2FS - Smokey Bacon

[SteveBedding]

... I have a friend with a BR(WR) 2mmFS layout who was talking of creating a steam special last year...using a converted pannier tank...I will report to him immediately...

 

Pete, don't be afraid to come out of the closet...

 

There is nothing shameful or furtive about having the pannier, indeed it could be considered remedial therapy for an otherwise unhealthy fascination with blue diesels... I'm sure that the doctor would prescribe a full conversion to steam, ideally pre-1947/8, but a dose of nationalised steam may suffice in the long term!

 

in the mean time, keep taking the tablets...

[2mm Andy]

That's looking good Steve. I thought I'd gone a bit over the top with planning the chassis for my 02, but it looks as though you're going through much the same process. It's definitely an advantage to have CAD and to be able to check things work before starting building.

 

One point - you can shorten the worm. The 2mm Assoc worms are far longer than they really need to be for most applications. I have reduced the length of mine by 3-4mm and it means I can shove the whole motor along a bit. Also, I think your drawing still shows the Faulhaber motor. The Nigel Lawton one doesn't have the narrow threaded section between the motor body and the motor shaft.

 

All this talk of chassis designs has tempted me to try and finish the 02 and bring out the Jinty I started last year.

 

Andy

 

 

[SteveBedding]

One point - you can shorten the worm. The 2mm Assoc worms are far longer than they really need to be for most applications. I have reduced the length of mine by 3-4mm and it means I can shove the whole motor along a bit. Also, I think your drawing still shows the Faulhaber motor. The Nigel Lawton one doesn't have the narrow threaded section between the motor body and the motor shaft.

 

Thanks Andy, CAD is definitely an advantage at this stage; I say 'definitely' as although I have used CAD packages in the past, it was a long time ago and my skills/memory has atrophied over the years - so it's another 'skill' to re-learn along with everything else! I note your point on the FH motor outline, I'm actually working on the CAD drawing at the moment and wanted to recheck the NL motor outline and mountings. Keeping the FH outline was OK for the first pass, but I recognised that there were differences in detail that needed to be addressed. As you said, the worm can also be shortened from 9.5mm down to about 6.5mm, but I'll check that as the design progresses.

 

One thing I am noticing is that there are discrepancies between the theoretical design derived from the scale drawing, and the outline/detail of Missy's frames; now I know her frames are good and work with the Farish body, so I now have a dilemma regarding the 'accuracy' of the casting. I'll continue with the theoretical design, and make a simple plasticard prototype, before the detailed chassis... ...oh well, another little task to do...

 

I'll just get this finished and will post an update later.

[bcnPete]

in the mean time, keep taking the tablets...

 

LoL - I'll have you know I cut my teeth in N with a GWR branchline complete with Farish pannier, prairie and hall classes...and then I sought refuge in BR Blue...so I am a reformed character

 

Back on topic I thought the 2FS pannier conversion kit was OOS? Am I correct in that you will use the spare frames as a basis and build from that?

[SteveBedding]

Thanks to everyone for the continued interest and encouragement, it's good to think that this is of use and provokes comment...

 

...I thought the 2FS pannier conversion kit was OOS? Am I correct in that you will use the spare frames as a basis and build from that?

 

I've not yet measured up the pannier casting in detail, but I'm working on the basis that it is slightly 'oversize' and if I can put together a design to the true dimensions, it should be (hopefully ?) straightforward to stretch the fit where necessary.

 

One of the advantages of the CAD package is the ability to insert more than one base image into the drawing and this allows me to switch between the scale drawing of the 57xx and a scan of the spare frame; both image files have been adjusted to match the scales exactly, and the origin (0,0) defined as the centre of the leading wheel. The first task was to copy/trace the spare frames and to ensure that the axle centres, and intermediate gear positioning, were correctly registered; this was successful, and confirmed that the spacing was set for the 28T:20T second stage reduction. It was apparent that the bottom edge of the frame, whilst nicely representing the profile, was considerably low compared to the scale drawing (almost 1mm). Initially I thought of correcting this, but very quickly realised that this was a very pragmatic approach to retain the strength of the frame - I did settle for adjusting the bottom edge upwards slightly, at the same time a lowering the top edge, to give an overall frame depth of 5.5mm which is a nice manageable figure to work with.

