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Member postings for Stewart Hart

Here is a list of all the postings Stewart Hart has made in our forums. Click on a thread name to jump to the thread.

Thread: Potty:- Helping Dad Grasshopper Engine
17/03/2019 20:06:30

There's is just one condition to you getting the plans and that is that you post a picture of the finished engine her on this Forum



17/03/2019 19:32:30
Posted by Philip Burley on 17/03/2019 19:24:07:

hello , are these plans freely available please , I should like to have a go at one

regards Phil

Just send me a pm with your email address and I’ll send them


17/03/2019 18:23:28

Hi George

I’ve sent you a pm with my email

To send a member a pm open there profile scroll down and you’ll find a tick box send me a message


17/03/2019 09:26:40
This is the video of the completed engine
16/03/2019 18:31:54

Hi John

I did submit it but it was never published probably because I’d had a couyof similar engines published and things were getting repetitive. If you want a set of drawings just send me a pm with your email address I’ll send you them



Thread: Building the 'Potty mill engine' the beginners way.
12/03/2019 20:33:37

Hi Peter

Don't think I've seen your completed mill engine running like all of your engines its looks very good, i always have a big grin when I see one of my engines designs completed and running.

I noticed a few comments regarding the drawings and copyright issues, I designed the engine to encourage newcomers to the hobby and to that end I'm quite happy for the drawings to be passed around and shared, I gave permission for Jewels to draw the engine up in 3D cad and to make his drawing public. As a word of warning to anyone contemplating using Jewels' drawing to build an engine:- they were created as a drawing exercise not as working drawings Jewels has put his own interpretations into his drawings making some aspects of it confusing, so for any one contemplating making this engine I would suggest they get hold of a copy of my drawings they are far more user friendly.

Keep Modelling


Thread: Vertical Injectors
20/02/2019 07:18:14

Hi Julian

Thanks for your input, I've always found your insight on injectors very useful and informative. That,s a very good point about the combining cones not being accessible, it never occurred to me. I'm planning on using the vertical injector for this years running season so we'll see how it goes.

The horizontal injector I've used for 2 years on my tank engine was the best from the batch of five I made, it seems very tolerant of water temperature I don't need to keep the water on to keep it cool, I must have got the insert depth of the steam cone just right (by luck). Getting the cones in the correct position is probably the most difficult part as most home workshops just don't have the equipment to control and measure the critical features to any great accuracy, I've found the best way round this is to just make a number of different cones and test them and choose the best ones.

The injectors I've made, from DAG Brown's chart would have a delivery rate of about 22-25 oz/min which is a bit on the high side for a 5" loco, they soon drop the boiler pressure, but as I use the axle pump when on the move and only use the injector when stationary I don't find this to inconvenient. The Horwich Crab I'm building won't have an axle pump just two injectors so at some point in the future I'll try and make a couple of lower rated injectors for it.


Edited By Stewart Hart on 20/02/2019 07:23:09

Edited By Stewart Hart on 20/02/2019 07:29:44

19/02/2019 07:42:46

Thanks for your interest gents

Some people say there is a black art in making injectors:- but all that is really needed is a good understanding of how they work this coupled with some careful machining and patience.

I was given a set of instruction by my friend that I followed and was amazed when the first one worked so made another 4 not one of which worked remade the cones being extra carful and they all worked.

There are plenty of good books out there the best for theory is probably D.A.G Brown's (Miniature Injectors Inside and out ISBN 1857611349) but with all respect to DAG his body design is far too complicated, so to his is method for making the cones. LBSC on the other hand is far to simplified relying on good luck more than anything.

This is the first injector I made


And some of the tools required


As for an article there have been lots of articles in the magazine on making injectors I don't know if the Ed would want any more.

The vertical injector body is made in two parts from hex or square bar and can be made in the lathe with the cross holes drilled the two parts can be silver soldered or soft soldered together. The cones:- which are the critical parts, need carful manufacture to get the critical features correct are made the same as any other injector. Our vertical design uses two over flows the top one (copper Pipe) takes the flow from the combination cones it shuts off when the clack valve closes due to the vacuum that's created, the bottom takes the surplus water from the delivery cone.

I think the main advantage of the vertical design is that you can simplify the pipe runs (less Bends) by moving the water feed onto the best suitable face:- I could have had a straight pipe from the water feed valve into the injector if I'd had its water coupling on the face, facing the valve, but I didn't twig onto this until I had the injector made.


Edited By Stewart Hart on 19/02/2019 07:56:36

18/02/2019 14:13:06

I've noticed that most Injectors fitted to smaller gauge loco (5" and Below) are mainly the horizontal type. You can get vertical injectors for larger gauges and for full size locos vertical injectors seem to be widely used.

