A Class 139 in 7mm

[peter220950]

A Class 139 in 7mm

 

Just thought this might be of interest, it’s been bubbling under for 6 years and is back on the workbench, a thread might help me with a more disciplined approach to see a completion of the project.

 

First a little history to fill in the background, (For those of you who read the articles in Railway Modeller in 2006 and 2007, on the Parry People Mover (PPM) look away now, there’s nothing to see here, come back at the end of this post.)

 

From the early 1990’s a collection of strange vehicles has been developed by John Parry in a small factory in the Black Country, these rail vehicles used a small engine to spin a flywheel which in turn drove a hydraulic pump, powering motors on the four wheels.

 

 

By this process, using the flywheel as an energy store, a vehicle carrying over 50 people could be propelled by a 2 litre engine, with greater fuel efficiency and less track damage than a conventional unit. Once the unit is running, the motor is used to power the flywheel back up to speed, and coupled with regenerative braking the power store is kept topped up. This system has recently been introduced to F1 cars, only their energy storage uses batteries instead of a half-ton flywheel, as this is a tad impractical in an F1 car.

 

The Parry vehicles took part in a number of demonstrations in cities and on Heritage lines, both standard and narrow gauge, and the principle was extended to a system utilising electric power, using fixed stations to power the flywheel at stops on a journey. 

 

 

I don’t propose to go into the whether this is a solution looking for a problem, or a leap in technology which has been sadly ignored, suffice it to say there wasn’t a huge take-up of the machines. Perhaps if there had been more unused lines and less heritage railways there might have been more suitable sites to run passenger services.

 

The trial of vehicles culminated in 2002 with car 12, a 50 person capacity unit, which saw service on the Chaswater Railway, Wensleydale Railway, and the Severn Valley Railway, demonstrating the concept of light rail commuter transport. This vehicle is the PPM that was to become a working unit on a Network Rail line.

 

 

Fortunately there is, near to the Parry works, what is believed to be the shortest branch line in Europe, between Stourbridge Town and Stourbridge Junction, a distance of 1.3km with a steep incline. (That’s only just over 100 feet in 7mm for a perfectly to scale branch line layout, though the operation would be a bit boring).

 

The line was originally a dual track line when built in 1879, earmarked for closure under Beeching, but was de-listed in 1965. It was used as a test route for early GWR Auto-coaches and railcars, and recently until 2005 was operated by Class 121 and 153 units.

 

A trial was arranged for Sunday working using the 50 person capacity PPM, (Designated class 999), with a journey time of 3 minutes and 6 services per hour. It was successful and the service became incorporated into Network Rail Sunday timetables.

 

An article appeared in the June 2006 Railway Modeller detailing this unit and I subsequently built a model, described in an article the following year, and this is largely repeated below to show how the original model, the spiritual parent of my 139 project, was built.

 

I blame it all on holidays, I had done my usual trick of taking half a dozen books and magazines to Italy with me in June 2006, and dipped in and out, as items took my fancy. By the end of the first week I had run out of articles to read, save for something which looked like the result of an alliance between a bubble car and a single decker bus, the Parry People Mover.

 

It was not until I had reached the end of the article that I realised it was a competition to construct a model of one, there then followed a couple of days when, without any conscious thought, but nothing better to do, I kept imagining how I would build such a vehicle, and before I knew it I was hooked.

 

Without access to any other information, or modelling materials with me, I started by setting out some basic parameters,

 

• It would have to be O gauge, I couldn’t see anything smaller.
• It would have interior detail, and therefore had to keep the motor and drive below the floor.
• It would attempt to copy the flywheel drive, as this seemed important to the competition organisers.
• It might be useful to be DCC chipped, as I could then use functions to operate features such as lights.

 

During the next few weeks some of these ideas were to become compromised, I had originally thought that fitting a second motor, with a flywheel, in series with the drive motor would give a simulation of the flywheel drive, generating some power when current was switched off, and thus allowing the vehicle to continue in motion. The miniature size of the parts, even in O gauge precluded much useful power generation, and coupled with the constraints of space for both motor and flywheel meant that this was not feasible as far as I could see.  In any case this effect could be replicated with inertia and braking controls on a DCC chip.

 

The simple fact was that there was no way to obtain a scale version of the propulsion system, relying as it does on a 2.0 litre car engine and power stored in a flywheel, mass doesn’t scale down well. I therefore decided to compromise by putting in a motor and a representational flywheel which worked, but which would not provide additional power. Even if the real system could be scaled down, there was no little man in the cab who could control it in prototypical fashion.

 

Several ideas were considered for construction, initial thoughts being resin for the roof and ends and plastic card for the sides, this was also to change during the planning stages.

 

There was one advantage that I felt I had over fellow competitors; I lived about 10 miles from Stourbridge, which would enable a closer look at the beast.

 

On return to England the first thing to do was prepare and plan, more information was needed, and a quick search on the Internet produced more information and photographs, including some of the PPM 50 with no clothes on.

 

 

It has to be said that the photos of the street level tram version were far more attractive, the rail version appeared top heavy and less well proportioned. The Internet pictures revealed a metal framed construction with glass fibre and metal cladding.

 

 

This tempted me down the route of a brass chassis and superstructure, with minimal resin use for roof ends and front panels (to get some consistency of shape). I decided that the top half of the sides should be in clear Perspex type material, with lining applied to simulate the window frames, this would reduce the amount of soldered framing, and the potential for out of square windows.

 

Having cranked the published drawings up to 7mm on the photocopier the next thing which became apparent was the space, or lack of it, beneath the floor, (about 20mm from track to floor). There was no great supply of suitable O gauge wheels, motors and gearboxes. I toyed with using Delrin chain and diesel wheels but there were very few suitable wheels of 14mm diameter . The final solution uses a cut down Terry Russell tram bogie, using a Tenshodo motor, and OO gauge Romford wheels widened to O gauge, which while a bit crude in its mounting seems to do the job, though I would have preferred in hindsight to have put in a proper gearbox instead of relying on bent wire to carry the motor and mesh the gears.

