A total beginners locomotive.

[dscott]

Dear All,
Some of you may have noticed I am in the middle of several total scale locomotives, these are also being built to prove the designs.
Now from time to time I find for bedtime reading when I cant sleep, deep in a catalogue with every other engine described as the perfect one to start with. HOW much for a set of castings, and what if I drill a hole in the wrong place!!!!!
A bit of research brings to light a Design and parts for a De-Winton. Down in Kent you can buy a ready made one for the price of a third hand MG Midget. So lets do one entirely from stock materials and found products, yes the latest are dog bowls
for the ash pan and smokebox. In stainless steel of course.
Now a prototype for our simple engine, Back at the turn of the last centuary The Southern Imperial Metal Products Company needed a new works loco, so from all 4 corners of the works came the parts, Short of time money and with the months overtime used up they shortened the companies name each side
to S.I.M.P. so following the new design a novice should have Steam In Moments Please. (c) Jan 2007
David Scott.

Saves dusting off the Rob Roy started 20 years ago by my cousin and who else!!!.

[AndrewP]

David

De-Winton, design? that got my attention being part way through the design process myself. Thats a very fancy way of describing it!
Do tell more, patience is not one of my virtues.

Andy

[Steve M. W]

This link my be of use
www.co2.pwp.blueyonder.co.uk/newstuff/geohenry.html

Steve

[AndrewP]

Cheers Steve, I have seen that excellent write up but it's a bit big for my Chester Cobra lathe and micro-mill!
It was the concept of a 'bitza' using stock materials that appealed. Since this is a first loco and I have never had my hands on a live steam loco I don't want to come up with something completely impractical

Yes I know, first loco ---use an established design! but if this was easy it wouldn't be fun, and besides I really can't wait years and spend thousands.

btw I am not a rivet counter so De-Winton inspired would be a better description of what I have in mind.

Cheers, Andy

[dscott]

Dear Andrew,
Just the lathe that my design is aimed for, The wheels are 3 1/2" in diameter and the 2 flywheels are slightly smaller. cylinders out of 2" square. So this gives you more idea.
I have just turned 4 eccentrics for it this lunchtime. And this morning I was in at 7.00 doing the fence that goes round the side. Do I miss the traffic, and a contraflow over the river.
We could all start on a 5" star class, what a beast, I have a set of drawings. But unless they allow a workshop in the old peoples home, Id be in trouble finishing it.
Price, fully finished buffers for George Henry, are £70 S.I.M.P. uses 4 blocks of square metal with a screw in the middle. could even use 4 childrens building blocks with 4 no 10 by 5/8" screws holding them in place. The 6" boiler barrel is £70.
Well I am convinced, I am doing 2 with a kit of parts.
David.
Oh, it uses 8 rivets at the moment if you are counting!!!

[Laurie_B]

dscott said:

Dear Andrew,
We could all start on a 5" star class, what a beast, I have a set of drawings. But unless they allow a workshop in the old peoples home, Id be in trouble finishing it.
!!!

I like it,I like it!I have the works G.A. and Cross sections for No.40 "North Star" the first in the class.An interesting loco as it was originally built as a 4-4-2,with unusual 'scissors' valve gear.
There is also a set of very detailed drawings by Peter Rich.
Maybe not really a total beginners loco though!!

But this looks an attractive little loco for a starter?
www.brunell.com/product.asp?numRecordPosition=1&P_ID=148&strPageHistory=cat&strKeywords=&SearchFor=&PT_ID=71

[AndrewP]

Is that Tich?
I counted up over £580 of bits and thats without frames, bodywork and boiler - slightly desirable bits!
I have seen Tich described as not ideal for a beginner and I would worry about its ability to pull all 18 stone of me very far. Besides there must be hundreds of 'em - mostly unfinished if ebay is any guide.

Andy

[dscott]

Dear Andrew,
No this is not tich, This is starting with a clean piece of paper and drawing down what looks right within an A2 piece of paper. Having a seperate crank and chain drive to the front axle you can choose the best gearing 1 to 1 or 2 to 1 for pulling anything slowly. The cylinders are 1" and 1 1/4" dia with a 2" stroke, just power all the way. And so far it is looking very heavy for excelent tractive weight.
David.

