greenglade Posted February 12, 2019 Author Share Posted February 12, 2019 Evening all Return cranks are now completed and fitted to their crankpins which have also been fitted to the crank axle wheels. I'll go through the last few jobs, first, with the return crank sitting tightly on its pin I needed to drill through the No.51 hole which just nips the corner of the square and then ream it for a taper pin. I did this on the rotary table, first using a square to check that the return crank was indeed at 90 degrees to its pin and then using the N0.51 drill to check that the hole was vertical. Here's the hole being reamed, unlike the trailing crankpin, this one I could do under power as I had plenty of room. next, I tapped the return crank 7/32, I had left this as I was going to follow Don's method of setting the crank (needing the 3/16 hole) until discovering that his jig can only be used before the wheels are fixed to the axle, something I hadn't picked up earlier if indeed it was mentioned, I've forgotten. Anyway, no big deal I just followed full-size practice but first here's a picture of the crank being tapped. Now I think that I mentioned before that Don described the tool used for setting the return cranks at the works, something he said that he had done a number of times himself. It's interesting to read his exploits and makes one wonder just how accurate this process was when fitting a new return crank which may involve moving the 'square' by adding weld and filling by hand to fit? Sounds great fun... the good thing though is that Don described the tool used well enough to replicate in miniature. Basically, if I understood him correctly, it involved a heavy scribing block which had a sprung centre to fit the axle centre hole and 3 blocks under it which I'm assuming was to keep the block level. I have copied it in my own way of what I think he's describing. The picture of my representation of this tool hopefully gives some idea although granted it might have been better to take it at a slight angle? Using an offcut of 8mm alloy for the base I drilled a centre hole to match a piece of BMS that I turned up with a point on one end. Marking a 20mm diameter circle around the centre I drilled 3 holes equally spaced to accept 1/8 snaphead rivets which were duly fastened to the block(this is my 3 blocks). A small hole 0.750 along a centre line from the first hole gave me my throw, the hole was large enough to accept a point taken from a compass. All I had to do was hold the block against the axle end, ensure the 3 rivet heads made contact and mark a small arc in my nice fresh paintwork, easily touched in later. It might be helpful if I show the drawing of the throw required. I seem to have missed a couple of pictures, one showing the jig in place and the other showing how I lined up the crank... nothing important then...lol I'll try to describe and hopefully, you'll get the idea. You can see how the scribe tool works, for setting the return crank itself I turned up another length of BMS with a fine point one end and a long section of its shaft threaded 7/32. This I threaded into the return crank aligning the point with the scribed arc, this is basically how Don's jig works but his fits around the axle and on his jig a length of 3/16 steel is used for the return crank to fit over before it's tapped 7/32. Don states to line up the two, apply Permabond, drop the crank pin in and let it set, job done. I'm a little different as my crank pins are a tight fit for the last 1/4". So I align the two arcs as described, mark the position on crank pin and boss,remove apply Loctite 680, refit checking that both the mark and the point are in their positions, unthread the marking point shaft enough for clearance and give the return crank/pin a tap with a hammer to seat it. This was of course done over a hard service under the wheel itself, not putting any strain the main crank. Does that all make sense?..hope so... Back to the pictures, I have now refitted the crank axle to the frames, perhaps for the last time? I'm sure they'll be a reason to remove it again at some point down the line. In this picture you can just see both return cranks in their correct positions or (as Don puts it) lagging behind the crank pin when moving forward), it gets a little confusing when the chassis is upside down... And lastly a close up of one of the return cranks, I spent a couple of hours filing off all of the machine marks and giving them a little polish. I have fitted a 6BA bolt and nut which required a little more filing to give a larger flat contact area on the tongue, looking at this close up I need to do a little more, I can do this later. Not sure what I'm going to do next, I'll get a hand to turn the chassis back upright and take a look tomorrow....thanks for looking in guys. Pete 3 4 Link to post Share on other sites More sharing options...
tigerburnie Posted February 13, 2019 Share Posted February 13, 2019 Are you allowed any form of locking method on the nuts and bolts, like a spring washer or a cotter pin to stop them coming loose? If not on the prototype would a dab of unseen threadlock be of use? Link to post Share on other sites More sharing options...
greenglade Posted February 13, 2019 Author Share Posted February 13, 2019 Hi The simple answer is yes, I will have a lot or this to do on final assembly. There will be a number of methods used, threadlock for some parts, many have castle nuts with split pins (especially on the motion) through them so I have a few of these to make and others use two nuts to lock against each other. In fact, if you look at FS's return crank today, she has two nuts to lock, plus the second nut is a castle nut which I guess has a split pin through it.....'belt's and braces comes to mind...:) regards Pete 1 Link to post Share on other sites More sharing options...
Mike Boucher Posted February 13, 2019 Share Posted February 13, 2019 Hi Pete, This weekend, my model engineering club is having its show at the museum where the 4.75" gauge loco my friend built is on dispay. Anything you want photos of? I may be able to get some, unless the reflecting off the glass is too challenging... Mike Link to post Share on other sites More sharing options...
greenglade Posted February 13, 2019 Author Share Posted February 13, 2019 1 hour ago, Mike Boucher said: Hi Pete, This weekend, my model engineering club is having its show at the museum where the 4.75" gauge loco my friend built is on dispay. Anything you want photos of? I may be able to get some, unless the reflecting off the glass is too challenging... Mike Hi Mike That's very kind of you sir....I can't think of anything in particular but would love to see any photo's of the model. Regards Pete Link to post Share on other sites More sharing options...