 

Inspiration came for the flywheel and drive, computer fans are available in all sizes, the motors are incredibly small, and some are rated at 12 volts, this meant I could get a flywheel of 25mm (approximately scale diameter) and motor, all in a depth of 10mm.  I butchered the mounting framework from the fan, and then cut the blades off, leaving a suitably sized drum. The sad fact in all of this is that the whole mechanism is hidden from view when the whole vehicle is assembled, and indeed on the real car the flywheel appears to be encased in a circular housing.

 

The photographs, and Squires catalogue sorted me out the various metal sections I thought I would need, and an order was duly phoned, the goods arriving the next day.

 

By now I realised that what was after all a mere whim (I had no interest in light rail cars) was starting to cost a fortune, the mechanism at £65.00, brass £18.00 and the fan unit £4.00 meant that I was already almost £100 out of pocket, and not even up to platform level.

 

The photographs of the original in its constituent parts lead me to think it would be good to have a similar system of chassis, spacer frame, and body. Given the need to replicate the flywheel system I felt it was therefore important to get the look of the chassis right as well as the body.

 

Window frames were the first things to be tackled, not because they were needed at this stage, but unless I had an idea of how to form them I wouldn’t be able to build all of the bits which interfaced with them, roof, front, etc. A rummage around in the spares box produced some 3mm scale rail in nickel silver which seemed to be about right for size and section, this would enable me to glaze into the channel of the rail at a later stage.

 

I formed the triangular side windows first, which surprisingly all seemed to be the same size – a good omen given my usual need to make a couple of dozen of anything to select four about the same size.   

 

 

The arrival of the power unit was interesting, the motor was tiny, to the extent that I couldn’t believe anything so small could carry the load, but I needn’t have had any concern, the unit also appeared to be easily incorporated into my plans – with a little butchery! The only issue, apart from the fragility of the motor mounting method, was the wire pickup on the back of two of the wheels, it seemed to be a less than perfect solution, a short wheelbase 4 wheel arrangement was always going to be difficult. I resolved to put additional wipers on the top of the wheel treads as soon as I got around to wiring it up.

 

 

Task one was to get a working chassis, for this is the base of the whole project, I wanted to end up with a working model not a model that might work. Having invested this much into the Project it would have to earn its keep.

 

The brass chassis frame was fabricated using rectangular box section, as in the prototype, and soldered up using a drawing stuck to plywood, and drawing pins to hold the various sections in the correct positions. The two sides were cut to length and cuts made at the angles, these were then filed out to allow the profile to bend to shape. Small pieces of strip were cut and bent to fit in the end of the sections to form a plug and socket which held them together while soldering, and give some mechanical strength, Cross members were then soldered in place using bar and box sections

 

 

The layout was broadly in line with the photographs I had obtained from the net, the only major area of difference being the spacing of the cross members in the centre to allow for fitting the mechanism. The frame was cleaned up, primed, and painted grey.  

 

 

The complex end shape would have to be next, as I determined to fit the windows and sides to the ends, rather than trying to make ends to fit the rest of the structure. I broke the shape down into two areas, the green upper, and the white lower section, and determined that I would make a master to be cast in resin, so that both ends would be the same.

 

 

I experimented with filing 80 thou. plastic card to profile, but with little success. As ever when I hit a block like this I left it alone for a day or two, and had a good look around me at items nothing to do with modelling. The basic inner shape of the lower part of the end was drawn up and fabricated in 80 thou card and left, awaiting inspiration.

 

In the interim there were loads of signs in and around the railbus, I replicated all of them word for word and obtained the requisite logos to add to them from the Internet. Once printed to scale they become meaningless blobs, and in many cases were too small to be seen, but many were used later.

 

The answer to replicating the middle section profile turned out to be sitting on my desk at work all the time, in the shape of a plastic binding clip for reports. Comparing the shape against my drawing showed it to be almost perfect, this would only need the corners replicating with a filler of some sort, but having the base profile was a long way towards achieving a result. It also looked as if the clip could be adapted for the top section as well.

 

I sawed up the clip and stuck it on the former with superglue, hoping that this, and body filler, would hold long enough to get the pattern made. Small sections with a slight contour were then attached to the lower corners as there is some rounding of the shape.

 

 

On top of the lower section I built a front panel to the level of the front window, then stuck on another former of binder clip. The sides were next, followed by the angled corners which take a different path to the base, following the window line.  These panels also drop in level from back to front giving a droop to the window line. The embryonic window frames were propped in place along with a dummy roof profile, to get some idea of the final layout.

 

 

The corners and sides were filled and smoothed roughly to shape with Milliput, the photograph shows the first stages, awaiting filing and smoothing to shape.

 

 

The next task was to get the end filed to shape, again it was a relatively painless, if not a bit messy, exercise. The plastic binder parts were used as guides to level, which only left the corners to be shaped. This was achieved with the help of the photographs taken on site. Next holes were drilled for the lights, brass tube was cut into short lengths and superglued into the top ‘headlight’ recesses.

 

The outer sides of the main lamps were shaped with a file and craft knife, leaving minor filling to be done. At this stage a coat of spray primer was applied to start to get an idea of how the shape compared to the real thing, the uniformity of colour seems to help give a better idea of where the remedial works were needed. The paint finish at this stage is unimportant as the whole thing would be rubbed down with fine wet and dry paper once the fine filling was completed. The paint/fill sand process was then repeated until I was happy with the end result.

 

 

Next on the agenda were the other items that were to be cast in resin, so that I could get all of the moulds made at the same time.  The end roof sections, which were identical at each end, and the seats, were fabricated in plastic card, together with the front section below the cab.

 

 

The final Milliput smoothing was then applied, sanded smooth with wet and dry, a final spray of primer applied and a start was made on the sides.

