Sprung Class 47 Bogies

[jjnewitt]

Having had a nose through this section of the forum I've noticed that in the matter of chassis and suspensions it all seems to be about steam locos. Nothing really wrong with that but I thought I'd do my bit to redress the balance a little in the direction of the diesel and electrics!

The latest project to land on my workbench are some fully sprung bogies for a pair of Bachmann class 47s. I thought it might be of interest to some of you who might be thinking about dabbling in the dark arts of diesel suspension to see how I go about them on a step by step basis. Each of the bogies is basically an 0-6-0 steam loco chassis with guitar wire springs connecting the wheels through hornblocks to the chassis. To this will be added some secondary coil springs to connect the bogies to the locomotive. A bolster flange and recieving plate made of telesocping brass tubes will keep everything where it should be. The original drive train on the Bachamann locos will be recycled to provide the power to the wheels. At the moment I intend the drive arrangement to be of a B1-1B configuration though with a bit of extra work a C-C is very possible. Hopefully it will all look simpler than it sounds.

Before the construction can begin there's a bit of theory to contend with. For each type of bogie that I've built the first thing that I've done is draw up a 'Data Sheet' outlining the basic dimensions of the sideframes and the arrangement of the primary and secondary suspension. On previous bogies I've used 'centre load on beam with two simple supports' principal as described on CLAG's website http://www.clag.org.uk/beam.html. This envolved a lot of faff cutting, drilling and then fitting twelve spring supports made from brass L section for each bogie. I'm going to try the 'end load on cantilever beam with single fixed support' method to try and simplify things. The final make up of the secondary coil springs and connection to the body will involve a bit of trial and error with regard to the dimensions and set up. I don't possess the engineering prowess to get too technical about coil springs. Given the choice I'd prefer to use the wire beams but there isn't anywhere to hide them on these sorts of bogies so coils it will be. I suppose you could dispense with the secondary suspension but I haven't figured out a way of satisfactoraly transferring the weight of the loco to the bogies without it. Perhaps others will have better thoughts on the subject.

Recipe

The ingredients:

Ingredients

Class 47 Bogies 1.JPG (67.98 KiB) Viewed 15446 times

An all wheel drive wibbly wobbly bannana bogied Bachmann Brush type 4 (they definately didn't have P4 conversion in mind when they designed this)
Heljan cosmetic sideframes (the Bachmann ones are a bit 'weedy')
3 (2.95 actual) x 1.5mm and 2.5 x 1.5mm brass L section for the primary spring supports
1mm brass rod to 'rivet' the primary spring supports to the sideframes
2 x 1mm brass flat for a hornguide setting jig
1/8", 3/32" square brass tube and 1/16" rod for the secondary spring arrangement
0.010" and 0.018" nickel silver sheet
28swg phb wire for the coil springs
Gibson P4 frame spacers
High Level 2mm hornblocks
0.011" Guitar wire for the primary springs
Ultrascale 3'9" diesel disc wheels

There's probably something I've forgotten about but that's pretty much it.

The first thing to do is the most tedious and certainly the hardest on piercing saw blades, namely cutting out the sideframes. Sometimes though there's nothing for it but to get your head down and get on with it. It doesn't take too long with something half decent on the radio or stereo. I cut a strip of 0.018" nickel silver 9.5mm wide then cut that into 82mm lengths which were then soldered double to form a pair of sideframes. If there's one thing worse than cutting out four lots of sideframes it's cutting out eight! A cut was made on the top edge to permenantly mark the centre for reference and then they were cut to shape. Etches for this would be lovely but that would mean learning CAD which could be a very dangerous thing for me to do. I think I might like drawing etches a bit too much and spend all my time on the computer! A note on the sideframes, they don't need to be work of art but the top edge must be flat and straight. This is the datum from which everything else is set.

Sideframes

Class 47 Bogies 3.JPG (62.68 KiB) Viewed 15446 times

More soon.

[grovenor-2685]

Great start, I look forward to more of it. I managed to get my B47 more or less holding the track by choosing the least banana shaped of 4 bogies and then fettling those. Further improvement is on my list when I get through rebuilding the layout and can resume work on rolling stock.
Regards
Keith

[craig_whilding]

Great start there. I've got one of these too and the banana bogie class 37 generation too. I was intending on etching up some form of keeper plate and subframe for mine so I look forward to seeing what you do.