 

 

 

It was an iterative process working between the two images, and cross referring to some sketches and dimensions I'd taken of the completed chassis, but eventually a theoretically workable outline was achieved. The 'solution' showed that the location of the intermediate gear had rotated clockwise around the trailing wheel, and that the motor had to be relocated further towards the rear and slightly higher in the body cavity.

 

 

This does raise a slight alarm-bell as it appears that the motor is now too high and will interfere with the fitting of the body casting - this where I'm optimistically looking for the 'errors' in the Farish pannier, but this is worse case, and there is still scope for adjusting the location of the intermediate gear and motor should it be needed. On the positive side, this has shown that the principles of the design work (well they should do since I'm copying someone else's!) and that I think I'm starting to understand what I'm doing...

 

The picture below shows the outline plans for the way in which the frames, frame spacers, and footplate/buffer-beams, will be put together...

 

 

...and although this looks very neat in theory, I suspect that what actually end up being soldering together (what with all the adjustments and fettling that no doubt will be needed) will look slightly different !

 

I had suspected earlier that a plasticard mock-up would be needed, and this is now a certainty. Even with measuring the Farish body casting, the design will still be theoretical until I know that the realities of the sizing and spacing. Again another positive outcome of this will be that once the correct solution has been discovered, it will be a very simple matter to adapt this design for the 57xx to one that will allow for a representation of the 54xx using a modified Farish 8750 body

[bcnPete]

Very nice drawings Steve - I do like the overlay of CAD on the originals...it's good to see the process and reflects work in progress...

[Donw]

Just think if you had a CNC miller you could just feed it the CAD and hey presto the frames. Most impressive its all a bit high tech for me. What CAD package are you using?

Don

[SteveBedding]

Just think if you had a CNC miller you could just feed it the CAD and hey presto the frames. Most impressive its all a bit high tech for me. What CAD package are you using?

Don

 

Shssshhhh - not so loud....

 

That's a dream/plan I have in the background; I've got the plans and sourced the stepper-motors & driver, but the software is is still a grey area at the moment... There are some reasonable conversions for a Proxxon MF-70 on-line and I hope to progress this little project later in the year - just don't tell SWMBO As to the drawing package, I use both AutoCAD and AutoSketch (oldish versions) since that is what I was familiar with; I tried TurboCAD but couldn't get to grips with it (probably a lack of perseverance). One day I'll try to get the hang of the 3D elements, then I'll have a go at 3D printing - that may solve the delays in the Dean Goods that may eventually be available from N Brass...

[SteveBedding]

Ah, it all comes back to me now… …said the skunk, when the wind changed direction!

 

Lots of fiddling around and thinking/planning rather than actually doing anything - the discrepancy between my ‘theoretical’ frames and the spare ones I was using as a baseline was nagging me – until I had an brain storm, and realised that they were the Mk I version that was designed to fit straight into an unmodified Farish body shell! (I’m sure I had been told this before, but with a memory like a sieve, this had some how been overlooked!).

 

 

Suitably reassured, it was time to look in detail at the Farish body casting; since this is an N gauge model (nominally 1:148 scale as opposed to 1:152 for 2mmFS), I expected it to be slightly oversize. In reality this would be a slight advantage The difference between the two scales is around 2.7% and a quick measure of the length & width of the body shows that whilst it is still slightly oversize, it is close enough for government work... For instance, the length over the buffer beams should be 55mm at 1:152, thus at 1:148 it would be 56.4mm, and the Farish casting is 57.4mm - I don't know about everyone else, but my eyesight can't tell that difference!