 

The brass sides went together smoothly with only minor adjustment to make them the same size and square. Brass strip the height of the side below the windows was cut to length, and channel and ‘H’ sections cut to form the framing for doors and windows. The framing was laid out on the drawings, as with the chassis, and the whole thing soldered up.

 

 

As the step provided an essential part of the structural stability of the doorway I attached this at an early stage It is of course, by attaching them on the wrong sides, quite possible to make two sides with the doors at the wrong end, three guesses how I know.

 

As the sides were relatively rigid, and the window frame was a channel section I experimented with using overhead slide projector film for the windows. This can be purchased in a form that is suitable to put through either a laser or ink-jet printer. If required a slightly thicker sheet can be put behind, to give some rigidity to the area. In this way I do not have to form all of the window frames in brass, just the outside.

 

The resin casting masters were prepared by spraying them with primer and a coat of gloss, in order that they would release from the moulds.

 

 

Plastic card boxes were fabricated, and the parts held in place with double sided tape. Mould resin was then poured over the masters and filled to the top of the boxes. Once dry the mould sides are broken away from the rubber like block, leaving the master in place. A little gentle flexing of the rubber released the master and leaves a void in which to pour resin

 

 

The problem with resin and moulds is that they are addictive, within a couple of days I  had six ends and roof sections, still I was sure they would come in handy for practice pieces. The mouldings did exactly what I wanted and provided a consistency of shape that I would not have been able to create with filing individual pieces.

 

While the resin sections were curing the opportunity was taken to clean up the sides, and add brass sections to the left of the doorframes at the point where the ends join. I was originally going to butt the resin ends up against the doorframe and add a cover strip, but later revised the layout.

 

The floor was marked out on double sided printed circuit board, which allowed the sides to be soldered in place. The ends were bonded to the board with Superglue, and then the sides were taped to the ends and checked to ensure they were vertical and flush with the resin ends. Low melt solder was then used to attach the sides to the floor and produce a rigid result.

 

 

A cross member at roof level was then soldered to the sides at each end, this provided a platform on which to mount the roof end castings.

 

 

The underside of the roof ends were sanded smooth, then marked to enable the casting to be rebated underneath and give something like a correct roof line above the front widows. The surplus material was removed with a rotary sanding drum in a rotary tool, a job to be carried out using a mask and preferably outside as the volume of dust is huge.

 

 

The first four window frames, those connecting to the sides, were soldered together at the join in the frame, then attached to the sides with low melt solder. The underside, butting onto the resin end, was then flooded with superglue to increase mechanical strength.

 

 

The windows, as I feared, proved the biggest problem. In hindsight I should have built a jig to build them off the model, or make them out of Perspex, in practice I started from the outside and worked in towards the front middle window, the finished result seemed o.k., though needing a lot of cleaning up, I now had a nice model greenhouse.

 

 

The section below floor line was tackled next, the two resin ends were located in the correct positions and a hole drilled at each end to attach them to the floor with 12 BA bolts.

 

 

The ends were then removed and a 60 thou plastic card sub floor was cut to the same size as the printed circuit board floor, holes were drilled to coincide with the end fixing bolts, the resin ends were then re-attached with superglue,  and the whole assembly was bolted back to the main structure.

 

Plastic section was then attached to the floor to form the first area below the floor, rectangular in section and tapering in to the ends, once dry a vertical sheet of 60 thou card was attached behind it, and attached to the floor, to form the full depth of the skirt. The bottom edge of the rectangular section was then filed to a 45 degree chamfer, as the prototype, and a moulding fabricated out plastic card to form the middle section.

 

 

Two cross members were then installed to the void under the floor which set the chassis at the correct level, this meant that the chassis became a push fit under the floor, I have used the small towing brackets as a push in through the holes in the front and rear mouldings, to lock the chassis in place.

 

The roof was next for treatment, the end sections were cleaned up a bit, and the rear faces of the mouldings sanded flat. Two sections of brass channel were glued to a flat piece of 10 thou plastic card inserted into the channel, the overall width slotting into the channel at the top of the sides, this provided a roof base which slotted into place and which hid the join in the rainstrip to the windows.

 

 

The resin roof ends were next glued to the plastic card sub roof, and vertical pieces attached to form the infill between the ends.

 

 

Plastic card sections in 10 and 60 thou were used to form the clerestory roof leaving the profile to be moulded with car body filler. By working in this order the roof builds up into a rigid structure which fits securely, and which enables the clerestory area to be cut out from underneath once the necessary strength has been imparted into the structure.  

 

 

The roof came in next for final filling, using car body filler to smooth all of the various parts together into a harmonious structure, the filling was carried out in stages, with a light sanding between, to establish the correct profiles, and then filling the low areas. Do not be afraid of getting a coat of primer on, it helps greatly when rubbing down as it highlights high spots. Because of my fears of losing detail in this process I left the clerestory framing until after the main shape had been sanded smooth.

 

 

Filling to all of the window corners and the side joints was tackled next, in order that I could get a coat of primer onto the shell and see how it looked. There was still some concern over the roof end location, and finishing over the windows which needed resolving.

 

The week also saw the arrival of the transfer paper which was to be used for producing items such as the number and the Parry logo. The first thing to do was to sort out the artwork, I copied the Parry People Movers logo (in Green) from the website, and put it into Photoshop where it was converted to grayscale and then the individual pixels were changed from grey to a yellow colour in Microsoft Paint. At this point I also added ‘www.’ and ‘.com’ to either end of the logo, I am sure there are better ways to achieve this end, but I don’t know them!

 

The side windows were simply produced by setting up a computer spreadsheet with black columns and rows at the frame positions, this was then printed onto paper to establish the required scaling up or down to print at the correct size. The film is then cut out and slipped into the side frames, a thicker clear layer behind gave some additional stability to the windows.