I haven't forgotten about the S.Wales WTT's btw but a new job after xmas has meant some long hours so far..

[Paul Townsend]

when I get through rebuilding the layout
Keith

Tell us more?

[grovenor-2685]

Not really much to tell, I had to take all the boards out to have some roof repairs done, and decided to rewire with CBUS as I put them back, for various reasons the work is going slowly.
Regards
Keith

[John Bateson]

How about this?
Very straightforward to get this etched.

John

Drawing base on earlier submission - needs checking though since I am not knowledgeable about 47s.

[Penrhos1920]

Justin,

Where do you get spare Heljan bogie side frames from?

What sizes are the 2 large brass tubes, top left?

[jjnewitt]

Hi all,

Thanks Craig. Whenever you get time will be fantastic. Hope the new job's going well.

Your drawing John looks pretty spot on. I should get around to learning CAD as it would make things a bit easier with things like this. My concern lies not in the difficulty but in my propensity to go a bit overboard at times. Take the sideframes for example. To make things even easier it would make sense to include the frame spacers so the whole assembly just folds up. Then it would be good to perhaps include fold out supports for the primary suspension, perhaps allignment holes for the High Level hornblocks so we can just solder them to sideframes without recourse to jigs and also an etched bolster plate to save messing around with tube just to get a circular hole in a sheet of nickel silver. Then of course it would be nice to do something about the brakes and etch them and also some sort of fold up drivetrain reusing the Bachmann gears so I don't have to file back the hornblocks to get everything to fit. I'm sure there would be space left on the etch for some detailing parts... I'm not sure I'd know when to stop! There are loads of things I would love to have etches for, replacement cab and bunker for the Bachmann/High Level pannier tank sat on my shelf, a conversion kit for the Finney Hall to represent Hawksworth's modified variety, sprung underfames for David Geen's milk tanks (done two of those using Masokits W-Irons, brass sheet and flat bar, takes an age). I will get around to some of those things one day but for the moment, while I haven't learnt CAD, I can't and so more progress is made on current projects that I need to get finished and there's lots of those.

The tubes are 5/8" and 21/32" OD from the K&S range. I meant to include that in my list. Must have missed that on the redraft after my laptop lost network connection and half of the post disapeared. The 5/8" tube is almost and exact match for the width over the sideframes when they are assembled with the Gibson frame spacers.

The Heljan sideframes came via Ebay. They crop up on there ocassionally. They can be had from Howes Models though when they have them in stock, which they do at the moment http://www.howesmodels.co.uk/Railways/viewProduct.php?ProdID=6902. £0.90 a pair, bargain. Annoyingly they sold out of the fuel tank/battery box mouldings before I got chance to buy a sprue. I need another set for this project.

[John Bateson]

Justin,
Its always a dilemna deciding just how far to go with a design, something I have learned in a little enterprise of mine. Designing in a few location holes ought to be relatively easy though, but totally fold up etches including spacers for EM, P4 and possibly 00 would be counter-productive for a small run.
Fold out supports for axle boxes are a little easier.
Costing it out was also quite easy, allowing for 6 sets of doubled frames per A4 sheet, so the first etch would cost around £40 and subsequent etches £20.
This means a sale cost of say £7.50 depending on how many people would want to use these.
I would be happy to forward the TurboCAD V18.1 DL drawing to anybody who might want to take this on, it is way outside any of my current plans, but it is still the basic frames, nothing else, no frills.
John

[jjnewitt]

Interesting how much these etches would actually cost John. I guess it comes down to personal preference as to what cost effective actually is situations like this and whether it's quicker for a pair or two of bogies to get the skrawker and piercing saw out or sort out etches. Etches would make things easier though and if they'd been avaliable I'd probably have brought some to save the time. My piercing saw blade supplier might not be so keen though!

