.
Here is what I’d like to achieve. I’ve already simplified things, particularly the circuit-breaker, but I may have to do more.
The marks are the same as for the previous photo.
Dimensioned cross-section of the insulators and circuit-breaker
These drawings allow me to machine the insulators using the method described in the article Making lathe tools my way.
Note: the values are approximate and do not reflect the actual dimensions of these parts.
Connection part for the circuit-breaker components
It may look crude compared to the real thing, but, having tried to make it out of thin sheet brass, I did not manage to hold the elements together for soldering.
- Hole for vertical insulator.
- Hole for arc chamber.
- Hole for auxiliary chamber.
Lathe-turning insulators
The insulators are brass turned parts. As I don’t own a lathe, I work on a mini-drill with cutting tools I made.
Finishing (rounding) is done with fine files and 400-grit sandpaper. Here is as an example the circuit-breaker arc extinguishing chamber.
Detailing some insulators
I tried, and I think succeeded, in adding details made of ⌀ 0,29 mm bronze wire. For this, I had to drill ⌀ 0,3 holes in the cylindrical parts, and I broke only one drill bit!
Spark gap of the roof feed-through
Note: the electrodes have been shortened slightly since.
Circuit-breaker disconnector contact
First, I had to create a flat on the ⌀ 0.8 top cylinder, then drill two juxtaposed ⌀ 0.3 holes. The holes were then milled into a taper to facilitate wire insertion.
Click on the image to zoom in.
These wires were then soldered with liquid solder in very small quantities, then re-cut to a suitable length.
Two aspects of this disconnector:
Assembling the roofline
To make it easier to solder the roofline, I installed the parts to be assembled on an epoxy plate on which I reproduced all the holes for the insulators. I couldn’t solder directly onto the plastic roof, given the relatively large mass of some of the parts, which required a great deal of heating. The line itself consists of 0.4 mm nickel silver wire.
The parts have been burnished beforehand, and the areas to be soldered pickled and tinned. Further burnishing will take place after the solder joints have been cleaned.
Testing on the roof
Click on the image to zoom in.
The connection between the circuit-breaker’s arc chamber and the roof feed-through, which is actually made of copper braid, will be represented at the very end of the assembly with self-adhesive copper tape.