About Henk Bunte (owner of Modelbouw Atelier Apeldoorn) and his hobby:

(Scratch)building live steam locomotives for 45 mm gauge


Ik heb de eerr een Aster Schools op te stoken
I have the honour of firing an Aster Schools class loco




Een overzicht van mijn tuinbaan: 40 meter PECO flextrack
An overvieuw of my layout: 40 metres of PECO flaxtrack in gauge one

End of the eighties it happened, I got the 'Live-Steam-Loco' disease.


Een van mijn eertse modellen: een tramloc in 1: 32 schaal het origineel van MAFFEI, spiritus gestookt, 1 oscillerende cilinder tussen het frame met 3:1 tandwielvertraging
One of my first models was a tram-loco, also in scale 1:32, the original built by MAFFEI,
spirit fired one oscillating cylinder between the frames and also a 3:1 downgearing.


In the meantime I found out that it is also very convenient to have a track to drive your locos on. So I decided to make an oval track in the garden of about 40 meters lenght gauge 1 flexrails from PECO at a minimum radius of 3 metres (thanks to the ASTER Locos).

The track is laid level to make it possible to run also Live Steamers without Radio Control. (see photo above)


In 1993 my hobby really grew out of my hands: we started 'Modelbouw Atelier Apeldoorn' .

And now about coal firing on 45 mm gauge in 1 : 22,5 scale


De essentie van kolenstoken: In de hand houden van een kolenvuur van ca. 1200 graden Celcius, op een rooster van 52x29mm!
The substance of coal firing:

Being in control of a coal fire of 1200 degr. Centigrade on a grate of 52 x 29 mm!






En nu vol stoom vooruit met de ''freelance'' kolenstoker met Regner tender. De flexibele slang tussen tender en loc is verbonden met de ''bypass'' - afsluiter om de watertoevoer vanaf de kruishoofd-voedingspomp naar de ketel te kunnen instellen.

And now full steam ahead with the new coal fired 'free-lance' loco and REGNER tender.
The flexible hose between tender and loco is connected to the bypass valve,
in order to tune the water supply from the crosshead feed pump to the boiler.
Just behind the rear axle the firebox (stainless steel sheet) with ashpan cover can be clearly seen.
The colour of the frame and the upper side of the firebox is turning to black, due to the heat of the coalfire!



How it started:

Some time ago I started the building of a G-scale DR 995001, a little 0-4-0 loco as was used at the 'Harzquerbahn' (LGB calls her 'Unsere Kleine Dicke'). This loco has a relatively big boiler diameter, also, a boiler with a good water content for a gas-fired single-flue boiler.
The building of the loco went on: frame got ready, cylinders and Walschaerts gear from ROUNDHOUSE, wheels from REGNER, the gas fired boiler was ready. In other words: it was almost time for a steam-up test.
But then it happened!
I was browsing through a series of articles written by Jos Verouden in our Dutch steam hobby Magazine 'ONDER STOOM' and was infected by the coal firing virus. But I was to lazy to built the whole loco which was described: a 4-6-0 loco NS 3900 (with tender: 3 -4 years of work).
After some sleepless nights the idea grew: Why not convert the DR 99 5001 to coal firing? What I certainly could not use was the gas fired boiler, machine and frame could be used for a small coal beast.
The only thing I had to drop was the scale model of a 99 5001, because without a tender with feedwater and hand pump coal firing is very difficult.
When I browsed through 'Taschenbuch Deutsche Schmalspurlokomotiven' I saw a very wide variety of 0-4-0 locos fitted with a tender for extra water and coal. So I decided to convert the 99 5001 in a 'Freelance' design complete with a tender kit from REGNER. Which had to be rebuilt with a water tank and a hand feed pump. In this way it was possible to make the first coal fired trial runs within 6 months!