Right next step is to solder the hornguides to the frames. To my mind there are two ways of doing this. Either you can set them using the hornblocks or the hornguides. If you have an Avonside Chassis jig then it would be dead easy. Use the Bachmann drivetrain to set the jig to the correct wheelbase and away you solder. I don't have one of those jigs nor do I even have a pilar drill so it's difficult for me to acurately drill holes in something like a block of paxolin to replicate that kind of arrangement. So I rely on an engineers square an my Vernier Caliper. This is the same method that I've used on all my sprung bogies and works fine. My jig is quite simple, two pieces of 2 x 1mm brass flat 'guides' soldered the required distance apart and square to the edge of a small sheet of 0.018" nickel silver.

Class 47 Bogies 4.JPG (67.42 KiB) Viewed 15207 times

The pairs of bogie sideframes are unsoldered from each other and cleaned up so that any stray solder is removed from the all important top edge. The sideframes and jig are then clamped together against a straight edge so that everything is in the right place. This is one of the times where the cuts I made in the top of the sideframes to mark the centre come in handy. I've marked one of the 'guides' with where the centre of the axlebox would be and lined it up with that cut ensuring the middle axle will be where it should be. The horguides are then held against the correct sides of the 'guides' on the jig and then soldered in place. This all ensures the hornguides are square to the top of the bogie sideframe and the correct distance apart for the wheelbase.

Class 47 Bogies 5.JPG (56.5 KiB) Viewed 15207 times

Since the wheelbase is symetrical the third hornguide can be set by simply unclamping the bogie sideframe and moving it across leaving one of the 'guides' free. When done the jig can be recycled and the sheet and brass flat used for other things. All very green! Hopefully the illustrations will make my waffle clear!

[jjnewitt]

Next job is to sort out the primary suspension foundations while things are easily accessible. The foundations consist of 3 (2.95 actual) x 1.5mm brass L section onto which the springs will be soldered. They need to be arranged so that the distance from the edge to the spring bearer on the hornblocks are consistent. To do this I need some sort of jig. I made one from a scrap piece of 0.018" nickel silver and some spare 3 x 1.5mm U channel. The nickel silver strip was cut and then filed down to be exactly 12mm wide and the piece of U channel was soldered centrally and square to it. The hornguide setting jig came in handy for this.

Class 47 Bogies 6.JPG (63.29 KiB) Viewed 15098 times

The idea is that the jig is placed in the central horngide and the primary spring foundations are soldered up against the edge of the jig. This sets them 6mm away from the centre of the middle hornguide. The primary spring foundations were carefully cut then filed to 17mm in length, this was checked using the vernier caliper. This ensured that they were the correct distance from the outer hornguides when soldered to the sideframes. The straight top edge of the sideframes ensures that the foundations are all set at the same height. Some of you may notice that half the foundations are wider than the others. This was because I didn't have enough 3 x 1.5mm L section to do 4 bogies so I had to use some 3 x 2mm as well. The long side was filled down ever so slightly to make sure it was the same width (2.95mm) as the 1.5mm deep variety.

Class 47 Bogies 7.JPG (53.63 KiB) Viewed 15098 times

I was a bit concerned about the primary spring foundations moving when soldering the springs to them (or removing them if they need changing at any point). So in order to make sure they don't move from where they have been carefully soldered I pinned them to the sideframes using 1.0mm brass rod. Holes were drilled slightly undersize in the sideframes then carefully opened out so that the rod was a nice tight fit then they were soldered in. This might seem a bit like overkill but I didn't want to take any chances. One of the benifits I found in chosing the method of primary springing that I have is that these bits of brass L section stiffen up the very flimsy sideframes nicely.

Class 47 Bogies 8.JPG (53.5 KiB) Viewed 15098 times

After all these foundations were in place the axleboxes were put in their guides. I went through some orientation checks by eye to try and ensure that the holes for the axles are as central as possible but the High Level hornblocks are very well engineered and I'm not sure they made a lot of difference. This wasn't the case with the original type Exactoscale hornblocks that I've used before. Some of the holes were so off centre that I had to solder shims to one side and then file the other down. Of course if you can set the axleboxes using the axle holes then none of this care and attention is necessary.