 

The inner bulkheads were constructed in plastic card, with openings for the glazing. Handrails to the partitions were fashioned from signal laddering, in order to fix them to the partitions 3mm rail section was applied to the edge of the plastic card, and the handrails were soldered to the nickel silver to impart some strength to the fixing.

 

 

Fire extinguishers were fashioned from round plastic section, the ends rounded, and a short length of brass tube superglued into a hole in the end. A piece of brass wire was then inserted into the tube, and bent at right angles and the rounded end was formed in Milliput.

 

The consoles at either end were then fabricated from plastic card, again the ideal of reproducing the console in detail was discarded when I realised just how small it was.

 

 

The ticket machine was fabricated from various bits of plastic section to give an approximation of shape and the handrail was fabricated from brass rod with a hole drilled in the floor to locate the vertical and the horizontal rail fixed to the bracing cross members which support the roof. The rails were left to glue in position rather than solder as the final positioning was to take place after painting, enabling the interior fittings to be positioned.

 

Having smoothed off the initial filling to the skirt, roof and body, they were washed in soapy water to remove all residue of flux and finger marks, rinsed in clean water, dried and placed in a dustproof box prior to painting. At this stage the components were handled whilst wearing gloves to prevent further grease getting onto the parts. An undercoat of white primer was applied as a base coat then the laborious process of fine filling of marks and indentations began.

 

The imperfections were filled with Milliput or car body filler for the bulk filling work. The Milliput takes a little longer to dry, and is not much different to sand smooth, but it has the advantage of remaining workable for a longer period, and can be smoothed with water while wet. Once dry the filler was sanded with fine wet and dry paper, wetted with a little soap, rinsed, and left to dry. The primer was again applied and the whole process repeated until I was happy that I had achieved the optimum surface for the final coats. It was also at this stage that the clerestory roof panelling strips were inserted into the rebates left in the roof. These were then blended into the roof in the final fill/sand process. The whole process for carrying out this work involved about 6 cycles of fill, sand prime.

 

This process takes a long time, but it seems to be an accepted view that a good paint job can do wonders for a poor model, but a poor paint job can ruin a good one, time spent in preparation is never wasted.

 

The distinctive draw bar and lamp iron fitted at the front and rear was used as the basis for securing the chassis into the skirt. The small brackets were fabricated from rectangular tube, with bar fixed inside, a small section of the rectangular section was also soldered to the top of the chassis at each end, which coincided for height with the openings in the front and rear skirt. This meant that the chassis could be clipped up into the skirt, then retained by pushing the draw bar through the skirt hole into the socket on the chassis, thus locking the chassis to the skirt.

 

The final two coats of filler were carried out with a primer filler, which aided the process by smoothing out some of the imperfections, following which lining tape was used to provide the seam covers that exist on the roof of the real thing. The roof was then inverted and the clerestory area was cut out.

 

 

The flywheel was also fixed in position, such is the lack of space that I had to cut the plastic card from the top of the skirt to get an extra 80 thou. of clearance. The space under the floor was beginning to get a bit crowded, in addition to the motor bogie, flywheel, a loudspeaker and casing, and the chip (which is not exactly small) take up most of the space, I did want to get as much detail onto the chassis as I could.

 

 

The roof was sprayed blue, leaving only a coat of white on the underside to finish, The centre section was finished in white as a base, and the lower skirt in grey. This then left the masking for yellow and green to be carried out.

 

 

Front panels masked off, primer applied, yellow applied, some sort of reaction with the paint, panel all crazed,…..ARGHHHHHHHHH. Not what I need two weeks before completion, change in strategy called for, perhaps try enamel paint on the sprayed white finish?

 

After a lot of time spent re-finishing the affected areas I decided on safety rather than try to spray the yellow blue and green, enamels were purchased and the areas masked and brush painted, ready for a clear coat on completion.

 

 

The transfers were made by printing the logo’s and numbers onto the film, then spraying with clear varnish.

 

 

The paintwork received final touching up and cleaning up of untidy bits of lining and not very straight edges, and the partitions had the notices and seating attached. Seats were painted grey then lightly sprayed with a mist of blue to give the flecked appearance of the real thing, and the transfers attached to the body.

 

 

Another heart stopping moment as a coat of satin varnish once again caused some crazing, but a quick rub with wet and dry and a touch up of the paint restored its condition. On applying the transfers the yellow on clear ‘Parry People Movers’ logos became almost invisible as the ink was not solid enough to give a visible logo on a green background.

 

A little thought and I re-did the artwork with a green surround, this was then printed onto a white transfer film, the logo was then cut out with a craft knife as close to the yellow lettering as possible.

 

Windscreen wipers were fabricated from wire, the glazing to front and rear cut to size, and the doors and steps were fitted. 

 

 

I had assumed that the submission of photographs was the first stage to thin out the entries prior to a judging ‘in the flesh’. It came as something of a surprise therefore to get a letter some time after submitting the competition entry which confirmed that I had won, (there must have only been 1 entry), along with tickets to Warley exhibition and Pecorama.  All in all a satisfying end to a project that I would not normally have undertaken, but which had, nevertheless been enjoyable.

 

So there we were then, at the end of it all, over £200.00 worse off (Even if I won it was a pretty poor return on capital invested!), but it’s not really about money. It was an interesting build, different to a locomotive kit, where you need to work in logical order, and it suited my butterfly nature, being able to start with window frames, move onto the chassis, then build the ends, etc.

 

Would I do it again? no way, but then again I do have several spare castings, there is a proposed articulated version, and the road level tram was much more attractive…………………..

 

 

As soon as I can re-size and sort the photo's of the progress to date on the big brother Class 139 and continue the saga.

[peter220950]

The Class 139 Build

 

With regard to the PPM post above, that’s where it would have ended had it not been for two things that happened at the prize presentation at the Warley exhibition in November 2006, firstly I met John Parry, who presented the award, and secondly Grainge and Hodder were handing out N gauge models of an etched brass Land Rover.

