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Member postings for julian atkins

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

Thread: Gordon Smith safety valve spring
03/04/2018 22:32:34

Hi All,

I can say without a shadow of doubt there is an error in the drawings for Gordon Smith's 'squat valve' PSV#2E from Polly. I had to go back to Gordon's original EIM articles to work out what the error was as the valve would not close till pressure dropped to 50 psi, working pressure being 90 psi. The answer was in Gordon's original articles and taking 10 thou off the bottom of the shroud resulted in perfect performance.

I have not seen the drawing that John has worked to, but in the light of the above the drawing I was making them to had an error.

The springs supplied by Polly were spot on and excellent in my case.

The parts do need to be made to a very high degree of accuracy, especially the body internal bore around the shroud retaining the ball, and the shroud itself.

Cheers,

Julian

Thread: How do you fix a leak in steam loco copper fire box?
18/03/2018 00:26:57

Hi Simon,

Most if not all older miniature locomotives will have crown girder stays between inner firebox and outer firebox. These are secured in position by a few or more rivets on the inner firebox crown before silver soldering. These rivets are silver soldered in the course of the above, but sometimes they are missed or the silver solder does not penetrate properly.

Any repair attempt is determined by whether any of the adacent firebox stays are either comsoled and nutted threaded stays, or silver soldered.

Crown stay rod stays as opposed to girder stays are quite another matter.

A very careful examination of the inner firebox crown is required.

This requires the attention of an experienced club boiler inspector and his assessment and any repairs are going to be difficult.

Depending on the design of boiler and it's detailed construction (which you do not state or the design of loco or it's age, history and usage), and any inward bulging of the inner firebox crown on discovery of the leak, I would have serious doubts about an easy repair.

Usually such a leak would condemn the boiler.

Cheers,

Julian

Thread: super heaters
17/03/2018 22:18:48

Hi Chris,

I suggest you ditch the coaxial superheaters as they are not very efficient. The LBSC type is far better in copper pipe and spearhead return bends, but the return bends do need to be sifbronzed up to the copper pipe.

The coaxial type originated with Don Young's Mountaineer design in ME early 1970s at the suggestion of Alec Farmer.

A few years ago I became a convert of stainless radiant stainless superheaters extending into the firebox - that have to be TIG welded at the return ends, and is a job far beyond my capabilities. But friends with the requisite skills or contacts have provided the necessary.

I would never build a loco without superheaters in 3.5"g or 5"g. If you are a good attentive driver you notice the difference after the first half lap. The loco is more lively, uses less water and coal, and the valve gear can be notched up further so further using less steam. You also go through a tunnel and spectacle wearers like myself do not get their glasses 'steamed up' preventing seeing signals. The saving of coal and water is quite considerable in my experience.

Cheers,

Julian

Thread: Safety Valve
16/03/2018 00:50:08

Hi Kevin,

I would 3rd going down the Gordon Smith designs route.

Cheers,

Julian

Thread: 5 inch gauge "Maisie"
06/03/2018 00:46:51

Hi Gary,

The Blackgates Clarkson drawings and casting are the route to go by. The NRM have lots of drawings available, and there is a complete set of drawings for the LBSCR H2 Atlantic which devolved from the original Ivatt drawings, and which is being recreated in fullsize on the Bluebell Railway.

I have a GA from Doncaster of the Ivatt Atlantics as per Maisee, but LBSC took some liberties with his 3.5"g design.

I have not seen the Clarkson drawings but would imagine they are very accurate but not easy to interpret unless you have a lot of background knowledge.

W A (Bill) Carter built his 5"g Gold Medal winning example that won the top awards in 1967 and 1968 if you refer back to ME of this period. It was also a working miniature that proved itself on the track on the SMEE exhibition track for many years and at Beech Hurst.

I would also particularly recommend you acquire the RCTS LNER volume relevant to the large boilered GNR Atlantics and this will give you some appreciation as to the Richardson balanced slide valve version as to the later piston valve version.

Cheers,

Julian

Thread: Cry for help with 5" gauge manor class loco
28/02/2018 09:40:28

Hi Chris,

You will not find the angles of advance for the eccentrics on the Torquay Manor drawings because Martin Evans did not know how to work this out.

With Stephensons valve gear there is an optimum setting of the eccentrics for best valve events.

You can these days work all this out accurately and quickly on a computer on a valve gear simulator such as Prof Bill Hall's. Or you work everything out mathematically using Don Ashton's book.

Or you can guess the angle of advance by laborious minor alterations at certain cut offs and noting the amount of lead at Front Dead Centre (FDC), and Back Dead Centre (BDC).

On a piston valve loco I would use the cylinder drain cocks to find out when the valve opens to steam, checking first that the drain cock holes are not obscured by the piston at the end of it's strokes.

The GWR Churchward Stephensons valve gear uses relatively short eccentric rods which causes lead to increase far more as the gear is notched up when compared with other arrangements.

