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SHM 26

Detailing - Working the (small) appliances

Detailing is essentially that: working on very small parts ;-) On this page you will find a plethora of small thing that need to be done, even on a small locomotive with so few appliances like this one.

I describe them in detail in the first place for myself, just as a kind of diary to remember what I did for following occasions. Secondly I hope to give you as a reader the advantage of picking up ideas.

This page describes

The sandboxes

The sandbox is measured from the centre of the spigot to the edge
That distance is scribed in the smokebox support
I have a DYI rivet press. It is also useful to make a pilot dimple to prevent the drill from running away

Pre-drill with 0.5 mm

Final drill with 0.8 mm

One hole was not accurate enough, so with a round file I "relocated" the hole.
Sandboxes soldered in place


The snifter valve

SHM 26 has a snifter valve on right hand side.

This valve is an automatic anti-vacuum valve used when a steam locomotive is coasting. The word Snift imitates the sound made by the valve.



When the driver shuts off the steam to the cylinders while the steam locomotive is in motion, the moving pistons could create a partial vacuum in the cylinders. This would give rise to two problems. Firstly, the pumping action would absorb energy and prevent the engine from coasting freely. Secondly, when the exhaust valve opened, soot and cinders from the smokebox could be sucked down the exhaust pipe and into the valve chest or cylinder, causing damage.


The snifter valve was not present in the kit so I had to make it myself

From my detail parts box I retrieved a part that provided a good basis.

I snipped off the valve and filed the valve body straight.

I turned a 0.8 mm brass rod partially back to 0.4mm by putting it in a drill head and file it while turning
I drilled the modified valve with 0.4 mm
Fits! I soldered the two together and snipped off the oversize part of the brass rod and filed the cutting edge flat.
The whole snifter valve is no more than 1.7 mm long.
In place on the boiler. I did not fix it but stored it for now. As most of the valve will stay clear brass I will put in place only after painting.



I had not noticed that the whistle was attached at the back of the steam dome. That was a hard place to get at with a drill once both domes are in place. But with patience and perseverance I could hand drill a hole.


Washing plugs

Another issue that needed resolving was the fact that there were only two washplugs present in the kit where the protype has three. So I needed to fabricate one my self

At the right an original wash plug.

I started with a piece of brass rod of 2 mm diameter

Chucked in my Proxxon drill

I set the speed to about 7000 rpm.

I used my square file to create the spigot of 1.0 mm

I cut the thick end back to approximately 1.0 mm with a flush sidecutter and then turned it down to 0.7 mm with a flat file
I think I pretty much succeeded in making a third wash plug. Proudly looking at this photo I suddenly felt that the original wash plug was too thick by far. I decided to turn them all three down to say 0.3 mm.

0.25 mm! I dared not turn them even thinner
Considering that the wash plugs are almost flush with the boiler cover I think this is about the best result I can get. I glued them in place with epoxy.


Roof of the cab

Once I had prepared the roof of the cab I turned my attention to the few details on the roof
The rain gutters were easily made from 0.3 mm brass wire
Blu-Tack serves to hold them in place when the brass wire was tack soldered on its outer ends and later in the middle
Once the whole wire was soldered it was sanded flat and down to appr. 0.15 mm


The roof's bell


The bell on the cab's roof was not provided in the kit.

I initially made it deforming a American style example I had in my scrap box

Not Bad but Too Big
Somehow I always have difficulty parting with the brass sprues that remain after all cast parts have been separated. I keep them in a scrap box labeled "you never know". Now I needed to turn a smaller bell from solid brass and guess what? Out came the brass sprues to see which could potentially give a good go and one of them suited my needs!
I turned the new bell in my Proxxon drill with files. The narrow cut is made with a metal saw in  preparation to separate the bell from it base.
The first attempt taught me how to work but the result was…to small! (middle bell). So I had another go and within minutes a had a bell that was almost spot on.
Before separating the bell from its base I drilled a hole
Now that is a difference! The new bell has a diameter of 3.1 mm, the old one 4.5 mm
I even found the opportunity to create a clapper. Instead of using a metal saw again to complete the cut and separate the bell, I used a sharp knife. This left the part of the saw cut standing, thus mimicking the clapper
I needed the hanger of the old bell so I cut that bell out with a diamond disk

I worked the base with a file all around to give it a more fitting size.