 

 

John invited me to visit the factory and meet his team, which I did on a couple of occasions thereafter, he wanted to borrow the model for some PR events,

 

 

and discussed the possibility of making a low cost model for shareholders, but his desire for a replica for around £40.00 was not a realistic proposition, nevertheless it started a thought process that wanted to try to get something which would be a bit better finished. Using a modular build method it could also be adapted to cover the many alternative vehicle designs, including the original PPM 30 low floor unit.

 

The Grainge and Hodder connection came with the realisation that it was possible to etch the end windows in brass, to get greater accuracy and consistency. Artwork was drawn up and a couple of weeks later sets of test etches were delivered, these proved a better way of producing the end windows, but the artwork was slightly out in shape, putting a tilt on the roof if fitted without adjustment. The solution was good, but it still remained a labour intensive operation that produced windows that were always identical.

 

 

A clear cast resin end was considered and some development work was done to make a solid end mould, but this again turned out to be another dead-end, a recent look at some cast pieces done a couple of years ago has shown this would not work well, the resin having yellowed over the years.

 

 

Weeks turned into months and progress stuttered along, but without any real progress, and my project might well have died had it not been for the order for two new larger vehicles, the Class 139’s, which was awarded in 2008.

 

The PPM 60, a vehicle over a metre longer, seemed somehow a more sleek design, and better proportioned, much of this was down to a combination of cleaning up odd details and a more modern colour scheme, the idea of a new PPM once again reared its ugly head.

 

 

The idea of making a larger vehicle revived interest, coupled with meeting up with fellow RMWebber WillJ, who was employed by Parry’s to do artwork and produce workshop manuals for the vehicles amongst other things.

 

Will had also produced a laser-cut N gauge body of the 139, to fit a Kato tram chassis, made from layers of 3mm MDF. I made a mould from the master for some early resin bodies.

 

 

Will has subsequently gone on to 3D printed versions but also did some laser-cut sides and components for the 7mm car, in addition to a very nice exploded drawing of my ideas for the latest model, and some printed sides in card.

 

 

Once again things bubbled along in an on/off manner but were hampered by work, life, and other modelling commitments, and again it all ground to a halt, with the bits and pieces put back in the roof, a bit further on, but not significantly so.

 

Then to screw it all up along came Ian (Redgate Models), who contacted me in 2013 regarding the PPM, wanting to build one in 7mm for his son.  At the time I sent what bits I had spare, and once again it brought the bits down from the roof.

 

Shortly thereafter Ian passed the base to Pete Harvey and before long an etched chassis/power unit had been developed. At this point I decided it was time to lay this project to rest by finishing it, as I could then send Ian the revised cab and body units, and get myself a couple of cars built.

 

Retirement also meant I now had more time on my hands, and the rapid pace of technology has meant several new options existed for producing parts, which had not been as commercially available even 5 years ago.

 

So here we are today with a project developing a bit faster, this is the current situation :-

 

 

The floor pan and skirt.

 

This is largely sorted, a new master has been made to match the longer car length, although slightly different in design it will also be possible to chop this down to suit the shorter cars or join two to make a larger one. A recess has been made in the underside which was designed to take a resin plug, into which a pair of 00 wheelsets, cut in half, could be fitted to form a static model. This part had gone well, producing a relatively easy to make set of parts that just required spraying black to finish.

 

 

A review over the last couple of days, now that the final product is developing, revealed that one end of the master was a thou or two out of square, so I have just smoothed it out ready for a re-paint and a new master mould. Once this is done the floor pan is a completed section, the PH Design chassis fitting in place of the solid plug for a working model.

 

 

 

The Roof.

 

The revised design for the 139 has ends which incorporate the roof above the cab, so the roof section is only the plain middle section.

The original PPM roof I built was wrong both in section and end design, the section being too bulbous,

 

nevertheless, rather than start from scratch I took a mould from the PPM and made a couple of castings, which were then cut and shut to the correct length. The profile was corrected to a less bulbous section and the clerestory section tidied up from my original efforts, which were a bit scrappy.

 

 

This revised section is now just undergoing final filling and smoothing prior to a coat of gloss and making of a master mould.

 

 

 

 

The Ends.

 

The original PPM was not actually right at the nose end, the windscreen being set too far back, and the screen rake was wrong.

 

 

 

New ends have been put together over the last year or so, using the incorrect etches, cut and shut at the top rail to correct the inaccuracy of the etch.

 

 

One end was better than the other, having less projection of the nose in front of the cab window, this has been fettled but is currently still some way away from completion. The original plan was to form a rebate for glazing, but it would be difficult to resin cast cast the window pillars in this way. I have since beefed up the etched brass with sections of plastic to give a thicker pillar, to take a laser cut clear window, or a clear thin surface fixed film which has been experimented with, and which is closer to the real thing.

 

 

I have still not totally discounted the idea of making a 3D printed master, or one made on a 5 axis milling machine, which I may have access to, but these rely on twisting the arms of others with more skill and equipment than I have, as it means a 3D drawing, the jury’s still out on that option.

 

 

The Centre Box.

 

My original re-design thought along the lines of a clear acrylic box, with some form of transfer or applied side to carry the logo. Consideration was also given to providing a brass etched side to give window and door detail, applied on top of the clear acrylic.

 

 

This design developed further when Will produced the laser cut box, this gave a rigid solution in MDF, laser cutting, whether plastic, acrylic, or timber, being the best solution for making the sides.

 

 

Once again this is a bit fluid at the moment, it looks as if I will build a box from a mixture of Rowmark and acrylic, with the window and door detail cut out, this will then be overlaid with 0.5mm clear acrylic. On the real thing the sides are plain glass with all of the framing inside, so once again I am getting closer to prototype. The bottom half of the acrylic can be painted grey, and either transfers or cut vinyl used for the black and green lining, doors, and logo’s.

