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LTM 51 in HO

Detailing of the drive units

In March 2021 I was caught running around in circles at the start of the detailing of the boiler cradle. I kept staring at photos, where which tube would go along the boiler. And everytime I picked up the model to do the first details I got in doubt again, put the model down and achieved nothing once more.

To break this stalemate I turned my head to completing the drive units. There the situation was much clearer.

The drive unit at the start of detailling. Click image to enlarge.

Even so I had make a substantial to do list. It was quite a lot more work than I originally thought.

Phase *)

What

Where

Left

Right

No.

1

Engine cover

Close the gaps in the etch and file / sand smooth

 

x

10

1 Steam pipes Fill and sand back side smooth, drill two holes, add steam pipes     2

1

Equaliser tube

Between watertanks (at the front below)

 

 

1

2

Lubricators

At the front side of the engine cover

x

x

2

2

Handgrips

On the hatches of the engine cover

x

x

8

3

Sanderboxes

At rear of the water tanks

x

x

2

3

Lubricator pump

At the rear of the running board

 

x

1

3

Actuator

Lubricator pump

 

x

1

3

Upright plate

Lubricator pump

 

x

1

3

Indeterminate "box"

On the running board, left, front

 

x

1

3

Tube/rod

From lubricator pump to almost the indeterminate "box"

 

x

1

3

Lubricator

Between the hatches of the engine cover

x

x

2

3

Water hatches

On the running board

x

x

2

3

Water level indicator

Side of the water tank

 

x

1

3

Manhole

Side of the water tank

x

x

2

3

Handgrips

At the step in side of the water tank

x

x

2

4

Step

Below the step in side of the water tank

x

x

2

5

Profile

Below the skirt under the buffer beam

 

 

1

5

Remainder of the rail cleaners

Below the skirt under the buffer beam

x

x

2

6

Handgrips

Below the buffers on the buffer beam

x

x

2

7

Steam heating hose

Buffer beam

x

x

2

7

Air hose pressure brake

Buffer beam

x

x

2

7

Air hose vacuum brake

Buffer beam

x

 

1

7

Vacuum pipe

From buffer beam towards engine cover

x

 

1

8

Coupler

Buffer beam

 

 

1

9

Buffers

Buffer beam

x

x

2

10

Headlight

On the running board above the buffer beam

x

x

2

11

Guardrail

On top of the buffer beam

x

x

2

*) The phase indicates the order in which I want to attach the parts to reduce the chance of damage or cumbersome working.

Work that has been completed is marked in green.

Prepping the engine cover

Detailing work started with filling the gaps that where visible on the top edges of the engine cover. In the original etch there were slots etched and I partially filled them up with solder but did not manage to get rid of them entirely.

The engine cover as I found it on the etch The black lines clearly signals the etched through surface.

Even when filled the seam is still visible

I filled them with JB Weld.

The etched recesses at the back of the engine cover (left) were also filled. This side was etched as if it had hinging doors like the front side but on close inspection no doors could have existed at that location, just plain metal sheet.

After sanding I gave the superstructure a quick primer to reveal the spots I had missed during filling and filing. After a few minor adjustments I was happy and removed the primer again.

 

Steam pipes

 

I was now supposed to drill two holes in the back of the engine cover to allow two steam pipes to go through and somehow mount these pipes. After careful consideration I decided not to.

It is fiddly to drill them at all and the steam pipes may conflict with the free movement of the drive unit relative to the running board of the boiler cradle.

 

Once painted it will be a very dark spot and the absence of these pipe is not immediately apparent. You have to draw a line somewhere in what you can do in 1:87

Equaliser tube

The equaliser tube does exactly what the name suggests: it equalises the water levels between the left and righthand water tanks. It is slung under the the frames and the two water tanks in a stretched U-form.

 

It is not possible to model the entire pipe. The horizontal tube woulds interfere with the frames during assembly. I decided to model the elbows and a stub of the horizontal part, leaving the frames free to pass.

It makes the fabrication easier as well. It is no longer necessary to aim for a specific width of the horizontal tube. It also makes bending the elbow esaier as you will see.

First I turned the elbow-to-be from 3.0 mm brass rod, leaving two flanges proud of the surface.

