Wright writes.....

[Brocp]

Any LMS modellers out there with 3d printers that want to start doing this sort of thing for us? Pretty please?

[Iain Mac]

I've made a start on some LMS subjects for rendition in 4mm scale initially. All CAD stage at the moment and 1 : 1 at that but readily scaled down and modeling standards applied they can be printed or etched, or combination.

Working through the 1939/40 Coronation Scot artic and singles coaches which were predominately finished post war.

Only general arrangement drawings exist in archives so a lot of work has gone in to working out materials and practice to complete fully detailed drawings and CAD models of the prototypes.

It's not something any of the rtr manufactures are likely to produce due to expense v's profits. I want a couple of sets so it is something that can be offered as a by product of my desire to model them to anyone interested.

 

Iain Mac.

 

Edited July 2, 2020 by Iain Mac
Removed 'g' and replaced with 'h' in the word 'the'. Pleasures of phone typing.....

[Tony Wright]

Next stages...................

 

 

Comet's crossheads are not handed and cater for both left- and right-hand sides, with the little end of the connecting rod running a pocket. This must be completely clear, with the assembly broached for clearance. 

 

 

Without modification, the little end will jam. Note how I've enlarged the bearing holes in both the big and little ends. The latter will be anathema to proper engineers, but remember that the rod will be driven by the wheels, not, as on the prototype, it driving them. Plenty of clearance means fewer chances of tight spots.

 

 

The little end is held in place by a 16BA screw, secured with a 14BA nut, soldered securely in place. These are not supplied in the chassis kit. 

 

 

The piston rods are too long as supplied; better than their being too short!

 

 

They must be shortened to fit. I do it by nibbling bits off with the Xurons. 

 

 

They mustn't be shortened too much, however. This is perfect. 

 

 

The crossheads (which are lost wax brass?) needed some cleaning up before they'd fit into the etched slidebars, but the fit was finally snug. Don't arrange the slidebars according to the drawing, otherwise they won't fit into the slots in the cylinder rears. The inner one needs shortening to remove the lug, otherwise the slidebars will end up too far back. 

 

More later................ 

[grob1234]

Brilliant as ever, Tony. Valve gear photos like you have posted are invaluable. 'A picture paints....'

 

May I dare to offer a D120 LNER pigeon van. I know there is a little controversy surrounding these - possibly a jack of all trades, master of none. All I know is it looks reasonably LNER'ly to me. First attempt at Teak. It's perhaps a little darker than I wanted, depicting a van about 10-15 years old. Comments welcome, as long as they're nice

 

[Tony Wright]

The next stage..............

 

I admit, I can't rivet valve gear. 

 

Actually, that's wrong; I can rivet, but the result is either two components pinched together or way too slack! 

 

Thus, for joining moving components, I use brass lace-making pins and solder.

 

 

As a barrier to the solder and to give a working clearance, Comet's instructions' paper is perfect. 

 

Once happy with the joint, the excess pin is snipped off and dressed clean. 

 

Both sides completed thus far. It's essential at this stage (at every stage) that all the moving parts have no tightness in them, before any oil is applied. 

 

 

Forewarned is forearmed....... 

 

If left full-length, the expansion links will foul the underside of the motion support bracket. 

 

More later......................

 

 

 

 

[t-b-g]

27 minutes ago, Tony Wright said:

The next stage..............

 

I admit, I can't rivet valve gear. 

 

Actually, that's wrong; I can rivet, but the result is either two components pinched together or way too slack! 

 

Thus, for joining moving components, I use brass lace-making pins and solder.

 

 

As a barrier to the solder and to give a working clearance, Comet's instructions' paper is perfect. 

 

Once happy with the joint, the excess pin is snipped off and dressed clean. 

 

Both sides completed thus far. It's essential at this stage (at every stage) that all the moving parts have no tightness in them, before any oil is applied. 

 

 

Forewarned is forearmed....... 

 

If left full-length, the expansion links will foul the underside of the motion support bracket. 

