greenglade

Afternoon all I have 12 pictures to get through today so best get on with it.. First up, was the outside cylinder steam entry holes, as planned I marked the position on the cylinder and then I placed the running boards, both lower and upper in place. At first, when I looked at this I wondered if something was wrong but on checking the drawings I could see that the steam pipe isn't central to the running board hole, I'm sure that I will discover the reason why later, most likely to give plenty of clearance for the steam pipe as it curves in towards the smokebox as one would expect. Here's the picture to show the lay of the land so to speak. Please ignore the bad paint, I've already described the reason for this and as stated before this will be redone, hopefully, later this year. Don shows a 30-degree angle for the steam entry into the cylinder, this is of course angled towards the front. I held each cylinder against the angle bracket and using a digital angle gauge set each in turn for 30-degrees, the gauge was calibrated with the mill bed first. Here the first cylinder is having it's opening hole drilled. And here's the second cylinder now being opened up to 8 mm using an end mill, drawing shows 5/16 but the closest I had was this which is only 0.07mm wider so no big deal. So, here we are with both steam entries drilled and checked again for position. Next up, steam ports for the main bores, IIRC Don states file a flat on the edge of the bore, drill 3 No.22 holes in line and then finish off with a mill, I do things a little different, first, though, I needed a 4mm long series end mill which didn't have. Not to be beaten I dug out some BMS hex, cut to a length that would give me enough clearance but also not compromise it's rigidity. Centre drilled a 4mm hole and placed a 4mm endmill into it securing with IIRC Loctite 640 which is a very fast setting high strength retainer. The picture shows the item in question, before it cured I checked for runout of which there was none, job done... Now, the way I did the ports and this is a little different to the middle cylinder is to mark out their position for width, place the endmill further inside the bore by about 1mm than it needs to be and just let it kiss the bore. Since the cylinder is placed at a 35% angle (this was the angle that I decided would work best) I could engage one edge of the cutter working my way down slowly until just half of the blade cut a flat edge, I then bring the cutter out towards the front to it's final 'Y' position, 'X' start and finish positions were also noted. I then remove the endmill, now using a drill, much smaller then N0.22 but large enough not to impede the 'no cut' area of the endmill, move it in a little from one end of 'X' and drill right through into the chest below. I make a note of the 'X' position for said hole, refit the endmill into the chuck and plunge cut approx 30 thou, move carefully along the 'X' axis in both positions to the start-finish plots. I continue doing this until I break through to the steam chest below, picture shows the mill having just broken through. And this photo shows the moment when I can breath again as if I had misjudged the angle (nothing given on the drawings) I could very easily have cut into the two rims either side of the cavity which the liners fit tightly into and of course the liner ports all sit within the two rims. happy days...I have placed the cutter deeper so that you can see it easily, the small mark is where the cutter had been at and as you can see, there isn't a lot of room for error. Here's the finished port, now I made a silly mistake when drilling the pilot hole, I completely forgot about the extended drill that I made for the middle cylinder and just went ahead with a normal centre drill, totally forgetting about fouling the studs and yes as you can see i broke a stud...don't you just love this hobby... So, after a few chosen words had been said, I took a closer look at the situation, there was just a small amount of the stud protruding from the cylinder. using a thin Dremel cutting disk, I cut a small groove into the stud but not enough to mess up the important sealing face below. I did this in two stages, cut a small groove, unscrewed a couple of turns and then cut a deeper groove now that I had more stud showing. I'm happy to report that what could have set me back for some time took no more than a few minutes to fix, I was also thanking myself for only using a thread sealant and not a locker or retainer, it would have been a different story if I had done so. moving on I then needed to take a look at machining the steam chest covers, my son had kindly supplied me with a 4 1/2" length of 2" PB102 bronze which is a lot bigger than the 1.250 required. On looking at this lovely piece of metal it dawned on me that it may just be possible to get not only the 5 covers from it but also the 3 pistons, the thing was though, that it wasn't long enough if I parted it to make the two different dia parts seperately as i wouldn't be able to hold them. So, I first faced and then machined a 2" length to just over 1.750, swapped ends, centre drilled the other end and between chuck and live centre machined the rest down to just over 1.250, well 1.254 to be precise. I then swapped the ends again and was ready for doing the pistons first. My reasoning for doing it this way was that whatever was left over from doing the pistons could then be turned down to match the other end ready for the covers. The pistons are done with most of the work to the rear, there is a 1/2" wide ( I made mine 11mm to ensure good clearance on the piston gland)tapered spigot that's 3/32 deep. This, in turn, is drilled/tapped 1/4" x 40 TPI and then has a counterbore 1/4" wide and 1/4" deep for the piston rod to lock against. Once this was complete it just needed to be parted with an overall width of 1/2". Last picture for tonight shows the 3 piston blanks, two rears and one showing the plain front. I can't finish these until I have made the stainless steel rods, then each piston will be securely locked to its rod, Don states to screw it on and the machining operations will lock it in place, I will for extra security also use a strong retainer so that they are even better secured. When fitted to the rods each piston will need it's ring slot machined to spec for the 'O' ring chosen and it's front face finished. Next week I will start with the steam chest covers, I still don't have the flat bronze required but I can do all of the turnings and plot the mounting holes too, once those are transferred to the cylinders and the studs cut and fixed I will give each cylinder a final tidy before painting with a special auto paint that i have. Once that lot is done, except for needing to do the slides, I'll be getting close to fitting the middle cylinder for the last time and then a whole host of things open up for me. The final stages of the smokebox (which needs repainting) can be done and perhaps making the steam pipes ready for the outside cylinders too. All this and the boiler will be in progress in the not too distant future t, Adam (Cro fittings) has received the steam valve/clacks ready for the boiler and the manifold is also in the works so to speak... It should be a very productive year... more soon guys Pete