The frame:

Is machined out of a solid aluminium block with a pressed/glued in brass bushing for the driven axle (a bushing over the whole length of the axle i.e.: no problems with lining out) as a bearing. The front bearing is also a bushing supported by 2 spiral springs to give a smoother running.
Between both bushings, in the centreline of the solid block, a vertical hole diam. 6 mm is drilled. This in order to fix the boiler, which has a support stud of brass diam 18 mm soldered to the underside. A stainless steel M6 bolt can be srewed into this stud to fix the boiler to the frame. In this way the boiler has only one mounting point.
As an extra, an insulation ring of a kind of fiber is put between stud and frame block.
To the aluminium block side plates are screwed, made of aluminium sheet, quality 51 ST of 1.5 mm, a very nice material: easy to cut and machine.
The buffer beams fore and aft are also machined out of solid aluminium blocks.
Only the frame sideplates along the firebox are made of 0.5 mm gauge stainless steel sheet with openings cut out in order to let out the enormous radiation of the firebox., because it is really getting 'red-hot'!


De ketel met geopende rookkastdeur. Rechts van de loc 2 uittrekbare pennen met aspan en het rooster (slechts 52x29mm)
View of the boiler with opened smokebox door,
on the right hand side of the loco two removable
pins with ashpan and grate (only 52 x 29 mm)
and the tip of the gas lighter for lighting the fire.



The boiler:

The most exciting part of the project was: how big it has to be, does it fit on the exsisting frame, is the grate of the right dimensions, etc. etc.
And then my friends, it was clear that "we are standing on the shoulders of giants". Jos Verouden , a famous bulder of gauge 1 coal fired locos in Holland, noted down all his expertise in 'Technische gegevens voor spoor 1 locomotieven' or in English: 'Technical data for Gauge 1 live-steam locomotives' (it's a pity that its only in Dutch). Thanks to the very detailed info, also about coal-firing, it seemed to be possible to make a boiler for this loco.
I was in the possesion of copper pipe 67 x 63 mm and with this as a basis, the boiler design was made according to the sketches below.
All dimensions were checked with the diagrams from Jos Verouden's notes and after the first steam tests it was clear that the boiler had the right dimensions.
I was very amazed that such a tiny grate (only 52 x 29 mm) gives the loco such an immense power!

Click here to look at the boiler drawings

The engine:

slide-valve cylinders and valve gear (semi Walschaerts) are from ROUNDHOUSE: cylinder diam. 14.288 x 15.875 mm stroke.
Glands and piston are fitted with silicon O-rings. In my experience a very dependable system.
Wheels are brass castings from REGNER and were chemically blackened after machining.



This is done by the most dependable system I know: The main steam supply to the engine runs transverse throuh a brass container of diam. 12 mm and 45 mm long. The bottom of the container is closed with a plug soldered in.
The top is closed with a removable plug with screw-thread fitted with an O-ring for sealing .
In the main steam supply line (where it runs through the container) a tiny hole of 1 mm is drilled.
And look: here you have a ROSCOE lubricator: simple to make and very dependable.


A very important issue is the draft through the firebox. The blower pipe is of 1.5 x 1.0 mm copper pipe and runs to the top of the exhaust nozzle of the cylinders.
The diameter of the exhaust nozzle is made so much wider in diameter that it compensates for the surface of the blower pipe.
The relations of the dimensions of the exhaust nozzle, inside stack, petticoat etc. are calculated from formulas as stipulated in 'Technische gegevens voor spoor 1 locomotieven', but also the locomotive construction book of Martin Evans gives info about this subject .
In order to prevent 'false-draft' it is also very important to take care for an 'air-tight' smokebox and firebox connections to the boiler.

Boiler feed pumps:

The boiler water is supplied by a hand pump located in the tender. But this is not sufficient to drive the loco with a safe water level.
An extra pump, driven by the engine and in series with the hand pump, is neccessary in order to give the boiler a dependable supply of water during operation.
The problem in this case was that there is not enough space between the frameplates to fit an excentrically driven pump.
Therefore a 'crosshead-driven' pump, diguised as a dummy air-pump on the side of the smokebox , was chosen.
The plunger has a diam. of 3 mm and is driven by a crank which has a fixed turningpoint, halfway along the crank, on the footplate i.e. the pump has the same stroke as the cylinder.
The output of the pump is connected to a boiler feed valve and a bypass valve to the tender in order to tune the water supply to needs of the boiler.


