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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: Fitting horn blocks
25/01/2018 21:13:03

Hi Peter,

As the horncheek castings (whether of cast iron or gunmetal) will be softer than the steel frames, then I would drill the frames first, checking of course that where you drill will avoid any ribbing on the castings etc. Then spot through one hole at a time into the horncheek castings.

Add temporary bolts as you go de-burring the castings as you go if gunmetal (easy if for 1/8" rivets and use temporary 5BA bolts).

When you rivet up, add all the temporary bolts etc and do one rivet at a time.

Then I put the 2 frames outside facing outside if that makes sense, then mill the final working faces in the vertical mill.

Cheers,

Julian

Thread: Roedean
25/01/2018 00:55:19

Hi Nigel,

I agree the fullsize examples of the SR 'Schools' were and are still very impressive locos!

Unfortunately, LBSC's 'Roedean' is not well drawn, and IMO requires considerable input and detailed knowledge of the fullsize locos to put right plus the middle cylinder valve gear problems.

I may be coloured in my own opinion when the only example I saw close up on boiler test when first built had the firebox crown collapse. This was the LBSC version, not Clarksons.

Cheers,

Julian

24/01/2018 23:27:33

Hi Nigel,

Roedean was originally described in English Mechanics with the rather less detailed description of construction that equally applies to Speedy also described in English Mechanics. ME subsequently acquired English Mechanics so then owned the copyright to Roedean and Speedy.

As stated above, ME reprinted the English Mechanics Roedean articles in recent years in 2011. Sadly the drawings especially the boiler were NOT updated though this was an ideal opportunity to do this.

In 35 years at this lark I have never seen a Roedean in steam on a track, and there are numerous complications with the middle cylinder valvegear and weighshafts and I would not consider Roedean by any stretch of the imagination to be a beginner's loco.

So I wish you all the best with a design that many have struggled with and many more simply avoided.

Cheers,

Julian

Thread: Don Youngs Lucky 7
24/01/2018 21:24:45

Hi Gary,

You need to obtain the relevant copies of LLAS if it was described in LLAS (Don Young's quarterly magazine). I will need to check if it was so described as a construction series in LLAS.

It is a fantastic loco to drive! I drove a rather poorly made example that nevertheless went like a rocket, steamed superbly, and rode like a bogie coach. It is an excellent design IMHO.

Cheers,

Julian

Thread: Where to Start
23/01/2018 10:42:13

Hi James,

I will chip in with my usual advice for beginners not to choose a loco with piston valves or a boiler with a tapered barrel and belpaire firebox or combustion chamber.

The Black 5 and Brit have tapered barrels and belpaire fireboxes and piston valves.

The A3 has piston valves, 3 cylinders (which in the case of Don Young's 5"g 'Doncaster' are very expensive castings and very complex to machine), and the boiler has a short combustion chamber which complicates things.

Also bear in mind that a big ie long 5"g loco is uncomfortable for many people to drive and fire properly on a raised track, and on ground level 7.25" you are likely to have your face in the exhaust most of the time and many people also find the driving position uncomfortable. 5"g ground level is even more uncomfortable IMHO.

So best to join the Llanelli club, and find out a bit more first.

Cheers,

Julian

Thread: 3 1/2 inch small boilered TICH
19/01/2018 13:32:48

Hi Ryan,

You can use copper and I note you appear to have some big pieces noting how your firehole ring was turned out of solid. LBSC often used copper for the dome bush.

Personally, I hate turning copper, and drilling and tapping it even less. Save the copper for something else.

The fixings - you will need bolts to hold the dome to the dome bush. Brass screws are not strong enough. I prefer to have an unthreaded plain shank up to the bolt head which aids sealing. Commercial bolts in stainless will probably be undersized on the thread, and won't have an unthreaded portion, and the heads will be too big and will interfere with the dome itself. So I make them all myself out of stainless hex.

Cheers,

Julian

19/01/2018 10:07:55

Hi Ryan,

I have always drilled and tapped the dome bush, regulator bush on the backhead, and regulator bush on the smokebox tubeplate before silver soldering.

I have always used hard drawn phos bronze for these bits. The usual tip is not to fully complete the tapping in case the threads get damaged by the long heat ups on the boiler and repeated dunking in sulphuric acid. I have never had this problem, but it might be more of a problem if you use gunmetal for these bushes.

