Wright writes.....

[t-b-g]

1 hour ago, Michael Edge said:

It isn't intended to be full compensation as I'm sure Nick knows but it is much better than all rigid.  With regard to central beams, a quick look at full size practice (always a good idea) reveals that compensating beams are always placed as close to the wheels as practicable, I don't see why we should do something different. In case anyone thinks there are rules about this, have a look at the GEC 6wh diesels built in some numbers for British Steel, NCB and ICI and still in use. These have the first and second axles connected with compensating beams on the LH side and the second and third axles connected on the RH side - I haven't built one of these yet but I'm fascinated to see how it will work. These locos do of course have springing as well but the compensation is intended to help with uneven track.

This is quite a bit more complicated than the average model system but it's compensation nonetheless. 

 

Some ambitious engineer wanting to make a name for him or herself by inventing yet another way of keeping the wheels on the track!

[Mike 84C]

Can I throw my hat into the J17 ring? Bearing in mind that all the posted photos are from different angles, I think that looking at the preserved one and using that as a basis to compare. I think the whole smokebox boiler unit on Tonys model sits too low.  My reasoning stems from looking at the r/h sandbox and to me the curve of the smokebox  goes several inches   above the sandbox before it starts  the major curve of its diameter, the boiler also seems to have more space underneath it. So raising the whole unit 2mm? brings the firebox top closer to the cab window frames.  As a confessed fan of GW locos I shall take cover!

[Mike 84C]

2 hours ago, t-b-g said:

 

Some ambitious engineer wanting to make a name for him or herself by inventing yet another way of keeping the wheels on the track!

Looking at the photos and drawing its a very clean, neat and probably low maintenance solution.

[t-b-g]

14 minutes ago, Mike 84C said:

Looking at the photos and drawing its a very clean, neat and probably low maintenance solution.

 

Very likely but I don't think it was adopted widely on other loco types. I have never seen another one quite like it.

Edited May 18, 2020 by t-b-g

[Andy Reichert]

3 hours ago, Bucoops said:

 

What have I started?

 

The beams are not connected - although the axles of course connect them to a certain extent - there will be very little independent movement.

 

As I have said earlier, this is my first "compensated" build - it will be interesting to see how it works out.

 

3 hours ago, Michael Edge said:

It isn't intended to be full compensation as I'm sure Nick knows but it is much better than all rigid.  With regard to central beams, a quick look at full size practice (always a good idea) reveals that compensating beams are always placed as close to the wheels as practicable, I don't see why we should do something different. In case anyone thinks there are rules about this, have a look at the GEC 6wh diesels built in some numbers for British Steel, NCB and ICI and still in use. These have the first and second axles connected with compensating beams on the LH side and the second and third axles connected on the RH side - I haven't built one of these yet but I'm fascinated to see how it will work. These locos do of course have springing as well but the compensation is intended to help with uneven track.

This is quite a bit more complicated than the average model system but it's compensation nonetheless. 

 

Pretty much all UK locomotives use springing as the primary suspension with side equalization only added for extra wheel movement if needed.  In the US it's typically a mixture of equalization with springing as much track is far more uneven than in Europe. In the example above, the prototype's small degree of track twist is handled by the springs.

 

Unfortunately for we small scale modellers, our track is not at all as flat and springing does not scale down at all well to emulate the prototype's sufficient track holding effect. So like you I use twin beams (or just moving side frames) close to the wheels. But for the typical model degree of track twist I have to add soft springing or proper transverse equalization to cope. The good thing about using transverse equalization is that it can obviate the need to build a the rigid parts of the chassis precisely square and true on an extremely flat surface.