The possible reason for this is that the ball clack that shuts off with the vacuum, needs a little help from gravity so simply turning a horizontal injector on its side will not work. In larger sized vertical injectors it is possible engineer the clack so that this is not so much a problem, but its not so easy for smaller injectors.

Some time ago myself and a friend started to experimenting with smaller sized injectors our objective was to come up with a simple design for a vertical injector suitable for a 5" loco. After a few false starts we started to understand the issues involved and came up with this design.


On my friends test boiler it worked well, at this point I didn't want to fit it to my loco as I had an injector that was working well, but when its hydraulic certificate ran out and it needing a little maintenance , I decide to fit one of our vertical injectors.


I've now testing the injector on my loco and I'm really pleased how it works it picks up straight away even at low boiler pressure.

I was wondering if any one else has had experience with making vertical injectors for 5" gauge locos.


Edited By Stewart Hart on 18/02/2019 14:48:12

Thread: Water/Coal Wagon
07/02/2019 16:10:59

When I started to build my Horwich Crab I had the opportunity to buy a part finished tender at the right price. It wasn't quite the correct tender for the crab but for me it was near enough, now that I've got the part built engine running on air I thought I'd better finish off this tender. Having a good look at it I realised that it just would,t be quite a suitable tender for the crab (wrong wheel size). To cut my loses I decided to convert it into a water/coal wagon from my Simplex Tank engine, as it would be good practice making a water tank.

This is the finished wagon


It took me a good 1/2 dozen tries to get the tank water tight but I got there in the end.


Thread: Sealing water tanks
23/01/2019 10:40:37
Posted by JasonB on 23/01/2019 09:18:48:

A lot will depend on what access Stew has to his tender, if just a small hole it will be hard to brush anything on, with the POR and epoxy you just pour some in swill it about and then drain the waste.

Thanks for you help full replies chaps, I've left the top of the tank off so that I can get at the inside getting the top sealed is less important than the bottom


23/01/2019 07:45:01

I'm trying to build a water tender tank and I'm having problems getting it water tight by just using soft solder. Is there a sealant I could use to do the job I understand that some people have used petrol tank sealant can any one point me in the direction of a supplier.



Thread: Best way to turn long, thin brass job
24/12/2018 06:54:48
This is what you want if you PM me I'll send you the drawings
Thread: Helping dad vertical engine
21/12/2018 07:05:48
Posted by Jim Greenhill on 20/12/2018 16:04:21:

Hi I have just about completed the first tried on air the other day could not get it to work at all, reset the timing nothing tried timing again 180 degrees nothing. Went back to it today working my way through how it should work following the air route.

I have not cut the top of the cylinder to meet up with the port hole, so when you put the cylinder caps on no air could get to the piston. I now remember I did not have a small end mill to cut this I was to order one , guess who forgot, carried on the build.

End mill now on order. Will let you know if and when it runs ( No I should say WHEN it runs)

Next is the horizontal , I do hope the third will be coming out as I am learning a lot. Stew, like to take this time in thanking you for the time and effort you have put into these projects much appreciated


Hi Jim Thanks for your kind comment and interest in the Mill engine. As for the air passage as Jason said it doesn't have be to fussy as long as their is a way through for the air it will work you could just use a small file or even a small chisel to make the passage..


Thread: 2-6-0 Horwich Crab
03/11/2018 06:37:53

Thanks for your comments chaps.

When I've got the last bit of linkage made and done a little tinkering, its going away whilst I do a short term project I have planned then I'm going to finish off the tender before dusting it down and getting on with make more bits for it.


02/11/2018 18:48:48
I've just achieved a significant milestone with this build in that I've just got it running on air
Its runs a little lumpy because I only roughly centred the valves by eye and I had left some of the brackets lose so things should get better . I've still got to make the radius link to complete all the motion works but I'm very pleased that I've reached this important milestone.
Thread: Train In a Bottle
06/10/2018 18:43:42

I've just made this novelty for my youngest train enthusiast grandson's 4th birthday




Thread: 2-6-0 Horwich Crab
05/10/2018 06:56:30

I've not updated this since February I have made progress since then but progress was slow through the summer months as other things got in the way. I've more or less completed the motion with one or two thing needing tidying up and one more link to make but I can't do that until I've determined the hole centres then its a mater of setting the valve events to try it on air.



Ignore the date on the photo I still havn't got round to setting the camera to the correct date.


Thread: Unusual Oscillating Cylinder Locomotive
01/10/2018 08:18:39

Thanks for the input and photo Grant


30/09/2018 19:42:05

A Little more information via a utube comment I'll do a little more online research

"Real versions of this sort of engine were briefly used by American logging companies in an attempt to idiot proof locomotive running gear. I believe they were built mostly if not entirely by Dewey Brothers Locomotive Works and supposedly they worked alright for industrial purposes, although wear and steam tightness of the cylinder pivots were an issue

Edited By Stewart Hart on 30/09/2018 19:42:54

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