Afternoon all Well, I got most of what I planned to do for this update, just have the steam pipe holes to do. First up, now that I had transferred all of the mounting holes was to remove the spigot's on the rear of the covers. The small dia spigot was cut off with a hacksaw and the larger dia spigot ( used to help align the cover with the bore) was machined off using the outside jaws. The first picture shows this, it was a relief to see that the blind holes that I had drilled for the central mounting bolt for the shield have remained 'blind' after machining the spigots off. I also machined up two plugs to fill the wrongly drilled relief valve holes, I didn't take a picture of this as it's just simple turning/threading. Here's the right-hand cylinder with the cover off and showing the plug fitted, also the long stud in the middle which will be shortened once I have made the shields. From pictures, there is very little thread showing once the nut is fitted to hold the shield which I will try to emulate. And lastly, for today (nice and short this update), I have placed the cylinder back in its position to check all looks good. I was also happy here to see that the cover studs do not foul the flange bolts. Other jobs done are to drill/tap both the draincock holes and the rear relief valve hole, 3/16 x 40 and 7/32 x 40 TPI respectively. The first job for tomorrow will be to put in place the running boards and plot the exact position for the main steam pipes into the cylinders. As the boards with their holes for said pipes are already finished this job shouldn't take too long, good job as some may recall that I moved my smokebox back 1/8" further than Don has drawn to match the prototype. Not that this affects anything here as I haven't drilled the steam pipe holes into the smokebox yet, another job to do very soon. I will then go over both cylinders and tidy any bits that need it. I may then take a look at the 5 (two different sizes) steam chest covers, I have the bronze bar but not the flat section for the guides, nor do I have the 1" bar for the liners which I may do in CI. My youngest son said he may be able to sort these out for me, good job, as bronze flat bar of the size required isn't cheap. Next update soon guys... Pete

Clearly, I was having one of those days yesterday as I thought it was Friday and hence why I posted an 'end of week' update?.. hmm... going mad he is...lol Ok, so I had one more day to play with and made the most of it, I mentioned yesterday that I had started to clean up the bore faces and that is what i started with this morning. I machined down the face with the arc just touching the steam chest and then widened the cutter enough to allow the cover to sit flush, this is course had to be cranked by hand. The picture shows the first one done bar a little tidying where the outer arc stopped, this was done after this picture using a sharp chisel and file. Next job was to transfer all of the cover holes to their respective cylinders and tap 6BA, I won't show pictures of that as it's the same as the middle cylinder but will show this picture to show why the relief valves have to be outboard. As can be seen, inboard they would foul the front mudguard. and lastly, both front covers held on with temporary screws... Next week I have a fair list of what I'd like to get done. I will cut up some 6BA stainless studding (hope I have enough), deburr the front face threads and fit the covers properly. I bought nickel plated nuts as used on the middle cylinder but may need to use smaller to allow for the cover to sit over them, I'll have a better idea once the studs are fitted. I also need to drill tap the 3/16x40tpi draincock holes and the rear 7/32x40tpi relief valve hole. Once those are done I plan to put the smokebox in place and work out where the steam pipe entries need to be in the cylinders, I can then drill those, the 4 mounting holes around them for the steam pipe flange I'll do once the flange has been made. Well that should get me started, I'll need to think of what to do on Tuesday... haha.. yeh right.. see you then guys Pete Read more: http://modeleng.proboards.com/thread/5733/building-don-youngs-doncaster?page=144#ixzz5kEzQlQcB

