Member postings for julian atkins

I understood Geoff's query to be about the front and back tolerance between the horncheeks and axleboxes.

Others have commented on sideplay of same with the wheel assembly, the need to slightly curve the edges of the axleboxes against the edges of the horns to allow the wheelsets to tilt, and what tolerance to provide in coupling rod bearings.

I provide 1/32" sideplay each side, except the driving axle has this halved.

How much play you need in coupling rod bushes depends how well the loco is made and how well the wheels (or if outside frames the outer cranks) are quartered. You ought to be able to start with a 1 to 2 thou clearance on crankpins to coupling rod bushes especially on the driving axle, and a thou on any knuckle joints.

As Neil says, valve setting can be done far more accurately (or shall we say is much easier) if there is no slop especially on the driving axle assembly.

Depending on how good your track is, the tilt requirement on the axles may vary. I allow 1/8" to 3/16" either side (up and down) of the running height on each axle, with stronger springs on the front and driving coupled axles. The rear axle on an 0-6-0 loco I fit softer springs.

The above is for 5"g.

Most designs have far too much sideplay, and if ordinary coil springs are fitted great care to ensure they dont restrict the 'tilt' movement.

Cheers,

Julian

Hi Geoff,

As you are not building a miniature steam loco you can get away with larger clearances. If I can squeeze a 1.5 thou feeler gauge between the horns and axlebox slides I leave it at that ( so in effect 3/4 thou either side). If much more I shim the horns. However this is for miniature loco work where there is a considerable battering ram effect on the axleboxes as the reciprocal motion is transfered to rotating motion. This wont apply to your loco.

Cheers,

Julian

Hi John,

My procedure is to carefully insert the boiler or sub assembly into dilute sulphuric acid when hot but after it has cooled down quite a bit. If the copper does not come out sort of dirty pink there is something wrong with your acid - it may not be strong enough or it may be contaminated.

The boiler is then hosed down with the garden hose.

The boiler then gets transfered to the domestic draining board and scrubbed with hot soapy water. It is surprising what extra muck comes off at this stage.

Flux - firstly you are using the wrong type of flux anyway for boiler work. Due to the longer heat ups J&M Easyflo flux will be exhausted too quickly. Also depending on what grade silver solder you are using you need a more active flux anyway. So instead use J&M Tenacity 4A, or Thessco F flux, or the equivalent grade supplied by CupAlloys.

To remove glass hard deposits of flux J&M recommend soaking in a hot strong solution of Sodium Hydroxide/Caustic Soda. It is very cheap and available from Wilkos etc. Do this after the pickling, rinsing, and scrubbing stages.

You may need to pick about at the flux deposits a bit with a dental probe or scriber.

Cheers,

Julian

Edited By julian atkins on 19/08/2016 10:11:41

Hi Derek,

John Baguley is the expert in this field. Be guided by him.

Cheers,

Julian

Hi Michael,

You really need to get the full set of drawings and the construction series which was in in ME 1969-1970. I have the full set of MEs for this period if you have any queries.

It is pretty obvious from the drawings how the frames are assembled to everything else, and the frames are NOT rivetted to the buffer beam angle or the drag box.

Cheers,

Julian

Midge is a very old design and the drawings would require quite a bit of work to bring them up to modern spec IMHO especially the boiler. Not usually on anyone's 'to do' list these days.

I was asked about Romulus. It is pretty basic compared to most 5"g designs and one of the boiler options is very - erm - basic with an appalling tube layout and no superheaters.

I like brass domes and copper capped chimneys and GWR green...

**LINK**

Cheers,

Julian

Hi Michael,

Can I suggest to you the 'Speedy' build thread on the modeleng.proboards site?

Roger Froud has made his cylinders out of solid. My current miniature loco build has them machined out of solid too.

Cheers,

Julian

Hi Derek,

Forget the problem with the exahust pipes for the moment. They cant be seen, and neither can your non-existent boiler under your new cleading.

It is pointless worrying about exhaust pipes if the loco has no boiler.

Cheers,

Julian

I dont know the answer to this.

I agree with Jason that something you really want to build and have an interest in scores more highly than overall cost, which when spread out over a number of years is of less importance, plus Bob's very salient points that very rarely do you have to buy castings.

If I were to build a 7.25"g loco I would choose Don Young's IW Terrier Newport design. It is an excellent loco, one of which Don was very proud of shortly before his untimely death due to cancer. I have done a revised/improved valve gear design for it. There is a 7.25"g variant of his Tom Rolt design which is quite excellent but it wasnt done by Don (he did the 5"g version).

The Ken Swan designs are well worth considering, but if 'Wren' which I have some experience of, the boiler could do with superheaters added.

The GLR/Kennions 1366 class GWR 0-6-0PT loco is a nice design in 7.25"g

I just hope you dont build one of those dreadful Tinkerbell or Romulus locos!