Something needs to be done at this point about the width of the hornblocks on the driven axles. As supplied they protrude 2.6mm from the inside of the sideframe. The width over bearings on the Bachmann drive train is 11.2mm. Something's got to give! There's room to take a bit off the Bachmann bearings but nowhere near the 0.7mm that's needed. There's only one thing to do and that's take some of the width off the hornblocks. I took then down to the horncheeks on the hornguides. Now the hornblocks protude 1.7mm from the sideframes which should be plenty for clearance.

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The final job to do before the sideframes can be assembled with the frame spacers is to solder spring bearers to the hornblocks. These bearers are made from 2.5 x 1.5mm brass L section. For the sake of honesty the 2.5mm L section I had was only 2.4mm as supplied so I soldered some 0.005" brass to the short side and then filled back to give 2.50mm on the Vernier caliper. This was then cut into strips 1.0mm or 1.5mm wide depending on whether they were intended for the thinned or as supplied hornblocks. The bearers were then soldered on so that the L was orientated away from the primary spring. This helped keep the 6mm length of beam that I was aiming for with the primary spring.

Class 47 Bogies 10.JPG (52.61 KiB) Viewed 15098 times

The next stage is to turn these sideframes into bogies.

[jjnewitt]

Inbetween work on other things more progress has been made. Now that the sideframes are ready they can be formed into bogies. Alan Gibson P4 frame spacers were soldered to one corner of each sideframe and 5mm below the top of the sideframe. This was done with the aid of a strip of 5mm thick hardwood that I had lying around and a jig made of aluminium angle, flat bar and plywood. The jig was originally built to help with construction of coach bodies, the idea coming from one of Stephen Williams' Wild Swan books, but comes in very handy with these bogies as well and keeps everything square.

Class 47 Bogies 11.JPG (58.46 KiB) Viewed 14968 times

The two sideframes then are brought together and soldered. An Avonside Chassis jig would be great at this point but I made use of Brassmasters Axle Setting jigs and some extended axles made from silver steel rod. It works fine as long as the etched jig is clamped parallel to the side of the aluminium angle onto which one of the sideframes is clamped and that there are slots that match the wheelbase. Fortunately there was in this case.

Class 47 Bogies 12.JPG (69.54 KiB) Viewed 14968 times

The next step was to sort out the secondary suspension stirups. These are formed of 3mm long pieces of 1/8" square brass tube from the K&S range and strips of 0.010" nickel silver bent to shape. The 1/8" square brass tube will act as a guide for coil spring and it's bearer. Another piece of the square tube was cut to act as another little jig to keep the distance from the bottom of the stirup to the guide constant. It worked out at 6.3mm. Like most of the dimensions on these things I suppose what matters most is not whether a dimension is 2.95mm or 3.0mm but that it is the same throughout the bogies where it needs to be. Everything was then held together using a clamp and a piece of 3/32" square tube and soldered together. Hopefully the photos will better illuminate this part of proceedings.

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Class 47 Bogies 14.JPG (58.33 KiB) Viewed 14968 times

Once tidied up all the bits were clamped back together and a 1/16" hole drilled in the bottom of the stirup using the 3/32" tube as a guide. This will help the 1/8" square tube 'guide' the spring bearer which will be made of 1/16" rod and 3/32" square tube.

Class 47 Bogies 15.JPG (78.42 KiB) Viewed 14968 times

These assemblies can now be soldered to the bogies. To help do this I made yet another jig from a piece of 3/32" tube 9.0mm long and 1/16" rod. This will ensure that the bottom of the stirup is the same distance from the top of the sideframe on each one. I filled the top of the assembly back a little where necessary just to make sure the jig stood proud.

Class 47 Bogies 16.JPG (66.59 KiB) Viewed 14968 times

The bogies were clamped to an engineers square so that the edge of the square was 13mm from the centre of the bogie. The stirup assembly was then soldered in place using the jig.

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Class 47 Bogies 18.JPG (73.19 KiB) Viewed 14968 times

The last magor bit to be added to the bogies, save the primary springs, were the bolster flanges. These are made from 10mm long pieces of 5/8" brass tube again from the K&S range. In order to help locate them to the bogies cuts were made parallel to and 2mm from one end on each side. The tube was then split at these points and bent so that there would be something to solder to the sideframes.

