Ian_C's workbench - P4 and S7 allsorts

Discussion in 'Workbenches, including workshop techniques.' started by Ian_C, 21 May 2017.

  1. Threadmark: More boiler fittings and modeller's block?

    Ian_C Western Thunderer

    I do sometimes reach stages in a project where I get stuck, can't see a way forward and lose interest for a while. The dome and top feed cover has been such an episode on the 8F.

    As previously posted the parts were modelled on CAD and sent for 3D printing. It tool a while for the parts to arrive. Here's what I ended up with.
    3 d print dome.jpg
    The dome came out OK. There is the inevitable 'grain' from the layering of the printing process but the dome isn't too difficult a shape to rub smooth with wet dry. The tiny holes to mark the fixing screw positions can just be seen. The edge of the dome is nice and thin. It's about as thin as I think you can get away with using this process and I have to confess that I managed to chip the edge on a couple of prints when I was smoothing them down. And fortunately it sits nicely on the tapered boiler with out any fettling.

    top feed 3d print.jpg
    The top feed cover didn't work so well. I misjudged the thinness of the edge I could get away with on the 'top hat' cover ,and you can just see in the photo that the layering has broken the edge into a number of strands. That had to be filed off and replaced with a tiny brass shim part. The other problem, that I'd kind of anticipated but thought I'd see how things turned out, was that it's a relatively small part with some tight features and curvature and it's not very easy to clean up. I did model the fixing screw heads but they don't show up well in the photo, and anyway, they all were sanded off in trying to clean up the surface of the part.

    3d prints fitted 1.jpg
    I thought I 'd have a go at fitting them to the boiler to see how they looked. I found it difficult to get a feel for them in the native whitish print material so sprayed them over grey temporarily. OK, the paint job's pants. I didn't clean up thoroughly, hence the horrid little hairy, gritty bits. Not to worry, it'll all be cleaned off before proper painting. The dome doesn't look bad. You can still see some traces of layering but I think another gentle sanding down with fine wet & dry will make them disappear under the final primer. The screw heads were made by drilling through the guide holes 0.5mm, inserting short lengths of wire and filing them back to just proud of the surface. They're appropriately subtle. You can see that the top feed cover ended up quite a mess and it'll have to come off. 3D printing isn't the way to go with parts like the top feed cover in my opinion.

    So I'm still stuck for a top feed cover. There's the option to use the casting supplied with the kit but that's not great either, and in using the drawings in the Wild Swan book to produce the CAD I did confirm that it's actually too small in most dimensions. The only option left now is to scratchbuild one, and that doesn't look straightforward to me. Much head scratching before scratchbuilding.
  2. thruxton

    thruxton Western Thunderer


    Having started to use 3D prints quite a bit, I have found the newer 'self levelling' acrylic primers to be a boon (eg Badger Ultimate Primer). Rather than sound the material to shape, the stratas can be easily filled and the primer sanded smooth, which is often not even required on flattish surfaces.

    These newer acrylic primers fill and sand very well, and also come in black to help with metallic finishes.
    Rob Pulham and simond like this.
  3. Threadmark: Top feed cover from scratch - part 1

    Ian_C Western Thunderer

    I'm not great at sculpture, so the prospect of taking a lump of brass and filing away all the bits that didn't look like a top feed cover wasn't an option. It did seem possible to make the basic shape on the milling machine and finish the radii by hand. Something like this...

    basic shape 1.jpg
    Lump of brass squared up and set in the vice. The hole is on the centre of the boiler section at the top feed position. Since this has already been modelled up in CAD all the dimensions required are to hand.

    basic shape 3.jpg
    Here's the blank with the thicknesses and widths of the central cover and the flanking clack valve covers cut to the final size. You can see where this is heading...

    milling curve 1.jpg
    The blank is mounted on the rotary table using an arbor made from an offcut of steel bar. Having previously positioned the rotary centre in line with the spindle, the table is moved to position the milling cutter to cut exactly the radius of the boiler beneath the top feed. Much tedium ensues as many passes of the cutter nibble away through the blank. There's some approximation here though. The boiler (or more correctly the boiler cladding on which the top feed cover sits) is tapered, and theoretically the section at this point isn't quite circular, it's a slight ellipse, conic sections and wot not. A small amount of fettling with a file will be needed to accommodate the taper so the top feed sits nicely upright on the boiler.

    milled blank 1.jpg
    Here's the milled blank, and you can see that it's somewhat bigger than the casting supplied with the kit. I suppose I could have milled the angles on the flanks while it was on the rotary table, but didn't think about it until too late.

    milled blank 2.jpg
    Here it is with the angles sawn and filed and the machining marks cleaned off.

