PRMRP 7mm Class 50

[Hull Paragon]

Day 5

 

My short break took longer than I thought!

 

It would be prudent to make a small comment on the difficulty of lining up the axles. I could have easily lined them up with the axle boxes if I had not opted to utilise the drive belts. (I don’t know how easy it would have been had I chosen the Delrin drives instead).

 

On to the brake cylinders. There are 3 on each side of the frames…..12 in all. The white metal castings are sealed within a polythene compartment which is part of the packaged bits and pieces.

 

 

They need to be cleaned up a bit but that doesn’t take long.

 

The bogie side is cast with 4 half depth slots. There is a half depth  hole at either end and 2 half depth holes on the rear face. The bogies are ‘handed’ and each side is the mirror image of the other. It follows that whichever one of the central slots is utilised on one frame, the other will be used on the opposite side. The castings are, therefore, arranged so that any frame side can be used for either ‘hand’. You just need to be careful that you get the arrangement the right way round and drill out the correct mounting hole from the rear. (Actually, I used a 2mm end milling tool).

 

Front

 

 

Rear

 

 

I marked the frames to remind me which positions were to be used.

 

 

I started off by thinking that the blanked slots for the brake actuators were not what I wanted. The prototype has the slots opened up, and they are quite a bit narrower. I decided to drill them out and slide a milling tool along the slots to open them out so that the actuator arm just slipped through. Unfortunately, in my haste, I made several mistakes on the first hole which resulted in the slot being far bigger than I wanted. I mixed up some Milliput and closed it up a bit. As I seem to be accident prone today, I decided not to go down that route for the rest……black paint will give the impression of a hole there so I will be content with that. I shortened the actuator arm a touch and superglued the cylinders onto the sides.

 

 

The unused slot will be filled in and filed smooth.

[Hull Paragon]

Day 6

 

Actually, it’s Day 6.5! I took a couple of hours yesterday to do a few things, including priming the bogies.

 

 

I painted them with a quick coat of Satin Black and bolted them together……..not without minor difficulties though.

 

There are a couple of things I should have been more careful with.  The stretchers are different at each end of the bogie. The front end must have the stretcher which has slots for the guard irons.

 

 

I made sure this was the case but somehow, the mounting holes didn’t line up properly in the configuration of inner frame/bogie I assembled and I had to file them into slots…..

 

Incidentally, I have powered both bogies and they run although they are a little noisy.

 

 

When I feel confident weathering things I’ll spray them with frame dirt etc…….

[Hull Paragon]

So, on to the body. I have spent a lot of the day trying to be sure that everything is identified and fits. There are so many areas which are not quite right that it is difficult to select one as the datum to measure all the rest. I’ll try to address each as they come up……….

 

The body is supplied in one piece. The brass has been pre-rolled but in my case, the roof/bodyside curves have ridges and although I tried to remove them, they still don’t look right. (I have decided to rub them all down after the body is built). In addition, the roof is rolled but the profile doesn’t line up with the roof end casting which is flatter. More on this later.

 

 

In the meantime, I marked the ends so I don’t get mixed up. The arrangements are different on either side.

 

 

I chose to set the lower body angle first. (Is that a tumblehome?). I measured the prototype and found that the angle is around 20°.

 

The body has a nearly full length half etched band on the inside to assist in the forming of the bend. It’s very awkward to do, but I managed in the end.

 

 

 

The prototypical bend doesn’t go the whole length of the side. The shape of the body is not very complex but it changes quite subtly at the front ends. I took a whole load of photographs of ‘Lion’ to try to understand this…….

 

It’s not too easy to see but the lower fold goes from one end door to the other while the area between the door and the body front straightens in the vertical plane, and at the same time, the whole body sides close inwards at the ends in the horizontal plane. There is a further bend at the end which is lower than the bottom of the main body side…….(this can be seen at the extreme end of the picture above). The effect on the prototype is further confused by the colour scheme which seems to suggest a fold all the way along the body. This will be more apparent when the front end is built.