De ''Kale'' loc op de testbank, rechts een bakje met voedingswater en een handpomp. De door het kruishoofd aangedreven voedingspomp is nog niet gemonteerd. De ketel heeft 2 veiligheden (altijd bij kolenstook!) elk afgesteld op 4 Bar werkdruk. De dunne koperen leiding langs de ketel loopt van de blazerkraan naar de blazer in de rookkast

The loco on the test bench, on the right hand, a container with feed water and hand pump.
The crosshead driven pump is not fitted yet.
The boiler has two safetyvalves (always important for coal firing!)
each tuned to 4 Bar (approx. 60 psi) working pressure.
The thin copper pipe along the boiler is running from the blower valve to the blower.
On the right hand side of the boiler picture (below), behind the water gauge, the fire door can be seen hanging open.
In the middle of the underside of the boiler the mounting stud can be seen.
It is the only fixed connection between boiler and frame.



Because I had no experience with coal fired locos, a test bench was made out of some aluminium profiles and brass rollers (see photo above).
This gave me the opportunity to test the loco in my workshop on the desktop.
A very useful gadget when you have no practice with coalfiring, because you can easily sit and watch what's all happening, during the process of firing and running the loco. As coal 'anthracite', is used. It's delivered in paper bags of about 5 kgs in small lumps (no5).
Even these lumps are too big . The first thing you have to do is to crush the lumps with a small sledge hammer.
Then you have to make a 2 stack strainer, the upper one needs a mesh of about 12 mm, the lower one a mesh of about 4 mm (both diagonal dimensions).
The crushed "anthracite" is put in the upper strainer and after screening of the coal, the stuff which stays on the lower strainer is the right one for your loco.
Then you take a bag of charcoal (the one we use here in the barbeque) and follow the same procedure as with the "anthracite', in order to get more or less the same lumps of charcoal.
After that the charcoal has to be soaked with paraffin (lampoil).
And now my friends you have the right stuff ready to fire your loco!
The only thing you still have to make is a coal shovel , a very important utensil, which makes it easy to fill your firebox in the right way.
I made it as follows: Take a length of about 60 mm thin walled (approx. 0.3mm) brass pipe with a diam. of about 17 mm. Cut it in 2-halves over the length of the pipe.and use one half for the shovel. Close one end with a hard soldered piece of brass sheet. Round-off all the edges and solder on (at the closed end) a handle made of 4mm diam. brass. This procedure gives you the right shovel.



Now we are ready for the first steam-up as follows:

  • water in the boiler (approx. 10 mm above the firebox crown sheet) and steam oil in the lubricator.
  • a layer of approx. 30 mm of lam poil soaked charcoal in the firebox.
  • electric blower on the smokestack and switch it on.
  • light the charcoal through the open firedoor (I do it with a long gas lighter as used in the kitchen), close the firedoor and you will hear the "roaring" of the fire.
  • when the pressure gauge reaches 2 Bar (approx. 30 psi) the blower valve can be opened in order to get a real draft on the fire, and the electric blower on the stack can be removed. The charcoal will glow more or less 'white' now.
  • when the charcoal is glowing really 'white' coal can be shoveled in to just under the firedoor-ring, the firedoor has to be immediately closed after filling, to prevent cold air coming in throuh the firedoor opening.
  • the boiler will very soon reach a pressure of 4 Bar and the 2 safety valves will blow. Then , carefully, open the regulator valve and close the blower. After some 'spitting' your engine will start to run!!
  • during running of the loco: fill-up with coal regularly, one big shovel in the front of the firebox and one in the back of the firebox. Otherwise you have the chance that there comes an air-hole in your fire and it will die out immediately.
  • use your watergauge and bypass valve to check the boiler feed pump and on a regular basis in order to keep your boiler water on the right level .


