Bonds Standard Pacific
This was a chassis acquired from Ebay a few years back and I have decided to start a rebuild of it. The main reason is that I and another 2½" gauge/Gauge 3 enthusiast organise the National 2½" Gauge Association stand at the Midlands Model Engineering Exhibition and this year we are featuring the locomotive designs by Henry Greenly. These were originally marketed by Jackson Rigby and later taken over by Bonds of Euston Road, London.
Chassis as received
The chassis is quite nicely made but was missing the correct cast rear frame which is featured in the design. Fortunately, I managed to pick one up from Ebay again complete with another trailing truck. The drawing below is the earlier Jackson Rigby version from 1924.
The Bonds versions do sometimes differ slightly from the earlier Jackson Rigby e.g. the wheelbase of the driving wheels is sometimes different for some reason.
I've just noticed on the drawing to see the articles in Junior Mechanics Jan to Aug. 1924. I'll have to try and get hold of some copies but I think they will be quite rare nowadays.
The Standard Pacific is one of a number of Henry Greenly designs that are based on a set of 'Standard Parts'. The designs usually consist of a general arrangement drawing for the locomotive and tender and then a set of drawings that show these standard parts which are common to all the designs. A very good idea as it cuts down on the number of different castings required.
Unfortunately, the Henry Greenly designs tend to be over shadowed by those brought out by LBSC which is a great shame as the Greenly designs are very good ( they should be seeing as Greenly was a professional designer of steam locos in all gauges) and perfectly capable of hauling a passenger around a track. Although the above drawing shows a meths fired boiler there are several coal fired boilers in the standard parts drawings that can be fitted instead.
The much later Bonds designs included a very nice Duchess and a Black Five but these were designed by George Layton and not Greenly. Layton also designed another freelance Pacific 'Victory' which seems to be more or less the Duchess design but with a round top firebox instead of the square top Duchess one.
Anyway, onto the rebuild.
First job was to strip the chassis down so that everything could be given a good clean and then rebuild the frames using the cast rear frames. The main frames cleaned up nicely but there are a few holes that will need filling where the cast frame will fit.
However, before this the cast rear frame needed a bit of work. I think it had only been filed to shape on the rear face and the mounting faces and these were not flat or true. Although it had the frame mounting holes drilled and tapped in the right places according to the drawings, whoever used it last had not used these and drilled some new ones as well! Hopefully, I can use the proper holes when I come to reassemble the frames and just fill the unwanted ones.
The cast frame is a bit awkward to hold for machining but I eventually managed to clamp it vertically to an angle plate on the mill table. There was enough travel on the head to raise it high enough for this to work.
The first operation was to machine the rear face true and flat. The platform should overhang the rear beam by about 0.063" but the beam had not been cut away to allow this. This had resulted in a step in the rear face instead of it being flat all the way across.
Care was taken when it was set up to make sure that the sides of the frame were vertical so the frame would still be square after all the machining was done. A brand new carbide endmill made short work of the machining. Gunmetal is dreadful stuff to machine with blunt tools as it cuts like cheese then and burrs over on the edges of the cuts.
The casting was then turned upside down and the bolting faces machined. This needed about 0.025" taking off the bolting faces to get them flat. I'll have to use shims when I reassemble the frames to bring the bolting faces back to the correct width.
The next photo shows the cleaned up frames, the cast front buffer beam and the rear frames.
It looks as though the front bufer beam will need some work as well.
I spent an hour tonight sorting out the main frame plates. When I looked at them they were all shapes! They were like a dogs hind leg lengthways and twisted vertically as well. That was sorted by judicious bending at the right places and then the frames were bolted together as a pair and the ends of the frames skimmed in the mill to make sure they were perfectly square. They were actually quite close and only neded a few thou taking off.
To align the frames parallel to the table of the mill I bolted a couple of milling arbour spaces to the table and set these with a dial indicator in the mill chuck. The top edge of the frames were simply butted up to these which acurately aligned them to the table.
The horn slots and most of the holes in the frames seemed to line up quite well which would suggest that these were cut and drilled with the frames fastened together but some of the holes were miles out of alignment and had obviously been marked out and drilled with the frames separated. Why do people do this!! The angled part of the rear of the frames were also totally different for some reason!
You can see that the original bolt holes for the rear frame are miles out of line in the two frames and heaven knows why the outline of the frames are different. I'll have to adjust that when I fit the cast rear frames. I'm beginning to think that more than one person has had a go at this chassis. I wonder what other horrors await!
Whilst the frames were still bolted together I drilled the new mounting holes for the trailing frame by clamping the frames to the mill table and using the DRO to position them. I decided to go for the hole positions shown on the drawings and hoped that most of the new holes would miss the original holes in the trailing frame which they did. A couple did clash though but I was going to fill in all the existing holes anyway so that wouldn't be a problem.
The drawings showed the fixing bolts to be 1/8" BSW but as there are seven of them I thought that a bit over the top so decided to use 6BA instead.
To fill in the original holes which I think were 3/32" BSW I drilled and tapped them the next size up and screwed in 6BA brass screws. The larger holes were 1/8" BSW. I didn't have any suitable brass screws to fill these so threaded some 1/8" brass rod and used short lengths of that. I think whoever drilled and tapped the original holes must have been drunk as they were at all angles to the bolting face! These were all then soft soldered in place to make them really secure.
After soldering, the screws were sawn off close to the face of the casting and the excess milled off to within a couple of thou of the face. The faces were then cleaned up with a file.
What I should have done was to fill the holes before I originally remachined these bolting faces! That would have saved me the trouble of setting the casting up in the mill again and having to do the job twice.
The ends of the screws on the inside of the casting could do with cleaning up flush but I'll do that when the new fixing holes have been drilled and tapped.
To mark out the new bolt holes in the rear frame I clamped the frame to the mill table and clamped each frame plate against the rear frame and spotted through each hole by hand using a cordless drill. That guaranteed that the bottom of the frames would line up correctly with the bottom of the trailing frame.
I only did three of the holes to begin with and then the frames were bolted together to make sure that everything lined up properly. Once I was happy, the rest of the holes were drilled and tapped.
I did the drilling and tapping in the mini mill as it is ideal for this sort of job.
I then moved on to the front buffer beam which was pretty rough. The front face had been left as the rough cast finish and was also a bit bent. I straightened it out as best I could and then milled it flat. It was a bit tricky to hold in the vice but I worked out a way in the end.
The ends of the beam were also just as cast so I machined them straight and square using the same setup. I also cleaned up the bottom edge of the beam and reduced the thicknes of the ends to the correct dimension. This has resulted in the beam being about 1/8" narrower than it should be but the original casting was too narrow anyway. I'll just adjust the width of the running boards to suit. It is a freelance loco after all!
To be continued