Therefore your Manor should be set for the valves to provide negative lead in full gear cut off of say 79%. A good starting point would be negative lead of 10 thou in full gear. This will result in lead not being excessive when the gear is notched up.

Each time you alter one eccentric or both the valve will need centralising again to produce equal leads - which is rather time consuming on a piston valve loco.

FDC and BDC must be accurately established and not guessed at.

Cheers,

Julian

Thread: Boring axle boxes
18/02/2018 00:02:29

Hi Peter,

I would agree that Don's description is not clear except I have most of his construction notes for his many designs both in LLAS and ME, plus knew Don, and I think my interpretation is the correct one, even if there may be better (but far more complicated and time consuming methods). I haven't had any problems doing the axleboxes as per my interpretation of Don's description for your design, which is much clearer in his other construction descriptions.

Obviously you need to know your 4 jaw chuck well.

I think the other suggestions are serious overkill.

Cheers,

Julian

Thread: "It" comes to life again
17/02/2018 21:46:06

Hi Dean,

I have been watching progress with much interest.

Yes, 'Tugboat Annie' in your above pic with the special unique Holcroft valve gear. I am not so sure if 'Curly' considered it his 'magnum opus' - I think his 3.5"g 'Grosvenor' was his favourite. No published plans for either but Carl Jones has done an excellent job of re-creating 'Grosvenor' in 3.5"g.

'Grosvenor' was also Stroudley's favourite loco and arguably his masterpiece, so a working miniature example in 3.5"g would have had a special place with 'Curly'.

Holcroft was a regular visitor to LBSC's home in Purley. Holcroft was a valve gear expert as well as an ex GWR draughtsman who knew Churchward and was given the job of designing the GWR 43XX class. Later on with the SECR and SR he developed the 3 cylinder locos with conjugated valve gear under Maunsell.

Cheers,

Julian

Thread: Boring axle boxes
16/02/2018 22:27:41

Hi Peter,

I think you have misinterpreted Don's writings. Just do each axle box in turn in the 4 jaw slackening off the same 2 jaws and turning around the L-H axlebox when compared to it's corresponding R-H axlebox.

Cheers,

Julian

Thread: Steam locomotive more technologically advanced than modern airliners for its time?
14/02/2018 23:13:35

Hi Simon,

Not sure this is the best forum for your question. Have you come across NatPress?

Some poor sod in LNER and BR days was paid a pittance to shovel tons of coal into an A1 firebox getting backache and blister on his hands, scorched legs, and covered in coal dust. The same poor sod had to work the injectors and keep a watch on the water gauges on a draughty cab. He would have to get up at all hours of the day and night on shiftwork and was not paid enough to own a car so would walk or cycle to work in all weathers probably from a small terraced house or council house.

Some other poor sod had to shovel out a smokebox of ash, and empty the firebox of clinker, if the fireman was lucky not to have to do this also. No covered accommodation for this - the wind would blow everything all over you and if it was raining you got soaked.

The fireman would have to go down and couple up the coaches or goods vehicles to the loco/tender which was precarious and risky and also very dirty.

Long shifts at unsocial hours, and to no set pattern.

Then you get a poor loco long overdue for a shopping that shakes you to bits and gives a very rough ride and steams poorly and you spend your whole shift in discomfort and struggling to make steam.

You finish your shift filthy dirty and your home does not have a modern bathroom, neither do you have facilities at work to wash and change before going home.

(Suggest you read Harold Gasson's books)

Cheers,

Julian

Thread: My first foray into clock repair
13/02/2018 21:43:27

Hi Brian,

Listen to the noise the clock makes when set up. I know this sounds elementary but a trained ear will be able to tell when the escapement is correct simply by listening to lots of other well set up clocks.

Cheers,

Julian

Thread: silver solder
10/02/2018 20:35:01

Hi Nigel,

As a rough rule of thumb I use about the same amount of silver solder in cost of the copper for the boiler. This would be for boilers with all silver soldered firebox stays. There are only a few grades of silver solder recommended for boiler work post the cadmium ban, that have the required ductility etc.

There are lots of reasons why people have problems silver soldering up miniature loco boilers, and one of these is meaness in applying the silver solder.

Cheers,

Julian

Thread: What Regulator type.
07/02/2018 21:31:56

Hi James,

I have never made a screw down regulator. They were rather frowned upon when I started this lark because they gave poor regulation of the steam plus a non prototypical angle of opening for the regulator handle, plus if not eased off after a steam up would seize up on cooling down.

The Martin Evans shape of the screw down valve conical end is not optimal for graduated regulator opening.

I am surprised no one has yet mentioned the use of modern gas pipe valves. There would be ample room in a 7.5"g loco such as Holmside with a dome to fit one. They are quite common in miniature locos these days. Far too modern for me, but then I am a bit of a dinosaur!