 

 

A floor of Romark will set the sides the correct distance apart, with cut outs for the vertical end walls and internal glass panels either side of the opening doors. The floor then extends out at the doorway to a protruding step.

 

At roof level a couple of stretchers will span the body to take the roof, while allowing internal detail to be inserted if required.

 

This is now pretty much designed, subject to my proposed material thicknesses proving adequate, the major obstacle now being the need to learn Autocad or similar to plot all of the sections. A favourable quote from York Modelmaking has shown this to be a practicable and cost-effective solution.

 

The development of either transfers or cut vinyls for the sides will also depend on producing decent artwork, once again advances in technology make such things practicable via the Internet, early development work has showed some progress, with home brew transfers.

 

 

 

Internal Layout

 

I originally made a mould for the seat squabs, further development has not been progressed as yet, the only possible thing to consider is the need to incorporate supports for seats into the internal box structure, this will be done along with the learning exercise for the 2D drawings, and any changes will be incorporated into the final design.

 

The master for the driving desk has been made, and a mould produced, but this may need revision if the cab end is made in a different manner.

 

 

That’s where we are today, I shall continue to update on progress as I get items completed, and anticipate that as bits become available I can pass them on to Ian to help complete his build, which I note from his Blog has now started.

 

Meanwhile I think they might be starting to breed.

 

[RedgateModels]

Look what I have almost running

 

 

should be viable for Coventry, I might even screw it to one of the resin bases .....

[Griffin Road]

Peter ( I hope that is correct ) ,

 

What an absolutely fascinating article . Thanks for sharing and I look forward to further posts .

 

I went to Stourbridge a few Decembers ago specifically to see and ride the PPC . I , along with a few others , did four trips up and down the branch . The train staff were very welcoming and treated us all with great enthusiasm . It was their pride and joy and they let us know it . The vehicle is one of those things that you could very easily sneer at but once you have a run on it you are hooked ( well I was ! ) . I would encourage anyone on here to go , if in the area , and have a shot . It has the spirit of The Titfield Thunderbolt about it but a more modern version .

 

I didn't realise Parry had made so many other versions as shown in you photographs . What happened to them - or are they still running ?

 

I remember there was talk of trying one from Gobowen into Oswestry at one point .

 

Once again great article and superb modelling .

 

Regards

 

Mike Bartle

[peter220950]

Look what I have almost running

 

DSC_0764.JPG

 

should be viable for Coventry, I might even screw it to one of the resin bases .....

 

Yum Yum, how do the drive shafts connect to the gearboxes?

 

Peter ( I hope that is correct ) ,

 

What an absolutely fascinating article . Thanks for sharing and I look forward to further posts .

 

I went to Stourbridge a few Decembers ago specifically to see and ride the PPC . I , along with a few others , did four trips up and down the branch . The train staff were very welcoming and treated us all with great enthusiasm . It was their pride and joy and they let us know it . The vehicle is one of those things that you could very easily sneer at but once you have a run on it you are hooked ( well I was ! ) . I would encourage anyone on here to go , if in the area , and have a shot . It has the spirit of The Titfield Thunderbolt about it but a more modern version .

 

I didn't realise Parry had made so many other versions as shown in you photographs . What happened to them - or are they still running ?

 

I remember there was talk of trying one from Gobowen into Oswestry at one point .

 

Once again great article and superb modelling .

 

Regards

 

Mike Bartle

 

Thanks for the nice comments,as you note the staff are very proud of the service and even stopped one of the runs outside the station so I could get out and photograph from track level, without having to ask. The whole set-up is typically British, running on a shoestring and making do and mending, using old school engineering, but has a tenacity that has seen it survive over the years, driven more by John Parry's belief and vision  than anything else.

 

The previous versions have a habit of getting re-cyled so I'm not sure quite what's left, or even how many  were really originals in the first 10 or so, certainly one or two of the earlier 'Heritage' style ones were at the works until recently. I believe that some of these could just be re-tracked to suit standard or narrow gauge.

 

Of the more recent style the original PPM 30 low floor version, the one that ran in Bristol is still at the works, and the PPM 50 that ran at Stourbridge originally  was re-painted and used on the Mid Hants Line for a trial,

 

 

The proposed 'Car 22' which I have a soft spot for, and would like to model, is actually a proposal to take the PPM 50 and the PPM 30 and stick them together, so re-cycling is very much the order of the day!

 

 

Peter

[RedgateModels]

Yum Yum, how do the drive shafts connect to the gearboxes?

 

 

good question, Pete has some silcone tubing that he's going to bring to Ricoh, but I'm experimenting (not very successfully) with other types of tubing in the meantime. If all else fails some 2mm bore brass tube with Loctite threadlock should do the trick, but ideally I'd like a bit of flex ......

 

another thought was to use a couple of 2mm bore flywheels - would make it more prototypical at least!

Edited September 4, 2014 by RedgateModels

[Pete Harvey]

Already ready for you don't Loctite the brass tube as you won't get it off just be patient and wait do some work on the grinder maybe?

[RedgateModels]

don't worry, the loctite option was only if the silicone tube doesn't work, the gearboxes need a bit of "shove" to get them to start at the moment

 

I have plenty to do on Fourgig for now

[peter220950]

Nothing much has been happening for the last few months as I was awaiting developments on the cab end and roof.

 

Peter Harvey has kindly done the computer modelling, as it's outside my limited abilities, and before Christmas he came up with some indications of what the 3D model would look like:-

 

 

Today I picked up the real thing, and quite stunning it is! It needs a wash and spray to get a gloss finish but then it can be put into some silicone rubber to make a mould to be resin cast.

 

Many thanks to Peter at PH Designs for his work, a roof is being printed in FUD to get the parameters for etched sides sorted, and a fine printed roof will follow for a future mould.

 

Things are beginning to move on this project again, though the kitchen units I also picked up today are probably a sign that I have to do some boring DIY instead of playing trains.