 

There is no need for rules other than fundamentally complying with basic geometry and the Laws of Physics at a small scale. Those are quite sufficient to predict and evaluate the effectiveness of a model design.  So I am curious as to what you understand the advantages of the Dewry mode's suspension  over a rigid chassis to be

 

Andy

 

 

 

 

 

[t-b-g]

35 minutes ago, Mike 84C said:

Can I throw my hat into the J17 ring? Bearing in mind that all the posted photos are from different angles, I think that looking at the preserved one and using that as a basis to compare. I think the whole smokebox boiler unit on Tonys model sits too low.  My reasoning stems from looking at the r/h sandbox and to me the curve of the smokebox  goes several inches   above the sandbox before it starts  the major curve of its diameter, the boiler also seems to have more space underneath it. So raising the whole unit 2mm? brings the firebox top closer to the cab window frames.  As a confessed fan of GW locos I shall take cover!

 

I can see why you have that impression as I had it too but then I had another look and changed my mind.

 

I think the splashers are a bit oversize to allow for over scale wheel flanges, which does alter the relationship with the curve on the smoke box. It also covers some of the gap under the boiler slightly more than it should. The dummy frame above the footplate is also slightly taller than it should be, reducing the gap under the boiler. I do think the relationship of the top of the firebox to the cab front and the boiler/firebox position is about right now and raising it up by 2mm would cover the windows. I don't think Tony W has any intention of altering it again, whatever anybody says!

Edited May 18, 2020 by t-b-g

[Woodcock29]

I'm prepared to show my old Bec J17. It was built originally in the early 60s by my father before we left England. I gave it once over in the mid to late 80s. Fully stripped it down, this was the very original kit version which had an inaccurate cab roof and spectacles so I reshaped the spectacles with filler and redid the roof. Fitted Romfords, Crownline chimney and smokebox door, Wills safety valves from N7 kit and more recently (2000s I think) it got a Buhler motor and Ultrascale gearbox. Despite the inaccurate wheelbase and the 'extra large' splasher protruding out of the cab front its not too bad. It runs regularly on one of the pick-up goods in my operating sequence.

 

The interesting thing is I managed to pick up a Crownline J17 kit at our last BRMA Convention in Canberra in 2019 for around £40 so another one on the roundtuit list. 

 

 

Clearly this J17 could do with brakes but I'm not sure I can be bothered - it is what it is!

 

Time to go out to the shed - don't tell 'St Enodoc' that I'm starting to work on some scenery. Mind you I might soon get bored with that and get back to real work - locos and other rollingstock!

 

Andrew

[St Enodoc]

59 minutes ago, Andy Reichert said:

 

 

Pretty much all UK locomotives use springing as the primary suspension with side equalization only added for extra wheel movement if needed.  In the US it's typically a mixture of equalization with springing as much track is far more uneven than in Europe. In the example above, the prototype's small degree of track twist is handled by the springs.

 

Unfortunately for we small scale modellers, our track is not at all as flat and springing does not scale down at all well to emulate the prototype's sufficient track holding effect. So like you I use twin beams (or just moving side frames) close to the wheels. But for the typical model degree of track twist I have to add soft springing or proper transverse equalization to cope. The good thing about using transverse equalization is that it can obviate the need to build a the rigid parts of the chassis precisely square and true on an extremely flat surface.

 

There is no need for rules other than fundamentally complying with basic geometry and the Laws of Physics at a small scale. Those are quite sufficient to predict and evaluate the effectiveness of a model design.  So I am curious as to what you understand the advantages of the Dewry mode's suspension  over a rigid chassis to be

 

Andy

 

 

 

 

 

But model track generally is very rigid so doesn't flex in response to the weight of locos passing over it.

[manna]

G'Day Folks

 

Hey, if you want a laugh, this is my rendition of a J17, made out of a Tri-Ang 3f, a B12 cab and tender, with bits from a King and Thomas.