 

 

 

     

[Hull Paragon]

The kit comes with a 3mm angle which has to be soldered along the inside bottom of the body side. It forms a ledge on which a number of bits and pieces are fitted; specifically fuel tanks and the cross members for the bogies. The angle is supplied as a flat strip which must be folded. This is a challenge, but can be done! The instructions suggest that a ‘U’ channel can be utilised instead, so having decided some time ago that I liked the idea of a stiffer construction, I bought some. Unfortunately, I discovered that 3mm ‘U’ section isn’t! It’s more like 2mm so the folds on the fuel tank etchings don’t fit inside it without the lower part of the ‘U’ cut away. Additionally, the profile at the front changes which means bending the angle/’U’ to accommodate this. Clearly, the ‘U’ is stiffer and therefore more difficult to shape. So I ended up utilising the kit supplied angle.

 

Angle as supplied.

 

 

Angle folded.

 

 

'U' channel. Even in the picture it can be seen that the available space in the internal channel is much narrower than the 3mm of the angle.

 

 

I smeared the edge of the body with 188 solder paint, ‘clamped’ the angle on and with a series of passes, gas torched them together.

 

 

 

[Hull Paragon]

I then spent some time thinking about how best to go on from here. The body is quite springy and bends all over the place when it is worked on. It needs to be stiffened so I thought I would simply solder a couple of cross pieces in across the angles.

 

Cross piece (not fitted yet).

 

 

In order to measure the gap, and to fit a piece that is reasonably close to the internal width of the body, I unwrapped the cast roof and end/bonnet pieces to test fit them. This will close the body sides down to the proper width. The roof castings are not good.

 

 

The castings are quite flat, (elliptical), but the rolled roof is quite round…..therefore the pieces don’t fit together well. The front of the body has to wrap around a little to get the shape mentioned above. The instructions are not helpful. They simply say ‘…..fill any gaps with solder or a car body filler such as Isopon……’. It will take a lot of fiddling to fit them.

 

The end castings are slightly better.

 

 

The instructions suggest that the end casting should be fitted first, the roof next and then finally the etched window frame.

 

 

 I’m a bit nervous about this as it is quite difficult (how many times have I used that word?) to be certain as to the accurate locations for the pieces. Even having a dry run is almost intuitive guesswork at best. As I write, I don’t even know which way up the window frames go yet!

 

There are two problems I need to consider before I go any further. The first is the roof. The kit is for the final rebuilt Class 50. The casting appears to be for the first version, with if I have guessed right, an etch to wrap over the casting to represent the rebuilt version. It's very unclear.

 

The etchings and folded roof panel (unsoldered) are shown here.

 

 

 

I have dozens of photographs….but none at high level so I need to look further to resolve this issue.

 

The second problem is with the ventilator etchings which have a fold at each end. This means that they will stand back from the body side about 1mm and I need to understand what the prototype has and what the final result will look like on the model. The other issue is that if the whole etch sits back from the body, the central portions will be unfixed and will therefore push in when handled.

[Druid]

 

Hi

 

 

 

Build looking good . I have built a few of theses type of kits over the years and would suggest the following re the body springing .

 

 

 

A) Add two brass bulkheads where the cab bulkheads would be ,helps with stiffing and the body profile . Also could add stringers further along to maintain the profile and helps with the following .

 

B) I usually add a floor out of thin ply to fit between the lower body also helps with the stiffing , the bogies can then be attached plus any underfloor pieces to the floor pan . Floor would sit between the bulkheads attached with bolts screws etc

leaving cab area free . Helps with running in and wiring ie can just detach the body and test run to solve any faults etc

 

C) Re cab roof castings Dave Parkins original producer of these kits has mentioned some were to solder the Whitemetal casting from the outside as the best method of attaching to the cab sides . As I fell into the trap of soldering from the inside and often made a pigs ear of it I would certainly take his advice .

 

All the best

 

Andrew

[Druid]

 

Forgot to add :

 

The floor also helps when you come to the painting stage . Attach floor to body and add a another scrap piece of wood to using to hold ( I will attach a picture easier to see than describe shortly )

 

Andrew

[Druid]

Please find photos as indicated :

[Hull Paragon]

Hi

 

 

 

Build looking good . I have built a few of theses type of kits over the years and would suggest the following re the body springing .