greenglade Posted February 14, 2019 Author Share Posted February 14, 2019 Evening chaps My first thought for today was to fit the leading coupled axle so that I could turn the chassis over but realised that in doing so I wouldn't later be able to fit the brake shaft and cylinders so I inadvertently found my next job, the brake shaft, the cylinders I made when building the tender although still have a little work to do on these two for the loco. I began by printing the drawing and rummaging around for the materials required, the shaft is 3/8 which of course was missing from my stock, however, I had something close (a little smaller) and that will do. It's a pretty simple shape, IIRC, 3 3/4 long with 1/4 x 5/16 either end to fit the bearings and a taper from said journal. My taper is a little shorter due to using smaller radius stock but it's not something that will be noticed. Don specified lead-free BMS as it's to be silver soldered, I used silver steel which I've had no issues when silver soldering and being a little stronger makes up for the smaller dia. Having machined the shaft I then needed to look at the arms and very nearly wasted an awful lot of time. I had got as far as to find some 1" x 3/8 flat steel bar and was about the mark out the profile when I remembered that some years back Malcolm (MEL) had cut a kit of brake parts for me, on opening the draw that they had sat I found they included the brake shaft hangers... happy days.... On to the first picture, here's part of the kit along with the shaft already machined. There was a couple of issues with the parts, so far anyone else using the kit be aware of two things. First, the large holes seen here I have opened up to suit the shaft, the holes as supplied are 1/4" which is the journal dia so I guess just a case of misreading the drawing. The other thing is that there should be 4 cranks (for want of a better word), there are only two (not seen in the picture as I've already removed them from the sprue. This will make more sense in the second picture. The cranks are 1/8 thick, I found some flat bar this size, cut off some small squares, drilled the two holes and bolted then with one of the laser cut parts and filed to shape being careful not to remove too much from the pattern. The picture shows the 3 bolted together. Here we now have a full kit of parts, along with the two remaining vacuum cylinders to be fitted. The small holes are No.30 to take 1/8 pins, IIRC there's just over 30 of these pins required for the brakes which I'll do together later, for now, I'll use some 5BA bolts. The 4 small ends seen in the last picture are to make up the two yokes that connect to the cylinder shafts, I decided to cut through the arms except the very middle to help with removing this section after silver soldering everything together. The picture shows the two arms with the slots cut, these are just under 1/4 back from the hole centre. To stop and silver solder filling these I filled them with ordinary hand bar soap, I've used this in the past and it works very well. I also covered the end face with soap to stop the solder spreading. The arms have a spacing of 1 7/8 and so I made up two threaded poles to keep the space as required, this is important as it needs to match the positions of the cylinders. The picture shows one setup, note I have included two of the ends, something I hasten to add that I had forgotten when first putting things together. And here we have the assembly ready for brazing, the spacer studding was also covered in soap. As can be seen, I have wrapped silver solder around the shaft and made up a rectangle to push against the ends that will make the forks. The cranks were set at 90 degrees to the arms and two magnetic blocks were used to help keep everything together during heating. And afterwards, happy to report that it was a successful single heating session, extra silver solder was fed in where required. I must be getting very forgetful in my old age as I seem to have forgotten to take a picture of the completed shaft on its own, it is basically a smaller version than that I made for the tender many years ago so nothing fancy. After cleaning I gave it a coat of 'Acid 8' and then satin black. Here's the last picture for this session showing the brake shaft fitted along with the vacuum cylinders, which I have temporarily connected up with 5BA bolts. So that's another part ticked off the list, one thing that is becoming very obvious is the difficulty of getting one's hands in as more parts get added, I struggled to get the leading wheel springs in as my fingers are too big. God knows how I'm going to get by when the area is covered in all the 'pipework'(steam, oil, Vacuum), not to mention brake rigging? Might need to train up the grandchildren 'quick'.... More soon guys Pete Read more: http://modeleng.proboards.com/thread/5733/building-don-youngs-doncaster?page=136#ixzz5fY2iIWJ9 3 2 Link to post Share on other sites More sharing options...
greenglade Posted February 20, 2019 Author Share Posted February 20, 2019 good afternoon to all I'm currently in a tidying/completing mindset as I have a lot of 'half finished' jobs to take care off, one of which is the coupling rods so I'll cover those today. The bolt that connects the two via the knuckle has a castellated nut fitted which I had made a start on but still needed to cut the slots to create the 'castle' so that's first on the list. I had already made a start with some Hex bar that had been drilled/tapped 2BA and had the front face rounded off for where the slots go, the first very poor picture hopefully shows this. For cutting the slots I have used a carbon disc (closest thing that I had to the size slot I wanted), each nut was held in the rotary table, disc set to middle of the nut and each slot cut across the flat, 3 cuts in all to create the 6 slots, hopefully, you get some idea from this badly focussed picture. Here's the finished nut on it's knuckle pin, I have made the slots large enough to take a split pin which I'll take care of later once I have cross-drilled the pin, yep it's never finished is it?... The other job remaining for these rods was the various oiling plugs/corks, I first drilled the bearings for the oil to pass through, no need to bore you with a picture of that. I then tapped the large oil holes 3/16 x 40tpi and used some small hex to make the plugs themselves. I was in a quandary here as on FS today she has both hex and plain caps on her rods, the hex seem to outnumber the plain and so I went that route but also as these are easier to tighten. The picture shows both corks fitted to the main crank pin rod and the smaller knuckle joint. The knuckle is drilled/tapped 8BA and just has a cork screwed directly into it. The larger Hex as stated is threaded 3/16 x 40 at approx 4mm depth and then has an 8BA hole drilled/tapped right through it to oil the crankpin bearing, I need to add some thin steel washers to match the full size plugs which I think are one piece but washers will look just the same. For the cork, I have used wooden cocktail sticks which look ok to me. To give an overall feel to how this is all looking I include this last picture for today. Note that I still haven't cut the trailing taper pin too length and nor have I fitted the leading crank pin bolts. I'm still in two minds over these, I have some metric csk bolts that fit with nylock nuts but the nuts are a little big to get a socket into the retaining cap to tighten properly so I may have to bite the bullet and make the things. These are also supposed to have castellated nuts but much smaller than the knuckle pins, much, much smaller. I was hoping that this would be the final fitting of the coupling rods (I can't see why not?) but I still have a little work to do on the vacuum cylinders so I think it prudent to take the wheels off again as it would make life easier and deal with those once and for all, and I thought this hobby was supposed to be fun?... Pete 2 3 Link to post Share on other sites More sharing options...