The location of the holes were marked and the hole were drilled

From 0.3 mm phosphor bronze wire I produced the hinge including the lever for the pull cord. I soldered the hinge to the base frame. The paper shim is to prevent solder slipping into the bell.
Now the bell can actually move


Installed on the roof and for comparison below a photo with the first bell. Personally I think the new bell's frame is too big but again: there are limits



The air pump


First thing to do for the air pump was to construct a suitable support. The kit did not contain one, although pictured in the manual. I tried to follow the outline of the support of the prototype

It is a bit smallish. The man, "my uncle", is a 1:87 figurine.

0.2 mm brass can easily be cut with scissors. Fast and precise. Flatten it by rolling with a steel bar.
After folding and corrective work (filing and sanding)
Before fitting the pump I found it useful to mimick a bit of the space under the boiler. The prototype has the motion between the frames and the motion is accessible by an opening under the boiler, as driver Jaap demonstrates below

As you can see above, this space under the boiler is delimited by rather hefty L-profiles and I thought it would be nice to copy that, to hide the conspicuous nothingness under the boiler of the model.

I cut a strip of 0.2 mm brass sheet, clamped it between two steel rulers, aligned it well...

...and folded it over and rolled it until a good sharp straight angle was achieved
An L-profile of 0.75 by 0.75 mm
Soldered in place
Now I soldered the pump to its support. To do that I clamped it in an ordinary laundry peg. The pump is difficult to hold and clamping in a normal vise will damage it.
The holes for the pipes were drilled at this stage
Installed in place with the most important tubing. There are numerous grease feeds to the pump but it is impossible in this scale to mimick these as well


The coal bunker hatch


The coal hatch has an issue you wouldn't expect in a quality kit like this: it is too small. There is a distinct and obtrusive gap between the hatch and the boiler.

In theory this could be correct if the coal bunker were to stand proud of the boiler. But my photos confirmed what I already suspected: the coal bunker hatch has a hinge some 15-20 cm away from the boiler and there is a strip on top of the coal bunker that completely fills the void between hatch and boiler cladding.

So I made a strip of 0.3 mm brass sheet, soldered it under the hatch and filed it to fit.

First the boiler needs to be soldered into place. The hatch has a little notch to accomodate the boiler ring passing along the hatch. If you solder the hatch first, the boiler will get stuck when you try to insert it.

Undoubtedly there are tricks to manipulate the boiler once the hatch is in place, but make it yourself easy and solder the boiler first.

Soldering took place from the outside. That requires some extra cleaning but it is simply impossible to solder it from the inside.

I used 140 C solder so I would not disturb other nearby solder seams. I did not solder the seam between the hatch and the boiler. The solid brass boiler drains all heat and the solder simply will not flow. I made that seam as narrow as possible by working very accurately.


The lubricator


The lubricator is another part that was not included in the kit. This is excusable as the lubricator was probably not present before the restoration of 2000. anyway it is a very modern appliance, easing the task of the engineer.

From the phot I estimated the height and from there the various other sizes. I also had to decide which details to leave out. Modelling in 1:87 is not so much about how to model details but to acceptable choises about which details to leave and yet get the idea.


I "turned" a brass basic form of just 6.1 mm, excluding the spigot

I filed the insde of a brass rod and turned the front side. The upper scale is in millimeters

And this is the resulting lubricator. I kept the lubricator on it original brass from which I turned it so I could handle it more easily. Just before soldering I cut the spigot where it comes out of the rod. I even considered drilling holes for the grease tubes


I had great diificulty positoning the lubricator in its hole and keep it there. After some halfhearted attempts I called Blu-Tack to the rescue. A nice blot to grab, position and support the lubricator and hold in place until the job was done.

Done. I'm still fretting if I should have added the grease tubes....