 

 

 

A) Add two brass bulkheads where the cab bulkheads would be ,helps with stiffing and the body profile . Also could add stringers further along to maintain the profile and helps with the following .

 

B) I usually add a floor out of thin ply to fit between the lower body also helps with the stiffing , the bogies can then be attached plus any underfloor pieces to the floor pan . Floor would sit between the bulkheads attached with bolts screws etc

leaving cab area free . Helps with running in and wiring ie can just detach the body and test run to solve any faults etc

 

C) Re cab roof castings Dave Parkins original producer of these kits has mentioned some were to solder the Whitemetal casting from the outside as the best method of attaching to the cab sides . As I fell into the trap of soldering from the inside and often made a pigs ear of it I would certainly take his advice .

 

All the best

 

Andrew

Andrew

 

Many thanks for your comments. I like the plywood floor idea.....it will also help to keep running noise down too I suspect. I think I will attach the spacers/stringers first, then attach the interior grilles and glazing before fitting the roof castings. My method will be to brush flux paste on both sides of the joints, position the roof, add a couple of small lumps of low melt solder on the top join, then run the gas torch over it until the solder runs. This method could also work doing it from underneath but you won't be in as much control of the roof position if it should move at all. Almost all of my white metal work is done like this and if you are careful to allow the heat to build up slowly, the solder will run before the white metal!

 

Ray

[Pete Harvey]

Message sent you Ray check your messages.

[Hull Paragon]

I mentioned earlier that I had no pictures of a Class 50 taken at high level.....I couldn't find any clear ones on line either. I took theses today. Maybe they will be useful to someone building a Class 50 in the future.

 

No1 End

 

 

 

 

No 2 End

 

 

 

 

Edited October 25, 2017 by Hull Paragon

[Hull Paragon]

Before I write up my next post, I'd like to thank Peter Harvey at PH Designs. Peter read my posts and very kindly offered to send me a set of etched air horn grills from one of his detaling kits.

 

 

I have not seen these before and I think they look superb.

 

Thanks! (And please note that until this exchange, I have no connection with PHD!)

Edited October 26, 2017 by Hull Paragon

[Hull Paragon]

Day 7

The next steps have been to try to form one of the front ends. I stuck with my plan to put the roof on first, then the front/bonnet and finish with the windscreen. I am part way through this plan for one end but although the assembly of the parts was relatively simple, the subtle changes of curves and angles of the body were not.

 

 

The cast roof has a very small rim on which to locate the brass body. It is so small that when trying to set the pieces up for soldering, I found the roof popped out of position which made things less than easy. Also, you will see form the picture that the roof profile as delivered and the casting profile are (slightly) different. I wasn’t sure how best to re-profile the roof and in the end, as the difference was quite small, I decided to fit the casting, then apply pressure to make the brass line up with the white metal before soldering. (I’ll use this profile to make a bulkhead to fit to the other end which will prevent this happening again).

 

After setting it all up, I put a few pieces of low melt solder along the join and soldered it together.

 

 

The next section sounds considerably more simple than it was.  The internal angle stiffens the body….but the body has to be bent inwards to accommodate the bonnet casting.  At the same time, the body side straightens in the vertical plane so the body side bend has to be straightened at the front end, which means that the internal angle has to be bent to allow this reshaping. (The instructions do refer to this but the detail isn’t apparent).

 

Eventually, (and I mean eventually) I manoeuvred the body, casting and three dimensional  shaping with two hands and a few bits of wood, clamps and wishful thinking, and soldered the two together. Here is the end result…..photographed to give the best view as I still need to tweak it!

 

 

You will notice that the side window frames are not yet properly secured, but even if they are bent to the roof profile/curve, the front window frame etchings don’t fit by about 2mm. Maybe if I’d followed the instructions, this wouldn’t have happened? For the other end, I am inclined to carve a former from balsa but I don’t think I have the necessary skills to do it accurately, but I will have the experience of this end to help me make a better job of it.

 

At least it suddenly begins to look like a Class 50!