[dscott]

Dear Laurie_b,
Yes this is a very attractive little engine but it comes with a long list of castings which puts the price up for someone just starting out. I have sourced some ready turned wheels for s.i.m.p.
which are £9.00 each, crossheads you build up and bore out and the big ends are axle boxes cut in half. So we are using lots of common parts, and the tollerances are forgiving.
I looked at the 2 Star sheets covering the bogie at lunchtime, just about the same amount of work involved as the simple engine. Then build the rest, then the tender.
David.

[AndrewP]

David
It gets better and better! I realise that simp isn't Tich, I was referring to the link in Laurie's post to the Brunell site, sorry for the confusion.

I figure a 2 foot gauge prototype running on 3.5" gauge is modelled at 1 3/4" to the foot so a De Wintons 6" bore and 12" stroke comes out at 7/8" and 1 3/4 - pretty close there.
Prototypes wheels are 1' 8" so scale is 2.916" and the 3" wheels I got on ebay will do for me - hey I've got 9 of them I could make two

Prototype boiler is 3' 1" so 5" copper tube is close - I haven't worked out how to do boiler calcs yet so don't know if disembarking from scale to get a bigger boiler would be worthwhile, I'm sure I read somewhere that most models are 'over boilered' and that that is no bad thing.

OK not quite true - my first attempt says I need 39 cu ft of steam per hour which at 80 psi 100 deg superheat is 6.5 lbs/hour. Just got to find out how to design a boiler to produce at least that.

So a question - with 3" wheels 4mph is 456 rpm, is that a reasonable expectation from such an engine? - Stephensons valve gear if it makes a difference.

It seems such a shame to make all that lovely valve gear and hide it between the cylinders, I really fancy mounting the valves outboard so we can see everything going on, that would upset the purists even more though.

I sound as if I am against true scale modelling - very far from it - envious more like, but I know my limitations!

Andy

[Shawki Shlemon]

dscott said:

Dear Laurie_b,
Then build the rest, then the tender.
David.

I always built tender first as when one completes the engine the urge is to run it .

[dscott]

Dear all,
As the engine is aimed at the total beginner, I have surgested 8 wheels and make a sit on tender with somewhere to hold the water and a tray of coal. you could carry a spare!!
On a real De-winton all the valve gear is hidden, I have it sitting on top with the crank held by the frames. Valve bits on the outside which is nice and so get atable for timing etc. Great you can gear it up to 4 to 1 if you like and save lots of steam, or go for slow move anything on the track with a 1 to 2. what a choice. As you say what speed of the engine.
Trying to sort out a boiler at the moment, now we have to use a published design, great find one that was published 50 years ago when we could get away with anything.
5" boiler drawing avalible. T.C. M.E. and LBSC. did it, well published.

David.

[dscott]

March update,

Work on the cylinder drawing has gone well this week and in between drawing the nothing smaller than 5 BA on the outside easy to get at to time the valves, steam chest bolt holes, I set our power hacksaw the task of cutting all the common size bearings for the whole engine. All of the split type and in fairly cheap cast iron.
Reeves do a drawing for a 6" dia boiler which sells for about £14 inc postage, so I am happy on that part.
Back to work in the morning to draw the various cylinder covers.

David.

Where using metric and imperial on a simple drawing makes it look complicated.

[dscott]

We start with a big question over riveted fabrication, or milling, or soldering something together.
Over in the corner of our kitchen or little box room having a brazing torch could be a bit of a problem. So I have opted for fabrication of things like forks out of 3 parts riveted together.
This also has the bonus of making the full stephenson link motion look quite old and or repaired at some time in its long life. Also being on the outside, there is plenty to see going on.
Now on my 8 th set of links, I know what they are like and without the special curved slot tool for the lathe, this is the most dificult bit without having to make someone drill and file the curved slot, I shall try out an idea next week to get round this.

Any comments are very welcome.

David.