greenglade Posted February 26, 2019 Author Share Posted February 26, 2019 evening chaps I've been a bit busy with my classic car of late but have done a little to 4472, again just some tidying up exercises really. I wanted to finish the coupling rod knuckle pin which mainly concerned cross drilling a small hole to take a split pin. the picture shows one of the knuckle pins dealt with, you can just see the IIRC 0.8 mm hole drilled through the pin thread. I really should stop zooming in for photo's as the surface finish looks awful, trust me when I say that this can not be seen by the human eye, thank god... With the hole drilled that just left fitting a suitable split pin, in this case, a 1/32 pin. I then went back to the vacuum cylinders, I wasn't happy with the PTFE tape used for sealing the piston gland and have now fitted a small rubber'O' ring in it's place which works much better. I still have one job left to do and that's to make the plunger pins, I can fit these at any time. At the same time, I will seal the threads for the release valves which I can do either with PTFE tape or a thread sealant. With the cylinders back on the loco, I decided to do a small test before refitting the leading wheel. Doing the usual trick of causing a vacuum through a rubber hose using the compressor I tested both vacuum cylinders independently. I videoed how it looked, There's not much movement yet (more than I thought there would be) as the rubber hose pushed onto the outlets was very loose and as mentioned previously I haven't made up the connecting pins yet and thus there's a lot of play in the piston to brake lever connection due to the temporary undersized bolts. Hope this video works... https://imgur.com/Y0zt5RX Thanks for looking in chaps Pete 4 1 Link to post Share on other sites More sharing options...
tigerburnie Posted February 27, 2019 Share Posted February 27, 2019 Hi Pete, have you looked at these type of seals as opposed to "O" rings, if there's room for them , they can be more durable I found https://www.123bearing.co.uk/section-seal-rotary-shaft.php (I haven't used this particular supplier, just bumped into them on google) Link to post Share on other sites More sharing options...
greenglade Posted February 27, 2019 Author Share Posted February 27, 2019 Hi No, I can't say that I have, they look interesting for other applications. I think that standard O rings should be ok for the job in hand. I'm assuming that the seals in the link are designed for rotating shafts? There are no rotating parts on these cylinders, just simple 'push-pull' action. I have plenty of other parts coming up in the future that will rotate though, most of the valves on the backhead fittings for example. I'll try to remember these seals when I make a start on said fittings. Many thanks Pete Link to post Share on other sites More sharing options...
tigerburnie Posted February 27, 2019 Share Posted February 27, 2019 Hi Peter, no I used to use them as nose seals on pneumatic cylinders for example and also as the piston rings, so no rotating parts, might not be suitable, just bouncing ideas around for you to consider. I wasn't working with steam but air and also oil in hydraulic circuits. Link to post Share on other sites More sharing options...
greenglade Posted February 27, 2019 Author Share Posted February 27, 2019 New ideas are always welcome sir... this whole project is one big steep learning curve...:) Link to post Share on other sites More sharing options...
greenglade Posted March 1, 2019 Author Share Posted March 1, 2019 Hi guys Not much done this week as I've been out enjoying the car in the good weather of late but I have finally got her on all wheels again and getting ready for the jobs planned for next week. Once the chassis was the right way up I took this picture of the brake shaft and cylinders, looks very much like the prototype to me. Of course, today, I believe her to have a different set up with either Steam or air brakes (I'm sure someone will tell me which) which would mean different cylinders and mounting apparatus. here we have her on her feet so to speak, the rods are now refitted for perhaps the last time? in loo of this, the front crank pin bolts have been done up fully with some thread sealant applied (low strength). The trailing crank pin taper pins have been cut to length and all parts given a light coat of oil before assembly. You may have an idea of what my next job may be as there's a large part missing from between the frames.. And here's the job for next week, the centre cylinder. Monday I'll spend some time making a new between the centre's tool to bore the steam chest and get it set correctly onto the lathe cross slide. You may recall that I have already made the jig for holding the cylinder for machining both its flat surface and that of the inclined 1 in 8 or just over 7 degrees. The picture shows the cylinder sitting on the 1 in 8 wedge, I will bolt this back onto the cross slide (position is already fixed by the mounting bolts) and add a spacer to bring the steam chest up to it's correct height, this looks to be approx 1/4 inch, that's me just eyeballing it, I'll work it out properly on Monday. I will probably do most of the jobs involved with this cylinder before moving on again. I currently have no suitable gauge plate so won't be able to do the slide bars just yet, there's plenty of other things to keep me busy though. More soon... Pete Read more: http://modeleng.proboards.com/thread/5733/building-don-youngs-doncaster?page=137#ixzz5gvvHnI7L 2 4 Link to post Share on other sites More sharing options...