    marking blank 1.jpg
    Next job is to mark on the centre section the lines that will be the guides to file the radius. The first pair of lines away from the corner mark the 45 degree tangent surface to the radius. The second pair of lines from the corner mark the tangent where the radius runs out. By filing the 45 degree first it's relatively easy then to blend the resulting chamfer to the tangent lines. There's an earlier post about the firebox back head that covers this approach in more detail.

    filing blank 1.jpg
    A bit of careful filing up to the lines with a big file produces the first 45 degree chamfer (and quite a lot of gold dust).

    marking blank 2.jpg
    Following the same approach the filing lines for the clack covers are marked next.

    filing blank 2.jpg
    And a bit more filing produces this with all the 45 degree chamfers made. Had Stanier been an adherent of the Cubist movement I could probably have left it at that. Unfortunately the Crewe tinsmiths were less progressive in outlook and their aesthetic demanded radiused edges all round.

    on base 1.jpg
    The base plate cum mounting flange shape, when made a flat pattern by CAD, is a damned funny shape given that it wraps to a slightly conical surface. I didn't fancy trying to mark that out. Instead I cut a rectangle of brass shim somewhat larger than the top feed cover, curved it to sit tightly on the boiler, lightly tacked it in place, positioned one of the 3D printed top feeds on it and marked round the edge carefully with a very sharp scriber (so the 3D printed top feeds were useful for something in the end!). Voila, the outline of the damned funny shape! The flange was cut by snips, piercing saw and filed to the final shape. It was fairly flattened in the process but it was easy enough to form again to match the boiler. The fixing holes were marked and drilled 0.5mm. Here's the blank with all the radii filed and cleaned up and tacked to the mounting flange.

    Take a break here. Part two follows...
  4. Threadmark: Top feed cover from scratch - part 2

    Ian_C Western Thunderer

    We're back to worrying about the differences between Stanier and some Ivatt top feed covers again. I know that 48142 had an Ivatt type cover with the little raised cover on top at this late stage in it's life (1965-66). The hair shirt of authenticity itches mightily so I have to make the top cover. Here's the bit I can't be certain of. Originally all the 8Fs (apart from 8000 - 8011 with domeless boilers) would have been fitted with the typical Stanier type top feed and clack valves, and would have had the matching sheet metal covers with a hole in the top of each of the clack covers through which the valve setting screws projected. That's clearly seen on most photos of 8Fs. Later on there came an improved top feed and clack arrangement from Ivatt that was fitted to some later class 5s. This arrangement moved the clack valves to a more central position beneath the central part of the cover, and there was no need to have holes in the flanking covers since they only covered the feed pipe joint. The little Ivatt 'top hat' covers (not shown on the following drawing) allowed access to the clack valve screws in their new location.
    clack valve compare.jpg
    The clack valve positions are marked in orange on these scans (from the Wild Swan Locomotive Profiles for 8F and later Class 5s).

    Some 8Fs clearly had the later type of top feed cover, witness the 1965 photo of 48142, but it doesn't necessarily mean that it had the later type of top feed arrangement because the original arrangement would fit equally well under the later cover. As boilers were exchanged at overhaul it's possible that some Ivatt style top feeds found their way onto 8F boilers and it's entirely possible that the metal work for covers got mixed up as well. What I'm not sure about is whether 48142 had the original clack covers with the now redundant holes in, or a later set of covers without any holes. I've looked at lots of 8F and Black 5 photos and I've not been able to clearly identify any covers with the Ivatt 'top hat' that had holes in the flanking covers. Therefore my supposition is that 48142 had no holes in the top of the flanking covers. And I'm waiting for the Irwell 'Book of the 8Fs - part 2', which will cover 48142, to come along and prove that I guessed wrong!

    Still have to make the 'top hat' though since I was unable to remove the one from the top of the 3D printed top feed without damaging it. That thing was a swine to make last time so I made a little press tool to simplify things this time around.

    press tool 1.jpg
    A slot of the correct width and depth was milled in an aluminium offcut and the mating part was machined on another, making allowance for the thickness of material (0.08mm brass shim as it happens). A strip of brass shim the right width was placed in the tool and the whole squeezed in the vice.

    pressing 1.jpg
    You end up with this. Rivets are pressed in to represent the fixing screws and the cover is cut from the strip and tidied up. At this size it's not possible (for me at least) to get the rivets in the right place by eyeball every time, but now it's a moment's work to press another one I made three and used the one with the least wonky rivet pattern.

    finished top feed 1.jpg
    The solid cover is soldered to the mounting flange, checking that it all still sits on the boiler neatly. The joint between the cover and the flange is in reality a continuously curved piece of sheet metal. I built up as big fillet of solder as I could and filed it back to neat join. I'd have preferred a bigger fillet but the solder just wasn't having it. We'll see how it looks when it has a coat of primer. The fixing screw heads are represented by 0.5mm brass wire soldered into the holes and filed down. Mr Ivatt's top hat was zapped on with the RSU. I've omitted the screws that fixed the flanking covers to the central cover; difficult to do and with a high probability of messing up. If you were going to point that out I've just saved you the trouble!