 

(These are very rough measurements (particularly the 'depth') and will be refined once the footplate and surplus material has been cut away)

 

The 'cavity' space in the casting is adequate in terms of width to fit the NL MidiMotor and there is still the option of some slight 'widening' between the leading and drive wheels should this be required, though I suspect that when the rubbish under the panniers is cut away, this will not be an issue. There is some concern over the 'roof' of the cavity in that it slopes down from the cab end towards the front; this may require some adjustment of the motor positioning, or grinding away some of the surplus material in the roof.

 

Whilst looking at the Farish body, there are several areas where the casting needs to modified, either to fit the chassis, or to enhance the detailing and look of the model...

 

 

Interesting point I've just noticed. Whilst I'd not been able to find any definitive Route Availability information (GWR colour coded weight restrictions) for the Calne Branch, there is a snippet in G Tanners

The Calne Branch

(pp9) that states "

From Chippenham... At the the approach to the point where the track became single, a notice stood which stated that no engine classified blue or red was allowed on the branch

". A quick check (Farish was right!) showed that the 57xx/8750 class panniers were designated Blue disc, and theoretically could not have been allowed on the line - that said they were the standard engine for the goods traffic (and some passenger services) from Chippenham.!

 

The other common loco's on the line (54xx, 48xx/14xx, 45xx, Dean Goods, and Collett 2251 were all Yellow disc or unclassified (no disc) and so were not restricted.

As previously indicated, a plasticard mock-up of the chassis would be a sensible test of the design and 'proof of concept'. Although the draft plans at this stage are based on true 2mm scale, and some adjustment will be required to match the exterior dimensions of the Farish body, the principle dimensions (wheelbase and gearing) will remain the same. Again another advantage of using CAD allows a quick drawing to be made by copying the major components which can be fed through a RoboCutter that will scribe the outlines directly on to plasticard sheet.

 

 

The resolution of the RoboCutter is not as good as the mill, but is sufficient to replicate the gross dimensions of the components which can be assembled into a reasonably accurate prototype of the chassis.

 

(I've fitted an additional 'spacer' between the frame sides where the motor mount would be to reinforce the plasticard prototype - this will be omitted on the final version)

 

It's very rough & ready and no effort has been wasted on the finishing but it proved that the assembly was viable and components all fit together as hoped. It also showed that when the final chassis is built, it will have to be made as two major sub-assemblies (the frames/spacers, gears, and wheels, as one, and the footplate/beams as the other) as the wheels cannot be fitted and quartered when fully assembled in one go. The motor and decoder will have to be properly fitted last.

 

I've still got to get busy on destroying adapting my 57xx body casting to fit the new chassis profile, and I hope to be able to test-fit the prototype chassis block (in true Blue Peter style - here's one I prepared earlier...) to Missy's model this evening, but I'm getting quite confident that apart from some (already known) alterations, there is a light at the end of the tunnel

[-missy-]

Hi Steve.

 

I didnt realise my engine and sideframes were being reviewed to that degree so publically!!

 

What you have done is very thorough for sure! As its a first chassis I guess it can be justified.

 

Missy

[scanman]

Hi Steve -

 

I've just put a 'High Level' chassis with representative motion under a 4mm pannier. I *definitely* would not go to the trouble of putting working motion in - even in 4mm there's not much visibility. Just having 'daylight' showing through would be reward enough in 2mm!

 

 

Regs

 

Ian

[2mm Andy]

Hi Steve,

 

That is a very thorough job! I've never seen a plastic mock-up of a chassis before, but it does look to be a useful way of approaching something (although I have heard of a 2mm modeller assembling a cardboard mock-up of a etched kit design to check fit, etc.)

 

I'm interested in where the drawing of the pannier tank came from - I have several Farish bodies (large prairie tank, 4MT tank loco, etc.) that I'd like to put 2FS chassis under and finding drawings is sometimes a problem, especially when it's this funny GWR stuff (puts on tin hat and ducks!)

 

The metal that the Farish bodies are made from is fairly soft, so it's quite easy to mill. I found it fairly straightforward to remove some of the metal inside the body of the Jinty.

 

Andy

[SteveBedding]

...What you have done is very thorough for sure! As its a first chassis I guess it can be justified.