greenglade Posted March 4, 2019 Author Share Posted March 4, 2019 back with the middle cylinder then, I took my time setting this up on the lathe's cross slide. After bolting the angled wedge back to the cross slide and checking it was square I set the height using two centres as a guide. The picture shows the cylinder bolted to the 1 in 8 wedge once happy with it's position. using some suitable packing I now had the height and the cylinder running parallel longitudinally. I also added a large 'G' clamp to hold the cylinder to the wedge stops that's not shown here. This left the distance between the two bores to sort out, I have mentioned before that this particular casting isn't the best, but serviceable. Things were now beginning to show that confirmed my earlier suspicion that something may have moved during the casting being made. The steamchest bore core, for example, isn't central to the outer ring, it's a little too far to the left of the casting as fitted to the frames. Not a big deal as I can machine it where it's supposed to be as there's plenty of metal but it could catch someone out. I can't recall the measurements sitting here at the PC, but after noting the distance required between the main bore and the steamchest centre's I needed to move the hole approx 1mm away from the camera. I was working in mm and the distance required away from the left-hand side to the center of the steamchest is IIRC 15.08mm. Before doing this I did a roughing cut at the bore's center as cast, this was to get rid of all the rough lumps that had been left in the steam passageway slots which I couldn't reach with a Dremel cutter. Having done that the bore was easier to see what I had and thus I could adjust the centre line and begin boring the steamchest properly. Regarding the boring bars used, I began with the 1/2" bar which was also used for the main bore. I made a bigger dia boring bar from 15mm to take over once the smaller tool had opened the steam chest enough. The final job was to use an adjustable reamer, more on that later. The picture shows how I measured the 15.08mm, BTW, Don states that this measurement is very difficult to measure accurately and isn't critical anyway, so I wasn't too concerned about this 'Heath Robinson' approach that I have used.. A rear view after the first few passes have been made. This picture shows the guides at the rear and side to register the casting, you can also see the 'g' clamp which is close to the chuck. At this stage, I removed the boring bar and double checked the centre distance between steamchest and piston gland at the rear which looked good, I was now happy to continue boring to the required size of 7/8th. The next two pictures were taken before moving up to the larger boring bar, this one at the front shows the various steam passages that are part of the cast beginning to be cleaned up. And this from the rear and here is where I had clear evidence that something had moved during pouring or the pattern was damaged. The outside, which is also clearly seen here I already knew and had pointed out that it looked odd, hopefully, you can see what I mean? But now look in the bore at the rear steam passageway, that vertical length of flash shouldn't be there, it should be clean like the front. It's not a problem as long as I can remove it as it may hinder the steam flow, or at least make it unmatched to the front flow. Here the bore has been machined to 5 thou undersize ready for reaming and you can see that I have removed most of the offending flash, to do this I sharpened a small tool chisel that could reach that far into the bore and tapped it out using a small hammer. The remaining piece of flash I will have to do with the Dremel, I'll need to make up something with a long enough shaft for this. I have checked that the openings into the main bore are clear of which they are, so all's good there. The last picture for tonight shows the first pass with the reamer, first, as I did this one cranking the chuck by hand, I'll do another tomorrow under power. Some may ask why use a reamer if they have been bored? well the boring bars are very long, there will be some deflection over such a long length, also I have 3 of these to do and by using the reamer which is set, I can get all 3 the same and not have to play around when making the 6 valve liners which need to be a very accurate fit, well at least that's my thought process... next job after I'm happy with the bore will be to face the two ends, it will be nice to finally clean up that mess..lol, I'll make up a 'knife edge tool' that uses the boring bar for this job. This I believe will leave one more job at this set up, that being, boring the recess for the valve liners to fit. I need to look at this carefully, not knowing the full state of what's going on with the casting exterior, ie, just where the facing ends/starts. This should keep me busy for a couple of days... Cheers Pete Read more: http://modeleng.proboards.com/thread/5733/building-don-youngs-doncaster?page=137#ixzz5hFNxBYzp 3 3 Link to post Share on other sites More sharing options...
greenglade Posted March 6, 2019 Author Share Posted March 6, 2019 evening chaps... I wasn't going to do the next update until I had finished the basic machining of the middle cylinder but after taking 10 photos covering today's efforts in the workshop, i decided otherwise as these writeups take a lot of time, especially as they are adapted to post on each of the 3 formats. For those that don't know, there's a good reason why I log all of this in detail. One day I hope to publish a book on this build, all of these updates are basically 'bullet's to remind me of each topic which hopefully my memory will get a jolt to help me write a much more detailed description of the build, well that's the plan. So back to today's efforts, I did as stated and ran the 7/8 reamer through the bore again but this time under power, I'll show a close up at the end. The first picture is the setup for machining the front face, I first made a 'knife-edge' tool from 8mm tool steel, cross drilled the larger of the two boring bars 9towards one end) and cross drilled that for a 6BA grub screw. The picture shows the first cut made across the face, I did as mentioned first study the drawings some more to get an idea of how much material needed to be removed from this 'spigot', the answer surprisingly to that was nearly all of it? This will become clearer later. I best add this picture of the knife edge tool, I basically machined away half of the 8mm tool steel bar over a length that covered the area that needed to be machined. I then gave the trailing side a 'rake' and the final job (not seen here) was to sharpen the leading edge with an 'oil stone'. Oh, I also machined a flat on the edge to be held in the bar. I then hand machined most of the excess material leaving approx 1mm to go, you can see how much has been taken off in the photo. I stopped 1mm short as I needed to ensure that both ends had the same amount of depth to the steam passages either side. The actual length face to face is 3 29/32 