[Hull Paragon]

I have had to come inside to calm down after a fraught morning attempting to put castings into the 2nd end. I soldered the roof casting in without too many issues, but the end casting is proving less easy. I'll do it in the end but the process is so excruciatingly awful and stressful that I have resolved never to buy a PRMRP kit again. Others in replies to my posts seem to have built them but I just can't get the alignments right. The flange of metal on the castings is so tiny that holding things rigid to solder is almost impossible......I've wired, taped, blu tacked, tack soldered....but nothing will stay put for final assembly. I soldered the roof casting on once before but afterwards I discovered that it was not level and I couldn't wrap the window frames round properly.....so I took it off. Each time I try to line something up, the brass casing bends putting pressure on thin etchings such as the window frames.....these have to be straightened and now look 'dishevelled'.

 

I am not giving up, but the pleasure has long gone. I wish I had paid the extra money and bought the JLTRT version

 

Thanks to Peter and Peter Snr for good service etc, but (in my opinion) the kit is so bad...........never again!

[The Nth Degree]

Don't give up! I'm having a long look at my Class 40 at the moment and may end up fabricating the supplied cast parts. I will probably end up building a rolling ladder-frame chassis as well so it's easier to add mechanical and electrical components.

[Pete Harvey]

Email sent.

[Hull Paragon]

Don't give up! I'm having a long look at my Class 40 at the moment and may end up fabricating the supplied cast parts. I will probably end up building a rolling ladder-frame chassis as well so it's easier to add mechanical and electrical components.

Thanks for the encouragement. I have worked all afternoon and failed to get it done to any level of satisfaction. Peter Harvey has suggested asking JLTRT if they provide 2 made up cab ends and I have emailed Laurie to that effect. If they can do it, I will get them....if not, I am going to sell the bits I have left and buy the JLTRT kit in December.

[Hull Paragon]

There is too much wrong with this kit to continue with it as it is. One of my objectives is to enjoy what I do, but there is no pleasure with this. I have damaged the body and the castings trying to fit them today. I'm sure if I had taken a bit more time and been a little more precise I would have avoided that......but I shouldn't have to be that precise for a kit that costs this little. Anyway, if I can get the cab ends (see above) I will fit them and complete from there. (I don't want to give up altogether!). The fuel tank sub-assemblies are done and so are the bogies. (And the bogies were tedious enough without the roof and end problems I have had today).

 

This kit is over 30 years old and was probably designed well before that. It feels like an aid to scratchbuilding, not a kit. I'm not a scratchbuilder, and at my age, I have no intention of becoming one! I said at the start of these posts that I am not an expert, but I have some experience and I was once the recipient of some very good engineering training. I have some idea; perhaps more that some. But I have to admit defeat with this kit. It is just about the most frustrating project I have attempted to date (which includes a Connoisseur loco with Brake Van and Lowmac, an old etched brass Grampus kit which was quite fiddly, and a Scorpio Britannia tender....part completed, but which, so far, looks very nice and was pleasing to work on.

 

In some respects the kit is exactly what you pay for. A low cost alternative to the JLTRT products. I don't have a problem with buying a cheaper product and getting less for my money, but there seems to be too much 'less' for my liking. One or two reference points or holes or slots would have been really useful, and a bit more metal on the ends to assist with the mating with the main body.

 

PRMRP were very helpful when I first bought it and were very customer focused. But the body was badly rolled and right from the start I was on the back foot. PRMRP suggested I roll the creases out myself and perhaps I should have asked them to do it.....but I thought it would be simple enough.....it wasn't. I would have preferred base, sides and roof all separate which would have been much easier to work with.

 

The instructions are very poor. They should be completely re-written and detailed references made to the shaping of the front as well as the bogies. I could go on but I don't want to be critical for the sake of it. As Peter said to me at Telford, '..........people say my kits are not as good as JLTRT.....so I tell them......go and buy the JLTRT one then....... Before I started I would have agreed with him......today, I wish I had taken his advice. If the cab ends are available for JLTRT and they are cost effective I will buy them.....but if not I will sell the box of bits to a more formidable soul, recover some of my outlay and get the JLTRT Class 50 at Reading in December.

 

Please note that these are only my own opinions, experiences and disappointments. Others I hope will be more successful.