The regulator stand is ok because the fixings are tapped into it and not the copper.

One of my least favourite jobs is making all the fitted bolts out of stainless for all the fixings.

Good luck!

Cheers,

Julian

17/01/2018 21:52:15

Hi Ryan,

Your LBSC drawing on 15th January of the regulator arrangement would not be ok on a new build in the UK or Australia.

Instead of the copper backhead and smokebox tubeplate being threaded, bushes are now required which are threaded and silver soldered to these plates (the threading is only partly done before silver soldering the bushes to the plates).

The threaded smokebox end of the regulator steam pipe into a further threaded bush is quite tricky to do, and so I would also recommend John Baguley's arrangement.

I would silver solder a bronze tube to the smokebox end of the copper regulator steam pipe. (The regulator pipe should be of thick wall copper tube to accept the thread to screw into the regulator valve body). A screw driver slot can be added to the smokebox end which if bronze will be undamaged.

I am very interested in Pete's use of a turned PTFE bush to seal the smokebox end between regulator steam pipe and the wet header.

Cheers,

Julian

Thread: Cameras or Dishes?
16/01/2018 23:11:00

Does the Jodrell Bank thing still rotate on a track on ex-GWR Castle class bogie sets?

Cheers,

Julian

Edited By julian atkins on 16/01/2018 23:11:30

Thread: Channel 4 (UK) tonight Sunday Jan 7
14/01/2018 21:38:19

I am losing the will to live watching the second instalment.

What could have been a fine example of model engineering in the smaller gauges has become utter rubbish and drivel.

I am just about to change channels or fall to sleep.

Cheers,

Julian

Thread: Ferric Chloride Disposal
13/01/2018 19:15:33

Hi Simon,

3 litres is a lot!

Can you pour it around the base of neighbours' leylandii trees?

Cheers,

Julian

Thread: valve events
09/01/2018 21:11:40

Hi Robin,

Fowlers Fury is quite correct that ordinary PTFE piston valves will leak on air, but should be ok on steam when the cylinders have warmed up.

Note also that I do not use steam oil when running on air, and use Singer sewing machine oil to lubricate the valves and pistons.

On the modeleng.proboards.com forum site, Roger Froud has developed a way of making piston valves with PTFE and 'O' rings underneath that seal on air and steam.

Cheers,

Julian

09/01/2018 10:41:45

Hi Robin,

As you are probably aware the GWR Stars, Castles, and Kings have inside Walschaerts valve gear operating the inside cylinders and their piston valves.

The outside cylinders have their valves driven by cranked rocker arms worked off the valves to the inside cylinders.

The expansion links are very difficult to access, as is most of the internal valve gear without a major strip down of the whole loco. There is a substantial horizontal frame stretcher on the top of the frames which contains the expansion links and the intermediate weighshaft (which is split into 2 sections).

I presume your acquisition has piston valves, which are not easy to set accurately, and in any event there are peculiarities with the gear geometry that require subtle non centralising of the valves to get all the cut off and exhaust positions the same, compromising the admission points somewhat.

Any slack in the inside gear makes setting the outside piston valves difficult to achieve with accuracy.

Checking the valve settings the proper way is very involved on a GWR King, but essentially the same process is used as you would on a simple 2 outside cylinder loco with Walschaerts.

The complications arise because the expansion links are pretty much hidden, even with the boiler, smokebox, and front bogie off, and checking the correct setting of the 2 eccentrics and the correct length of the eccentric rods is similarly inaccessible.

If you say the loco runs on steam, I would give it a decent load on the track and listen.

You ought to have 4 distinct beats from the exhaust, each side of the loco exhausting at the same time, and you ought to be able to notch up the gear on the reverser to at least 25 % cut off with the beats still being loud even and clear.

If the beats are ok and you can notch up the gear then I think I would leave well alone. If however you are getting a 'whoosh whoosh' then there is probably something wrong with the piston valves leaking. (There is a further fullsize proceedure that can be used in miniature to check this further).

The exhaust pipes and passages on the GWR Kings are rather complicated and in miniature I have yet to see a 5"g example that really sparkled as it should, and with the distinctive GWR 'bark'.

Do not start to dismantle the loco unless you are absolutely sure what you are doing, and are absolutely sure you will be able to put it all back together again!