    Finally I have a top feed cover, but the boiler fittings aren't defeated yet. Oh no! There's still the matter of the single cone ejector...
    Nick Rogers, cmax, P A D and 18 others like this.
  5. Rob Pulham

    Rob Pulham Western Thunderer

    Superb Ian!
  6. Threadmark: Some more boiler fittings - the single cone ejector

    Ian_C Western Thunderer

    Some of the earlier 8Fs , of which 8142 was one, were built with single cone ejector instead of the much more common double cone ejector that came later. It appears that some of the locos had the single cone ejector replaced by the double cone ejector later in their lives. The only photo of 48142 that I can find was taken from the wrong side so I can't be sure which ejector was fitted in the mid sixties. Studying lots of other photos of 8Fs suggests that most 8Fs fitted built with a single cone ejector retained them into the BR era. Therefore I'm assuming the 48142 would still have had the single cone ejector in 1965. Again, can't wait for the next Irwell book to prove me wrong!

    So far as I can tell nobody offers a casting for a single cone ejector of this type so it'll have to be made from scratch. There are some decent photos showing the critter and it is shown on the pipe arrangement drawing on page 85 of the Wild Swan book. There's enough information to have a go.

    As usual it was scaled from the drawing and referring to photos to sense check the thing it was possible to model it roughly in CAD.
    ejector CAD.JPG
    Helps me get a sense of the thing and I can then break it down into simpler parts that I can actually make.

    ejector parts.jpg
    That's one problem with CAD, everything's the size of the screen. It's not until you sketch up the individual parts and start making them that you realise just how small this thing is. Here are the components, including the mounting bracket to the firebox. Most of the parts are designed so that they're positively located for soldering. That way you don't have to hold them in position as you solder them, and early parts don't come off when you solder on later parts (most of the time!). Here are the bits, including the mounting bracket to the firebox. I was encouraged to have a go at this by reading about a chap called David Smith making injectors and similar parts for 7mm models, worth a look at his website ...
    LMS 5F5P Class Mixed Traffic No. 5108 and 5XP Class No. 5663 Express Passanger Locomotives

    single ejector finished 1.jpg
    Here it is soldered together and cleaned up. The main body was a casting in real life so I've left some solder fillets in corners and rounded off the outer edges a little. I'll admit to some approximation; the two round thingies projecting from the top of the body should have hexagon tops. I'd probably make more of a mess by trying to file them to a hex so I'm better leaving them alone. The photo is a cruel enlargement so it'll not be very noticeable on the model.

    single and double ejectors.jpg
    Here's a comparison of the double cone ejector casting supplied with the kit (and correct for the majority of 8Fs) and the single cone ejector. You can see there's quite a difference.

    Somewhat of a diversion, but if you fancy reading about some of the more unusual attempts at steam powered railway locomotives check this out...
    Loco Locomotives.
    ...including a locomotive with non-circular wheels.

    Blimey, it's 2019 already. I wish you a peaceful and successful New Year.
    P A D, Pencarrow, Focalplane and 16 others like this.
  7. Threadmark: Some more scratchbuilding - the live steam injector

    Ian_C Western Thunderer

    The casting for the live steam injector supplied with the kit wasn't correct for an 8F, some of the inlets and outlets were pointing in the wrong directions. Ragstone do have a casting that appears to match, however Mr Ragstone says that the tool needs renewing so it'a a long wait for one of those. Having had reasonable success making the ejector from scratch, and inspired by David Smith LMS 5F5P Class Mixed Traffic No. 5108 and 5XP Class No. 5663 Express Passanger Locomotives, I thought I have a go at making one from scratch. It's a Gresham & Craven No 11 live steam injector and there's little information to be found on the web. Also beware preserved locos, seems like one of the preserved 8Fs at least has had a different type of live steam injector fitted, probably a more reliable one! It was possible to puzzle it out from some of the drawings in the Wild Swan book and a few photos that show glimpses of the critter. Usual approach: scale from drawings, sketch (scruffy), CAD and then break it down into simple parts to make.
    live injector sketch.jpg

    Modelled in CAD with connections labelled...
    live injector CAD 2.JPG

    ...and the other side...
    live injector CAD 3.JPG

    ...and just for fun, a screenshot of the CAD with just datum planes and some section curves showing. Struck me as being a bit arty, what you'd end up with if Gresham & Craven had commissioned Mondrian to design the cover of their 1932 injector catalogue...
    live injector CAD arty.JPG