 

Dimension

mm

in

Pipe diameter

2.15

0.085

Flange diameter

2.80

0.110

Flange width

0.4

0.016

Distance between flanges

2.80

0.110

The tubes are very wide and bending a 90 degree corner in 2.2 mm thick brass rod is no easy feat. So after turning I annealed the brass rod. I made myself two bending handles from steel in which I drilled a 2.2 mm hole.

With the handles the bending operation becomes relatively easy.

By gently bending the elbow a bit over 90 degrees and then ease it back with a bit of luck the flanges stand at 90 degrees. It is a bit of trial and error. I chamfered the ends on handles after bending the first elbow to make the bending "over 90 degrees" easier

The final result

Lubricators

At the front of the engine cover there are sets of three lubricators. Well actually two and a kind of junction in the lubricator pipes. I decided to mimic them as three lubricators. I am now at the edge of what I can still do. In fact before I started I was more or less convinced I was over that edge: simpy too tiny. But I did not want to leave these details away without trying. So I tried. Judge the result yourself.

L-profile: legs 1.3 mm by 1.3 mm and 0.2 mm thick!

Drilled and cut to length

The lubricators are mounted on a bracket. First I milled an L-profile from a piece of rail profile that I soldered to a sacrificial piece of brass. Legs 1.3 mm by 1.3 mm and 0.2 mm thick! After milling I drilled the holes on their appropriate places and cut the profile in lengths of 5 mm.

One hole was mis-drilled. The other holes vary a bit because you can't pre-drill a 0.5 mm hole, so the drill point wanders a bit before settling in the material.

I turned the lubricators from 1.2 mm brass rod. Dimension: 1.2 mm high, 0.8 mm wide and the stem is 0.5 mm wide.

They were soldered on the brackets in trios.

And the bracket on it turn was soldered on the engine cover.

Handgrips of the hatches

Making the handgrips on the hatch covers is a simple job but requires a good amount of patience. Here repeatability is of the utmost importance. When four identical parts are not identical it immediately attracts attention. After soldering the excess material on the inside of the superstructure is cut short and filed flush

One final photo of the lubricators and handgrips with my thumb to show how small this all is.

Handgrips (continued)

After having eight handgrips by hand, I got fed up with tiresome work of getting them all exactly in the right shape, which more or less a hit and miss affair. So I decided to make a forming tool: a U-shaped slot into which the wire was preseed in the right form.
The slot shoulbe as wide a the outside size of the grips which is 1.76 mm. I do not have the tool tot meaure an inside size this small. So I first made a positive of 1.73 mm wide.

Then I filed a negative slot in which this positive would just fit in. So the theory is now that this slot is just a few hundreds over 1.73.

Now lay a wire on the slot

Take a piece of steel 1.2 mm wide (that the width of the U minus twice the wire thickness of 0.3 mm).

Push the steel in, drawing the wire with it. Gently tap it with a nylon hammer (or a piece of wood, not a heavy steel hammer).

Done! Exactly to size and with nice crisp corners.

Fits perfectly

And five minutes later I have eight identical grips.

Guardrails

At an early stage in the detailing process I already did some preparations on how to make the guardrails. It was clear to that I would make them from phosphorbronze wire. This material is far more springy than brass wire which makes it more resistant to an accidental bump. That is an important feature at the very exposed position of the guardrail.

Next question was how to solder them in the running board. The answer was hidden in the prototype. The guard rail had a king of lug at the bottom that was bolted to the running board.

LTM 51 in the cutting near Gulpen

So I made them on my Unimat lathe. Admittedly they are tiny

Dimension

mm

in

Total Height

          1.30

        0.051

Flange thickness

          0.20

        0.008

Flange diameter

          1.50

        0.059

Shaft diameter

          1.00

        0.039

Hole diameter

          0.50

        0.020

I also did an experiment with the connection of the guardrail poles and the horizontal bar. I filed the end of the vertical bar to a D-shape, only 0.25 mm thick. I annealed it to make the metal soft. As the material is very thin annealing only takes a few seconds. Be gentle. Then I bent the D-shed end 90 degrees outward, put the horizontal bar in a vise and curled the D-shaped end of the vertical bar around it. A touch of the soldering iron fixed it in place.
I am happy with the results of both experiments. I now know I can make the guardrails without problems. But it will be the last thing I do because they will very vulnerable while handling the drive units.