In the years 1952-1953  45 locomotives of the class 625 were converted  into the class 623 with the addition of two side-mounted Franco-Crosti pre-boiler stages.

The gr623 showed good savings in coal consumption, though at a time in which it made no longer a difference. As steam was being progressively replaced by diesel and electric traction, saving of 10% on an abundant commodity did not matter.

However, the more complex maintenance these machines required made their fate. To maintain efficiency, the pre-boilers required frequent cleaning..  Sadly they were retired earlier than the class 625 they came from, with not a single specimen surviving the torch.

I found the Franco Crosti locomotives very interesting to reproduce so like FS I derived my gr623 design from my gr625 design.

Every operation to make the model is identical to the one written for the gr623.

The 625  class made a relatively large group of  all-use steam locomotives. The class included locomotives originally produced under new design, but also locomotives  transformed from the  older class 600. Many of the transformed 600 class had the Caprotti valve gear. This valve gear is very suitable for reproduction in Z scale as, unlike the Walschaert valve gear, the Caprotti has just one linkage. 

The loco was mostly attached to the standard T12 three axis tender.

Hence my model is exactly made of these two items (1), (2).

These can be painted in black and rosso segnale (3).

The motor plant comes from a Märklin mini-club Br24 (4).  This is a decent first order approximation, as the Br24 has equal spacing between drivers, while the 625 has an uneven spacing.

The motor plant requires quite some rework, including thinning, shortening and lowering. All operations to be done with a good set of files.

Even with all this cutting the motor will be visible in the back of the cabin, but so was in the Br24.

Inserting the wheelset is instead the only thing that needs to be done on the tender (7).

Overall not the simplest kitbashing but also not the most difficult.

The result is good and it has sufficient properties to pull quite some wagons.

173 of these locomotives were produced in the period 1907 and 1911, by Schwarzkopf of Berlin, Breda of Milan and other Italian manufacturer.

For their elegance, these locomotives were nicknamed 'signorine'.

They appear identical to the class 625, from which they differ by the size of the drivers which are much larger in the gr640, which was meant to pull faster light trains.

It took quite some time to make this locomotive as I had to wait long to finally see a suitable set of wheels put on ebay.

For this locomotive I had to design a complete new chassis. I adopted an unusual position of the motor, placed within the boiler.

This to allow the see-through effect that you can appreciate in the real locomotive.

The whole model is made of 3 3D printed parts: 

1. the shell combining cabin, boiler and front 

2. the chassis 

3. the tender

The shell is attached to the chassis by sliding the motor into the boiler.

This arrangement leaves the cabin completely empty. 

Current pick-ups are made of phosporous-bronze wire that touches the inner plates of the wheels.

The riding properties are very good.

The FS group 685 design was derived from the group 680 one by changing to superheated steam and single expansion engine. The design was produced by the Florence Design Office of the FS for pulling fast passenger trains on the main lines.

Initially 271 locomotives were produced, of these 30 had Caprotti system valve distribution, they entered service starting from 1912 and served till 1976.

Considering the excellent performance of the group, between 1921 and 1930 FS carried out the transformation into 685 of a large quantity of 680 locomotives which gave rise to the 685.300 series (with Walschaerts distribution) and 685.500 (with Caprotti distribution).

The 685 have been considered the best performing steamers of FS, and were nicknamed 'regine' (queens).

They have had a number of derivatives as well.

4 locomotives were equipped with the Franco-Crosti pre-heater and also received a beautiful streamlined cover. 1 locomotive got the motor replaced by a steam turbine.

One day I may reproduce these, today I have reproduced the version with Caprotti system distribution, which, having no control rods, is particularly suitable for a reproduction in Z.

The chassis has the motor placed into the boiler, this allows a cabin completely empty.

The motor feeds, with a reduction 2:1, a transmission shaft that engages the wheel pinions by means of three worms.

Drivers are from a bastler Märklin steamer while for the two bissels I have used nickel strips cut and folded to hold wheelsets coming from other bastler Märklin steamers.Considering that the locomotive has a tender on bogies, I have decided to place the pick-ups on the tender. By using Japanese style wheels one can realise pick-ups with no additional friction.

The first print of the model was equipped with motor, gears ,wheelsets and distribution rods and it worked immediately.. The tender you see in the video is provisional and built using two unpowered shorty bogies.

The US Army Transportation Corps already in 1941 commissioned the production of a great number of these locomotives. 

Thousands of them were massed in Wales ahead of D-day.

At the end of the war, the FS purchased 243 of these locomotives. 6 other locomotives were recovered from a ship sunk in an Italian port,  of these 5 could be put into service.

Many European countries acquired S160s, including Poland (575 units) , Austria (30), Czechoslovakia (80), Greece (52), Hungary (510), Spain (6) and Yugoslavia(80).

FS grouped the  s160  in the class 736, which served prevalently for freight traffic on graded lines, finishing service in Sicily at the end of the 60s.

I have used as power plant for this model the chassis of a Br55. While wheel size and spacing matches well the prototype, the electric motor protrudes too much from the cabin. 