    Quite a long time in the workshop listening to rain hammering on the roof and a handful of small parts results.
    live injector parts.jpg

    The parts were designed to be pinned together with 0.8mm brass wire to help keep things together as the assembly was soldered up. Wire soldered in hole and parts threaded on.
    live injector assy 1.jpg

    A fillet of solder was left round the joints and cleaned up to make it look a bit more like a casting.
    live injector assy 2.jpg

    Working from one end to the other and being very careful not to melt the solder on the preceding joints gets the thing together. Unusually I used a higher melting point solder (Carrs 224) for this to improve my odds of fixing the pipework in situ later without unsoldering the whole show. live injector finished 3.jpg
    live injector finished 1.jpg live injector finished 2.jpg
    The two wire stubs sticking out of the mounting bosses will be used to pin the injector to the rear steps to provide a positive location.

    Surprisingly no swearing on this job, but the whole week's quota of gumption was used up in one go. The photos are cruel and show up lots of minor messiness. It really is a little thing, about 11mm top to bottom, and partly hidden under the cab behind the steps, so it'll look OK. Should I dare to add bolts to the pipe flanges?

    Attached Files:

    Last edited: 18 January 2019
  8. adrian

    adrian Flying Squad

    Superb research - I've bookmarked this for when I get round to my build.
    Love it.
    As a suggestion - as you've taken the trouble to design it with pinning together I'd seriously recommend silver soldering the components together. This pinning together of items is exactly what I'd do when silver soldering together items for pattern making. Because of the way you heat the whole component when silver soldering the way that the silver solder flows into the joint is extremely satisfying and it flows very evenly and will make it look like a casting.

    The other thing is with silver soldering is that you can see very clearly when the solder flashes across the joint, the valuable point to note is that when you make a silver soldered joint you then need a slightly higher temperature to remelt the joint. Unfortunately I can't find a reference to back up my claim, however from my experience with a little care when heating the joints it is possible to use the same silver solder on a new joint without melting a previously made joint. You can get silver solders that melt at different temperatures usually about 4 different grades although I have found that the higher temperature silver-flo solders don't seem to flow into the joints as cleanly as the easy-flow solders.

    If you silver soldered the injectors together then you wouldn't have any concerns about it falling apart when soft soldering in the copper pipework.
    Len Cattley and Dog Star like this.
  9. Brian McKenzie

    Brian McKenzie Western Thunderer

    At one time I was making a lot of patterns for investment casting. These were assembled by press fits or with pins as Adrian suggests. All were silver-soldered (to withstand the pressure and temperature when vulcanising the chunks of rubber - stacked all around and poked inside the pattern - to eventually compress down into a solid rubber, before splitting it open as a mould).

    Easy-flo No.1 rod (50% silver) was used, by hammering the end of whatever diameter rod I could purchase into a thin foil wafer*, then slicing tiny slivers off that - to apply to the joint. Powder flux was dropped from the fingers onto the joint as it heated up. The silver-solder alloys with the base metal surface to form a new metal that obtains a slightly higher re-melt temperature. This has been enough to stop any earlier joints re-melting.

    The occasions when any re-melting of a LARGE joint has been necessary is when I can get into trouble, as the higher heat required can sometimes round off the edges of thin components if not careful. Mild steel has more recently been used in patterns to best retain sharp edges and detail crispness.

    Ian would have no trouble doing any of the above, it's easily learnt and the use of silver-solder in some joints would ease assembly. I delight that Giles Favell is such a good proponent of this process.

    *buy silver-solder in foil form if you can.

    -Brian McK.
  10. Threadmark: Injector by silver soldering - new things to learn

    Ian_C Western Thunderer

    Egged on by the estimable Mr McKenzie and the ever present Adrian I've had a go at silver soldering. I already had a tiny butane torch so all I had to acquire was some silver solder, a suitable flux and a little heat resistant block to work on. I went for Easy Flo borax based flux powder and a couple of solders, one 'hard' and the other 'extra easy'. I purchased online from Cooksongold - Jewellery Making Supplies | UK Supplier , but there are plenty of other places. The difference between hardness and easiness being the melting point of the solder. My hard solder melts in the range 745 - 778 C and the easy 630 - 660 C. The latter is similar to Brian's Easy-flo 1 recommendation I think.

    The soft soldered injector was taken apart and all the solder cleaned off. A few parts had to be re-made to obtain a proper interference fit. The wires were soldered into the main body using the hard solder and the other parts were added using the lower melting point solder.