 

Three reasons for the 'thorough' approach - 1) I'm not a 100% sure of what I'm doing so it prevents me rushing in..., 2) it gives time for people to shout out when I'm about to go drastically wrong!, and 3) it's a thinly disguised cover for procrastination

 

I've just put a 'High Level' chassis with representative motion under a 4mm pannier. I *definitely* would not go to the trouble of putting working motion in - even in 4mm there's not much visibility. Just having 'daylight' showing through would be reward enough in 2mm!

 

It had never crossed my mind to include any representation of the inner workings - and now that you mention it I find the thought scares me witless If all goes well, I'll include the brake work and obvious pipes on the exterior of the chassis but that is as far as I aspire to get to. The little 'daylight' that can be seen between the leading and driving wheels will be nice, and so will being able to see the (dirty) 'reddish' colouring on the inside of the frames.

 

That is a very thorough job! I've never seen a plastic mock-up of a chassis before, but it does look to be a useful way of approaching something (although I have heard of a 2mm modeller assembling a cardboard mock-up of a etched kit design to check fit, etc.)

 

I'm interested in where the drawing of the pannier tank came from - I have several Farish bodies (large prairie tank, 4MT tank loco, etc.) that I'd like to put 2FS chassis under and finding drawings is sometimes a problem, especially when it's this funny GWR stuff (puts on tin hat and ducks!)

 

The metal that the Farish bodies are made from is fairly soft, so it's quite easy to mill. I found it fairly straightforward to remove some of the metal inside the body of the Jinty.

 

For me the choice of plasticard for a mock-up was an easy one, (again stealing someone else's idea - thanks mitziblue!) I bought SWMBO a RoboCutter about a year ago and that coupled with the basic CAD packages means I can 'print' to plasticard the components as drawn - the down side is that it only scores 0.5mm plasticard as it's cut depth is 0.3mm max, but that is enough to get the outline done. The real justification was to eventually produce the frames/carcasses for the buildings on both Smokey Bacon and the Oxford groups layout, but I keep finding other uses for the toy tool.

 

As to the body drawings, I have several books on GWR locos (to be expected really... ) and Russell's Pictorial Record of Great Western Engines has drawings of pretty much all the required motive power. I'll have a look through the good book to see what I can find on the large prairie (I assume you mean the 61xx class?) but I don't think I've much on the BR standard classes.

 

Thanks for the tip on the metal. I'm still not that confident with using the mill for this sort of task and so I was intending to butcher the body with a saw and files. I suppose that this is a good time to get practising with the mill so I'll see how that this progresses.

[Kris]

Very smart mock up Steve.

[bcnPete]

Excellent Steve

 

The use of the mock for the chassis is a great idea - I might have to 'make reference' to that when I build my first one.

 

Its going to be something else this pannier when finished.

 

How did you pull the stunt of buying a robocutter as a present...and then hijacking it? I tried that with the digital photo frame...but with less success

[Andrew Peters]

Interesting point I've just noticed. Whilst I'd not been able to find any definitive Route Availability information (GWR colour coded weight restrictions) for the Calne Branch, there is a snippet in G Tanners

The Calne Branch

(pp9) that states "

From Chippenham... At the the approach to the point where the track became single, a notice stood which stated that no engine classified blue or red was allowed on the branch

". A quick check (Farish was right!) showed that the 57xx/8750 class panniers were designated Blue disc, and theoretically could not have been allowed on the line - that said they were the standard engine for the goods traffic (and some passenger services) from Chippenham.!

 

The other common loco's on the line (54xx, 48xx/14xx, 45xx, Dean Goods, and Collett 2251 were all Yellow disc or unclassified (no disc) and so were not restricted.

 

Steve,

 

From what I have been reading these last few weeks as reference for my idea You would find that the 57xx would be able to run on the line even if it's Blue dotted, BUT it would be restricted to a maximum speed of 25MPH. I know that the Strawberry Line was Dotted Blue and have read that there was a Manor class brought through to test the new turntable at Wells and that there is a picture of a 9400 class which is 'RED' dotted on the line .

