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Post by Deleted on Oct 9, 2016 19:10:06 GMT
Thank you, Page...I hope it's of as much benefit to you and anyone else reading it as the other great build threads on this forum are to me. I both learn and get incentive to continue my own build by reading other's, I find inspiration from them all.
regards
Pete
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Post by Deleted on Oct 12, 2016 14:11:49 GMT
good day folks Ok so what's next?...while playing with the chassis along it's short display track...(like one does.. I looked at the chassis to decide what to tackle next.. there's so much left to do ( I reckon that I'm only about 40% into this build) that it's very daunting when considering just how much work is left to do. Brakes will involve a fair bit, suspension still has a long way to go and as for the motion?..well that's a lot of work on it's own. anyway while pondering over this the one thing that did stand out as missing is the front buffers and so these are what I'll concentrate on for now. I had in fact already completed the more involved part of this area , that being the spring housings themselves so it did make sense to continue where I had left off some time ago now. I have started with the buffer heads as I had the material to hand, in fact, I bought this at the last Midlands ME which btw I'm very much looking forward to again at this weekend's show, so it's about time that I got on with them. First I had to decide if I was going to add greatly to my swarf bin by machining from solid or whether to machine the heads and shanks separately, I took the later route. I did the shanks first and the first picture shows the rear part that fits into the housing, this thinner section is what holds the rubber and steel washers that form the resistance to the operation of the buffers, so no springs here, unlike the tender buffers. The shanks start life as a length of 5/16 BMS bar, the rear section is turned down to a diameter of 9/64 over a length of 1 9/16, there is a small spigot on the end and a 1/4 length 4BA thread. as seen here. We next step up to 17/64 over a length of 1 11/16 Here are the finished buffer shanks, note the extra part on the ends, this is where I have modified and added a short length of 1BA thread that will screw into the heads themselves, the threads will be shortened to fit the heads once they are done. The big lump in view is the material for said heads. Having cut down the stock to a more manageable length it was turned down to the 1 21/64 required and was then faced at 8 degrees for the rear of the buffer head, note that I have left a flat section in the middle for the shank to sit against, this also gives a little more meat to the head for the shank thread to screw into. Last job for this picture was to start parting off at 3/16 which is the heads overall thickness ,not including the radius where the shank screws in. The head was then drilled and tapped 1 BA to match the shank (being careful not to go too deep), the shank was then fitted using Loctite 638. To ensure that the shank remained central while curing I used the drill chuck that loosely held it in line, this was me being careful which such a short thread. Now Don states to braze the two parts together, I decided to go the loctite route as these buffers are pretty delicate in comparison to the tender's, they could withstand a fairly hefty bang but these with such a fine shank are less likely too. By bonding them instead of brazing, if they did ever get severely damaged I could just replace the shank (most likely part to suffer) and reuse the head. After around 10 minutes ( enough for initial curing) I parted off the buffer. And so we have two partially machined buffers, I placed them in their positions and left overnight to cure fully before machining the radius on the front face, that even bigger lump in the picture is what my son kindly dropped off when I didscovered that I had no material big enough to machine the buffer stcocks, this was the smallest scrap length that he had, it's 60mm and I needed 42mm so a fair bit of turning coming up over the next few days.... So a fresh day and back to the grind, I have covered this part with more pictures than usual as the question of 'how did you machine the buffer heads' seems to come up a lot. Some will remember that for the tender I used the slack cross slide and measured bar resting between headstock and saddle trick, this time around I decided to go purely by eye. With the shank fully cured to the head and now held in the chuck I first turned down the middle of the face at an angle of 8 degrees to match the rear face, I did this in stages alternating between the two buffers, a method I used throughout the machining of the two buffer front faces. I next reduced the angle to 4 degrees and machined the inner section of the face, note I left a flat part in the centre. I then took the angle out to around 20 degrees and machined the outer edge. Something to note here is that on the early photo's of 4472's buffers she had a flat outer edge which can be clearly seen, this seems to have disappeared to a more uniformed curve (as she is today) in the mid 30's perhaps made during her other small changes in 1935. She certainly doesn't have it in a photo for 1936 and so for my chosen era of 1939, I have omitted these flat outer edges. The rest was done by hand with files and paper, first, a radius was filed onto both front and rear outer edges, then the high points were filed off to give a curve which was finsihed with paper and then sanding sponges of various grades until nice and smooth. It took less time than it might sound. apologies for the quality of the picture.. Thus the buffers are finished and shown here back in their positions Next, it's the buffer stocks, think these may take a little longer... more soon. Pete
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Post by Deleted on Oct 13, 2016 21:50:05 GMT