Sorry to hear that David... it's all very well cross-checking which can be done to some degree but when building something as complicated as a steam locomotive, I defy anyone to be able to read through all of the drawings with thousands of dimensions and pick out each and every error, like most things in life, you tend to find them when they bite you...;) Upwards and onward, as they say, hope you sort it soon.... Cheers Pete

Evening all, time for this week's final update and I found an error in Don's drawing on the front outside covers, the problem is I didn't spot it until I had machined them. Also, I'm not sure, but Don may have mentioned it later after having it pointed out to him by a builder, at least I have some recollection of this, I think? So, what have I done now?....here's the drawing, it has my pen notes for the degrees of each hole, I did this as they are handed and I didn't want to get confused during the operation. The few outer numbers are for the other side, this one is for the L/H cylinder or right hand as you look at it from the front. There, that should give some an idea of the error which I didn't spot? maybe this picture may help, here's the same cover after machining, placed over the bore. The error is that the relief valve hole should be outboard, not inboard as seen here, oh and yes, I did both covers before trial fitting them..lol No big deal other than having to reset each cover on the rotary table and drill/tap the two 7/32x40tpi holes again in their correct positions, here we now have both covers with two holes, just not what the doctor ordered. I don't have any bronze hex to hand so will need to get some to plug the holes but I had another idea which some may be able to answer, where would one fit a connection for measuring 'Cylinder pressure'? I had thought about fitting such a gauge before but now I may just do it due to my not paying enough attention, or more to the point, forgetting what I think Don had already warned about. Next week I'll finish off the bore face, I've already made a start on one, the bore is still a little overlength but I may leave it for now as extra clearance. Once i have the pistons and rods made and some of the other motion I can check to see if the stroke as it should be. Thanks for looking in again chaps/chapesses Pete Read more: http://modeleng.proboards.com/thread/5733/building-don-youngs-doncaster?page=143#ixzz5k9Pul0hY

It looks like this end of week's update is going to be a little bigger than of late so I'll do it in two parts to safe my sanity at the keyboard. This picture shows the last stage of lapping the cylinders, luckily last week I had cut down some of my apple tree and have now used a small section for lapping the cylinder. This was turned to a good fit within the cylinder, I then mixed up some more of the cutting compound and slid each cylinder in turn onto the wood and worked them by hand. They were a tight fit to begin but soon loosened up, each now measures 1.7455 so I've gained another thou and a half which is good enough for me. It didn't take long as all I'm doing is removing any high points from machining. I now move on to the cylinder covers, these come as cast discs including a spigot with the cylinders. First job was to true up the spigots, for this, I used the outside jaws and held the cast in the most concentric position. I then refitted the internal jaws and machined the front face, the picture shows one of the covers having had it's face machined and the other with just the spigot done awaiting it's turn. I do each cast in turn for each operation, makes things much quicker. Then on to the rear face, as with the middle cylinder, I have added an internal spigot to fit the bore to help locate the cover for when transferring the mounting holes, this will be removed once the cover has had it's holes drilled and been mounted to the cylinder. the cover hear is still oversize so i wasn't worried about marking it in the jaws. Now to the front and here I have deviated from how the middle is as I want them to look like the prototype including the cosmetic covers that sit over the studs. I have made 3 changes although one may not be needed now that I've looked closer at the cover in relation to it's fit on the cylinder. Perhaps Don covers this later, but I've not found it. IIRC, Don states that the covers are 5/32 thick to give a scale appearance, on looking at my reference photo's this doesn't really work out, it's too thick for just the cover without it's outer shield and too thin to be both, well that's how it looks to me at least. So I have reduced it's thickness down to nearly half, I have also added a small step around the outer edge, the idea for this was to give a register for the shield but on further investigation, this may not be required. The third difference is I have added a central blind hole tapped 6BA to secure the shield as per prototype. Here's a photo of the full size that I took to show what I mean..although today the shields are painted black, for my era they are polished steel, I haven't decided how I'm going to make these yet, they could be spun or machined from solid, the material that I use will have some bearing on which method I choose. here's the front so far, you may just be able to see a scored line half way across it's face, this will be explained in the next picture. And here we have the cover put roughly in place and we can see why I scored a line. The cover will be closer to the steam chest once it's had a small section removed to allow for this. I need to make two mirrored covers as they are handed to fit the cylinders. The scored line is to give me a vertical register for placing the holes, the first to the right will be on a 15-degree arc, the first to the left will be on a 30-degree arc and all other after will also be on 30 degrees. You can see clearly in this picture that the steam chest bore as stated previously isn't central to the cast, why? I have no idea. However, the last picture after this one did put my mind more at ease. As an added check, I do this a lot, I measured across the face of both cylinders to see how the cover would look. The cover dia is 1 1/4" and you can see that when placed centrally to the bored hole this will fit nicely in line with the lower edge so I don't think that the hole can really be out, very strange but I'm not going to let it worry me. I'll make the covers to size, fit them and then look at profiling the casting to match, it's strange as there should be no reason to touch this part of the casting and it should be to size which it clearly isn't? The important thing is that the dimensions are correct so no problem.. yeh right, if only my mind would let me drop it...lol Tomorrow, all being well, I'll set up the rotary table and plot/drill the mounting holes, I'll also drill/tap the relief valve hole and machine the small section off for the cover to clear the steam chest and sit nicely in their respective bores. Till then Pete