 

 

 

 

[Xerces Fobe2]

Great work you have done but sorry  I still do not like a flywheel powered blackboard rubber!

 

XF

[peter220950]

As I think I said early in the thread I have always felt they are a solution looking for a problem, and a bit of a technological anachronism, but at least they are a bit different! 

[peter220950]

Very little progress to report again, but I have got the excuse of being a Grandad for the first time, so I have had other things on my mind for the last fortnight.

 

However I have re-made the master for the control panel so that it now fits in the revised 3D ends.

 

 

And the roof moulding has arrived, it's in a cheaper material to check out the fit and enable work to proceed on the 2D side design and artwork, I think I shall get a print done in the same material as the cab end at a later stage, when I need to make a decent master, but at over £100.00 it's going to have to wait a bit.

 

 

The register of the ends to the roof is perfect, and should mean that with the ends bolted down to the floor, the roof will lock in place without any further need for adhesives. Once again thanks due to Pete Harvey for a superb job.

 

 

Now, like a  couple of other projects, it's down to waiting for etching to be completed, so it will be a while until anything progresses.

[RedgateModels]

Ok ok I'll see if I can get the time to work on the drive unit.....

 

Be nice to have it runningg on Fourgig East at the Mansfield Show

[RedgateModels]

It runs!

 

Last night I added pickups to the drive unit and had it running up and down my test track. I don't usually do pickups running on the faces of the wheels, but it seemed an obvious choice in this case and they work very well.

 

 

I've since fitted it with a Lenz Standard+ decoder so it can be seen running on Fourgig East at next weekend's Mansfield Show. All wiring is temporary as the top needs to be kept clear as it bolts to the floor casting. Final position of the decoder etc will be fixed to the underside of the floor unit where there is plenty of room for it and some hefty stay alive capacitors

[peter220950]

As with my Big Big to Lion conversion I was staggered to note that it’s 18 months since I last did anything on this project, but the ability to cadge some CAD skill from a fellow Club member has given me a new impetus to see this project back on the road.

 

I was quite surprised when I dug the bits out to find that the cab end had discoloured quite badly, and looked as if the material had somehow degraded. It was in a band across most of the print, indicating it was a section of the resin or whatever is used, however a quick blast of primer indicates it’s purely cosmetic.

 

The master for the floor section was amended slightly, as the perfect 3D printed end highlighted a millimetre or so out of square on one end.

 

A couple of days have been spent getting a design for the centre body part perfected. Pete Harvey had suggested a brass fold-up etch, but in the interests of simplicity, cost, and speed, I’m going for a 1.5mm acrylic box that I will get cut by York Modelmaking, followed by etched brass overlay sides. It’s probably not the ideal solution but it should be fine for me. The design work is completed and the cutting artwork for the acrylic was received for checking today, hopefully the etch artwork will be ready for sending for a test etch in a week or so.

 

With this in mind thoughts turned to the casting of the roof and ends, a job I had been avoiding, as my two part mould making has been a failure to date. I think I now have a handle on how to do it without everything getting stuck together, so it’s time to prepare the pieces, I shall probably start with the roof as it’s more robust and cheaper to replace..

 

A spray of primer indicates the difference between the £100 print of the end and the £40 FUD roof,

 

 

 

it now remains to be seen if I can get an acceptable finish on the roof, or whether it needs a similarly costly master, at least with the modular construction I can change course later if I need to.

 

An hour or so was spent today planning the mould for the end, and fitting some temporary shuttering to retain the moulding rubber in a manner that will allow the parts of the mould to be formed.

 

 

I now need to give some thought to glazing the ends, whether to use York to laser cut pieces or to use sheet inserted from inside, some mock-up’s are next on the list.

 

Peter

[peter220950]

Time for a quick update. I have not had a great deal of time to spend on modelling, as a new bedroom for grandson no 1 has seen a lot of work making Lego shelves and stuff.

 

The influence of Lego has led me down the route of using it for making mould boxes, the improvement in the moulds for other stuff has been invaluable, and should help when I start making the finished tram moulds.

 

 

The only other work done was to have a gently rub on the roof with wet and dry, early indications are that I can get away with using the FUD roof rather than spend another £100 on a high quality print.

 

 

Fortunately I have Elves who have been doing a lot of sitting in front of computers to produce a set of drawings for the etchers

 

 

there's also a few bits for the Lion build and a couple for the elf doing all the work.

 

There's also some files for York Modelmaking

 

 

which were sent to them for approval with a payment on 31st August and lo and behold on Saturday 3rd of September this parcel arrived.

 

 

 

What I would class as exceptional service from York Modelmaking, the individual pieces come with a protective film and have come out as planned.

 

 

The only thing I need now is some Acetone, as Butanone, cellulose thinners and cyno all seem to fail as suitable adhesives, so for the moment car body No 1 is held together with sellotape.

 

 

So as a quick re-cap we now have a fettled floor pan that's ready to re-cast.

 

 

on to which the acrylic car sits, and on which the etched sides will fit when received

 

 

followed by the 3D printed end

 

 

onto which the roof will fit

 

 

so it's all starting to come together. I now need to grasp the nettle and go for the two part mould for the end, which will be the really hard bit, if I run into problems I will go down the route of having them done professionally, but I would like to master the art.

 

Finally I spent a bit of time tidying up a new driver console, ready for casting.

 

 

Now it's a wait for the etchers to come back from holiday to see if the metal bits work as well as the plastic ones. The next thing to start thinking about is the vinyl side coverings with associated artwork.

 

Peter

 

 

[peter220950]

Monday saw the safe delivery of grandson No 2 and allowed us to return home to normality and some sleep. Waiting on the doorstep on my return was a set of etches from Grainge & Hodder that were primarily for the 139, and which look to be the dogs wotsits.