evening chaps Moving on to the stocks, I wasn't going to do this update yet but having looked closer at the drawings and realising that the design is a lot more involved than I had first thought, such as it's double telescopic having an internal sleeve with rubber dampers and their associated steel discs in both the housing and the stocks? a mixture of ten for the stocks and 26 for the housings. So I best get the description of the stocks out the way now. I haven't finished them yet but will show what I've done so far. The stocks are pretty little things but they sure do involve a lot of machining, especially when the steel bar that I've used is so much wider than required, so after creating a lot of swarf to get close to size I had a cleanup and then machined the basic stepped shape. Details are, looking from left to right, the stock flange is iirc 1.532 wide and 5/64 deep, the first step is 0.968 diameter and it's length is determined from the other end, ie it stops 3/8 from the right side. The small step is 5/8 diameter and of course 3/8 long, this is what we can see in the first picture. I have also made a start to parting off , the flange is oversize for now and will be faced off to the correct 5/64 width when the stock is reversed in the jaws to bore out the internal recess. I then changed the tool for a 6mm profile cutter and set the topslide to 55 degrees, note that the smaller spigot on the right is reduced further to 0.531. This makes life a little easier as I could machine the angle and continue into the spigot and then along stopping to allow a 1/16 lip. Hope that makes sense, basically, I did the basic steps first and then tackled the angle which has a small radius into the stock which the 6mm cutter did nicely for me. Final job was to finish the lip by file and also take the sharp edge of the top of the angle. Next, I bored out the stock to just over 13/32, this is the size that the internal sleeve will be when I get around to it later. And here we have the first stock after being parted off, the second stock is nearly at this stage too and then I'll need to reverse them to bore out a recess that matches the exterior profile, I'll show that in the next update, oh and once all machining is done I'll polish out all of the machining marks. I received today an order of some 1/8 nitrile rubber that I will use for the dampers, all 18 of them. I have to say that I'm quite looking forward to assembling these beauties, so many parts, iirc 21 for each buffer not including the housings....I just love that kind of detail.... more soon Pete
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Post by Jim on Oct 13, 2016 23:25:57 GMT
Lovely work Pete and very satisfying too as you see another component take shape on the lathe. With the buffers and stocks fitted to the buffer beam the 'face' of Flying Scotsman will really start to emerge. Jim
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Post by Deleted on Oct 18, 2016 19:57:41 GMT
Evening guys.. continuing with the buffers, once I had got the second buffer stock to the same stage as the first it was time to reverse them in the jaws to do the internal chamber. I used my recently purchased set of blacksmith drills to do this as the finished size was 13/16 which I had a drill to match. I started with a 9/16 as shown in the first picture, to begin with, I taped the drill to give me some visual control on depth but I later changed this to a pencil mark as the drill was greasy. Oh and I must get myself a set of soft jaws, I tried using some shim but it failed and thus I have some marks to take care off, they won't be seen once finished... such is life. next picture shows the final size of 13/16 and the pencil mark.. Now the angle is supposed to be 55 degrees, but since the drill tip is close at 59 that will do for me. The depth is determined by the outside profile having an equal thickness all round. the two stocks ready for the next stage I seem to have forgotten to take any pictures of the 4 holes being drilled on the rotary table which is very careless of me. basically, each stock was set in turn on the rotary table with some steel plates under the flange to give room for the drill to go through without hitting the jaws. A wobbler was then used to centre the table, once centred the head was moved out on the X axis by 0.625 to give the 1 1/4 diameter arc for the holes. It was then a simple job of clocking the table by 90 degrees for each hole which was first centre drilled and then finished with a No. 44 bit. Picture shows the first stock being checked for accuracy with one of the back plates temporary fitted which was laser cut for me by Malcolm (MEL). The back plates are 2mm thick and 1 5/32 square, I guess both Malcolm and myself got things right as they were a perfect match... It was then time to machine the flat edges on the stock flange to match the back plates, picture shows this, the backplate was placed in position as a visual guide to make sure all was going to plan. I was using a 12mm cutter and setting on X axis was 0.814. The first face was clocked 45 degrees from the first hole and then another 90 degrees for each of the others. The two stocks with backplates fitted and the corners radiused to 1/8. Here we have the components made so far, I still need to machine up the other stem, one of which can be seen here, this is made to fit into the stock and is a sliding fit. Overall length is 0.843, max width is 25/32 and the small width is 0.406 which is a sliding fit into the stock. Angle on the flange is to match the inner chamber. Final picture to show the assembly so far, well except I forgot to include the backplate...lol...with the backplate fitted the buffer doesn't stick out so far from the inner stem and looks just right when compared to photo's of the prototype. A point to note here is that I have opened up the bolt holes a little, reason being was that I wanted a hole that was a very good fit to one of the transfer punches for when I transfer the holes to the beam, the larger holes can't be seen once the nuts are in place. Next update should be the conclusion of the buffers, I have the other stem to do and then all of the 1/16 steel discs, plus the 1/8 rubber discs too. I then need to transfer the stock hole locations and drill tap the buffer beam for 8BA studding. I'll also clean up the marked stocks and give a coat of primer, I best also check out what else needs priming before the damp night's return. more soon... Pete
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Post by Jim on Oct 18, 2016 20:28:10 GMT
Excellent craftsmanship Pete and delighted to see you use the same Hi Tech depth gauge on your drills that I use, worth every penny. Jim.