or IIRC 99.21mm, this is more or less the distance between the exhaust outer castings at either end, so I knew that leaving the face a little over would be safe to measure more accurately once both ends had had most of the material removed as I would then have two machined ends to measure too. And on to the rear face, I have shown this picture to point something out that became clearer as I got further into the machining. This is going back to the poor quality of this particular casting, I hope there aren't any others out there? Note the overhang above the steam chest bore, I have been puzzled by this since the beginning but not knowing this casting I just assumed it was a 3 or even 4 part mould. Having now machined more of the excess away and getting close to the final size/shape I think that the top half of the mould/pattern not only moved out of step but twisted a little and the top lifted, the overhang being how much it lifted by? this will show better in some of the other pictures for tonight. sorry for the poor quality of this picture, what it shows is I have machined the rear face down also to approx 1mm oversize like the front and then using a piece of steel with a right angle at one end, inserted the angled end into the steam passage and marked where it came out of the bore. I then removed the marker, placed it in the front end and was very happy to see that both ends were more or less of the same length, same by eye at least. Now that I was happy that things were pretty central I measured the overall length to see how much further I needed to go, as can be seen, I have just over 2mm in total to remove. I did this but kept checking along the way that things still looked central before finishing at the 3 29/32 length required. Now, a couple of pictures to try and show what I mean by the pattern had moved or was damaged, take your pick. This is of the rear face, if you look at the right-hand side of the steam chest you'll notice the step. This is about 2mm and it continues around the top to the flange edge, this is why I say it has lifted and why it is stepped as seen by the 2mm step. BTW the casting sides also had a bad step on one side and the other had been ground down. When I began doing the steamchest bore it was a tense affair due to how misshaped the casting is, at first I asked myself, 'had I got it wrong? was the bore going at an angle as I could see that the face ring was smaller at the bottom than the top? I decided (rightly as it turned out), to ignore it, have faith in the setup and carry on, I could see on double checking everything that nothing had moved. Only when I had nearly finished the faces could I finally see what was going on and that I was right to ignore my concerns, my paranoia for want of a better word. Now we move to the front where we also have a step but this is on the bottom and not the top like the rear, this is why I say the top had twisted (remember the core was out too). There's not much left to see here as most of it was machined away when facing the main bore (which made things a little more problematic) but it is, in fact, a larger step than the rear, I can't see much sign of anything lifting here though, perhaps a little? BTW, in photo's in Don's 'words and music' the castings have no sign of any such steps so they aren't supposed to be there. Last picture to show the finish on the bore after the second pass with the reamer. Tomorrow if all goes to plan I'll finish the last machining job on this cylinder, that being the recess either end for the valve liners to fit into, I'll make all six liners together once the outside cylinders have been machined, they should be a walk in the park after this thing, it will then be on to the various covers. Today I ordered some 8BA lengths of stainless threaded rod, some nickel plated steel 8BA nuts and some 8BA washers, hopefully enough to complete the fitting of covers for the middle cylinder. It seems that by some luck and yes there has been some luck involved here, I have managed to get a serviceable cylinder out of a very bad casting. The outside castings look like the crown jewels in comparison... Pete Sorry for the duplicate picture, I couldn't work out how to remove it....? 3 1 Link to post Share on other sites More sharing options...
greenglade Posted March 6, 2019 Author Share Posted March 6, 2019 I'm posting this early as it gives me time to get my brain in gear, I think that I have finished all of the machining exercises for this setup but want to give it a little time before I de-rig, so if anyone can think of something that i've forgotten, you have about an hour to speak up... Well, today has been one of those frustrating days, I had two simple boring jobs to do and the gods were against me. I reset the boring bar for a little deeper cut, lined it up to the edge of the front face, zero'd 'x' and began to cut and guess what, my 'X' scale decided this was the best time to play up....lol Not to be beaten, I marked on the bar from the cutting tip a distance of 0.468 or 15/32, run the chuck to mark a constant line around the bar and then taped that to give me a depth to cut too. The first picture shows what I'm trying to describe. My procedure was to cut this with the tip at 3 settings, alternating between front and rear and stopping just short of the depth mark. I then did the final cut to give me a bore of 0.937 at it's full depth of 0.468 and was very happy with the result, well, nearly. Here's the front, you can see the steam passage which is basically an internal recess so that the steam can get in all around the valve liner and you can just see part of the opening for the front exhaust passage. The step between the two is very important as it's what the valve liner buts up against and why the depth of 0.468 needs to be fairly accurate. and then we have the rear and the casting throws one more curve ball at me, yes you are seeing right, a great big blow hole??? Now, this isn't really a problem for where it is, it doesn't go right through and it's not in a critical position. So, I repeat again what I said yesterday, I have been very lucky in getting something out of the bad casting. If this hole had been deeper and broke through into the main bore life would have become very problematic with possible sleave fitting involved.....grrr sorry, seems i'm still having issues with unwanted pictures, please ignore this duplicate of the front..lol this is the picture that should be here Once I have removed the cylinder from it's setup I will be able to take care of all tidying up jobs, such as filling off these steps that shouldn't be there, i will of course have to be careful with the rear step due to the unwanted blowhole. I can then look at the valve cover for the main bore and the rear cover for the steam chest, the front cover is quite involved and I don't have the material to hand so will have to wait a while. More soon chaps Pete Read more: http://modeleng.proboards.com/thread/5733/building-don-youngs-doncaster?page=137#ixzz5hOsUJCUj 4 1 Link to post Share on other sites More sharing options...