    First attempt at silver soldering, so what did I learn?
    1. There are a lot of really irritating people on You Tube who can spend a long time conveying no useful information on silver soldering. I guess I knew that anyway.
    2. Unlike soft soldering it's not so easy to prod things into alignment when the solder is fluid. You really do need to get everything in position before soldering and be sure that it'll stay there when heated.
    3. Applying the right amount solder to each joint is difficult (for me at this stage). The flux spits and bubbles when heated so resting a small piece of solder on the joint before heating doesn't work as the flux pops it off. I ended up fluxing, heating to dry and melt the flux, flame away, solder placed on joint, heat again until the solder flows. Which practically means that the item has to be assembled one joint at a time.
    4. Given that most silversmithing work is on a comparable scale to this model making work it's a mystery to me why the solder is supplied in such a large format. As Brian suggested, I ended up hammering the solder down to a thin strip and cutting off tiny bits with the snips. Blimey it's hard stuff though, and hammering seems to work harden it. Per Brian's suggestion, I haven't come across any solder in foil form yet, although I have seen solder paste.
    5. I agree with Adrian that the lower temperature solder flows more readily than the higher. But they all flow very nicely and it is gratifying to see the solder flash shiny and flow into the joint.
    6. Unlike a soldering iron you have to control the temperature of the work with the flame and how it's applied. It's another variable to get my head around and you have to watch the work closely.
    7. It gets easier with practice. Needless to say I didn't practice before jumping straight in, although adding the last parts to the injector was quicker, easier and neater than adding the first parts. It shows!
    Here it is...
    injector silver solder 3.jpg
    It's a horrible enlargement of a small part. It ended up much the same as the soft soldered version but as Adrian pointed out I can soft solder the pipework to it now without it coming apart, effectively the same as a brass casting.

    Silver soldering bonus - with this new capability I've been able to make a tiny bit of silver jewellery (is it jewellery when there are no jewels involved?) to add to my partner's charm bracelet. Valentine's Day coming up etc. Presumably all will now be forgiven?
    P A D, Pencarrow, David B and 15 others like this.
  11. adrian

    adrian Flying Squad

    Nice one - another skill to add to your repertoire. As you say there is something quite satisfying when the solder flashes across the joint.

    With respect to keeping everything in position - I agree it can be a challenge. In addition to the usual tricks of pinning or interlocking for some jobs I use iron binding wire. It's soft iron so easily wrapped around the items to hold together.

    Iron Binding Wire, 0.37mm X 100g

    For the flux spitting I get that problem as well. There are a couple of things to try. I find a little patience at the start helps, rather than applying the flame directly at the joint, just begin wafting the flame around the joint to slowly warm up the metal. It is possible for the water to evaporate off rather than boil but you do have to be patient, then once it's in the dryish powder state I then move the flame onto the joint. The other thing is a titanium probe, when the solder moves away from the joint which it invariably does you can use the probe to prod it back into position.
    Titanium Soldering Probe

    Finally the solder I have is in a flat strip but I don't hammer it down but just use some tin snips to cut fingers in the end of the strip, then cut across the fingers to make little pallets of solder.

    solder - 1 (1).jpg
    Rob Pulham and 3 LINK like this.
  12. Brian McKenzie

    Brian McKenzie Western Thunderer

    Hi Ian,

    Nice job on the injector and pleasing that you tried your hand at silver-soldering. :thumbs:

    Adding to Adrian's excellent advice, make sure any previous soft solder is fully removed so as not to contaminate a silver-soldered joint - which may not then 'take'. Heat the joint as much as (if) possible before applying solder, and heat to the rear of where the solder is placed so that capillary action will pull the solder through the joint. The solder will always go to wherever it is hottest.
    The latter may seem an unnatural action at first, and it's worth experimenting with a longitudinal joint in sheetmetal, by drawing the solder along the seam by playing the flame in advance of the molten solder.

    CuP Alloys offer silver-solder foil - and they attend some model engineering shows - as well as giving instructional talks to M.E. clubs.

    455 Silver Solder Foil £13.20
    Dimensions: 150mm x 20mm x 0.1mm
    55% Silver Cadmium Free Alloy
    Melting Range: 630 - 660°c
    Cup Alloys - Low Temp Silver Solder - www.cupalloys.co.uk

    On the expensive side, but very convenient, and enough for hundreds of injectors. ;)

    Cheers, Brian McK.
    3 LINK and simond like this.
  13. Threadmark: More pipe fittings, a bit more silver soldering and grinding small lathe tools

    Ian_C Western Thunderer

    Thanks for the guidance gents, I think I'm a convert now!