Cheers,

Julian

Thread: J Wilding scroll frame clock - fusee arbor pivot sizes?
07/01/2018 21:39:34

Hi John,

Thank you for the above very helpful posts and detail. One of the most interesting and informative series of posts I have read on this forum.

Mike, good luck with the clock!

Cheers,

Julian

Thread: hardening/tempering a bit of steel
02/01/2018 22:29:29

With the greatest respect there is no evidence that what Sean is proposing to use is silver steel!

There are various simple tests for silver steel.

If Sean's material is not silver steel then a lot of the above is academic, as is Sean's aim to harden and temper the material he has.

Cheers,

Julian

Thread: Live Steam Loco Questions
18/12/2017 08:39:49

Hi Stewart,

My advice would essentially be the same as that provided by Simon Collier - join a decent club and get involved.

The questions you posed are very broad.

If you ask a room full of model engineering club members the same questions you will probably get a different answer from each of them.

If you want to build a miniature loco to do a job of work and haul passengers rather than for display or just as an engineering construction exercise then you really do need to join a club.

Firstly you will need to run the loco somewhere when completed.

Secondly the condition of that club's track will have a bearing on what loco you choose to build - the obvious factors being whether ground level or raised track and the gradients.

Thirdly you may not like it! Operating a miniature loco requires a great deal of heavy lifting usually and a suitable car. You may find that leaning over a tender to get at the controls is uncomfortable. You may not like inhaling large quantities of smoke. You may not like all the mess and muck associated with running a miniature loco.

As for choice of loco and gauge, it is no secret on here that I would never suggest anyone build LBSC's Tich, and I would never advise anyone to build Martin Evans' 'Simplex'.

For a beginner I would suggest avoiding anything with a tapered barrel boiler and belpaire firebox, avoid anything with a combustion chamber, and avoid anything with piston valves. I also dislike sloping grates, marine type boilers, and anything with a long tender.

Certain well known designs have well known faults, and are best avoided unless you are prepared to depart from the drawings. Certain designs are not really suitable for a beginner and some are considered very poor.

So, I would stay clear of anything designed by Greenly or Jackson/Clarkson. I would stay clear of some of Keith Wilson's designs.

Also consider designs that have a construction series in ME/EIM/LLAS.

Have a good look at Don Young's designs (see Reeves website). Usual disclaimer.

Cheers,

Julian

Edited By julian atkins on 18/12/2017 08:47:32

Thread: Hackfly Requires a Rebuild says LBSC
14/12/2017 11:23:52

Hi Dave,

You have to bear in mind that when Hackfly was published in ME, Martin Evans was desperate for any miniature loco articles to fill the pages.

Issue after issue contained articles and letters by K N Harris, who at every opportunity criticised LBSC.

K N Harris and Turpin were friends. Turpin himself had written about his 5"g loco 'Hybrid' in 1956 in a manner that was not exactly 'modest'!

Note that K N Harris acquired 'Hybrid' from Turpin.

LBSC was very well informed and knew of the link between Harris and Turpin.

LBSC was wrong to resort to personal criticism of Turpin, but that was LBSC!

Cheers,

Julian

13/12/2017 22:30:24

Hi Dave,

Hackfly was indeed an atrocious design. It was perhaps the worst point in the history of the ME magazine.

It was atrocious and awful in virtually every design detail.

Given that 'tyro' model engineers often build miniature locomotives that are not the best designs and end up disappointed after spending a great deal of money and spare time, I think LBSC was quite correct to criticise the design. He did exactly the same some years earlier when Jack Austen Walten described with drawings a boiler that would have been quite unsafe for 'Twin Sisters'.

Anyone can look at the Hackfly drawings in ME and would no doubt completely agree with LBSC's criticisms, as I do.

Cheers,

Julian

Thread: Valve gear design
09/12/2017 21:17:42

Hi John,

I have sent you a PM.

Cheers,

Julian

03/12/2017 11:21:54

Hi John,

Don Ashton's book is available from Camden Miniature Steam Services.

On pages 28 and 29 you will find a worked example that would fit your requirements. Lap is 0.120" and note it is not necessary for the steam port to open fully to incoming steam so valve travel is a bit less than your 5/8"

In Don's example the eccentric throw is 0.460"

Cheers,

Julian

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