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Merryweather Steam Fire King self propelled

this is the story of my freelance constructed fire king

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Doubletop25/02/2018 08:57:09
409 forum posts
4 photos



Déjà vu? I'm looking forward to seeing what you have done

Although theres not much constuctional detail in the zip file Neil posted for me (scroll down to his post). You'd need to read the ME article

I'm currently working on a steam indicator using the same hardware


Werner Schleidt25/02/2018 12:46:45
77 forum posts
125 photos

Hallo Pete,

it is nice to see that I am not alone with my thoughts.smiley

Here are a few descriptions of my devices .

The data collection is based on a PIC 16F684 processor with 10 bit resolution. I have 7 analog channels and two digitals. 2 Channels are dedicated to Volt and Ampere the others are with flexibel input that mean 0 to 5 V input.With jumpers the Ampere channel could be equiped with a pre amplifier for a current clamp.

I want to have all modular ,because I want to build a test bench for my model aeroplane props and motors with the same unit. Temperature I can measure with a simple NTC resistor and with thermocouple amplifier type K.

The force measurement is based on a chinese luggage gauge. It spends the strain gage element. An instrumentation amplifier with faktor around 1000 amplifies it to the real calibration.

The pulse wheel is made with 12 magnets these give 6 Pulses at the hall sensor.

All is build on prototype boards and a 9 V accu can power it all for 1 hour as long as my android phone run in full power mode.

All is testet ,but I am waiting to make real measurement with better wheather conditions.

The pressure sensor is a cheap chinese sensor with 12 bar scale and integrated electronic. I will see how good a 10 € sensor could be when I have it.

At the moment the system can send 5 to 6 full data frames per second. For more static measurement it is good enough. And all is running on 9600 baud.

For an indicator I think the rate have to be increased. And a good contactles displacement sensor have to be used.

Here are some pictures for better understanding.

Data acquisition send via blue tooth to the android phone software


This is a graphic example


The force transducer


On the left side is the fixture to the waggon ,in the middle the luggage gauge and on the right side there is a mechanical guide to eliminate side forces. On top the amplifier.

By chance i killed one element .One wire in the middle was detached. So I was forced to order a new one

for 5 €.

stgage defekt.jpg

The pulse wheel


The thermocouple amplifier with a cheap chinese element


I think it is a kind of overkill , but I hope I can find some room for further optimization.

with friendly regards


Doubletop25/02/2018 19:22:37
409 forum posts
4 photos


We need to catch up. There are items of yours I could use and there's stuff I can share with you. I'll send you a PM


Werner Schleidt26/02/2018 16:12:18
77 forum posts
125 photos

Hallo Pete,

look very nice what you have made.

I answer your PM


Werner Schleidt15/04/2018 08:41:05
77 forum posts
125 photos

Hello all ,

I want to update my work with a test ride under steam pressure.

First test ride after some improvements over the winter .The new donkey pump learned under steam what to do. With temperature the flying piston was very often sticky at the beginning. After some run in it worked fine. The automatic blower valve worked good ,but the spring need a replacement in a stronger one. By chance I noticed that my air pressure test gauge count the wrong value to less. And tightening means that the coil is nearly blocked.

At the end of the day came the "lovely" clean up work .

Here is a video of the ride.

Steam is always an adventure . I hope I can test my measurement equipment in close time frame.
I hope you can enjoy the video
Doubletop15/04/2018 09:00:59
409 forum posts
4 photos


You have it running very well


Werner Schleidt01/05/2018 18:32:26
77 forum posts
125 photos

Hello all,

here is an update of my activities. We had our steam up at my local club the DBC Rhein-Main. The street steamer had now a new colleage with a traction engine. And a new setinel " elphant " made it first rounds in the public and I had my partly improved Fire King with new donkey pump and automatic blower valve and I added a small car for children to sit on. There were a lot of steam and electric locos on our club track.

In between with lot of improvisation I made my first real test with my measurement unit with the dyno and the pulse wheel and so on. There is a picture of the raw data on the quick look display on the phone.


The green line is speed and the white line is the dyno force. As I know now there is small lash in the coupling bolt and the road surface looked smooth ,but because of pavement it is rough with some noise in the dyno .


This chart is the averaged raw data of the dyno and the speed which is calculated from km/h to m/s to calculate the power in Watt. See next chart.


By the first shot I think it is not bad ,but I have some idea for refinements.

There is a video of the steam up at out club area.

I hope you can enjoy the video.

best regards


Oldiron01/05/2018 22:42:54
272 forum posts
17 photos

Really great job Werner. Very much enjoyed this build.


Doubletop01/05/2018 23:54:23
409 forum posts
4 photos


An excellent job.

You should expect the noise in the data, the engine itself introduces noise as a result of the reciprocating masses. It even happens with locos running on rails. Maybe some better fitting pins in the couplings could help a bit but don't try to do too much mechanical damping. Just do it in the processing of the raw data, as you have done.


Werner Schleidt29/05/2018 19:40:17
77 forum posts
125 photos

Hello all ,

here is an update of our activities at our club parking lot. The audience was so kind to park a few steps away to hold free the parking lot.

The Sentinel Elephant was in better condition ,but it want not to burn anthrazit coal ,but a mix with smoky coal it burns much better.

I had problems with my oil pump again. That is at the moment the only thing to improve.

For the automatic blower valve I made a stainless steel spring .It was wounded in my lathe and the material was adapted from a broken spoke of a bicycle wheel. Never throw away something useful!