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Post by Deleted on Oct 18, 2016 20:35:49 GMT
Excellent craftsmanship Pete and delighted to see you use the same Hi Tech depth gauge on your drills that I use, worth every penny. Jim. Haha...the simple things work best Jim.....
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Post by Deleted on Oct 21, 2016 16:52:32 GMT
good day all Today's' update see's the completion of the buffers, I'm glad that they are now completed as they involve a fair bit of work, especially when considering the buffers for the tender, I wonder if any other buffer design has so many components? I'd be very interested to hear if there are... Ok..so more pictures than usual tonight, some are probably not needed but they help tell the story. first picture is pretty simple, shows the disc's being set up with a stop in the tailstock and tooling set to cut at 1/16 width. All metal disc's are the same width but of two diameters, here we have the larger which fits into the buffer stock. The bar has already been drilled to fit over the buffer shank wider section, there are 4 of these. Once the disc's had been cut the same bar was then drilled tapped to be used for holding the rubber sectioned ready to be turned. The rubber is 3mm nitrile which was chosen as it's oil resistant, it also has what I thought a reasonable spring rate, I will admit to taking a guess here as I had no way of knowing how this would work once joined with the other discs, it just felt right and Don had mentioned to forget tap washers as they were too hard. Here I have all 6 rubber discs to be machined together. After turning.. here we have all of the large discs, I made a mistake here, on checking the size for the smaller discs I noticed that the rubber discs are slightly smaller than the steel, as these are hidden in the stock and as there is a 1/16 space around them I saw no reason to turn then down further. I didn't take pictures for the smaller discs as they followed the same method of machining, there are twelve of these so i did them in 2 batches and there are 14 steel discs, let's just say they kept me busy for a while. I thought this picture might help explain what's involved in just one buffer, in fact I forgot to include the 2 slim 4BA nuts and a small split pin to secure everything, the split pin will be done later, I have a few to do mostly for the tender. It was now time to drill the holes for the mounting studding, I first turned up a jig that was a sliding fit to the stock and a drift fit to the centre buffer hole in the front beam. with the jig tapped home I could simply slide each stock on and use a square for lining up and then transfer each hole. when doing this type of job I always do one hole at a time, drill, tap and fit a bolt to hold the stock on. check all is still square and then move onto the next hole. I forgot to take a picture of the studding being fitted, with all holes drilled/tapped i cut up 8x1" lengths of 8BA studding and using loctite 638 bonded each one into the front beam, i did consider leaving these removable for painting but decided there would be no problem painting/lining with the studs there, I may even paint the beam with buffer stocks fitted. Now I had one more thing to do for before I could begin assembling the buffer units, this was the small 1 bar diamond tread steps that sit centrally on top of each stock. I had considered a number of methods for doing these, machining, too much work, attaching separate bars, too fiddly and then thought why not press the shape. This would have involved making a stamp and I was considering this when I thought 'I'm making things too complicated' I'll just grind up a tool to tap out the shape on some brass. I first tried doing this to brass sheet of the right thickness for the step, yes the pattern showed through but it wasn't sharp enough to my eyes. So I decided to make each step in 2 parts, the step itself and a patterned shim to fit on top. Before doing anything I needed to set the scale, from the photo's that I took of FS at the NRM earlier this year I could see that there were 3 bars across the width of each step. Using the same photo's I worked out the width of each step, I then searched the web for drawings of the correct tread plate, put it into paint(windows) and reduced the image printing each time until I found a scale that gave me what I wanted. This was then glued to a sheet of bras shim as can be seen in the next picture, I also made use of an old punch and ground it down to a size that was just slightly smaller than a single bar on the drawing, the punch can also be seen in the picture.. this picture shows the results gained, I was happy with this, a couple of slips but more than enough area covered for both steps although the resulting pain from doing this would suggest that my poor wrist disagreed... Using a suitable length of steel that would fit inside the step I formed the steps themselves. Steps ready for their pattern This next photo is how I had planned to attach the pattern but then went a different way, here I was going to use loctite 640 (suitable for brass) and use the small pegs to hold while it set, I changed this as the test piece that I had done