Class 47 Bogies 19.JPG (58.76 KiB) Viewed 14968 times

It's important that once cut and bent in this manner the tube doesn't impart any force on the bogie sideframes either pushing them out or pulling them in. This is especially important if the tube is going to be cut through completely to clear the drivetrain unit. If there is any force inparted then that nice circular bolster will no longer be nice and circular. The tempation is to use the tube as an extra frame spacer but as I've found out to my cost it's not such a great idea!

Class 47 Bogies 20.JPG (68.29 KiB) Viewed 14968 times

Next attention can turn to the primary and secondary suspension and some wheels can be put in place.

[jjnewitt]

Time to sort out the suspension for these bogies.

Primary springs are 0.011" guitar wire simply soldered to the spring supports that were soldered and riveted to the sideframes. It was a bit of a pain to get the wire aligned properly as the spring bearers on top of the hornblocks are mostly only 1 mm wide and on half the supports i've used one peice of wire to spring two axles. It was easier on previous bogies to fit the springs using two simple supports but then the setting up of those suppots (fashioned from L section brass with 0.45mm holes drilled through) was more of a pain. Swings and roundabouts I guess. Once set up the springs work well.

Class 47 Bogies 21.JPG (72.75 KiB) Viewed 14860 times

As I might have mentioned before or elsewhere on previous efforts I used Exactoscale 2mm hornblocks. These worked fine but due to the amount they stood proud of the sideframes it meant that I had to shave some of the boss off the back of the Ultrascale wheels. I had expected to have to do this using the High Level hornblocks but was delighted to find that it wasn't necessary at all. It's always nice to discover you don't have to do something you thought you'd have to! Everything fitted perfectly.

Class 47 Bogies 22.JPG (82.26 KiB) Viewed 14860 times

The seconday springs are made up from 28swg phospher bronze wire. I wanted them to be 6.0mm long. I chose this figure so that hopefully when the springs were under compression the spring bearers would remain hidden behind the top of the cosmetic sideframe. I usually work on 2 turns per 1mm when forming the springs so I wanted springs with 12 turns in them. These were done by hand using the shank of a 1/16" drill bit held in a pin vice. Once the correct number of turns were wound the spings were stetched out by half their length, trimmed at either end and then compressed by hand. The springs will 'spring' out a bit after compression and then settle. Once done the springs were checked using a Vernier Calpier and the springs were trimmed a little if necessary to maintain a consistent length.

Class 47 Bogies 23.JPG (68.66 KiB) Viewed 14860 times

The secondary spring bearers were made up from 6.4mm (this was supposed to be 6.5mm but I cut some a little short so kept to the slightly shorter dimension) long peices of 3/32" square brass tube with 1/16" brass rod soldered together. The rod was cut so that it extended 7.5mm below the square brass tube.

Class 47 Bogies 24.JPG (58.63 KiB) Viewed 14860 times

After they were all done it was a simple matter to assemble the springs with the spring bearers in the bogies.

Class 47 Bogies 25.JPG (75.36 KiB) Viewed 14860 times

The next job was the bolster plate which would be fixed to the body. These were made from 40 x 27mm peices of 0.010" nickel silver sheet and rings which had been cut from 21/32" brass tube. The peices of nickel silver were marked so that the brass ring would sit centrally and then soldered in place.

Class 47 Bogies 26.JPG (66.78 KiB) Viewed 14860 times

The bolster plates were then cut to allow for the drivetrain and to allow the bolster flanges on the bogie to fit through. An etch for these would be lovely! It's a bit of a pain cutting around the inside of the brass ring and there's inevitably some tiding up to be done with a file. On the plus side there is a nice bearing surface in the system.

Class 47 Bogies 27.JPG (80.09 KiB) Viewed 14860 times

In order to help support the bolster plates lengths of 1/6" square brass tube were soldered on. It had been the intention to recess the bolster plates in the plastic solebar of the loco and fix them directly to the metal spine that contains the motor. This changed fo reasons that will become clear but the square brass tubes were arranged so that the bolster plate would atomatically locate in the centre of the 'spine'.