In general:

It is important not to be afraid of 'firm-firing' : open the blower valve firmly during steaming -up.
Take care for a firm load during running (a few pieces of wood clamped between the rollers of the testbench).
The loco has to work hard in order to get a good draft on the fire from the exhaust, otherwise your fire will die out and you can start over again.
The steam-up time from cold to 4 Bar (approx. 60 psi) will take between 5 - 10 minutes, not bad compared with spirit or gas firing, isn' t it?



De ''stof'' waarop kolendromen gebouwd zijn: Het witte bakje in het midden, gevuld met antraciet heeft de kolenschep over de rand hangen. Het linker bakje is gevuld met vetkolen; Ruikt en rookt fantastisch, maar bakt wel samen op het rooster! Aan het einde van een rijsessie worden er altijd enkele stukjes vetkool verstookt. Het bakje recht op de voorgrond is gevuld met in lampolie gedrentke houtskoolsnippers. Onmisbaar om de loc op te stoken. Rechts op de foto de 2 verdiepingen van de kolenzeef.

The 'Stuff' real coal firing dreams are built on.
The white container in the middle of the photo is filled with lumps of Anthracite,
the coal shovel is hanging over the edge.
The container left on the photo is filled with 'Fat coal'
is smells and smokes tremendous, but 'glues' together on your grate.
I always put in some lumps at the end of a running session.
The container in the foreground is filled with lumps of charcoal soaked in lampoil.
On the righthand side of the picture you can see the 2 stacks of the coal strainer.







Driving on the track:

And at last! The moment of truth! Loco on the track, all utensils at hand (charcoal, coal, water, steam oil, shovel, electric blower etc.).
Steam up the loco as described in point 1 to 8. When the safety valves are blowing: hook on the train,
close the blower valve, gear in 'forward' and crack the regulator valve!
After some condensation spitting out of the stack, the loco starts to run with 32 axles behind the tender!
What a thrill!
The regulator has to be openend only 20% in order to drive this train with 32 axles easily.
Check the water gauge on a regular basis.
My track is about 40 meters long and after three rounds I have to fill up coal (one big shovel in front and one big shovel in the back of the firebox).
When the fire is really good burning (one round of 40 meters after a coal-refill) the safety valves are starting to blow!
In other words: STEAM GALORE!


De loc kan met gemak een trein met 32 assen trekken. Aan de zijkant van de rookkast is de kruishoofd gedreven voedingspomp gemonteerd.

The loco can easily pull a 32 axle train!!
At the side of the smokebox, mounted on the footplate and against the smokebox,
the dummy air pump, which acts as a crosshead pump, can be seen.


General specifications:

  • Model: freelance
  • Tender: REGNER modified with built in water tank and hand pump
  • Scale: approx. 1:22,5 on 45 mm gaugeLength: incl. tender 460 mm
  • With: 105 mm
  • Height: 160 mm
  • Weight: 5 kgs incl. tender
  • Smokestack (modified) , domes, chime: REGNER brass castings
  • Working pressure: 4 Bar (approx. 60 psi)
  • Boiler: according to drawings enclosed in this document
  • Water gauge: REGNER with blowdown valve
  • Blower valve: REGNER for 3 mm piping
  • Regulator valve: REGNER steam regulator for RC
  • Safety valves: 2 pcs REGNER (modified to 4 Bar)
  • Cylinders: ROUNDHOUSE bore x stroke = 14.288 x 15.875 mm
  • Valve gear: ROUNDHOUSE semi Walschaerts
  • Wheels: brass castings REGNER diam. machined 35 mm
  • Pitch between axles: 67 mmFrame: aluminium block with side plates out of 1.5mm sheet aluminium 51 ST. (at the firebox sides out of Stainless steelsheet 0.5mm)
  • Building time: about 6 months, due to a lot of ,bought , standard parts.


With many thanks to Rob van Dort - Holland and Vance Bass - USA,. who helped me very much with corrections and advise for these pages.

Reactions or Questions ? I would be very pleased to help you!
E-Mail to: info@modelbouwatelier.nl
URL: http://www.modelbouwatelier.nl

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