good day all Continuing on from last week, today I machined the rear inner face of the R/H cylinder, I also cut the internal chamfer and begun to lap the bore. Before showing these I did a few more checks on the measurements mentioned last update as I hate it when things don't add up. I have checked everything and can't see why the steam chest cast seemed to stick out further than it should do?The only thing that could do this would be if the flange was too thick but it's exactly 4mm as to Don's words. The measurements from said flange are also correct so it's a bit of a mystery, I did consider that perhaps Don had drawn the wrong dimension, many have but it would be very unusual for Don Young. I put some 7/8 bar through each steam chest when fitted to the frames to see how things line up with the expansion link, it looks as it should do? So, I have moved on, it seems right and if not I can work around it easy enough later, however, I don't think that it will come to that as I'm 99% happy that all is ok. Ok, so on to today's effort, this has all been covered before in the middle cylinder description but basically, the cylinder is held against the angle, squared up and the boring head fitted. I have used the same tool as before, IE the one that I shaped from 1/2" BMS, which had a approx 3" length reduced so that the angled tip could cut both the inner face and also the chamfer into the bore. The first picture shows the tool in question, BTW after shaping it was hardened/tempered. the end result, this was done in two passes, starting from the middle out, had to be done in two as there was a fair bit of material to remove. The chamfer which can't be seen from this angle is just under 1/8 deep which is the distance that the tip sticks out from the tool shaft. Basically, I keep cutting and checking with some paper placed down the bore between the tool shaft to ensure that I don't touch the bore with the shaft. On to the lapping, for this, I have used 'timesaver', the 'Yellow' tub which is designed for brass, Bronze etc. I have used the very thin paste as the bores aren't too bad, to begin with. This comes in a powder which you mix with oil, type of oil isn't stipulated so I just used mineral oil. The picture shows the tub and a small amount that I mixed ready to apply, I did this with a small brush, both in the bore and onto the honing pads that I had modified for the job. this is what I used to hone the bores, it's a small brake/clutch cylinder honing tool, I have covered up the pads with some tough paper towel and soaked them in the solution, as you can see I have already used the tool in this picture. The tool in action, I varied the speed and kept the action up/down the bore constant and smooth, reapplying more solution as I progressed. Lastly, the finished bore, I have tried to tilt it to get the light to show the result, it's not as polished as the burnished effect but then it wouldn't be, I think it's good enough, once I have made the pistons/rods and the 'O' rings have arrived I'll be able to test it. Tomorrow I'll tackle the other side and then take a look at finishing the front face, I'm in two minds about how best to tackle this as a knife edge face cutter ( as used for the first stage) can't do the full job, I may just use a suitable cutter and machine the whole face on the mill, I'll give this some thought overnight. thanks for looking.. Pete