greenglade Posted March 9, 2019 Author Share Posted March 9, 2019 Evening all This is the last update for this week, there's been a few.. Next on the list was the cylinder cover for the main bore, I had machined a slightly oversized cover some months back when last working on the cylinder where you may recall I added a spigot on the back. The first job was to machine a flat on one side to clear the steam chest, once this was done the cover (still on it's spigot) was put back into the chuck and had the inner step (added spigot) reduced a little until it was a good fit into the bore, this step is slightly tapered to match the taper on the end of the bore. The first picture shows this. I then marked the bore's centre and drew a vertical line to help work out the bolt holes orientation in relation to relief valve and drain cock, for anyone else following my steps this is different to Don. I played safe and decided to start these bolts on the vertical plane, there are 12 bolts on a 2" PCD, so 30 degree's spacing between them. The picture shows the vertical line, the two black marks to the side are to show me roughly where the steam chest exit for the main bore is so that I can void drilling into it. When looking at this I thought that it would be best to orientate the bolts as stated to ensure they didn't enter the steam chest, Don has clocked them 15 degree's further so 15 degree's either side of the vertical line, this does fit and is in line with the prototype (all other prototype flanges on this cylinder (steam chest covers etc)are how I have done the main bore. Don's way might have fitted but the upper mark showing the steam passage position just looked too close for my liking. So as Frank would say, 'I did it my way'... BTW, the overhang of the steam chest flange will be filed flat later, I found a nice picture of SNG's restoration which clearly shows a flat here. It was then onto the rotary table to plot/drill the 11 (one's missing due to the steam chest and drill the no.34 holes. This picture I hope shows why I chose the orientation that I did as it's closely spaced around the steam passage marks. I drew the 2" PCD line and marked each hole position so that I could get a visual on how things looked. with the No.34 holes drilled I then drilled/tapped 7/32 x 40 TPI for the relief valve, this I clocked 15 degrees to the mounting holes, I did this to avoid the draincock and also equally place the point between two of the mounting holes. I searched everywhere in vain to try and find a picture of where exactly the relief valve is positioned on the cover but alas all photo's show the cover removed. BTW, the rear relief valve is on the centre line and I suspect it is on the front too but I have placed it here for the reasons given. I then mounted the cylinder on an angle bracket, ensured it was square and began to transfer the holes, these were drilled and tapped 6BA. When I do this I prefer to drill/tap the first hole, bolt the cover in place and then work my way around the others doing 'opposites' using, in this case, the back end of a sacrificed no. 34 drill to plot each centre for drilling. I position, I drill, I tap and I then fit a temporary bolt and move on to the hole on the opposite side. Next, the rear relief valve hole, drilled tapped 3/16 x 40 TPI, I then machined the face. A picture to show the mounting holes and the rear relief valve hole, you can also just see the steam passage between bore and steam chest and why I have positioned the bolts as stated. I include this picture to show the sizes of both the steam and exhaust passageways, I don't think that this loco is going to have any 'back pressure' issues with her exhaust.. the last machining job, for now, was the draincock's, the front is a little close to the lower mounting hole, to ensure a seal I'll Loctite the lower stud in place. One last picture to show the two components for tonight and so that you can see the draincock location's Next job, will be to cut/fit the stainless 6BA studs, attach the front cover and to machine the rear steam chest cover and spindle. thanks for looking in guys Pete Read more: http://modeleng.proboards.com/thread/5733/building-don-youngs-doncaster?page=138#ixzz5hd1IGX3S 3 1 Link to post Share on other sites More sharing options...
tigerburnie Posted March 9, 2019 Share Posted March 9, 2019 A question here Pete, when I had the cylinder heads off my old Aston Martin, we had a lengthy discussion about the merits of "gas flowing" the heads by polishing all the rough casting parts by polishing them with flap wheels, seems this could add as much another 100 bhp to the engine output coupled with bigger inlet valves(this engine was fitted with direct fuel injection and an Opus ignition rather than carburetors). Could this be of any benefit to more efficiency in a steam engine and it's parts? Link to post Share on other sites More sharing options...
greenglade Posted March 9, 2019 Author Share Posted March 9, 2019 The answer would be yes it can help, I think for steam the most common bottleneck is the exhaust hence my comment about the passage sizes in this particular cylinder. It's good practice to debur the pasages as much as possible to give a smoothy flow. I have started this but will do more still later. 1 Link to post Share on other sites More sharing options...
greenglade Posted March 10, 2019 Author Share Posted March 10, 2019 Hi all Unusually I've had some time in the workshop this weekend, mainly helping my son with his Cossie engine rebuild but I also managed a little on 4472 once the lathe/mill were free. Remaining with the cylinder, I now took a look at the rear steam chest cover. This is in two parts and it's easier to just show the pictures than try to describe them. They both have flanges which will need holes drilled around them for 8BA fixings, I'll explain where in a few photo's time. This part is the cover that bolts onto the cylinder rear steam chest flange. This is the spindle cap ready for parting off, both parts are drilled/reamed 5/32 for the valve spindle to slide in. here's the two parts finished in machining terms but still needing their relative mounting holes drilled/tapped. This is where they reside, the larger section will need 8BA clearance holes drilled into it's lower flange, these will then be transferred to the steam chest flange and drilled/taped 8BA for stainless studs. The smaller part sitting on top as seen here will also need it's 8BA clearance holes drilled which again will need to be transferred (drilled/tapped 8BA)to the upper flange on the first section...hope that all makes sense? back to the cylinder cover now, I first needed to fit the 11 stainless 6BA studs, I have taken this picture to show visually how I did this and keep all studs the same length. each stud had two nuts locked together to screw the stud fully home, I used thread sealant on each to make it easier in service when just wanting to remove the nuts for maintenance. I then used the spacer seen to measure where each stud needed cutting. The spacer has been made to give enough length for the nut and a little more for threading each nut on, hope that makes sense too? here we have all of the studs fitted... Lastly a picture of the cylinder cover in place, I have also made enough clearance so that the cover can be remoced easily without fouling against the steam chest. So, that's my little weekend excursion, next week I'll finish the rear steam chest cover and take a look at the piston gland and backing plate, all good fun... Pete 4 2 Link to post Share on other sites More sharing options...