 

Ray

Edited November 3, 2017 by Hull Paragon

[Park]

Hi Ray

I too have a Class 37 of the same stable and now regret it. It's now gone to the bottom of the pile and will be considered once I have completed my Gladiator Duchess. Whilst the Duchess is a steep learning curve at least it is a kit

 

During my visit to Telford I was tempted to buy a body shell off a Heljan 37 for £100. I think that could be my fix rather than spend so much time trying to make something decent from the pieces that are supplied. If I can get the bogies to run half decent that will be something, but I have already resorted to a separate chassis made from brass bar for the current brass body to sit on

 

This has been my biggest learning since being inspired by O Gauge

[Pete Harvey]

I was asked to rebuild a PRMRP 56 for someone ok i thought what a night mare I ended up just using the bogies, motors and body wrap and rebuilding the rest with a lot of help from Mr Parkin for a few parts and 3D printed cabs and new etched parts.

 

 

 

 

 

They were good kits in the day and they are a good starting point now but you have to think out the box with how to improve them to modern standards.

 

Ray you have done a lot and some JLTRT cabs will solve about 90% of your problems, they transformed this DJH 40

 

 

[Park]

Thanks Pete, that's another avenue to explore. I didn't know they supplied components

[Pete Harvey]

If you ask Mr Parkin if he can help I sure he will.

[djparkins]

If you ask Mr Parkin if he can help I sure he will.

 

Hi Pete -

 

I could only help with regard to the Class 56 as we had some roof castings available from our own Modern Motive Power Class 56 kit [soon to to be re-released in two versions]. This is a very different kit [with no common parts, obviously] to the one you have shown above which was an ex-Post-War Prototypes kit first released in 1982. But the existence of an MMP kit was the ONLY reason we were able to help with the cab roofs.

 

To broaden things out - In the case of the Class 50, MMP have never done one, or intend to, and so we have no parts that would help in this case.

 

Just a word of background to get things in context. The Post-War Prototypes Class 50 was first released in September 1982 at a price of £52.50. No cab interior - as back then most people used Bond's or Pittman motors that intruded in the cab, and I recall seeing several models with the cab windows painted gloss black on the inside, and with coarse scale wheels. These were still very different times! In the early 1980s my father ran a model shop and he used to carry the Jackson 7mm coach wheels. The CS wheels outsold the FS by at least two-to-one, even then.

 

When I sold Post-War Prototytpes in 1988 to RJH the first thing they did was to increase the prices by approx. 250%. They couldn't form the bodies - either of the locomotives or the coaches. I had modellers coming to me and asking if I could 'save' their Mk.2 coaches for them - so badly formed were they. I had some pretty fancy and heavy forming gear and it still took me over forty minutes to form a Class 50 body correctly. I don't think these kits have ever been sold with correctly formed bodies since 1988.

 

The major problem though was in connection with the castings. When RJH took over, the original brass masters, made with the correct shrinkage allowance 'vanished'. Who was involved with that I do not know, but the end result is that they had to make new moulds from either second or third-generation castings, which, by that time were of course all well undersize, so nothing fitted. In addition, the white metal sub-master roof units in particular could not survive the forces present during the vulcanisation process and 'flattened' into the condition you can see in one of the photos in this thread - the condition in which they were cynically put into £200 kits.

 

All the above things, and the huge price-hike [even allowing for the passing of the years] effectively 'did for' the range. Each subsequent owner has made no effort whatsoever to get the kits back to what they were, let alone do any upgrading or re-tooling. Neither have they reduced the prices! But I feel it important to point out the original ethos behind these kits, which at their original price and correctly formed and cast, sold in their hundreds, and at the time, provided a valuable resource to 7mm modellers.

 

Regards,

 

David ParkinS

Modern Motive Power

www.djparkins.com

[Park]

That's excellent news, MMP loco kits about to be re-released. I keep reading about them and the quality, if it's anything like the coaching stock we are I for a treat

[Park]

This thread has inspired me to have a go at doing more on the 37 and David was right on using low melt as filler

 

I remember back in the day, helping a friend repair his Morris Minor using fibreglass mat and body filler. To fit the windscreens on the 37 it looks like I might have to resort to similar methods