I hope you can enjoy the video

Edited By Werner Schleidt on 29/05/2018 19:41:24

Werner Schleidt24/07/2018 19:51:32
77 forum posts
125 photos

Hello all,

on the last weekend in my hometown was an vintage car and tractor event. I joined with my Fireking for Saturday and Sunday. On both days i drove about 8 km amd never before I had so long the fire burning.

There were many interested people and I had some nice conversations.

My oil pump was in function,but I think the piston is too small. At my locomotives I had much more oil in the cylnder and at the top of the chimney. Here at the fireking the chimney top is nearly dry and without oil. I have a cylinder bore of 42 mm and a 2,3 mm piston .In the locos I have a 40 mm bore and a 3mm oil piston.

Is there some kind of rule of thumb or choosen by try and error?

Here is the video I made.

best regards


Werner Schleidt22/09/2018 19:29:39
77 forum posts
125 photos


I want to add some new experiences . For the reason of flying sparks I added this year a spark arrestor made of a tea ball. At the Mannheim steam event I added in the bigger middle tube a turbulator to get better fire results.

I measured a decrease of 50 °C less temperature ,but from my feeling the boiler effience was not as before.

On sunday i decided to drive without spark arrestor and turbulator and found that the fire burns much better. In the exhaust less changes have more effect that i imagine. These two days brought lot of fun to give you an impression please take a look to the video.

best regards






Edited By Werner Schleidt on 22/09/2018 19:30:56

David George 122/09/2018 20:08:53
908 forum posts
301 photos

Thanks Werner for your contribution to the forum Thought the video was great. What machinery do you have to build and machine your models on?


Werner Schleidt23/09/2018 08:13:35
77 forum posts
125 photos

Hallo David,

I have a small lathe ,hobbymat, and a similar lathe to the emco compact 8. The most of the parts I built on the smaler one . Only the parts where I have problems or it is not possible I took the larger compact 8.

Both are precise but I like more to work with the small lathe. My milling machine is a BFE from the same manufacturer as the hobbymat. In the first build videos there are some pictures of the machinery . Then I have a bore milling machine and a self build hack sawing machine where i can use hand sawing blades as a replacement that is very cheap in comparison to band saw blades.

With a part of this equipment I started my steam career by building 45 mm steam locos.From this time I learned a lot. I have build 5 45mm locos and 4 5 inch steam locos. The last one in compound action.

By chance i found by ebay uk a boiler of a tea pot quarry locomotive. With some thoughts the fire king project starts all build after old pictures I found in the web.

Making the wheels was very tricky and i milled them round with much of improvisation.

I hope that answers your questions.


Ron Laden23/09/2018 08:48:02
1354 forum posts
240 photos

Thanks Werner for sharing the videos, I enjoyed them. I think your Fire King is very good indeed, you have done a great job with it and it is something a bit different...very nice.


Werner Schleidt31/10/2018 17:40:47
77 forum posts
125 photos

Hello , there is an update of my activities.

In a german steam forum there was an advice to use  a turbulator ,if you do not have installed a overheater pipe in the boiler. The turbulator give some friction for the heated air stream and a better heat transfer to the boiler pipe.

And a basic effect is to equal the heat over all available pipes. So the boiler effiency is better. That is the theory behind. In the first step i made one 20 mm wide steel stripe and twisted it as possible. That was not very good makeable. So I cut some fins out and twist them.

With this setup I drove with my friends in September at our Club track at the DBC Rhine Main.

There was a subjective impression that there is a slight improvement in steaming. The tests were made in the range of 18°C .

Please look from start or from 7.20 for road steam
After this impression i made a new setup like this
This four metal stripes are hanging in the overheater pipe. They work as spark arrestors and the function is as described in the beginning.
On our last steaming day in this year, I made a test with this setup. It was cold 6 to 7 degrees and very windy. It takes a long time to get steam , but then I was surprised. During driving I had a lot of steam .In many cases the safety valve was constant blowing and only by water pumping the pressure came down. All drivers had the feeling with the cold temperatures the need a lot more water. The performance was better then in conditions over 20°C. I was able to hold the pressure during full speed and water pumping. The only thing the pressure came down , I was not able to put coal in during fast driving.
To give you an impression please look the video.
For next year I have to add air doors at my ashpan and grate area.
If there is someone who have experience please share some thoughts.
Best regards

Edited By Werner Schleidt on 31/10/2018 17:41:16

Edited By Werner Schleidt on 31/10/2018 17:42:08

Edited By Werner Schleidt on 31/10/2018 17:45:10

Neil Wyatt31/10/2018 19:39:50
16559 forum posts
687 photos
75 articles

Nice video Werner, I love the sound your engine makes.


JC5431/10/2018 20:49:55
95 forum posts
1 photos


What a superb model and engineering. Many thanks for sharing this build with us. John

Werner Schleidt01/03/2019 09:18:49
77 forum posts
125 photos

During winter time I made some cleaning activities and I had to rework and improve the joint to my crankshaft.

The forces from the cylinder to the crankshaft I had underated. The oscillating force lead to a weak conection.

The fireking was running in two years 80 km .

On the last ride last year I had such a good fire after installing the turbulator device I decided to test fire damper doors for better controlling the fire with less blow off from the safety valves.

Here are picture s open and closed . I hope that work as it is intended.



I will try to measure the difference with a thermo probe and I hope the effect is as I wanted it.

Here is a collection of video scenes from 2018 to give some pre enjoyment for the new steam season 2019.

duncan webster01/03/2019 09:58:02
2226 forum posts
32 photos

Werner, I've enjoyed reading your posts, nice to see something different from endless locos. Do you have any drawings of your automatic blower valve, something I've always fancied having a go at.

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