Cheers,

Julian

Edited By julian atkins on 15/08/2016 22:50:15

Hi Derek,

The 2.5"g Society is a great society and John Baguley has done an awful lot in the last few years.

In the ME club I was secretary of in the 1990s I was responsible for deciding that on rebuilding the raised track the 2.5"g rail was omitted. No one had run a 2.5"g loco on the club track for the previous 25 years, and no club member owned a 2.5"g loco.

The popularity of 2.5"g was once very great. Very few clubs now have a 2.5"g track. I think this a shame, and in my own case take full responsibility for this but other factors were involved at the time.

The current market for ordinary 2.5"g stuff is reflected in ebay prices.

John Baguley's loco is not ordinary and has won the LBSC Bowl Trophy.

Your Flying Scotsman is a very old design and doesnt have 3 cylinders like the prototype. You have already described how the exhaust exits dont align in the cylinders. What other problems remain to be discovered with the chassis if the original builder couldnt drill the exhaust holes in the right place for both sides of the loco?

Cheers,

Julian

Hi Derek,

Your problem is easily solved with the right equipment and tooling. In fact what I have in mind would result in a much better exhaust arrangment anyway with larger exhaust passages. Nick and I are probably thinking along the same lines.

You mention limited funds...

Do you have the resources and equipment to make a new boiler, or buy a commercial job?

Cheers,

Julian

I cant comment on the above.

I had a short length of 'copper alloy' ex RN tube given to me many years ago. Aparently used on very high pressure steam lines.

I cut it up for various things including a number of displacement lubricator tanks for hydrostatic sight feed type displacement steam oil lubricators on locos all tested to working pressure of the loco. I have not the slightest doubt it was the copper nickel alloy referred to above. It silver soldered beautifully.

Cheers,

Julian

Hi James,

There is a lot to be said for altering the standard Martin Evans brake valve so that the spring is contained within the interior of the valve rather than on the external front. This allows a large diameter spring and reproduces a better scale external finish.

I would also silver solder the valve disc to the spindle. 10BA for the fixing screws is quite OK, and you can easily reduce the overall size to much smaller. If the back is elongated/extended to incorporate an internal spring, you have enough width to add a steam feed to the back and so avoid one port slot on the valve disc.

There really ought to be a release function on the valve notwithstanding Martin Evans' spring loaded valve on the steam brake cylinder which I set at 10 psi.

Anyway that is how I have always done mine.

Cheers,

Julian

Edited By julian atkins on 09/08/2016 23:04:39

Edited By julian atkins on 09/08/2016 23:05:48

Hi Brian,

I have a large quantity of gauge glass. If you know exactly what size you require I am sure I can find a length that suits.

Cheers,

Julian

Hi Derek,

I think Nick's suggestion is the best especially as there is not a lot of room.

Dont forget that the blast pipe must end up concentric with the chimney bore.

I presume that before you started screwing the cylinders back onto the exhaust pipes you checked the piston and gland packing and condition of the bores and port faces? I also give the cylinder blocks an air test off the frames and paint them before attaching to the frames.

Cheers,

Julian

I would agree that with practise free hand grinding of HSS lathe tools is easy and quick. If you havent got the knack then other more sophistcated set ups mght need resorting to.

I have some rather particular injector cone making lathe tools to very accurate sizes. They are all honed as per Hopper's methods.

I was taught how to get a good edge on woodworking tools when in my teens namely chisels and plane blades. That was a good grounding for metalwork lathe tools later on.

I also use clockmakers type gravers a lot in the lathe and this teaches optimum cutting angles on different materials.

Cheers,

Julian

Hi Derek,

Make the boiler, then the casing afterwards.

The very long barrel on a 'Flying Scotsman' type loco poses lots of problems for efficient steaming in miniature.

Cheers,

Julian

Hi Peter,

I have never had the problem you describe. So either it is wrong milling procedure or a problem with the mill.

One of the most potentially challenging jobs of recent years was to mill the channel section slide bars for my 5"g Terrier Stepney. Despite my worries and misgivings they ended up extremely good much to my surprise, having only a 3rd hand Dore Westbury mill.

For forked ends such as valve gear bits I drill out and hacksaw out most of the material to be removed first. Knuckle joints on coupling rods are rather problematic. Probably best finished with a warding file.

Cheers,

Julian

Hi Ken,

Depending on the club, most club boiler inspectors these days adhere to a very strict regime of insisting inspection of construction as it progresses and examining all internal joints, and seeing paperwork for boiler materials etc.

In short, 'home made' boilers by the amateur are expected to meet the same criteria of commercially made boilers.

My last 2 boilers have certainly undergone quite a thorough inspection at all stages by the club boiler inspector. This is very good practice. I have witnessed at least 2 amateur boilers fail due to the crown collapsing, and quite a few other horrors over the last 33 years in this lark.

Cheers,

Julian

For an exhaust pipe this might be OK, but not for a steam pipe!

Just goes to show the obsolescent original design I'm afraid.

Cheers,

Julian