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Building ‘Tantalus’ - Part One


MikeOxon

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The goods train involved in the ‘Bullo Pill’ accident, which is described in some detail in the Accident Report, was headed by the locomotive ‘Tantalus’ and comprised 20 cattle wagons, plus a third-class carriage at the rear, in which 8 drovers and the guard were travelling.

 

Tantalus’ was built in November 1862, in the last lot of those engines which, together, comprised Gooch’s ‘Standard Goods’ design. The name ‘Tantalus’ was taken from a figure in Greek mythology, whose name lives on in our word ‘tantalise’. I started building this kit in the hope that the finished item would not remain ever out of my reach!

 

Those who have read my earlier posts about building Broad Gauge Society kits will know that instructions tend to be somewhat sparse and some of the constructional elements are hard to achieve, especially in 4mm scale The instructions for this one, however, start with some re-assuring words: “What puts some people off is the apparent complexity of the etch, however these are essentially very simple engines and by breaking the construction down are less difficult than first it appears.

 

In the case of the ‘Gooch goods’ (BGS Kit F02), I have already had a practice run, by constructing a pair of sandwich frames. Rather than using the tiny brass spacers, as suggested in the kit, I decided to use my ‘Silhouette’ cutter to cut out a card in-fill to fit between the outside ‘flitch plates’. The advantage of using card rather than a plastic material is that the frames can still be soldered and, indeed, the filler makes it much easier to maintain the correct alignment during soldering. The details of my construction methods are contained in an earlier post.

 

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Pair of sandwich frames

 

According to the instructions “The two sides are connected with the front buffer beam and rear buffer beam or dragbox, and the motion plate will help hold it all together. The bufferbeams simply fold up with some overlays.”

 

When I have scratch-built my own chassis, I have used relatively thick bass-bar (1 mm thick) to form strong cross-members to align the ends of the frames. In this case, however, I decided to use the kit components, as they are already provided with holes for mounting buffers and coupling hooks. The front buffer beam starts as a long strip of brass, which has to be folded in three places to make an open box. I decided to adopt the same method I had used for the sandwich frames and placed a card insert within the box, which provided rigidity and also held the joint in alignment for soldering. At the back of the engine, the drag box was just a simple strip of thin brass, which gave little rigidity to that end of the engine.

 

I tinned the ends of the frames and the appropriate places on the back of the buffer beam and held them in careful alignment while soldering the parts together. There are also thin strips of brass to solder to the top and bottom of the buffer beam, so closing the box structure.

 

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Chassis frame constructed.

 

The instructions note that “There is no footplate extending forward of the cab. Outboard of the frames you have the curvy valence/splasher top over the wheels, something for the crew to stand on behind the firebox, and lots of open space

 

I looked in vain on the parts list for any footplate material but, although shown in a sketch, nothing is provided. I decide to re-assign some parts that are only needed for the saddle-tank version of this engine, to make some foot-plating that would also serve to strengthen the rear end of the chassis.

 

The next items to consider are the splashers. I’ve been there before with my scratch-built model of ‘Rob Roy’ so am well aware of the problems associated with these bicycle-like splashers.

 

I was interested to see how the kit would tackle the problems and my findings are none too encouraging. All the instructions have to say is: “once the frames and buffer beams are assembled with the hornguides in place, the valence/splasher assembly can be soldered in place. This can cause problems so bend carefully and take it slowly. If all else fails you could bend up and fit the splasher tops separately; use plenty of solder and then file to shape.” The key phrase I take from here is “This can cause problems” - quite an under-statement, in my opinion, especially after looking at the parts provided on the fret.

 

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Spashers fret.

 

We have 6 little ‘demi-lune’ pieces, which are the splasher backs, although there are no aids, in the way of tabs, to fix them to anything. Then there are two thin curvy bits, which are the splasher front valances (again, no tabs), and finally two straight strips of brass that, somehow, have to be curved to match the curves of the front valance. Mmmm!! A pause for thought needed here – I shall think of an alternative approach :)

 

I have already made the boiler from this kit and have described the assembly of firebox, smokebox, and boiler in previous posts.  I have tested the boiler in position on my new frames and found it a tight fit at the smokebox end.  My main purpose at this stage was to determine the size of the footplate that will be needed at the back end.  At present, the (loose) assembly looks like this:

 

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Boiler and Frames

 

In the meantime, I have made some more wheels, by means of my 3D-printer, to suit the front end of ‘Rob Roy’.  I had been using some other wheels, which I had to hand, as ‘stand-ins’. Having wheels of the correct diameter and number of spokes makes a significant improvement to the appearance of my model.

 

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Rob Roy wheels

 

I learned one or two new lessons along the way. After completing the basic design of the spokes, I decided to add curved fillets between each spoke and the rim. It’s quite tricky to see all these edges on the computer screen but the task is made much simpler by selecting ‘wire-frame’ in the view options. I also found that, if I selected the wrong edge by mistake, it was easy to delete the fillet simply by selecting the surface of the fillet and clicking ‘delete’ (I had searched many alternatives such as trying to re-set the fillet radius to zero before discovering this simple remedy) So many things in ‘Fusion 360’ (and probably many other CAD programs) are easy when you know how!

 

‘Rob Roy’ is still not painted and there are a lot of ‘finishing touches’, so I shall write no more about it for the moment.

 

Mike

 

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That's looking good Mike. It's so pleasing when a method you've developed for an earlier project - the card infill - can be used again.

 

I have to say I like the expression: 'This can cause problems'. If there was an instruction sheet for life, I would put that at the top.

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Great progress, very much looking forward to seeing this build come together. I think I might tackle the splashier tops as separate pieces: three curved bits and flat sections in between, filled and gently filed to appear as one strip. Bending and shaping the whole lot in one go must be nigh on impossible.

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2 minutes ago, 5&9Models said:

... I think I might tackle the splashier tops as separate pieces: ...

 

That was my approach when I built 'Rob Roy' but there I had some strong back support to bend the strips around.  My thinking at present is to 3D-print a suitable former.

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4 hours ago, MikeOxon said:

 

That was my approach when I built 'Rob Roy' but there I had some strong back support to bend the strips around.  My thinking at present is to 3D-print a suitable former.


I must admit I have found annealing the brass before bending makes a huge difference, particularly on boilers, but it might help here too.

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5 hours ago, MikeOxon said:

Do I detect Nordic angst in your comment on life? Mikkel


it does have a flavour of H2G2 in referring to Earth as “mostly harmless”...

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2 hours ago, 5&9Models said:


I must admit I have found annealing the brass before bending makes a huge difference, particularly on boilers, but it might help here too.

I wonder whether you could use the Silhouette to cut out the profile and use that as a jig?

Another "interesting challenge"! 

Best wishes 

Eric 

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I know it has nothing to do with this, and is completely off topic, but I think the somewhat preserved RFA vessel S.S. Freshspring was laid up outside Pullo Bill dock for sometime, and might still be.

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Thank you for commenting.

 

My information is that RFA 'Freshspring' was berthed at Collow Pill, Newnham on Severn, which is a short distance up-river from Bullo Pill.  I believe that it has since been moved to Bideford, where full restoration is in progress.  When I last visited Bullo Pill, there were a few houseboats there but very little other activity.

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