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Rob Pulham

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  • Location
    The Rhubarb Triangle
  • Interests
    Railway Modelling, DIY, Visiting Preserved Railways. I model in 7mm these days and I like to build kits.

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  1. Moving swiftly along from the brake standard modifications. You may recall further up the thread my making a stove for the brake van using my Silhouette cutter. Although I proved it was possible, it was extremely fiddly to assemble and I certainly wouldn't want to be doing a lot of them. It's also a perfect candidate for 3D printing so yesterday morning (after amending the brake standard files) I started to draw up the stove. It has proved to be my most ambitious and ultimately satisfying design project to date. My apologies for the image overload but I am delighted at how well it has turned out.
  2. After joint the Gauge O Guild's special interest group on 3D cad and printing I have been drawing up a few items that I have long been unable to source from the trade. Slaters do very nice lost wax castings of brake standards and stoves but they are both LMS in origin and I wanted the LNER versions so since having a dabble at drawing I decided to have a go at them. I started with a brake standard. and then with the version with the wooden box over the mechanism. More to follow.
  3. Looking to start adding as much as I could details wise, before assembling the main components. I dry fitted the tank filler and the vent pipe castings on the tank top plate. Although the latter are generally not bad castings, when I opened out the etched holes, they both sat lopsided. I attempted to tidy them up using a square needle file but wasn’t able to correct the lean. I decided to have a go at turning them, but gripping them to turn them in the lathe was going to prove interesting. So, I took a leaf out of the late David Smith (DLOS)’s book, and made a split collet from a length of aluminium rod. I had recently watched a YouTube video of someone doing just that and the guy who made the video had left a collar on his split collet to make it easier to get it in and out of the lathe collet. This shot shows how the casting sits in the split collet. You can see in the shot below how lopsided the base was. The rim of the base plate was so thin that I dare not turn too much off or I would have ended up having to turn a collar to replace it. Which was plan B if I hadn’t been able to get the existing base plate to sit flat Thankfully I got away with it and didn’t need to resort to plan B.
  4. Hi Ian, I am most definitely in the I prefer to make it camp. Much as I am enjoying the dabbling in 3D drawing it will never replace physical modelling.
  5. Modelling time has been in short spells just recently, hence my lack of posts. I have been beavering away at detailing the front and rear of the tender but I haven’t taken any photos yet. However, a discussion on the Guild forum about details of the coal pusher fitted tenders had me looking closely at the drawings of the modifications done to the 9 Ton tender to increase coal capacity to 10 Tons. There are drawings of the upperworks in LMS Profiles no 4. The tank vent castings cleaned up quite nicely by spinning them in the mini drill with a bit of scotchbrite and although the water filler was a reasonable casting, when comparing it to the drawing it’s a bit on the undernourished side. So, using the same bar as I used for the eccentrics which was just the right diameter, I decided to make a replacement. I had a look at as many photos as I could find and it seems that David Andrews has the type of hinge mechanism pretty much correct albeit that all the ones that I saw had plain straps without visible fasteners. After turning, I transferred it to the mill and used a recently acquired edge finder (less than £7 posted from Allendale) to help to accurately position the holes. I then used a 1mm collet to hold a .06mm drill and away we went. Fitting such small drill bits into a collet on the mill is a bit of a fiddle and you could really do with another hand but it’s worth it.
  6. Although I dressed the backhead a couple of weeks or so ago, I hadn’t managed to get it to fit into the cab before now because the stub of the whistle protruding through the cab roof stopped it from sliding in. One of those little few minute jobs that seem to take forever to get around to…. I finally got to it and the backhead now fits in place as if it was made for it.