    Here's another small plumbing fitting that's not supplied as a casting. It looks like a water trap or grease separator that's located in the vacuum pipework beneath the LH side of the cab. Same area as the live steam injector. Not very visible, but from some angles you see bits of it, particularly the odd triangular pipe flanges. Why on earth was it designed with triangular flanges when most everything else was round? Reminds me of Toblerone chunks. And Toblerone was 'invented' in 1908 so it's possible that some was being passed around the Derby or Crewe drawing office when the Assistant Senior Flange Draughtsman was looking for inspiration. Maybe.

    Here are the two parts. Lathe and mill job. Drill a hole through a piece of brass rod. Mill it to the triangular section. In the lathe to turn it down and part off to length. Saves having to make two identical triangular flanges and solder them onto a tiny length of rod. The other part is a simple turning.
    vacuum separator parts.jpg

    The assembly is held together with a short length of 0.8mm brass wire, much easier than the blasted injector this time! And the silver soldering is coming along too, no cleaning up of the solder on this part. You can see the tiny mistake when turning one of the flanges!
    vacuum separator assy.jpg

    Perversely I'm enjoying the challenge of making these tiny parts. At some point I'll have to get back to assembling a locomotive.

    Slight change of subject - lathe tools. It's always been a difficulty grinding tiny lathe tools by hand for this sort of work. I recently came across a Japanese or Korean chap on YouTube (didn't make a note and can't find the video again - sorry) who uses a Dremel clamped in the tool post of his small lathe to grind some quite remarkable turning tools from old drill bits. Tiny boring bars and micro thread cutting tools and the like. One day I'll acquire or make a tool & cutter grinder, but until then I've copied his good idea.
    Proxxon toolpost grinding 1.jpg
    Proxxon have a tool post clamp for some of their mini drill handpieces. Here it's being used in the quick change tool post with a carborundum slitting disc to finish a tool to size. It's made from 1/8" square HSS tool steel, ground carefully to near shape and size on a bench grinder and finished on the lathe. The relative height of disk and tool, the rotation of the lathe chuck, the topslide angle and the cross slide position can all be adjusted to cut just about any angle. In this picture the width of the tool is being ground down to size (0.70mm) by adjusting the cross slide and moving the carriage back and forth. The set up looks a bit goofy but it works well if the cuts are very light. Some care has to be taken to get the arbor and disk to run approximately true.
    Proxxon toolpost grinding 2.jpg
    This is a very useful tool for lots of the small, square shouldered turned parts like those above. It is parallel, has a clearance angle on both flanks so it'll cut in both directions, has a zero top rake angle and about 5 degrees clearance angle on the nose. It can be used for turning left and right, grooving and also functions as a parting off tool. It works beautifully in free cutting brass. When set up perpendicular to the work and dead on centre most small parts can be turned without needing to change the tool. Needless to say, light cuts are required to avoid tool deflection. It's entirely possible to make smaller tools than this by this method, but I've no idea what the practical limit is. This is a 400mm between centres lathe, and very nicely made, but it starts to feel a bit ham fisted with work this small. Accuracy isn't a problem because the lathe is DRO equipped and I usually just drive it by the DRO numbers, sort of human CNC (HNC?).

    And so to bed...
    P A D, Rob Pulham, simond and 6 others like this.
  14. Threadmark: Injector pipework complete and some brackets for the ejector exhaust pipe

    Ian_C Western Thunderer

    Finally the live steam injector has been fitted and plumbed in and some of the vacuum pipework beneath the cab has been fitted.
    injector pipework complete.jpg

    Working towards getting the ejector fitted to the firebox and boiler now. From the front end of the ejector is the exhaust steam pipe that runs to an elbow on the smokebox. It's a 3-1/2" O.D. pipe which scales to 2.04mm in 7mm scale, so I can use 2mm brass rod for that. Some time ago I bought some 'LMS large ejector pipe supports' castings from Laurie Griffin, his part 15-016. At this point I discover that they're too small to take 2mm rod and they're rather short so probably won't project far enough from the boiler on the 8F. No choice but to make some from scratch then.

    Took a bit of working out how to make them...
    Starting with 1/8" brass rod - face off - over to milling machine to locate and drill cross holes (cautionary note later) - back to lathe and turn OD to 2.7mm - groove to a diameter slightly less then the pipe through hole diameter, 1.9mm (it's that very useful tiny lathe tool again, see earlier post).
    ejector exhst lathe 1.jpg

    Gently profile the outside of the pipe clamps with a file. Hard to get them identical at this size, but there you go...
    ejector exhst lathe 2.jpg

    Drill the inside diameter to separate the clamp rings. Here's where you need to be careful. If you drilled the cross holes deep enough to project into the material that will be drilled out later then it's a dead cert that drills this size will wander off line, I know because I made that mistake first time round :rant:. So the cross holes are centre drilled to mark position and drilled 0.8mm only until the drill cuts full diameter. Drilling out the internal diameter using a succession of sizes 1.0, 1.5, 1.9mm increases the odds of staying on centre. At 1.9mm the drill breaks through into the grooves and the clamp rings are captured on the drill bit. 1.9mm is slightly undersized for the pipe but that gets sorted later.
    ejector exhst lathe 3.jpg