Class 47 Bogies 28.JPG (83.06 KiB) Viewed 14860 times

Now that everything was ready I placed the completed bogies under the loco with the bolster plates resting on the plastic solebar to see how everything sat. The bogies seemed to sit evenly everywhere they should and I was amazed to find that the ride height was almost exactly where it should be! It's perhaps 0.010" too low but that can be easily fixed by adding to the bolster plates or by placing packing washers under the secondary suspension springs. I'm not sure how this minor miracle happened especially given the guess work involved in setting the dimensions for the secondary suspension. Out the window went the idea of recessing the bolster plates and so I will fix them directly to the plastic solebar. Why make more work for yourself when it isn't necessary?!

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Class 47 Bogies 31.JPG (62.3 KiB) Viewed 14860 times

Finally I need to sort out the drivetrains including the pickup arrangement and the method of retaining the bogies within the chassis. Nearly done now!

[Flymo748]

Time to sort out the suspension for these bogies.
...
Finally I need to sort out the drivetrains including the pickup arrangement and the method of retaining the bogies within the chassis. Nearly done now!

Very nice indeed!

I'm seriously impressed with the engineering that you are putting into those bogies.

Any chance of these locomotives appearing on a layout at a show in the future? It would be wonderful to see how they ride.

Flymo

[Mike Garwood]

That's seriously good stuff. Not a huge diesel fan, but the engineering looks great. Like Flymo I'd love to see some u-tube footage of how they ride.
Cracking ideas.

Mike

[grovenor-2685]

This has been very helpful and I'm now looking for a round tuit.
Keep up the good work
Keith

[Russ Elliott]

Justin - would I be right in thinking the primary arrangement is:

47-query.png (1.47 KiB) Viewed 14757 times

[grovenor-2685]

Russ,
As I read it the centre axle is on a 6 mm single ended cantilever as for the outer axles.
what you have drawn would make the centre axle rigid.
Keith

[Russ Elliott]

what you have drawn would make the centre axle rigid

No, it would still deflect, and would be an example of a load between fixed supports. Rather unusual certainly, but hence my curiosity as to what the primary arrangement is.

[grovenor-2685]

Russ,
Justin has clearly said that the wire is soldered to the supports, hence, if continuous as you showed it, it can only deflect by stretching the wire, which would be effectively rigid by comparison with the cantilevers on the outer axles. Your example is not fixed just supported.
Keith

[jjnewitt]

Hi all,

Thank you all for your kind words. I don't think I've mentioned it on here but Terry Bendall has invited me along to this years Scaleforum to do a demonstration on sprung diesel bogies as part of modelling the diesel and electric era. All my sprung diesels will be there and hopefully I'll have something with me to be able to run them on so people can see them in action. I can try and sort out some footage at some point if your interested. I'll look into it when I get chance. My layout consits just of ply and extruded polystyrene at the moment. Hopefully once I've got everything sorted for Leatherhead I can make some decent progress on it and maybe get out and about with it from time to time. All these locos need somewhere to run around!
The primary suspension on the class 47 bogies consists of individual single ended cantilever beams on all axles. I did use one piece of wire to do two of the springs, the centre and rear ones, soldering the wire at both ends of the spring support to make life easier aligning things. However it behaves as two seperate beams. You can see on the following photo that the centre beam is single ended.

Class 47 Bogies 22.JPG (82.26 KiB) Viewed 14678 times

I hadn't got down the page on the clag website as far as the beam between two fixed supports bit. I imagine that it's going to take a lot of weight to get a spring to move in that situation. I'll give it a proper read though.

[Russ Elliott]

Thanks Justin for the clarification - the new pictures make the situation a lot clearer. It would indeed be very odd to use a beam between two fixed supports, particularly in conjunction with cantilevers, since the deflection slopes will differ by a factor of 64. We tend to use only a small number of the range of beams shown on the main CLAG beam page. 99% of visitors to those pages are not railway modellers.

[jjnewitt]

Now that I have a pair of bogies made up it's time to get them fitted to the loco along with their drivetrains .