Evening all only 3 pictures for tonight as most of this week's work is just a repeat, in this case, the steam chest bores. Before machining anything I double checked the centre position as it looked a little off if just using a bung to line it up. As it turns out, it was, what I mean is, if I followed the cast bore, the steamchest centre would have been more than the 1 1/2" out from the flange, not by much but best to keep the dimensions as per drawing. Its distance from the middle of the main bore was ok, I first clocked the main bore centre and then moved the cross slide out by IIRC 1.656 and it was within a few thou, so I kept it at that. The important measurements all added up, main bore centre is 1 1/4" out from the flange, steam chest is 1 1/2" out from the flange, it's also 15/16 down from the top edge and the main bore is a further 1 21/32 down from that so I think/hope everything is where it should be. Ok, so the pictures, first is just to show my set up for reaming as I don't think that I showed it before. I had to start with the reamer tongue held further into the chuck and got close enough to the other side, I could engage the live centre, undo the chuck, move the slide further from the chuck and retighten the chuck and then run the cylinder back and forth over the reamer. A bit Heath Robinson but it worked ok with no mishaps. The picture shows the final stage. I've included this picture taken after the final stages to show the difference between the outside cylinders when compared with the misshapen middle cylinder, there is very little inside the steam chest bore to clean up here. To complete tonight's pictures here's the two cylinders hung on the frames showing both chests now machined... Next week I'll use the mill and a boring head to clean up the rear inner faces of the main bores (as I did with the middle cylinder), check their depth and then finish the front faces, steam chest faces are to size although I may tidy them up a little to make them look more central to the outer casing. It was a tough call to not follow the cast centre's, one always asks questions as to whether they have made a mistake, after making numerous checks I ignored it and carried on, hopefully, I got it right, the figures say so... Thanks for looking in all.. Pete

evening guys and girls... I only have one picture to share tonight as there's little point in repeating the process for the second outside cylinder as it's the same but I will give a little background of where I now am. I machined the second cylinder as the first but this time took it out to 1.744 thou, so only 6 thou short of what the drawing states, I will probably leave it at this in as far as machining goes but will lap the bores to get the best finish that I can, they are pretty good anyway but can always be better and being a little under 1.750 isn't going to upset the applecart.. For the honing, I have ordered some 'Timesaver' lapping compound, the very fine paste suitable for bronze. I'll make up a mop to do this work under power. I have also been looking at 'O' rings and have ordered a couple of sizes to try, I have some PB102 which I'll use for the pistons and 5/16 stainless steel for the rods. I think that I have most of the materials for the cylinders except for the 21/64 Bronze flat bar required for the crosshead guides, this and the gauge plate for the slides will be sorted in due course, I have plenty to do before needing them. After I had machined the second cylinder to 1.744, I then returned to the first cylinder, reset it on the lathe and machined it's bore to the same size (it was 1.738)using the boring bar with the tip at the same setting as for the second, they are now both identical. hmm, that's a bit of a mouthful, hopefully, it all made sense. Here's the solitary picture to show both cylinders now bored, things to do other than the steam chest's are to machine the rear inner face and then finish the front face to give me the drawn size of 2 13/16 bore depth. I will also need to drill/machine the front steam passages/ports at some point, may leave that till the end, we shall see... Next job is to remove 1/4" off the bottom of the alloy jig to give me the correct height for boring the steam chests. Not my favourite pastime as it involves using the 3" surface cutter but, hey, ho, it has to be done.... Thanks for looking, folks Pete Read more: http://modeleng.proboards.com/thread/5733/building-don-youngs-doncaster?page=141#ixzz5jIxE6kny

Hi guys Ok, now for today's planned update, this is just me finishing off the final operations on the first cylinder's bore before de-rigging and moving onto the next. I only had two operations left, the front and rear facing. First picture shows the front face machined although not finished yet, this is as far as I can go with a full swing under power, the rest will have to be by hand. And here's the rear face, the depth of the piston gland as drawn is 3/8, I have stopped just short of this as it's not possible to get a true reading from the cast's rear face, they'll only be a few thou in it though. Lastly, the front face again after hand cranking the cutter to get the required 2 1/4" machined area for the cover. I stopped at this point even though the face isn't fully completed until I'm happy that I have enough depth for the bore which needs to be 2 13/16, I'm only a few thou short of that and haven't machined the rear face yet so things are looking good. The front face is good enough to seal, I'll make a decision after machining the rear inner face and chamfer as to whether I return to it or not, just playing safe for now.. That's it for this week Cheers Pete