 

manna

[Michael Edge]

6 hours ago, Andy Reichert said:

 

 

 

 

There is no need for rules other than fundamentally complying with basic geometry and the Laws of Physics at a small scale. Those are quite sufficient to predict and evaluate the effectiveness of a model design.  So I am curious as to what you understand the advantages of the Dewry mode's suspension  over a rigid chassis to be

 

Andy

 

 

 

 

 

It doesn't help at all with track twist but it does make the frame flexible in one plane. Many of our track imperfections are simply vertical, particularly at baseboard joints, this does at least stop the loco rocking lengthways on its centre axle. The diesel example I quoted above does seem to defy all logic to me though - I walked round this loco twice to make sure of what I had seen when we measured it - but they do work.

[Barry O]

Perhaps the designer had looked at the tender set up on a WD? Then thought.."kthis is my chance to cause modellers to scratch their heads"?

Baz

[Tony Wright]

7 hours ago, Mike 84C said:

Can I throw my hat into the J17 ring? Bearing in mind that all the posted photos are from different angles, I think that looking at the preserved one and using that as a basis to compare. I think the whole smokebox boiler unit on Tonys model sits too low.  My reasoning stems from looking at the r/h sandbox and to me the curve of the smokebox  goes several inches   above the sandbox before it starts  the major curve of its diameter, the boiler also seems to have more space underneath it. So raising the whole unit 2mm? brings the firebox top closer to the cab window frames.  As a confessed fan of GW locos I shall take cover!

Thanks Mike,

 

By raising the smokebox/boiler up by 2mm, the firebox will cover the bottom of the spectacles. 

 

I think my soldering on the spectacle plate and the back of the firebox gives the impression that there's a greater gap below the spectacles than in reality.

 

Anyway, it's staying now. There's a limit to how much un-soldering/re-soldering/swearing I'm prepared to countenance, before the lot gets chucked in the bin! 

 

As mentioned, much is dictated by the tabs and slots on the parts in the kit.

 

Regards,

 

Tony. 

[Michael Edge]

8 minutes ago, Barry O said:

Perhaps the designer had looked at the tender set up on a WD? Then thought.."kthis is my chance to cause modellers to scratch their heads"?

Baz

No, that's symmetrical on each side - this isn't. This is the opposite side to the compensated axles.

[dibateg]

I was a big fan of compensation back in the day - most of my 4mm scale locos were compensated - and Tony hated them....! I found though, that central beam compensation could be quite unstable, especially if the weight balance wasn't that good. It was all too easy for the front wheel of a compensated tender to lift. Probably my implementation of it. MOK kits in 7mm feature twin independent beams with a fixed axle on a 6 wheels. Disregarding the physics, it works very well. I don't build rigid loco chassis, they generally have hornblocks, where the axle bearing sit on the stops. Other builders were horrified that I don't fit adjustable stops. Well, just file a bit off, or solder a bit on! They should have springs, but its a faff to fit them, so I don't bother....

Regards

Tony

[Headstock]

The thing I don't understand about the kerfuffle  surrounding Firebox gate, why don't railway modellers use dimensional drawings any more?

[t-b-g]

7 hours ago, manna said:

G'Day Folks

 

Hey, if you want a laugh, this is my rendition of a J17, made out of a Tri-Ang 3f, a B12 cab and tender, with bits from a King and Thomas.

 

manna

 

I used to really love articles on such models in the press "back in the day". People who would take a Triang A3 and turn it into a V2 or a Princess into a Black 5. The resemblance of the finished models to the prototype was, shall we say, tenuous sometimes.

 

Yet there was a sort of innocent joy about such projects. Here was a model there that somebody had made from bits of this and that and it was unique.

 

In many respects, slight imperfections in a project like that seem to matter less than in a kit or a scratchbuild that sets out to make a truly accurate model.

 

So I for one am not laughing! I like it! 