 

There are a couple of minor tweaks once the brass is married to the acrylic, somewhere down the line the sides appear to have lost a millimetre from one end, not much but it affects the joint to the cab at one end, so a revised etch will be done for the final job. There’s also a problem with the height of the acrylic sides, again only about a millimetre, but it means the opening lights aren’t quite fully glazed, again a revised artwork will go to York Modelmaking for a revised side.

 

 

 

 

 

Otherwise I’m happy that the etches and acrylic are the correct solutions and that the proposed construction method will work well.

 

A mould has also been made for the control desks and the first resin casts completed.

 

 

 

 

and the roof has been put into a mould box ready for RTV

 

 

And finally the main stumbling block has been overcome. I have never successfully completed a two sided mould, and this was essential to get the ends cast, at around £100 a piece 3D printing was out of the question for more than a master.

 

 I blocked in the windows with plastic card, put a rear shutter in the cab, and mounted the end in a mould box, such was the trepidation I had for the job that I slowly added the silicone rubber in stages to prevent the master from floating out, or the windows collapsing inwards.

 

 

 

 

 

 

 

It’s also a measure of my fears that I left the half filled mould for a couple of weeks, fearful that if I completed it I would destroy the master trying to remove it.

 

 

Once filled and inverted the shuttering was stripped out, a filling sprue added, and the second pour of RTV silicone took place to make the mould for the inside of the cab.

 

 

Much to my surprise the two halves of the mould came apart well, and with a bit of waggling and a minor break the master was removed, the break was an old break that I had repaired, so resin casts should come out o.k.

 

Thursday saw the first pour in the new end mould, and much to my amazement the first one out of the mould is almost perfect, almost in that one air bubble in a window pillar has caused a break, but it was stripped out of the mould long before it was really hardened, because I was anxious to see how it looked. The roof, ends acrylic centre box, and etched sides all seem to fit together as planned.

 

 

 

The first cast of the roof has also worked, I was going to do a two sided mould but the initial pour has proved it works with a traditional open one.

 

 

The resin work was the final technical hurdle, which I’m pretty certain can be overcome on future pours, so after 10 years I can see the finishing line, a second pour yesterday has proved more successful, with a good end cast emerging from the mould, only a couple of minor air bubbles are apparent, and these can easily be filled, As the mould pours progress I usually find that the points where air is trapped can be pinpointed and eliminated by tilting the mould to allow air to escape..

 

 

 

I will now put a body together using the bits I’ve got to try it all out before I address the issue of transfers or vinyls and get the final etch and acrylic drawings corrected.

 

 

Peter

[Richie Kynaston]

Hi Peter,

Just spent an interesting half-hour reading through this. Very well done. What resin did you use for your mouldings?

 

Richie

[peter220950]

Hi Richie,

 

Sika Biresin G27LV resin and G26 hardener mixed 50/50 by weight. The LV is for a low viscosity version that flows almost like water, and seems to fill the detail better for me. I usually get mine from John Burn in Birmingham, but there are other suppliers dotted around the country.

 

The resin is relatively cheap, around £10 a litre, it's the RTV mould rubber that's more expensive, I'm now getting it from Ebay for around £40 for 2 litres.

 

Peter

[Richie Kynaston]

Hi Peter,
Thanks for that.  I need to go read up on resin moulding, but am I right in that what you have done for your 139 front ends, is to create the master, then sit it in a mould frame (made from Lego Bricks) and pour the RTV in?  How are you getting the master out afterwards, or is the master destroyed in the process?

 

Then once you have the master, fill it with LV resin, leave to set and remove - can the mould be used again?

 

Sorry to hijack your thread with questions, just like to have a vague idea of what is what before i go researching things, so that i know im reading up on the right things!

 

Richie

[RedgateModels]

I've said it before but I really need to get on with the drive mechanism......

[peter220950]

Hi Richie,

 

The master had all of the cab inside sealed off with false plastikard windows, and it was stuck onto a base. The formwork of Lego is built up around it and the RTV is poured in, in a couple of stages to stop the hollow cab trying to float.

 

Once set the formwork is removed and the base is carefully prised off the cab, while the rubber mould is still surrounding the cab.

 

The plastic windows are then removed from inside the cab, leaving the master with an outside skin of RTV.

 

Vaseline, or mould release is then 'painted' onto the exposed RTV that is in the window openings and around the base of the cab, it is inverted and the formwork is then built up again around the cab and surrounding lump of RTV.

 

A further pour of RTV into the inside of the cab then gives a solid cube of rubber with the cab master embedded in it, but the use of the mould release/Vaseline ensures that the inside plug pulls out, allowing the master to be removed from the first poured part. Putting the two parts of the mould back together leaves a void where the master was, and into which resin can be poured.

 

It's a bit more complex than that, needing a way to pour resin in, and a way for air to get out, but that's the principle.

 

The master, though brittle, survived the ordeal, and amazingly the cast ends come out pretty well, considering the slender Ness of the glazing bars. I did think I might have to resort to dropping lengths of wire into the mould, like reinforced concrete, but it's not proving necessary.

 

There are some useful YouTube videos around, just look for 2 part silicone mould, or 2 part RTV mould, they explain it much better than I can. - And don't worry about hijacking the thread, the only way I learned a lot of things has been from asking on RMWEB.

 

Peter

[Dave John]

Well, I have no experience of the  the prototype, but the methods for modelling it are very innovative. A first class read, many thanks. 

[RedgateModels]

Last night the parts were retrieved for the drive unit and the Delrin chain removed.

 

Following the testing of my Big Big Hymek at the Mansfield Show with just one drive axle I am convinced that the 139 will be fine with a similar arrangement. I'll do some tests this week with the chassis fixed to a lower body casting (the black bit in peter220950's photo above)  then I can get the assembly back to Pete Harvey for final design. 

 

I'll post what I have here before I box it all up mind

[Wigan Wallgate OO Gauge]

Any updates! Look forward to each one