Morning all I've had a few questions regarding my setup and can clearly see that by me forgetting to post the first sequence of pictures that things are a little confusing, so I'll do it now to make things a little clearer. the bit I forgot to cover was how I dealt with the blind bore, so here's what I did. the first picture shows the extended centre drill that I made up for doing the middle cylinder some time ago, after checking that it was running true I proceeded to spot the rear of the bore face. Then, using a 12.2mm bullet drill I slowly drilled through the rear face until it began to show outside on the piston gland, as with everything, I check and double check each operation. Here I have the tailstock centre close to the piston gland to check that things haven't moved off centre. And here we have the drill now all the way through and it's spot on centre. Confirmed by being along the casting line flash which indicates the join of the two halves. Lastly, the 1/2" reamer was used to finish. As the taper began to show at the other end I engaged the tailstock live centre with the reamer and completed the pass to achieve a parallel 1/2" bore, ready for the boring bar to slide through. Hope that clears things up and sorry for my mind forgetting that I hadn't posted this sequence previously... Cheers Pete

Thanks Richard... Yes, I've been very careful/particular with the 2-1 gear pivot pin position, this was all covered a long time ago so not shown on here. I recall setting the 2-1 gear stay in the frames and then clocking the distance from L/H frame inner edge to the pin position with the digital scales and drilled/reamed rather than do it off the chassis. Hopefully, it's correct...:) Pete

The steam chests are, not the main bores themselves...

Ahh.. I seem to have had another 'duh' moment, I forgot to give details machining the piston gland, sorry about that guys, please refer to the middle cylinder as it was the same...cheers

good day all I have now made a start on the first outside bore, well actually I've finished the bore itself just needing to face either end before starting on the next cylinder. I will cover what I have done so far now as it's already 9 pictures which equate to an hour or so doing the write-up...I must be mad... First order of business is a quick thanks to Richard for suggesting a piece of wood under the strongback, duly done sir... The boring bar is the same as used for the middle cylinder, all I needed to do was make sure that the tooltip was fully retracted before making a start, this just required undoing the grub screw and pushing it in as far as it goes until hitting the 1/2" shaft/bar. At this setting, I made two passes to ensure all was concentric, as before the return cut is done in reverse which buffs the bore giving a lovely finish, I did this throughout even though it's not really required until the final cut. The first picture for today shows the cutter in reverse coming out of the bore bringing with it a mixture of gunmetal and casting sand debris. there was an awful lot of sand in this casting, probably trapped in the steam passage although it seemed like more than possible? The black mark on the shaft is to show me when to stop the longitudinal feed and finish by hand to the rear face of the bore. You get a warning sound anyway as the cutter hits the steam passage but I like to play safe. a quick check in the bore to see how things looked, the recess on the rear face is there to give a larger passage for the steam as it flows into the bore, you can see the passage itself on the left as the cutter has begun to clear it up. I'm not sure if I covered how I increased the tool when describing the middle cylinder so will give a quick note here. All I do is cut small pieces of paper and measure their thickness, I found that two pieces folded double gave me around 18 thou and so that's what my advance would be giving me, of course, a 36 thou cut. I didn't want to risk deeper cuts as the boring bar is only 1/2" (it has to be to fit through the piston gland) it's fairly long and because of this, I didn't think it wise to drill/tap a hole below the cutter to adjust it with a screw. As things progressed I needed an easy way of checking the bore size, a normal plug gauge couldn't be used as it would require me removing the bar for each check, couldn't use a bore gauge and couldn't accurately measure with a vernier. I began to use an inside divider which wasn't very accurate. I then had a rummage through my tools for a better divider and re-found the pair seen hanging on the bar in the picture. It dawned on me that if I set the outside curve of these to 1.750 and hung it over the boring bar I could use these to easily check the size. Better still, they would spring in as I pushed them into the bore giving me some idea of how close I was, in effect they were doing the job of a tapered plug gauge... brilliant.. not me.. just the new found use... With the bore now only a few thou undersize (I'll leave it like this for now, as I did with the middle), the next job was to machine the 30 degrees chamfer on the rear face into the piston gland, this is for the piston to be able to go flat against the rear face as it has a raised section for extra strength around the piston rod. Here I had a 'duh' moment, I had used the tool made previously for the middle cylinder to bore out it's steam chest and forgot to replace it...lol So it was into 'Heath Robinson' mode to see what I could come up with not being able to use the lathe. The end result is seen in the picture, basically, I borrowed the mill's 'tapping chuck' and held a counter sunk tool in it which I have to say worked perfectly, happy days... And once that was done I ran the reamer through it to remove any burr, BTW, the stain seen in this picture is the oil that dripped out of the piston gland that I used to lubricate the boring bar during operation. This left one operation for the boring bar which was the chamfer on the front face, for this, I reversed the bar so that the tool was now facing the other way. Using the same edge as used to buff the bore and in reverse direction, I cut the chamfer. This picture gives an idea of the bore finish, the chamfer that looks a bit rough isn't really as only the inside part will be there after the bore's front face has been machined. Last picture looking down the bore itself. looks a bit of a mess in the bottom but the rear face and it's chamfer will be done later on the mill the same as with the middle cylinder. This picture gives a good idea of how large the steam passage is, the exhaust passages are just as large, those will be for another day though, need to finish the bore faces on this cylinder and then get the other to the same stage first. Thanks for looking in guys... Pete Read more: http://modeleng.proboards.com/thread/5733/building-don-youngs-doncaster?page=140#ixzz5ip30pntT