[t-b-g]

9 hours ago, Woodcock29 said:

I'm prepared to show my old Bec J17. It was built originally in the early 60s by my father before we left England. I gave it once over in the mid to late 80s. Fully stripped it down, this was the very original kit version which had an inaccurate cab roof and spectacles so I reshaped the spectacles with filler and redid the roof. Fitted Romfords, Crownline chimney and smokebox door, Wills safety valves from N7 kit and more recently (2000s I think) it got a Buhler motor and Ultrascale gearbox. Despite the inaccurate wheelbase and the 'extra large' splasher protruding out of the cab front its not too bad. It runs regularly on one of the pick-up goods in my operating sequence.

 

The interesting thing is I managed to pick up a Crownline J17 kit at our last BRMA Convention in Canberra in 2019 for around £40 so another one on the roundtuit list. 

 

 

Clearly this J17 could do with brakes but I'm not sure I can be bothered - it is what it is!

 

Time to go out to the shed - don't tell 'St Enodoc' that I'm starting to work on some scenery. Mind you I might soon get bored with that and get back to real work - locos and other rollingstock!

 

Andrew

 

So the wheelbase is a bit out and it lacks detail below the footplate but that is lovely workmanship and a very nice paint finish! Those transfers are as flat as any I have seen and seem to have no thickness at all. The shape of the curves on the smokebox is probably better than the etched kit!

[gr.king]

Compensated, sprung, rigid, raised middle axle, or some mixture of arrangements? It seems to me there is no "right" or "wrong" way to do things, as the method that gives the best result is highly dependent on the kind of track over which the model is to run. There's no sense at all in anybody insisting that their method is "correct" because the their theory (with its inherent assumptions) says so. Full, unrestricted compensation relies on the assumption that the track will always support the wheels. Fine if all of your crossing gaps are small, not so good if your locos have to contend with large crossing gaps. Rigid chassis are fine so long as your track is flat enough, but if it undulates and twists excessively then derailments or interrupted electrical pick-up become a problem. Build to suit the need.

Mike Edge's method looks like a reasonable compromise for many applications, but like any compromise it won't suit every situation perfectly.

[t-b-g]

6 minutes ago, Headstock said:

The thing I don't understand about the kerfuffle  surrounding Firebox gate, why don't railway modellers use dimensional drawings any more?

 

I do! I can't remember the last model I built without a GA or a drawing of some sort. What I call "modellers drawings" (done by modellers for modellers) can vary in quality so I am choosy about which ones I use. Even GA drawings can have errors but the main dimensions are usually correct. For Valour, I have 3 drawings, a GA, Nick Campling's from Railway Modeller and John Edgeson's "Isinglass".  

 

 

[cctransuk]

11 minutes ago, Headstock said:

The thing I don't understand about the kerfuffle  surrounding Firebox gate, why don't railway modellers use dimensional drawings any more?

 

Precisely ! .... or even an undimensioned drawing?

 

Having established that the drawing matches the prototype appearance, surely it is easy to establish where the error is in the model?

 

I spend a long time with a reliable drawing and photographs of the prototype, designing the drive arrangements. That way you become accustomed to the critical features of the subject.

 

When construction starts, components are checked against the drawing and, if necessary, modified before assembly.

 

Regards,

John Isherwood.

[Tony Wright]

It was indolent of me not to source a drawing before I started on the J17.

 

Never make assumptions, I always tell my 'pupils'. Assumptions such as the kit you've just shelled out some dosh for will be accurate, and that the bits will fit! 

 

Going back to drawings, it's vital that they're correct. I scratch-built an A1/1 decades ago, using the Roche drawing as my guide - what an ignorant chump was I! I also built an A2/3 using the Skinley drawing. Even more ignorance and chumpness! Anyone using the late Ian Beattie's drawings will make 'Enid Blyton' models, such is their fiction. Years ago, I bought his books of drawings; one would do better giving them to children to colour-in - a flat front to an A4's cab? A V2 with a banjo dome? German blinkers on an A3 so far back they'd be better lifting steam from the safety valves!

 

Even the revered Isinglass drawings should be treated with caution. Is one to average-out the position of the horizontal cab handrails on the A2/3? They're drawn differently on each side! 