Cheers,

Julian

Thread: Advantages of Hackworth Valve gear?
02/02/2018 22:52:52

Hi Simon,

Hacksworth valve gear does not produce near optimum valve events as the gear is notched up, due to it's simplification. A well designed Stephenson's and Walschaerts valve gear does provide such valve events.

When you also factor in the up and down movement of the driving axle on steam locomotives further compromising the valve events, then it is a poor substitute, except for it's simplicity and cheapness of construction.

I remember as a young Talyllyn Railway volunteer the late Ron Smith (TR Driver) adjusting the valve gear of TR No.4 'Edward Thomas' regularly. If Ron had properly understood the limitations of Hackworth valve gear it is arguable his efforts were in vain.

One of the supreme rare enjoyments of miniature locomotive driving is to have a loco with superheaters and a decent valve gear when you can open up the regulator and wind back the reverser to 20% cut off and drive on the reverser as per fullsize steam express locos! You adjust the reverser from between 25 and 15% cut off to cater for all track conditions and a heavy load of punters behind.

Very few miniature locos can be driven in this way.

Cheers,

Julian

Thread: Water Gauge
01/02/2018 22:47:36

I don't actually agree with Jeff re separate shut off cocks top and bottom of the gauge as in 3.5"g and 5"g these restrict the passageways, and in any event I have never found them necessary.

Cheers,

Julian (first of Jeff's 1 in 15)

01/02/2018 22:44:04

Hi John,

It was told to me by Don Young after his Eastleigh apprentice days, and also related in his writings. Try greenish ended water gauge glass if you dare! I haven't tested it myself, as I have a large tin of gauge glass of various sizes, and I am quite happy with non- greenish glass ends that have never caused a problem!

Cheers,

Julian

01/02/2018 21:02:38

Hi David,

Not sure why you raised this issue.

If properly made and fitted, a miniature water gauge is as easy to read as in fullsize. I have never used a commercial fitting, making all of mine. In 35 years I have never had a gauge glass break, and on the 4 yearly boiler hydraulic test they withstand a pressure of 1.5 x working pressure. I have followed a series of articles for many of mine from EIM many years ago.

Some miniature locos give a poor reading in the glass because of restricted water legs in the backhead and protrusion of the lower bushes and water gauge fitting. There is much turbulance of the water and foaming in this area of the boiler.

Reading the gauge itself is simplified by sticking a bit of white card behind with diagonal parallel lines written upon it in black ball point. A gauge glass against a black painted backhead is not easy to read.

I have never used schellbach glass (though I have a stock of it) because it is more brittle. Discard any ordinary gauge glass that shows greenish ends.

Cheers,

Julian

Edited By julian atkins on 01/02/2018 21:04:05

Thread: My first foray into clock repair
01/02/2018 00:22:45

Hi Brian,

You have a relatively mass produced clock sadly of no great value. However, I would be as keen as you to get it running again and overhauled.

In my youth, a number of striking clock mechanisms (of no particular worth) were left in a tub of petrol, and the petrol squirted through all pivot holes with something like a turkey baster moving the pivots for and aft.

Later, other valuable movements were treated better and more thoroughly in subsequent years, and worn pivot holes rebushed, and damaged pivots replaced. But the tub of petrol approach is not to be dismissed if all pivots show no play in the pivot holes.

I can cope with English movements and their striking, and Longcase clock movements and their striking.

However, I failed miserably with an American striking movement on a rather nice family heirloom, and I failed to re-assemble the striking mechanism correctly after repairing some worn pivots and pivot holes with the clock completely dismantled. It runs ok and keeps good time, but I do not wind up the striking mechanism as it goes mad. Your project has inspired me to have another look at it after some 23 years.

But I think my point is that in these cheaper foreign movements is to be very careful what you do so far as dismantling and the striking mechanism. Others far more expert than me will no doubt give you far better advice.

Cheers,

Julian

Thread: Fitting horn blocks
25/01/2018 23:11:47

Hi Peter,

For the final machining I use a long series end mill reserved for such jobs.

The frames are set up as you describe in the vertical mill with the frames horizontal and clamped together and bolted together. The horncheeks have already been machined before riveting to the frames. Less than perhaps 10 thou is taken off with the long series end mill to final size for the axleboxes to slide. The hornstay faces on the horncheeks are done the same time.

Years ago I used the same proceedure using the vertical slide on the lathe but the whole frame assembly had to be carefully repositioned for each hornblock pair.

What you want to aim for is as near perfect parallel and matching faces to the hornblocks/cheeks for the axleboxes.

Cheers,

Julian

Thread: Budenberg Dead Weight Pressure Tester
25/01/2018 21:19:23

Brian said "Surely miniature pressure gauges can only be used as simple indicators."

Not if you have FSD miniature pressure gauges!

These were all individually calibrated on Freddie Dinnis's dead weight tester.

Freddie also re-calibrated a number of commercial gauges on the club locos, painting out the old dial and re-doing them.

Cheers,

Julian

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