  7. After spending a week teaching myself 3D drawing, I was back at the workbench today. I had originally planned to just turn a couple of appropriately sized top hat bushes, file some flats on them where they come together and job done. My recently acquired mill offered more possibilities to make something that at least looks like the original even if it doesn’t attach in the same way. This will be soldered to the cylinder front in between the slide bars, instead of being suspended from a substantial bracket between the frames. This is my first real item produced with the mill and I am happy with how it turned out. This is where it will sit in between the slide bars on the cylinder front. I have added some fastenings to make it look as if it should be there, when it’s ultimately lost in the gloom between the frames.
  8. I went through the process again this time drilling the offset at 2mm which proved to be perfect for this particular application. I had been using a very thin cutting tool which someone had ground (not very well it turned out) which came in the box of bits with the lathe. After cutting the first one I thought that I would examine the tool to see if I could improve it or at least rub it on a stone to restore the cutting edge. When I looked closely at the cutting part I noticed that the bottom of the tool was wider than the top and although there was some rake away from the cutting edge the fact that it was getting thicker couldn’t be helping to make an efficient cut. This is a sketch of what the tool looked like originally albeit the bottom of the wedge is somewhat exaggerated. I have watched a few Youtube videos on sharpening lathe tools recently so I had a go at grinding the tool to take off some of the thickness towards the bottom making the two sides parallel. This improved the cut and I successfully cut the groove for the first sheave. Then I parted it off but I was a little too close leaving a very thin edge. During the parting off, the parting tool moved slightly in its holder which pushed over the thin rim of the sheave slightly closing the top of the groove. In the end it was usable but I decided to cut another pair to be on the safe side. It was while parting off the first one that I noted that my parting tool was in fact just the right thickness for cutting the groove without having to move the carriage as well as the cross slide to get the desired cut. Having discovered this the next one progressed much faster and modifying the fixture that holds the parting tool so that it grips the parting tool more securely by squeezing it in the vice made the third one even faster still. The parting tool is one like this albeit mine only has one tool. You will note that it’s a pressed steel fitting that grips the part with the aid of a cap screw. Mine didn’t hold the cutting tool very closely to the holder but it does now. https://images-na.ssl-images-amazon.com/images/I/41Uv-fAJmjL._AC_.jpg So here we have the finished sheaves. This is how they will fit on the axle once I work out their alignment with the crossheads further down the line. It turns out that I wasn’t far out with my 16mm deep offset hole, I had a measure of the remaining stock while putting this post together, and there is just about enough material to cut a 4th sheave had I needed a full set for a conventional inside motion build.
  9. Although the gent that I am building it for doesn't want full inside motion. One thing that is quite visible through holes in the front frames, is movement of the crossheads. I was asked if I could add some element of movement using the spare outside motion bits from the kit ( a set of Premier rods etc. has been supplied for the build). Having started to think about it long before getting to the actual start of the build I realised that with the axles being hollow I couldn't use traditional cranks to make the crossheads move (or rather I wasn't comfortable that I could make it work without ruining axles wheels). So I thought that a pair of eccentrics would impart movement while being able to be attached to the hollow axles without having to cut them. We agreed this as the way forward and I ultimately bought castings for the slide bars/crossheads and eccentric straps from Laurie Griffin. I was also going to buy some eccentric sheaves too until I recalled Nick Dunhill finding the new cast versions very time consuming to prepare. Further thought made me also realise that the LG cast ones wouldn't really work anyway. This is because in a 'normal' inside motion set up the eccentric sheaves are trapped between the cranks so the eccentric straps cannot slip off the edge of the sheaves. Of course, I planned to use them as a single eccentric so they would need to be restrained at either side. Instead of ordering a set of cast eccentrics along with the other parts, I bought a length of 12mm round brass bar instead. Initially I was going to offset in the lathe using a four jaw chuck to offset the bar but having done a bit of research online, most machinists were of the view that you could but if you had a mill it would be far easier to drill it in the mill. Not being as proficient with my mill as I hope to be in time I did use the lathe to put a small centre mark in the end of the bar before transferring it to the vice in the mill. Then using a centre drill inserted into my centre mark to centre it quickly, it was easy to plot the offset (2.4mm, more on this later) and then drill it out to 4.5mm. I then took it to final size with a reamer. Transferring it back to the lathe I took a skim off the outside and marked up for the first sheave. Some time later we had this. I tried the eccentric strap for size and found it was just a little too wide for the strap to close completely around the sheave. It was at this point that I noticed that the depth of cut of the groove to accommodate the strap was such that it was very close to breaking through into the offset hole. It seems that in setting my offset hole at 2.4mm from the centre to gain the maximum amount of movement was just too much. You may be able to see the mark where it’s just about to break through in the image below. This was made worse by having to apply a second slightly larger reamer than 3/16 (4.74mm) to get the axle end into the offset hole The plan is to start again from the other end with a 2mm offset hole and see how I get on. To be continued…
  10. Yesterday saw more progress on the motion for the J6, with the valves almost complete. I still have the arms to make that connect the valve rockers with the expansion link etc. But I am pleased that I have got this far as I had hit a bit of a mental brick wall with concern that attempts at soldering on the valve rocker supports would result in them dissolving into individual parts again. As happens often when procrastinating, I worried for nothing.