The other thing is that the maximum axle load on the front two alxes is only 17t 0c.

 

Hope this helps.

[2mm Andy]

Three reasons for the 'thorough' approach - 1) I'm not a 100% sure of what I'm doing so it prevents me rushing in..., 2) it gives time for people to shout out when I'm about to go drastically wrong!, and 3) it's a thinly disguised cover for procrastination

As to the body drawings, I have several books on GWR locos (to be expected really... ) and Russell's Pictorial Record of Great Western Engines has drawings of pretty much all the required motive power. I'll have a look through the good book to see what I can find on the large prairie (I assume you mean the 61xx class?) but I don't think I've much on the BR standard classes.

 

Thanks for the tip on the metal. I'm still not that confident with using the mill for this sort of task and so I was intending to butcher the body with a saw and files. I suppose that this is a good time to get practising with the mill so I'll see how that this progresses.

 

Thanks Steve - the NRM library/Search Engine is likely to have that book - I'll pop in at the weekend and have a look (it's only a 15 minute walk from home!). I've managed to find a reference for the Standard 4, so again that can be investigated at the weekend!

 

As long as you take it easy and make shallow cuts with the mill you shouldn't have any problems with the Farish body, and it is far easier to get a much neater finish than with a saw and files.

 

The CNC mill ideas sound interesting. I reckon you could be setting yourself up for bulk orders of sideframes if you get it working!

 

Andy

[-missy-]

Hi Andy

 

Of course you could always find them on the GWR Archive pages link thingy. What are you going to build?

 

Missy

[2mm Andy]

Hi Andy

 

Of course you could always find them on the GWR Archive pages link thingy. What are you going to build?

 

Missy

 

 

Thanks Missy - I don't think I have seen that website before!

 

I have a Farish GWR 61xx body and a Standard 4 tank body that are in need of 2mm chassis. They're a fair way down the list of priorities at the moment, but Steve's little project set me thinking...

 

I'll probably still have a look in the NRM library when I get time. I also have a list of magazine sources to investigate when I next pop over the the Vintage Carriages Trust Museum at Ingrow.

 

Andy

[Kris]

The CNC mill ideas sound interesting. I reckon you could be setting yourself up for bulk orders of sideframes if you get it working!

 

 

 

Andy could be right there, obviously depending on the other kit in development.

 

 

[Gingerbread]

Another possible source for GWR drawings is here

I suspect the main locomotive list is the same as from Missy's link, just presented in a different order to make comparison more difficult. It does have additional coverage of small tank engines and outside framed 4-4-0s, and some goods wagons and carriages (including a railmotor or two).

 

As Steve said, the recommended source for GWR locomotives seems to be Jim Russell's books, which come in three volumes. Volume one is pre-1900, volume two is post-1900, and volume three is absorbed locomotives (from a quick glance at a copy recently, this appears to mean the various Welsh railways absorbed at Grouping in 1923). Cost likely to be about £25 each second hand.

 

The other source to mention is RCTS Locomotives of the GWR, a series of 14 volumes published between 1951 and 1993. Prices vary, but typically £10-£15.

 

I don't think that the NRM have catalogued their GWR collection yet, so whilst the drawings you want are almost certainly there, you probably won't be able to find them.

 

David

[2mm Andy]

Another possible source for GWR drawings is here

I suspect the main locomotive list is the same as from Missy's link, just presented in a different order to make comparison more difficult. It does have additional coverage of small tank engines and outside framed 4-4-0s, and some goods wagons and carriages (including a railmotor or two).

 

I don't think that the NRM have catalogued their GWR collection yet, so whilst the drawings you want are almost certainly there, you probably won't be able to find them.

 

David

 

Thanks David,

 

I suspect the drawings in your link (another website I'd not come across before) are the same as those in Missy's link.