 

More later......................

 

 

 

 

 

If you model the loco in mid gear, shouldn't lifting links ( the ones that are, or should be, linked to a cross shaft and are connected to the reverser in the cab) be in a straight line with the valve rod, not angled upwards? That is my understanding of how the real valve gear is designed to work.

[Tony Wright]

All finished now..............

 

The motion support bracket, with everything hanging on. 

 

To hold the bracket, expansion link and radius rod in place, I solder a 14BA bolt to the bracket, both sides. I then fit the expansion link and radius rod over this, finally making all secure by soldering a brass crankpin washer over the inner end, then snipping off the excess. To prevent solder contamination causing binding, two Romford crankpin fibre washers are placed between the moving parts and any solder. Unfortunately, these most-useful little items are no longer available. 

 

Once happy, the inner supports were then soldered in place. 

 

 

Cylinders and motion support bracket just tacked in place for now - just to check all runs freely before a more-secure joint can be made. 

 

 

Everything now secure and running sweetly. I had to slightly crank the valve guides outwards, just to give greater clearance for the combination levers. 

 

 

Everything now in place, and time for a little running-in (not that any was really necessary).

 

Cylinder drain cocks are 15Amp fusewire. 

 

In case anyone thinks it's taken me all day to erect the motion on this V2, I have done other things as well, and taking step-by-step pictures slows everything down. 

 

I hope my pragmatic approach to making valve gear has been made clear. Some components should be of a sandwich construction, or have forked ends. Such niceties are for those who take their loco-building more seriously than I do. This is yet another 'layout loco', and it satisfies my requirements for that.  

 

Any comments/brick-bats, most-welcome. 

 

 

[Tony Wright]

1 hour ago, t-b-g said:

 

If you model the loco in mid gear, shouldn't lifting links ( the ones that are, or should be, linked to a cross shaft and are connected to the reverser in the cab) be in a straight line with the valve rod, not angled upwards? That is my understanding of how the real valve gear is designed to work.

Good evening Tony,

 

Have a look at the pictures I've just posted, please................

 

Regards,

 

Tony. 

Edited July 2, 2020 by Tony Wright
typo error

[t-b-g]

Just now, Tony Wright said:

God evening Tony,

 

Have a look at the pictures I've just posted, please................

 

Regards,

 

Tony. 

 

Just spotted you have altered them! I only mentioned it as I have seen it on a few locos on Little Bytham and I thought you might have done it deliberately to create an impression that they were in forward gear.

 

Does the Comet motion bracket go to the lower slide bar rather than the upper one? It isn't easy to tell from the photos but the impression is that it does. On the real V2, the whole slidebar is visible under the motion bracket but on the model it appears is if the bracket comes down over the outside of the slide bars.

[MikeTrice]

42 minutes ago, t-b-g said:

On the real V2, the whole slidebar is visible under the motion bracket...

Like so

[t-b-g]

7 minutes ago, MikeTrice said:

Like so

 

Cracking good picture!

[Tony Wright]

1 hour ago, t-b-g said:

 

Just spotted you have altered them! I only mentioned it as I have seen it on a few locos on Little Bytham and I thought you might have done it deliberately to create an impression that they were in forward gear.

 

Does the Comet motion bracket go to the lower slide bar rather than the upper one? It isn't easy to tell from the photos but the impression is that it does. On the real V2, the whole slidebar is visible under the motion bracket but on the model it appears is if the bracket comes down over the outside of the slide bars.

You're right Tony,

 

The motion support bracket should fix on to the top 'bar, but it's obviously too long.

 

I'm afraid it's too well-soldered together now to contemplate alteration.

 

Still, when the motion is weathered......................

 

Regards,

 

Tony. 

[Tony Wright]

Anyway, odd detail discrepancies apart, here is the second V2 posing for its 'official' picture.

 

 

The too-long bracket is an irritant, but I can live with that...............