 

I find GA/pipe & rod drawings bewildering. 

 

I sometimes wonder why I bother...........

Edited May 19, 2020 by Tony Wright
to clarify a point

[chris p bacon]

5 minutes ago, Tony Wright said:

I sometimes wonder why I bother.

 

Because it's an enjoyable hobby.........or it's meant to be 

 

 

[t-b-g]

1 minute ago, Tony Wright said:

It was indolent of me not to source a drawing before I started on the J17.

 

Never make assumptions, I always tell my 'pupils'. Assumptions such as the kit you've just shelled out some dosh for will be accurate, and that the bits will fit! 

 

Going back to drawings, it's vital that they're correct. I scratch-built an A1/1 decades ago, using the Roche drawing as my guide - what an ignorant chump was I! I also built an A2/3 using the Skinley drawing. Even more ignorance and chumpness! Anyone using the late Ian Beattie's drawings will make 'Enid Blyton' models, such is their fiction. Years ago, I bought his books of drawings; one would do better giving them to children to colour-in - a flat front to an A4's cab? A V2 with a banjo dome? German blinkers on an A3 so far back they'd better be lifting steam from the safety valves!

 

Even the revered Isinglass drawings should be treated with caution. Is one to average-out the position of the horizontal cab handrails? They're drawn differently on each side! 

 

I find GA/pipe & rod drawings bewildering. 

 

I sometimes wonder why I bother...........

 

Malcolm Crawley taught me how to pick the bones out of a GA drawing. I was like you, I used to see a mass of lines and my head would spin. He taught me to ignore most of the lines and look for the written dimensions. I can remember him saying now, "Never measure off a drawing if there is a written dimension there and if you have to measure off a drawing, check a written dimension near where you are measuring and in the same plane first to make sure that the printed drawing hasn't stretched or been distorted"

 

Drawings are a minefield but I would think that using something like an Isinglass drawing and a photo would soon tell you which cab side handrail was in the right place, or allow you to get it so close that any error doesn't show.

[Dunsignalling]

19 minutes ago, t-b-g said:

 

Malcolm Crawley taught me how to pick the bones out of a GA drawing. I was like you, I used to see a mass of lines and my head would spin. He taught me to ignore most of the lines and look for the written dimensions. I can remember him saying now, "Never measure off a drawing if there is a written dimension there and if you have to measure off a drawing, check a written dimension near where you are measuring and in the same plane first to make sure that the printed drawing hasn't stretched or been distorted"

 

Drawings are a minefield but I would think that using something like an Isinglass drawing and a photo would soon tell you which cab side handrail was in the right place, or allow you to get it so close that any error doesn't show.

There's always the possibility that the handrail discrepancy arose from two locos being measured and having such a variation between them.

 

Both could therefore be OK, but not on the same model, and sourcing photos of "your" loco remains essential.

 

John

[Clive Mortimore]

My experience with any drawings, they are only as good as the skill of the draftsman/draftswoman and the information he/she has on the subject drawn. As Tong Gee says use the quoted dimensions. Always check for distortion, especially photocopies.

 

Back in the day when I was scratchbuilding diesel locos I would find as many drawings as possible, scale them to 1/76th. Each one would have something that would help with the model. If there is something which the drawing doesn't show clearly check it against a photo or two.

 

I suppose I better do a quick summery of my findings of the various diesel locomotive and DMU drawings.

 

RS Carter, useful. Can include some mistakes.

S Fenn, oddly many mistakes found in the above are repeated. No basic dimensions in the joint book with C Marsden.

I Beatie, I might be an idea to check these against other drawings.

BR Diagrams, can be very helpful to get the correct shape. Best for DMU bodies.

EE weight diagrams, again very helpful for the correct shape.

B Golding, can be variable but still useful.

Skinley (DMU drawings) informative.

M Wells, best modellers drawings.

M Edge (shunter drawings), we don't want him to get a big head, but cheers Mike they are great.