[spurley]

Hi Dave

To make expansion links simple, have you considered Allan Straight Link valve gear? I don't know how prototypical it is for the type of engine you are proposing but I do know of several examples in full size including Baxter on the Bluebell Line www.bluebell-railway.co.uk/bluebell/pics/baxter.html . The advantage of this valve gear is that the link is straight, surprise surprise! But the weigh-bar shaft, ceratinly on Baxter anyway, moves the link and the valve rod when the reverser is operated. So two 'lifting' links per expansion link needed! Not sure how it would scheme out for your design though?

Cheers

Brian

[spurley]

Hi all

Here's another link www.southernsteamtrains.com/akpevt3br89.htm to show the valve gear as fitted to a Prussian locomotive. See what I mean about the weigh-bar etc?

Cheers

Brian

[dscott]

Dear Brian,

Thank you for the links, the Prussian loco looks impressive.
The valve gear that I am using is one that Martin Evans sent down to a friend in Somerset
for his Dougal loco. Now tried and tested and running like a scalded cat, I gave it a redraw with the intention of making it easy to make.
On all of my drawings the hints and tips and originators are credited in full.
Now for the links I started with a curved piece of 1/2" x 1/4" mild steel, cut filed or turned on the faceplate, then the outer piece is a pressed into a curve from a 1/4" x 1/8" mild steel bit held appart by two spacers and bolted together, skim these when the die block gets a bit worn.
The two rubbing faces can be lapped to a perfect fit against each other, there being only a small radius between to worry about.

David.

[steam4ian]

G'day Dave.

Your SIMP sounds a great project for me, I need to make up for years of lost time. It seems that generally you need to spend almost as much on tooling as the loco itself so I like your approach
A few questions:
Do you have any sketches or progress photos?
I assume it is a vertical boilered de Winton variation, is this so?
Is SIMP 5" gauge?
Are gears required for the transmisssion?
What type of valve gear?
Have you considered Hackworth or Woolfe?

A comment was made earlier about Allen Straight Link Motion; this valve gear was used extensively by the NSWGR in Australia; I guess some 6 classes totalling 600 locos.

Whilst still a kid I played on a road roller in a park, I recognosed it had Baker Gear. I knew Baker Gear because one class of loco on the SAR had it and that class frequently passed by my parents home. Years later I read that Baker gear was developed for road rollers! Not bad for a 12 year old kid?

For miniature locos I wonder at the need for notching up. At a local park the drivers never get the chance. Provided you have full forward and full reverse is there any need for other cut-offs? This could make a good topic for elsewhere.

One good turn deserves another.
Regards,
Ian

[dscott]

Dear Ian,

There are so many designs out there that are so called beginners projects, but as you say the ammount of tooling required is enormous. The biggest purchase is the boiler and I have gone for a 6" dia verticle from Reeves, a quoat of 950 pounds or I have just got most of the copper for just under 200 pounds from Mac Models, tubes inner and outer tube and silver solder etc.
Starting with an idea and a clean sheet of A3 the design began. you will need taps in 2, 4, and 5 BA or the metric versions. No castings, so in effect you could scale up or down, do a 4 3/4" gauge version for the States etc.
Some parts became too complex so I started again and in the handrails I have used one curved to provide the reverse lever notching up device, as the prototype was built by The Southern Imperial Metal Products Company in the early years of the last Centuary, and they were always short of cash
.
So this is to 5" gauge, full Stephenson link motion ( easy to build version ) It is chain or could be belt drive to the front wheels, and someone could if they fancy put in a gearbox!!! but that is getting complex.

I now have most of the drawings done and they are in Imperial and Metric, and this also covers the metal avalable. An interesting excercise.
The power plant is on seperate sheets so someone could put it into a steam car or buggy or a boat etc.

I could send you the General arrangement if you like, [e-mail] will find me.

David.

[dscott]

Here is Junes update.

The complet set of drawings were sent to a good friend, who set the valvegear into his software for checking. Came a reply that there is an even simpler valve gear with links only, that does not use eccentrics, and that the valve links are straight. Music to a simple engine.
and her builders.

The boiler got a look in last week with the two flanged plates being done over circles of MDF just the holes to do now.

David.