 

I was intending to have a look at Jim Russell's book to see if there were drawings in there - the new 'Search Engine' at the NRM has quite a good library of books that is 'self-service' with no appointment necessary and a photocopier available to make copies (within the published copyright rules), so it should be possible to call in and find the relevant information fairly quickly.

 

For the level of detail I need at this stage, I wouldn't bother looking at the works drawings anyway - even if I could find the ones I wanted! They usually contain far too much detail and would need quite a lot of time spending on them to 'convert' for 2mm use.

 

Anyway, I seem to have diverted Steve's thread slightly - any progress on that 57xx Steve?

 

Andy

[SteveBedding]

...You would find that the 57xx would be able to run on the line even if it's Blue dotted, BUT it would be restricted to a maximum speed of 25MPH. I know that the Strawberry Line was Dotted Blue and have read that there was a Manor class brought through to test the new turntable at Wells and that there is a picture of a 9400 class which is 'RED' dotted on the line . The other thing is that the maximum axle load on the front two alxes is only 17t 0c.

 

Andrew,

 

I suspected that this was the case but it's nice to get another perspective.

 

I've done a bit more 'digging' and found that the Calne Branch was subject to a 30mph limit along its length; the line was only 5.3 miles long, and the scheduled time allowed was 15 minutes so this was not really an issue. However, this was not always adhered to - there were several (in)famous recorded 'runs' where the 'need for speed' ruled! On one occasion, a 45xx out of Bath was timed at 7.5 minutes, a Westbury 54xx set a 'class record' of 8 minutes, and a certain Chippenham driver regularly did the run in 9 minutes in either a 54xx or a 48xx/14xx!

 

As to the loading and weight restrictions/prohibitions, this also seems to have been ignored when expedient A Bulldog (Bird) class (3443 Chaffinch), also Blue disc, hauled a troop train in the early 1940s and 3829 County of Merioneth was drafted in during train drivers strikes in the 1920s. This County class loco was not the only 'Red disc' engine to work the line; after Nationalisation, 94xx class 0-6-0 panniers drew the duty, and although I cant find the reference to hand, I'm fairly certain that 56xx worked freight runs up from Westbury. Lastly, during the last days of the line, D7000 (a Hymek Diesel-Hydraulic) worked the snow-clearing trains.

 

All this is very useful, as it gives a precedent, in addition to the usual 'operational expediency' during wartime, to include some unusual locos to haul the specials - oh goody, that'll be a cause for the Ixion Manor, Dapol's Hall, and hopefully someone will make a County soon . [Oh, and not forgetting the Q1, the forthcoming WD Austerity 2-8-0, a 28xx, and even a ROD 2-8-0 (though that's stretching it a bit...), and even a visiting WD J94 0-6-0 from Bicester (this last one is another stretch, but there actually could be a plausible justification...)]

 

 

Anyway, I seem to have diverted Steve's thread slightly - any progress on that 57xx Steve?

 

Yes - but I'm not sharing...

 

Seriously, I'm not that quick! A days serious modelling time was wasted by the need to help (allegedly) increase the national deficit, as will tomorrow However, I think I now have all the bits I need, the small adjustments to the intermediate gear and motor height are being applied, and SWMBO is working this weekend. I should be able to have a first stab at the real chassis and the modifications to the Farish body in this time...

 

...stay tuned

[buffalo]

...As to the loading and weight restrictions/prohibitions...

 

I may be wrong, but I don't think anyone has mentioned that the 57XXs were all reclassified as yellow route colour (except 9700-10) in 1950. Perhaps the folk on the Calne branch were just very forward-thinking?

 

Nick

[Pilgrimsjulie]

Well SWMBO has just read the post . I must admit I can see a really long wish list in paragraph 2!! I am not sure in how quick these can be got- but I am sure that I was shown a certain page on an auction site......so think that was a hint for at least one of them!!! Not only that but no wonder I am working again this weekend to be able to afford them . The dining room has already changed into the modelling room so trays it is yet again for meals!!!! Mind you I not mind as we can watch real rubbish as we are eating . Well I hope that the modelling goes well and look forward to seeing what comes out of it and how much is done.