 

All in all, though, it's as good a V2 as anything I've ever made - probably the best. 

 

Though RTR is getting better all the time, I still think there's no greater pleasure in this wonderful hobby than being able to say 'I made that'. 

 

Final testing on both the latest V2s was undertaken this evening......................

 

 

 

Both passed with flying colours, doing what any respectable ECML V2 should do - travel fast, hauling heavy trains.

 

I can see I'll have to lengthen that reversing lever in the lower picture..................

 

 

[davidw]

13 minutes ago, Tony Wright said:

Anyway, odd detail discrepancies apart, here is the second V2 posing for its 'official' picture.

 

 

The too-long bracket is an irritant, but I can live with that...............

 

All in all, though, it's as good a V2 as anything I've ever made - probably the best. 

 

Though RTR is getting better all the time, I still think there's no greater pleasure in this wonderful hobby than being able to say 'I made that'. 

 

Final testing on both the latest V2s was undertaken this evening......................

 

 

 

Both passed with flying colours, doing what any respectable ECML V2 should do - travel fast, hauling heavy trains.

 

I can see I'll have to lengthen that reversing lever in the lower picture..................

 

 

An excellent couple of V2's. I wasn't going to tackle mine until next year - but you are causing me to rethink.

 

[micklner]

Tony   

 

For the information of anyone building a Comet V2 chassis in the future .

 

Why has the valve gear/slide bar ended up in the wrong postion, there must be a reason? Looking at the earlier photo of 60892 the valve gear thereon is in the correct layout/position.

 

Personally I could'nt live it with it like that . The Piston Rod must be very close to striking the motion bracket on the return stroke as well.

 

[t-b-g]

I will make one more suggestion Tony. The pivot of the expansion link looks rather too obviously like the head of a bolt. I would suggest either filing it flat or filling the slot. Filing it flat would probably replicate the thickness of the bearing plate on the real thing better.

 

One of my pet hates in valve gear is being able to see bolts and nuts when they shouldn't be there and on such a good model, it seems a shame to have one quite so visible.

[Northmoor]

2 hours ago, Tony Wright said:

All finished now..............

 

Any comments/brick-bats, most-welcome. 

 

That the V2 looks superb goes without saying.  As someone who loves to use 40 year-old equipment, I'm very reassured if your enviable fleet is still powered by an H&M Clipper.

 

Rob

[gr.king]

I imagine that with an etched metal body, with thin running plate and thin representation of the angle irons, there would be scope for fitting the entire motion bracket assembly at a higher level, especially if the stretcher were made a screw-on fit across the top of the frames. That would allow it to be shimmed-up to get it spot-on before the solder joints to the slidebars were made.

 

With the thick running plate of a cast or printed body there's the option, if forewarned by the "test build" here, of trimming the various parts of the motion bracket while forming it up prior to fitting.

Edited July 3, 2020 by gr.king
Inserted missing word

[cctransuk]

17 minutes ago, gr.king said:

I imagine that an etched metal body, with thin running plate and thin representation of the angle irons, there would be scope for fitting the entire motion bracket assembly at a higher level, especially if the stretcher were made a screw-on fit across the top of the frames. That would allow it to be shimmed-up to get it spot-on before the solder joints to the slidebars were made.

 

With the thick running plate of a cast or printed body there's the option, if forewarned by the "test build" here, of trimming the various parts of the motion bracket while forming it up prior to fitting.

 

Looking at the photos of the prototype, I'm pretty certain that the lower curve of the model's motion bracket is far to deep. It appears to be horizontally symetrical on the model, whereas the prototype seems much deeper in the top curve than in the lower one.

 

 

 

If I were to build this chassis, I would be seeking to remove a section of the lower curve of the motion bracket, where it abuts the upper slidebar.

 

This could be achieved with the current model by soldering a piece of thickish fret waste above the upper slidebar, between the front and rear halves of the motion bracket. The fictional section of the motion bracket, in front of and below the slidebars, could then be cut away.

 

John Isherwood.