  11. Further progress on the tender has seen the basics of the body put together. So far, the only issues have been some bowing of the half-etched sheets which has taken a bit of work to get them soldered up straight. The worst being the rear sheets with the steps and the coal door. In the end I added a second sheet of 10thou nickel to back off the coal door. I still have more detail to add to the coal door.
  12. While I am distracted with outside jobs during the good weather, I have been working on another of the key outstanding jobs that is simple to pick up and put down. The back head/plate, is as I mentioned earlier in the build, a GNR Boiler Back Plate set from LG Miniatures. It wasn’t quite deep enough so I added a strip of thick brass along the bottom. Also missing from the set as delivered, were the injectors. Laurie includes a layout drawing in the set and it showed the missing injectors. An enquiry to Laurie had an apology and a pair of injectors in the post. I am not sure if they were from the GNR set or another more generic pair but a little bit of scratch building had them looking the part. I had to fabricate one of the levers for the right hand injector from a .9mm rod with one end squashed and drilled out for the pin and then tapered with a file in the mini drill (too small to old securely in the lathe). In the end I only used one of the hand wheels from the set because they came with cast stems on them and I wanted to fit them to the stem already present on the castings so I used some cast hand wheels from the spares box which had holes in the centres. Had I not had them to hand I would have cut the stems of the castings and drilled them for the ones with the cast stems but it would have been a bit tedious. The GA showed some kind of inline valve down the right hand side of the cab at the side of the back plate so I knocked one up from a couple of bits of tube and a cast handwheel from the set. My apologies for the greenish tinge it’s reflections from the green storage box that I propped it against for the photos.
  13. I had hoped to make further progress on the J6 motion today but last night my elderly neighbours' bed collapsed. I have spent much of today regluing and splinting the centre support for them. The splints were made from a couple of strips of oak that we had spare from a replacement pack sent for a damaged in transit headboard for our bed. The sun was shining and I like working with wood, so what wasn't to like about doing them a favour.
  14. With the brake hanger height sorted it was time to fit them. Because the wheels are on telescopic axles, they need much more wiggle room to be removable than the Slaters et al, types. It’s actually quite surprising how little room you need to remove a Slaters wheel. The lack of space around the brakes meant that for the wheels to be removable the brakes need to be removable too. I did this by adding a collar from microbore tube over the .9mm rods that the brakes hang from on the frames. And at the moment the cross shaft at the front of the tender is removable but I am sure that if this were fixed the brakes would pivot out of the way to get the wheels out. Just to prove that they are removable. I also made the two quite hefty support rods for the water scoop. Plus, a Blue Peter moment in that here’s one I did earlier. I fitted the brake cylinder that I turned when I first got the Unimat 3. A few general shots of the inner chassis, for no other reason than I got a bit carried away with the camera.
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