greenglade Posted March 12, 2019 Author Share Posted March 12, 2019 good afternoon folk Well this update is going to take me some time... 14 photo's?...gulp, think I got a bit carried away and I have already deleted some..lol so, what have I done since the weekend? first up is the piston gland housing and back plate, I have added something to this which I'll explain why when I get to it. The hole in the cylinder for the housing is 1/2 and it's a press fit so the first job was to turn up some bronze ( Don states brass or bronze with his preference being brass, I decided on bronze) oversize at 0.502. I next drilled/reamed a bore of 5/16 for the piston rod to slide through, I then needed to make a 'D' bit to machine a small curved recess for an 'O' ring to fit into. I have used a slightly different size to that recommended by Don, for no other reason than I used what I had to hand. After fitting the O ring over some 5/16 stainless I measured the OD of said O ring which came out at 0.408, a little smaller than the size Don recommended to remove at IIRC 0.437, that was close enough for me, BTW, for now, I'm just using a normal rubber O ring, I'll change this later for something like Viton. I had no tool steel large enough for this job so used a length of silver steel which when finished was heated/hardened. The picture shows the tool after machining, before hardening I filed some rake off the back edge. The tool was shaped to give me a visual stop (remember X scale has packed up) for a depth of 0.050, the ring was 0.058 thick giving me a little to compress, the plan being to get a good seal, we shall see how that works out when running on air, I can say that it feels good. I then tested if I could fully compress the ring using a collet, well I could but not hold it and take a picture at the same time, my fingers aren't strong enough for that these days... Then on to parting at 3/8 Once parted I then run the reamer again from the rear face to clear any burr... Before pressing the housing home I took the decision to cross drill and tap 6BA for a small grub screw, there is probably no reason for this at all except to give me peace of mind. The gland is a very tight fit, it will need a drift to remove but it just worries me that there's nothing to stop it sliding inwards if it did decide to move in years to come and when heat is involved I just want to play safe.. probably just me and my paranoia... Picture shows gland pressed home and grub screw being tightened. A picture to show the back cover for the gland... I then returned back to the rear steam chest cover and drilled the 7 No.44 holes, only 7 as there is no hole against the frames due to part of the circle needing to be removed. The picture shows the 7 holes having been drilled, the small dimble mark on the top flange is where I need to drill/tap for 10BA to hold the spindle. I did two extra things while the cover was set on the rotary table, marked the dimple as shown here which ensures that the 4 holes for the spindle are orientated from 0 degrees to match the upper hole on the lower flange, it also allowed me to accurately machine the flat side to fit the frames. Here's the flat edge being machined, note that I have had to reposition the part to allow clearance for machining, I just replotted the top hole (as seen when fitted) to ensure I was square. I include this picture to show a few things, first the rear cover and it's spindle in position ready for transferring the holes into the cylinder casting. Note that the flat edge lines up with the side of the cylinder and also the large piece of steel on the other end. This has a step in it to match the front cover recess and a 5/32 hole through it to match that of the rear cover, this gives me a solid datum to ensure that the valve spindle when fitted runs true between the two covers, hope that makes sense? Lastly, I have left the 5/16 rod in the piston gland to give some idea of the angle between the two. here we have the rear cover and it's spindle mounted using the same procedure as that for the cylinder cover. The flange to the cylinder is held with 8BA and the cover to spindle is held by 10BA, studs being used for the larger. two pictures of the cylinder back in position, I don't have the material for the piston, rod or front cover so will find something else to do for now. here's the cylinder from the front and the rear... Thanks for looking in folk, more soon.... Pete 3 5 Link to post Share on other sites More sharing options...
greenglade Posted March 14, 2019 Author Share Posted March 14, 2019 Evening all I wasn't really sure what to do next as I fancied a less stressful job for a few days but since I've got back into the 'cylinder mode' I thought that I would take the first steps in dealing with the outside cylinders. I began with checking the castings looked in good shape and that they were both square etc. It's strange that one could be forgiven for thinking they are cast in different metals, one being a light colour and nice and smooth and the other being very dark and rough, different temps when casting perhaps? anyway, they are both in good shape, with reasonably flat backs, a quick file over any rough spots soon got them in shape. I had a quick read through Don's notes to see if there's anything that could catch me out. First thing was that Don has started to use the top 'T' shape as your datum, well there are actually two important datums to consider. The top as Don states and also the back as the cylinder distance away from the frames is just as important as the height of the cylinder bore, well IMHO at least. The first machining job was to machine the top 'T' shape to its correct height of IIRC 7/32, the picture shows the 'T' finished. I have made use of the large angle for the machining stages just as I did for the middle cylinder, I checked a number of times with a square that the cylinder was held correctly and tightly. During machining of the top, I kept an eye on the distances to both bores as these are what is important, it's also nice to have things add up, ie the 7/32 was correct as were the distances to the bores. I used the vernier with a rule clamped to it to do this. This picture is out of sequence as it's at the beginning of machining the top and here I'm just setting up. BTW the rule isn't clamped square to the vernier in this picture, I repositioned and used a second clamp later. Once happy with the top, I then moved on to the bottom, this was easier as I now had a machined datum on the top so much easier to clamp to the angle squarely. The picture shows the finished bottom, the overall cylinder height, once these two faces had been machined, is just over 96mm. I got both cylinders to this stage, in fact, I'm doing all operations to both cylinders before moving on to the next setup. next up was the back face, I did look at doing this in the 4 jaw but wasn't too happy with how secure it