    The mounting pillars are simply turned from brass rod, diameter 1.3mm and 0.8mm. They're made quite a bit longer than I think they need to be. The excess length disappears inside the boiler on assembly. The rings are cleaned up and the cross hole drilled through to an interference fit with the pillars.
    ejector exhst parts.jpg

    From left to right -
    Silver soldered - parts assembled for soldering - the Laurie Griffin castings for comparison. Note on the silver soldering (and once again thanks to Adrian & Brian McK for pointing me in this direction, it's a huge step forward for me on this sort of work) -I've found that a silver solder fluxed paste is ideal for tiny parts Cup Alloys - Low Temp Silver Solder - www.cupalloys.co.uk . Tiny amounts can be placed exactly where needed with a cocktail stick, just heat the parts to complete the job. Also the silver solder joint is much stronger than a soft soldered joint which makes the cleaning up and fettling much less calamity prone.
    ejector exhst compare.jpg

    Parts are cleaned up and the internal diameter opened up gently with a cutting broach until the 2mm rod just slides through.
    ejector exhst brackets complete.jpg

    Still a few more bits & bobs to make before the ejector can be fitted.
  15. Len Cattley

    Len Cattley Western Thunderer

    hi Ian, it's a shame you cant'n give some of the parts you made to Laurie Griffin so he can make castings from them so other people can acquire them as well.

  16. Ian_C

    Ian_C Western Thunderer

    Funny you should mention that Len. I've got quite a crush on the 8F and I 've made a few 8F specific parts to that weren't in the kit or which are not available from suppliers. Some of them may be common with other Stanier locos. I'd be happy to make them available to others (the ones that are up to standard that is - there are many more talented people than me out there making patterns). I think it's a bit different when you make parts as casting patterns. I guess there's shrinkage to account for and probably some limitations of the process to navigate. Brian McKenzie's skilled in the art, I'm sure he'd offer direction on that.

    I did contemplate learning how to do my own castings from lost wax. I also thought about making some masters for brass wheel centres. Thing is if I got into that no modelling would ever get done!
    daifly, Rob Pulham and Len Cattley like this.
  17. Threadmark: Another small part - ejector exhaust elbow

    Ian_C Western Thunderer

    There's a casting for this in the kit, but it's not great. Couldn't resist making a replacement. In real life I think this is an iron casting. Here it's made from a scrap of N/S, a length of copper rod turned down to 2mm diameter and a small brass turning for the pipe coupling. I tried getting brass rod to bend sharply enough to form the elbow, but no luck. With a couple of relieving cuts inside the bend copper can be tortured into shape OK. Silver soldered together, of course! I think I have all the parts I need to fit the ejector now.
    smokebox elbow.jpg
    P A D, Jon Nazareth, daifly and 9 others like this.
  18. Threadmark: Ejector complete and installed

    Ian_C Western Thunderer

    Finally it all comes together on the loco.
    s c ejector installed 1.jpg

    Naturally I made my life difficult by not thinking far enough ahead. If I'd had any sense I would have added the drain bosses to the smokebox elbow and the ejector exhaust pipe before fitting them to the loco. Just had to do it the hard way. The drain lines were made from 0.4mm brass wire - much cursing.

    s c ejector installed 5.jpg
    Most locos had another flanged joint on the exhaust pipe a little way forward of the drain boss. It's shown on the C32552 pipe & rod arrangement drawing and appears in many photos. Photos show that some locos didn't have the flange. I don't know whether 8142 had it or not. I chose to omit it, the heavy rain beating down while I pondered flange or no flange and contemplated a trip outside to the workshop to turn said flange having no bearing on the decision of course.

    s c ejector installed 3.jpg
    ejector exhaust bracket 1.jpg

    They are small parts and the enlargement is cruel. Looks OK on the loco though. Makes the model a little different from a typical 8F and a bit more of a portrait of 8142.

    What next? Those sandbox fillers still don't look quite right...
    LarryG, Pencarrow, ianlbsc and 11 others like this.
  19. Threadmark: Top feed pipe covers

    Ian_C Western Thunderer

    More boiler fittings. This time the sheet metal covers that were fitted over the semi recessed feed pipes running up from beneath the footplate to the top feed. Brass castings are supplied in the kit. They're usable but they're a bit lumpy and would stand well proud of the boiler cladding. They could probably be filed down to provide a finer edge, but I wasn't convinced. After some fuzzy, low wattage thinking and bit of experimentation this is how they were made...
    top feed pipe cover story.jpg

    1 - I thought I'd try and make them from brass sheet. 0.071 mm or 0.095mm shim seemed about right. Thin enough to be easily formable but not too thin to be workable. After scaling from one of the Wild Swan drawings I worked out that I'd need a circular chord groove 0.6mm deep and 1.8mm wide. That's very close to a radius of 1.00mm so the groove was milled in a lump of spare aluminium using a 2.00mm diameter ball end cutter.