evening chaps I have spent today setting up the first of the outside cylinders, well I did finish the last update saying 'next would be something more serious'... No machining yet but I will take time to show you how I approach setting up the cylinders, I'm not saying this is the best way but it works well with the equipment that I have to hand... It didn't actually take me all day to set up as I had to adapt the alloy block that the middle cylinder sat on when it was machined first. This was why I did the more complex cylinder first as it's centreline is higher than the outer cylinders. After taking a few measurements, it worked out that I needed to remove 6mm from the bottom of the block to get the correct height, I did this with a 3" fly cutter which took some time, I can't do deep cuts with this cutter as it's too large for the machine, but works well if not rushed. My setting up approach was more or less the same as with the middle cylinder. Once happy with the height I double checked it was correct by sitting a cylinder on the block but not bolted down. I held the 1/2" boring bar in the 3 jaw chuck with it's bung slid along it but again, not fixed, the picture should help show this. I then advanced the cross slide towards the chuck adjusting the 'Y' axis until the bung would slide into the bore without binding or moving the cylinder, once happy with that I could tighten everything down. Now that everything is ready for machining here's a couple of photo's to show the final setup. first is from the front showing the bung in the bore, of course, the 1/2" bar is only just in there too as these are blind bores. And here's the view from the rear, we have the strong back across the top, I prefer one that gives a little so it wraps around the curve of the cylinder. There's a tool clamp at the front that holds the flange down, oh and this reminds me when taking the 6mm off the block, I also machined two 12mm wide groves for the clamps to grip. there's a G clamp at the rear and the two stops, one on the side and one at the rear. This gives me a 90-degree jig which locates the cylinder where I want it to stay. As with the middle cylinder I also double checked all was in line by placing the tailstock centre up to the piston gland boss, all looking good if I say so myself. As per usual, I hope my rambling makes sense. So, no guesses for what I'm going to be doing for the next week or two. I will do all of the machining operations (main bore, piston gland etc) for this setup on the first cylinder and then repeat on the other. It will then be a reset with more material needing to be removed from the alloy mounting block to bore the steam chests...that lot should keep me out of trouble for a while... Pete Read more: http://modeleng.proboards.com/thread/5733/building-don-youngs-doncaster?page=139#ixzz5ifBSlku3

The threads will be ok , reason for using bronze is it's so tough, the threads won't wear, it's the reason why all boilers these days have PB102 bronze bushes. To remove the risk of a fitting being blown out of damaged threads when at full pressure. It will also withstand many cycles of undoing and doing back up of the fittings, or in this case the small 10BA bolts that I plan to use. I can drill the holes oversize and still have enough thread for the job in hand. Admittedly the cylinders aren't made from PB102 but they are strong enough. As for my workshop, I wouldn't say that it's anything special, my lathe and mill are both of Chinese origin, not great if relying on the dials but can do accurate work with a DRO or constant mic checks, the biggest issue there is how much longer everything takes but you get to live with it in the end. One day I'd love to get myself a decent lathe and mill, life would be bliss in comparison. I can't moan, I have a well equipped workshop if not state of the art equipment...:) Pete

Well, you'd still need to tap the holes...:)...but yes it wouldn't be prototypical which I try very hard to follow..