was held so went back to the angle. This time I used 2 angles and sandwiched the cylinder in between them and used clamps to hold the casting down to the mill bed. Again here I am setting up and took this to show how I measured the distance from back face to the bore centre. I have used the same bung as was used for the middle cylinder but turned up another centrepiece to measure from. As can be seen the centrepiece has a small spigot on it, this is 76 thou wide, the distance from back to bore centre needs to be 1.250, this plus half of the spigot of 38 thou gives me my measurement to machine the back down too, that being 1.288. All I have to do is close the vernier to under the spigot to get my reading, hope that makes sense. BTW, there was a fair bit of metal to remove from both the top and rear faces, approx 1/16 for both. The bung isn't tapped home in this picture, when I had machined the first , I then also set a depth gauge from the back to the bung edge and used this as an extra check on the next cylinder to ensure both were the same. Here's the rear finished to size... Once happy with both cylinders having all of their external dimensions completed I decided to take a look at the mounting flanges as I plan to fit these to aid in holding/setting the cylinders for doing the boring. I marked out the centre's of the cast webs and then marked out the datum bolt hole that Don thoughtfully gave as being the most critical, it's actually on the bore centreline so makes complete sense to me. The picture shows that I have marked out the webs and plotted the datum hole, this is 1 3/16 below the middle web centre. I did this and checked a number of times that all looked well, this included laying the flange on top to ensure that all of the lines were central to the holes and that it was square in relation to the cylinder. Life was made a lot easier here as the cylinder is clamped squarely along the 'x' axis and thus once the first bolt had been fitted I could use the DRO and the drawing for the flange mount to check that everything was going to plan. And here we have the first (L/H cylinder) with it's mounting flange fitted, as you can see there were yet more copious amounts of holes (6BA) to drill/tap which takes time but we got there in the end. I will get the other cylinder to this stage in the morning. As per usual for me, now having a cylinder fitted to it's mounting flange it would have been rude not to see how it looked, here it is, tomorrow it will be joined by it's twin opposite and then there will be no more one man lifting of the chassis, not a change in hell...... Pete 2 3 Link to post Share on other sites More sharing options...
Moderators Howard Smith Posted March 15, 2019 Moderators Share Posted March 15, 2019 Pete - fantastic work, keep the updates coming, following with interest... H 1 Link to post Share on other sites More sharing options...
greenglade Posted March 15, 2019 Author Share Posted March 15, 2019 Thanks Howard.. next update.. It's the week's end which means time for one last update before the weekend, I first drilled/tapped the other cylinder to mount its flange which meant both cylinders were at the same stage. I also made a slight change to the exhaust opening in the flanges, I had clearly got a little carried away when making the holes for the exhaust which should have been at an acute angle rather than just a big hole, to correct this I silver soldered a small section to the top of the opening which can just be seen in the picture showing the flange after being dumped into cool water. If you look back to one of yesterdays pictures which shows the flange fitted to the cylinder it should give you some idea of how much metal needs to be filed off the cylinder to match the opening. This will be at a steep angle, I'll take care of this later and then the flanges can be attached to the cylinders for the last time. I will use a flange sealant around the exhaust joint to flange area which is quite large on final assembly. Next up was to grind some of the cylinder casting away where it's close to the rear bogie wheel, Don says to remove enough metal to match the flange, the picture shows the area concerned, I have marked it in black. here we can see that I have done as Don suggests, for this I made good use of a sanding drum on the Dremel. Now, talking of wheel clearance I will show, just how close things are. The early pacific's with their 'swing link' bogies were prone to hitting the rear of the cylinder with the rear bogie wheel. To address this, Gresley changed to the side control type bogie and moved it forward a short distance, in 5" gauge this equates to 1/8th and a good job too, I hate to think how close things are for those who are modelling a very early Pacific and choose to model the early swing link bogie as per prototype. Having fitted both cylinders I took a look at this and nearly gave myself a heart attack thinking something was wrong, if you look at the picture you can see why... After a few minutes getting my head in gear I realised a few very important facts, first I hadn't set the spring rates on the bogie yet, they are currently at max length, so doing nothing, second that the chassis was down at the front due to this and the strong springs on the rear trailing axle. All of this I had left as there's no point in setting up the springing until I'm closer to max weight which means I'll need the boiler in place which is the reason that I haven't changed the trailing axle spring rate as a lot of weight will be sitting over that. What I basically saying, is that all of this will have to wait, for now, I'll continue building to drawing and hopefully, everything will sort itself out later. What I did do though is lift the front to the bogie springs full length to see what room we have, at this setting the front was still down by approx 1/2 degree which again may sort itself out when there is more weight on the back. also, I haven't machined up any large ( I'll use bronze) washers under the bogie as on the full size yet, a little R&D for the future. And then there was three.... The last picture for tonight, I have laid one of the running boards in place to check how things are looking as everything is getting very close and I wanted to see if there were any issues, so far it's looking good. I still have a lot more machining/tidying up to do with the cylinders which I'll do soon... thanks for looking in guys and i hope you all have a good weekend.. Cheers Pete Read more: http://modeleng.proboards.com/thread/5733/building-don-youngs-doncaster?page=139#ixzz5iGYEBs2O 4 4 Link to post Share on other sites More sharing options...
mswjr Posted March 15, 2019 Share Posted March 15, 2019 This is a good gasket sealer Pete, I use it on my cylinders, As it is no paper gasket, Loctite 5926 1 Link to post Share on other sites More sharing options...
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