    2- A matching roller was turned from a steel bar offcut with a hole through the centre for a sort of rolling pin axle. The roller profile doesn't exactly match the groove as there's a small allowance for the material thickness. It's a bit statistical at this size so toolmaker accuracy isn't needed.

    3 - Here's the set up in the workshop bench vice. A quick trial with a piece of shim showed that if you don't constrain the shim it twists all over the place as it's formed. So....

    4 - The shim blanks were cut large enough to trap one edge between the vice jaws and the tool (RH side in the photo). That holds them still as you make couple of passes with the roller and gives a nice, straight U channel in the shim. I've no idea what state the shim stock is in and I didn't bother trying to anneal it before forming. Worked just fine straight out of the packet.

    5 - Knowing that there would be a bit of trial and error up ahead, and given how easy it was to make the formed blanks, I made about half a dozen of each. After forming there didn't seem to be a noticeable difference between those from 0.071mm and those from 0.095mm. They all got mixed together and I've no idea which thicknesses ended up on the loco.

    6 - Having cut them closer to size with snips they still need reducing to about 3mm width. Attempts to snip or scalpel them to width weren't great, always ended up with some distortion of the edge. The eventual solution was to solder them to a piece of scrap etch that was somewhat thicker (about 0.4mm? but I didn't measure it) .

    7 - One other thing I'd discovered when experimenting with the first rolled blanks and trying make them conform to the boiler was that they have a tendency to kink and flatten, particularly where there's a rivet impression, making it impossible to make a smooth curve. Similar to how a ductile pipe can be filled with Cerrobend to prevent it kinking when bent, I filled the back of the U groove with solder before I fixed it to the etch scrap. That forced the material in the U to stretch when bent rather than kink and flatten.

    8 - Once fixed to a thicker piece of brass it's easy to hold one edge in the vice jaws and file the other edge exactly to the line. Turn it over to do the other side.

    9 - And there you have a length of shim brass with the correct profile and width to make a top feed pipe cover. It's still fixed to the scrap at this point, and still much longer than necessary.

    10 - With the profile still soldered to the scrap it's relatively easy to bend them to match the boiler cladding. Forming them around a pot of Carr's 188 solder paste got them most of the way there quickly, followed by a bit of careful finger and thumbs, being careful not to put in any kinks. I did notice that there are some stretch marks on the outside of the U where the shim material has elongated, I don't think they'll show once painted. The ends of the profile don't bend uniformly, they stay straighter. But that's OK because they can be cut off to leave a section of uniform curvature which is marked and cut (by piercing saw) to match the top feed and hole in the boiler. Make them very slightly shorter than you think because the circumference of the shim is slightly greater than the circumference of the scrap and they'll wrap around a bit further when separated.

    11 - Once cut to length the shim profile and the supporting scrap are easily separated by heating them up and teasing them apart with the tip of a scalpel. Again, be careful not to kink the shim part. Because of all the solder inside the U it's kind of messy, but a fair amount remains in the U and helps to stiffen the shim profile for subsequent work. The excess solder is very gently removed from the shim profile flanges by filing across the back with a round file.

    12 - The covers are fixed to the boiler cladding with small screws. They're noticeable on the prototype and missing from the brass castings. I added a representation of the screw heads by making rivet impressions freehand with the trusty GW rivet press. The inside of the profile was blacked up with marker pen and the screw locations were marked with callipers and scriber. It was really difficult getting the point of the rivet tool right in the middle of a very narrow flange. It was a bit hit and miss and a couple of profiles were ruined that way. Not to worry there were plenty of blanks, and just enough patience! The finished covers were cleaned up and sweated to the boiler to line up with top feed and the previously made holes where the pipe dives beneath the cladding. The pipes, 2" diameter on the prototype, were made from 1.2mm copper wire.

    The finished covers look like sheet metal parts with a very fine edge, and the slight imperfections give them the look of sheet metal parts that have been removed, clattered around the workshop floor, and re-fitted a a few times. Sometimes our models look a bit too tidy - the prototype was often a bit battered in it's later life. They look OK - I think they'll do.
    P A D, Nick Rogers, Overseer and 9 others like this.
  20. Scale7JB

    Scale7JB Western Thunderer

    If only I had some power tools...