Edited July 2, 2020 by cctransuk

[micklner]

I have just looked at the old Comet Models site and there is a photo of the V2 chassis fitted with the old Bachmann body , there is at least a 2mm gap between the top of the cylinders and the body's footplate. However, it does look  like the body isnt actually fitted to the chassis , just sitting on top ?

 

 

 

 

 

[gr.king]

Having just checked back through photographs to confirm my otherwise uncertain recollection, I'm now sure that when I used adapted Comet V2 valve gear for my first couple of Bachmann A2 to A2/3 or A2/2 conversions (admittedly involving a different relationship of cylinders and running plate height) I had to take care to turn a  substantial lower part of each outer facing of the motion bracket inwards, in order to meet the foot of the inner element of the motion bracket and to rest on top of the correctly angled slidebars. It may be that the representation of that outer facing is a bit too big / tall, I can't say for certain.

 

I presumably did likewise when I equipped my resin-bodied V2 with a combination of new Bachmann chassis and adapted Comet valve gear, including motion bracket:

[Tony Wright]

13 hours ago, Northmoor said:

That the V2 looks superb goes without saying.  As someone who loves to use 40 year-old equipment, I'm very reassured if your enviable fleet is still powered by an H&M Clipper.

 

Rob

Thanks Rob,

 

All my loco-testing during construction is conducted using a couple of ancient H&M 'Clippers'. The one behind the V2 in the picture powers the longer test track (you can see it's giving no juice), and the test-bed and rollers are powered by another one. 

 

In fact, Bytham's main line fiddle yard uses a 'Duette' for the shuffle power, and the whole of the M&GNR bit uses yet another 'Clipper'. 

 

The main line scenic section is powered by a quartet of Helmsman O Gauge controllers.

 

Regards,

 

Tony. 

[Tony Wright]

14 hours ago, micklner said:

Tony   

 

For the information of anyone building a Comet V2 chassis in the future .

 

Why has the valve gear/slide bar ended up in the wrong postion, there must be a reason? Looking at the earlier photo of 60892 the valve gear thereon is in the correct layout/position.

 

Personally I could'nt live it with it like that . The Piston Rod must be very close to striking the motion bracket on the return stroke as well.

 

Thanks Mick,

 

'The Piston Rod must be very close to striking the motion bracket on the return stroke as well.'

 

I don't understand what you mean by this.............

 

The piston rod never gets anywhere near the motion support bracket. It's the round piece fitted at the front of the crosshead which goes into the cylinders, so the nearest it gets to the bracket is the length of the crosshead. 

 

I'm afraid I can live with the bracket discrepancy; we all have different tolerance levels - too fat boilers and 'pimply' domes come to mind.

 

Regards,

 

Tony. 

[Tony Wright]

Many thanks for all the recent V2 comments (which I did ask for). If one puts work up for 'inspection', then expect (in fact, invite) critical comment. I much prefer it this way, rather than an effusive gushing of 'likes', when I can only assume the commentators are myopic; or just far too sycophantic! 

 

Will I change things now? No. If that suggests an 'ostrich' mentality, then so be it. 

 

Clearly, the motion support bracket on the Comet valve gear ends up too long if assembled the way I did. Or, as Mick's picture (for which I thank him) shows, if its bottom edge rests on the top slidebar (which should not be open, as it is on the Comet ones), then the body hovers in mid air.

 

When all the motion is finally-weathered, discrepancies such as screw heads and fixing positions will be far less-obvious - 'a coat of paint hides a multitude..............' and so on, but if I were to build any more Comet V2 chassis I'll alter them accordingly.

 

I still think the Comet V2 chassis is an excellent product, which produces a very sound piece of motive power.

 

Thanks again to all. 

[MikeTrice]

37 minutes ago, Tony Wright said:

 if I were to build any more Comet V2 chassis I'll alter them accordingly.

Forewarned is forearmed as they say. I have been noting all these points pending building my own Comet valve gear.