Well hopefully the tapping will go to plan, there are ways to remove broken taps from bronze which I hope aren't needed. My approach will be to drill larger tapping holes than normally required as there's nothing structual here, just cylinder cover fixings...

I think that the sun must be shining on me of late as for a second weekend I've had free time in the workshop, I fear this may end soon but hey, ho, while the sun shines and all that... as anyone who builds steam models will know, you have stressful days and you have more relaxing enjoyable days depending on the job in hand. I for one find boring the cylinders pretty stressful, I think that's mainly down to the cost of these things as there's nothing complicated about the job itself although the 'unknown' is always a factor to bear in mind. Anyway, the other type of day are those where you are sitting down with your feet up type of days, were you are actually having fun...it does happen, honest... Today has been one of those days, not a care in the world and just having fun, so what did I actually do? Well, first I took a close look at how the running board sits over the cylinder as it's actually bolted to the cylinder by, in model terms, 2 8BA bolts which match the size of all the other bolts down the side valance. The casting does have a small step for the running board to sit in which is great but of course, it doesn't have square corners since it's still as it was when taken from the mould. Taking a quick look at the fit and looking at photo's I took 3 years ago at York I could work out how it should fit/look. the first picture shows that I have taken a small amount from the area to give me a square vertical surface to bolt too. This is a lot easier to set up now that the cylinders are bolted to their flanges. I then refitted the cylinder and placed the running board back in place, not bolted down though, just loosely held there to show how one mates to the other. I haven't drilled the mounting holes yet as I need to be sure of their position. From pictures it seems that the bolt positions varied, in some cases there are 4 instead of 2, some in line with the cladding, others not. I will look for better images for my era of 4472 before committing to hole drilling. Right now I'm thinking that the cylinder cladding bolts are smaller, if so I'll use 10BA, not that I'm looking forward to drilling/tapping those in bronze on a curved surface...lol... anyway, here's how it looks... This is one of the many pictures that I took of 4472 while at York, April 2016. It's a good picture to use for comparison purposes, tit shows how the cladding meets with the running board valance and the two different sized bolts used. Before looking more closely at this I had assumed that the cladding sat under the running board valance but having now seen that it butts up to it it becomes obvious that having it under the valance would be a real handicap for maintenance. This picture also shows that the cladding covers approx half of the cylinder lip and even cuts into it, I'll probably draw a line of doing that one though, we shall see. So, what else did I do while relaxing with my feet up, slippers on, etc, thank god I don't smoke or there may have been a 'pipe' in that mix too... I went back some years to a job I didn't do when doing the main horns, you may recall this is the second time that I've returned to the main horns in recent months, this time it is for the lubricator pipe connections that are screwed into the top of the horns. I won't bore you with manufacturing pictures as they are basic turning but in essence, they are made from 5mm hex brass stock, threaded both ends with a small hole through the middle. The end that screws into the horn is 5/32 x 40tpi, the other end is 3/16 x 40tpi and is centre drilled for a cone to fit. I will say here, right now, that I am not going to waste time making all of the cones and nuts for this loco (of which there are many), I have enough to do as it is. The connectors like these though are custom jobs so need to be made to spec, well loosely as they are not critical. a picture to show the 6 that I made, there will be others but as you know, I hate repetitive work.. Lastly, a picture showing 4 of the connectors that I have temporarily fitted 3/32 nipples and 3/16 nuts, I may go smaller on the nipples if I can find them commercially, I have an old one here which is smaller that fits the copper pipe that I ordered from China for the draincock cables, it looks a possible candidate for the oil pipe too, if I can find the nipples. Well, that was my weekend play time, tomorrow I will get on with something more serious, or will I? Cheers Pete

Thanks for the suggestion David, I have used that very same stuff on the car, it's good. I have a number of types that I can choose from when the time comes, that may be a while yet though...:) Pete

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

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

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

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