I will have to make a bespoke chassis in a future version. For now I will live with the shortcoming.

FS Gr741 

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The class 743 was derived in 1934 by the transformation of a number of  locomotives of the class 740. These saw the addition of 2 Franco-Crosti pre-heaters. The heaters use the fumes of the main boiler to pre-heat the cold water reaching the boiler.  

I always liked these odd-looking locomotives. In Z they also present the advantage that some extra ballast can be added in the body of the pre-heaters.

The body is 3D printed together with standard FS  22mˆ3 tender and its bogies.

For the motor plant I used the usual Märklin mini-club Br55 to which I added a front bissel.

The Br55 chassis needs to be reworked. First the metal top of the chassis need to be removed. Then the font walkboard needs to be cut. Finally the motor needs to be filed on the sides so that they appear flat and not bulging.

The FS class 60 was a group of 85 combined steam-locomotive/baggage-car/postal-car.

They had been conceived to pull very minimalistic trains (just 1 passenger car) on lines that had little traffic, thus reducing costs to the minimum.

The idea, however, did not work as power was very limited and it did not allow adding additional cars in the not-so-uncommon case of more passengers than one single car could accommodate.

So after few years of unsatisfactory use, the class was scrapped, few units were transformed in heating cars and 16 units were transformed in small switchers, with the suppression of the baggage/postal compartment and the idle axle.

The switchers were grouped in the class 800, even though they were known to all railways people by the name of 'cubo' (Italian for cube) due to the very boxy shape.

Most switchers of the class 800 were sold to industrial plants for in-plant switching. Very few remained in service with only one surviving the scrapyard and now at the beautiful FS railway museum at Pietrarsa (Napoli). 

I have realised this locomotive in Z scale. The part I found appealing is that the boiler is placed vertically and in Z scale has the same dimensions of the Chinese micromotors I use. So it was possible to to make a model that has a cabin interior similar to reality.

The model [1] is made just of 2 3D-printed parts. The cabin and the chassis.

The latter hosts the motor, mounted vertically, which engages with its worm an asymmetrical chain of cogs leading to the two wheelsets.

I have used 2 wheels from my stock of bastelware-Br89s, and the two power rods from the same wreck.

This was the first locomotive of FS specifically built as switcher.

370 of these switchers were built from 1906 to 1922 and served in Italian yards till 1984.

I developed this model to use a motor plant from the Br89 Märklin mini-club.

In order to ascertain the compatibility with the Br89 power plant, I created a first coarse model in CAD (1).

I then printed it in transparent resin (2).

The transparency helps in detecting volumetric interference

Eventually, by operating on the power plant and on shell I got a good match (3).

The Br89 chassis needs to be spoiled of couplers, lamp, capacitor. It needs also to be shortened at the back so that the motor block is flushed with the metal base (4).

The Class 940 was designed for the  Appeninian railways, in oder to negotiate gradients up to 2.7%. It was based on the successful plant of the class 740 which was morphed in a tank design with the inclusion of very large side water tanks, a coal store and a rear bissel to enable reverse speeds equal to the forward ones.

The result is for me the most beautiful tank engine I have seen.

I am not into American railroad modelling, though I was momentarily fascinated by the exotic ugliness (hence beauty) of the camelback.

So I modelled this 0-6-0 of which I found drawings on a model forum.

It is actually not a real model. More a fit check item. It will take a lot more effort to make it a good model.

The chassis comes from a Märklin Br89 and it has been fitted with a 4mm 5V motor.  I also re-used the cylinder block of the Br89.

Maybe one day i will make a real model out of this, but for now I stop here. 

A1 - shell - in 3D file

A2 - chassis - in 3D file

A3 - cylinders (2x) - - in 3D file

B - motor 615S micromotor.eu

C - M0.2 worm 2.8mm ? outer diameter, 3.5mm long, 1 mm ? bore

D - M0.2 gear 15 teeth, 1mm thickness 0.8 mm ? bore

E - 3.8 mm long 1mm ? brass rods (three times)

F - M0.2 gear 15 teeth, 1mm thickness 1mm ? bore (3 times)

G - Märklin BR89/V60 geared wheelset (2 times)

A1 - shell - in 3D file

A2 - chassis - in 3D file

A3 - blind axis swing mass - - in 3D file

B - M0.2 gear 22 teeth, 1mm thickness 1mm bore

C - M0.2 worm 2.8mm ? outer diameter, 3.5mm long, 1 mm ? bore -- B and C are soldered together

D - 406S motor (2 times)

E - M0.2 gear 8 teeth, 1mm thickness 0.8 mm ? bore (2 times)

F - 10mm long 1mm ? brass rod

G - 3.8 mm long 1mm ? brass rods (three times)

H - M0.2 gear 12 teeth, 1mm thickness 1mm ? bore (2 times)

I - M0.2 gear 15 teeth, 1mm thickness 1mm ? bore

J - M0.2 gear 22 teeth, 1mm thickness 1mm bore

K - Märklin BR89/V60 geared wheelset (3 times, the central one has wheel discs removed)