The first thing to do was cut the Bachmann drivetrains nearly in half and tidy them up. I doubt that I will ever have the space to run full length trains so I'm just going to use two powered axles per bogie in a B1-1B arrangement. Although you are effectively losing a third of the adhesive weight the springing should compensate. It wouldn't be too much of a problem to make up a spur train to take the power to the rear axle, the spare gears could be used. It would perhaps be interesting to make some up for the other set of Class 47 bogies to see how much of a difference having that extra axle powered makes.

Class 47 Bogies 32.JPG (68.17 KiB) Viewed 14541 times

The pickup arrangements are via 33 SWG phospher bronze wire with little coils wound into them bearing on the flanges of the wheels. These are soldered to bits of spare Masokits etches that are screwed to the drivetrains. They are set up so that the wires that take the power to the motor don't get in the way and interfere with the workings of the bogie. A little adjustment and filing here and there ensured the drivetrains fitted properly and the pickups didn't come into contact with with any part of the bogie inparticular the brass wire used to retain the wheelsets.

Class 47 Bogies 33.JPG (74.76 KiB) Viewed 14541 times

The bolster plates were blackened and then Araldited to the plastic locomotive 'solebar' to the correct bogie centre distance. As I mentioned earlier I had originally intended to fit these to the metal spine of the wagon so I needed to add 0.020" strips of plasticard to the peices of square brass tube that centralise the bolster plates in the chassis. It's perhaps overkill to have arranged things like this but I always find that it's much easier to glue things accurately along one axis rather than trying to do it along two at the same time if possible. These 'centralising beams' also help support the bolster plate.

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The last major job is to arrange some method of retaining the bogies in the chassis. I wanted to try and keep this as simple as possible and so reused the Bachmann idea. The holes in the chassis that served as location points for the bogies were enlarged and the drivetrains were trimmed so that no weight was transfered to the bogies from the chassis. There was enough plastic left around where the Bachmann retaing screws had been to put an M2 thread in. I just used a peice of M2 studding to do this rather than a proper tap as the plastic Bachmann use is quite amenable to this kind of treatment and I don't have an M2 tap! I also found I didn't have any M2 bolts either so some were made up from studding and nuts. M2.5mm washers were soldered to these bolts which were just large enough not to pass through the holes in the chassis. I cut some peices of 2mm inside diameter plastic tube to act as stops on the bolts and prevent me from screwing them too far into the top of the drivetrain and either not leaving enough room for the bogies to move or interfering with the universal joints. The whole arrangement seems to work perfectly satisfactorily.

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All that remained was to wire it all back up, fit the driveshafts and away she goes all wheels firmly on the track and looking as if she weighs a hundred odd tons. For all the advantages of the springing with regard to track holding etc it's this impression of mass that I find most pleasing. My most vivid memory of a diesel locomotive at work was standing on the down platform at Leominster while a class 60 thundered through with an empty steel train. The whole world seem to shake, the wagons rattled around but the loco seemed to barely move. It seemed like it was the track that was moving at 60mph not the loco. For me these sprung bogies help to move things away from being just converted models and a little bit closer to the real thing and that I guess is ultimately what it's all about.

[Jonathan Hughes]

Another inspiration thread. I'm doing some detailing work on one of these at the moment - blogged on RMW... and have a set of Ultrascales to drop in.... and keeping fingers crossed. Otherwise I'm really going to be following this even closer.
Spendid work

Jon

[jjnewitt]

Thanks Jon. I've seen some of your work and that's also pretty inspirational. Nimbus is beautiful. I've seen your Blog on the Class 47. I'm waiting to see how you get on before ploughing on with mine , particularly with regard to the body. Hopefully I'll get chance to make a start on detailing the bogies and underframe gubbins soon on mine.

There was something I meant to mention in my last post but forgot for some reason. As the eagle eyed may have noticed the holes where the main body retaining screws go are partially covered by the bolster plate. I need to open out the hole in the plastic solebar and chassis block so I can squeeze a big enough screwdriver through. The bolster plate can't be altered as the screw hole lies right underneath rear secondary suspension bearer. I'm not sure if Bachmann did this deliberately but I had a similar problem on my Class 37!