first was taking too long to set, it was cured but not strong enough for me to bend the sides down for the next stage so I ditched that idea and tinned each step and sweated the pattern on. with both steps completed they were then sweated onto their stocks, first one shown here. Once all was cool and primed I moved onto the assembly, the large discs where first inserted into the stocks, backing plate fitted and slid onto the studs and bolted up, alas I forgot to take a picture of this stage. With the buffer itself also in position this left the discs for the housings, now this is a real pain. At first, I tried to feed each disc on one at a time but this proved impossible as the assembly as a whole is compressed and although I could get most of the discs on I couldn't get the final few. I then remembered that don stated that in full size these discs are all bonded to form two springs, he did give them a name but I can't remember it just now, I can look it up if anyone is interested. So I took them all off and using a suitable transfer punch bonded each disc to the next using rubber superglue which worked very well as shown in the picture. After still more effort I got the sprung unit into the housing, I have to say that it certainly looks the part and works as intended, the housing spring is softer than the stock spring so that you get two rates of action, both are very strong, I struggle to compress the stock spring which is how it should be. a last resort so to speak although as Don states buffers on the front of an engine aren't going to do a lot if hitting the end of a platform with a 500 ton train, I'll remember not to do that ... The first buffer in place, also of note is that the front beam is now finished and that the 3 front running plates have had their overhang reduced to match the prototype, i've taken abpout 3 mm off. I've tried to take this picture at the same angle I have of the prototype that best shows the buffers. This picture was found on the web, I'm afraid that I don't know the author... thanks for looking guys, more soon.. Pete
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Post by Jim on Oct 21, 2016 21:39:31 GMT
Just flicking back and forth between FS and your work to date Pete there's no doubt at all you have a perfect miniature of the real thing. Absolutely stunning workmanship with all the photos of how it is done.ππ
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Post by Deleted on Oct 21, 2016 22:02:54 GMT
thank's Jim....so, so much more to do.....think I may get the steps out of the way next, both cab and front buffer beam...I also need to do the guard irons which have been left far too long. all these bits take time so best to get some done now, I still need to do the upper running boards and the 4 hinged flaps too...did I say I had lots to do? ??... Pete
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on Oct 21, 2016 22:34:37 GMT
Hi Pete,
Excellent progress! You would almost be forgiven for thinking the buffer assembly was a much work as your crank axle!
Do you have a pic off the fullsize FS's buffer stocks?
The first thing Don Young did when inspecting any miniature locos was to compress the front buffers. If they were hard to compress approval was received. I dont know quite why Don always did this - but perhaps it had something to do with his appalling driving of miniature locos going far too fast and bumping/crashing into trains 'in advance'.
Any reason you fitted rubber discs instead of springs?
Cheers, Julian
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Post by Deleted on Oct 21, 2016 23:05:52 GMT
Thanks Julian I have a few pictures,, not very close though but close enough.... I haven't bothered with the cast lettering... regarding the rubber discs, this is as per prototype, Don certainly knew his stuff when it came to Gresley Pacifics....you can just see the rubber/steel discs in this picture, Don has told what these were called, I must dig out his words to remind me, the discs are bonded together and actually called springs, I just can't remember their name now. cheers pete
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jma1009
Elder Statesman
Posts: 5,901
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Post by jma1009 on Oct 21, 2016 23:31:03 GMT
Hi Pete,
Note how the right hand buffer has a curve on the boss greater than that on the left hand buffer. The right hand buffer looks more like the original type.
But I'm no LNER Gresley expert!
Eddie will hopefully comment in due course.
Cheers, Julian
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Post by Deleted on Oct 21, 2016 23:35:42 GMT
Can't say that I noticed, probably just down to whoever machined it or perhaps wear, it's not the original as those had a different shape altogether with a flat outer ridge
Pete
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Post by Jim on Oct 22, 2016 0:03:31 GMT
I think the 'sharp' edge to the curve on the RH buffer housing may be more to do with the lighting as it doesn't appear obvious in the outdoor shot of Flying Scotsman. That might be a good excuse for me to book a flight to come over to check....if I'm allowed.
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Post by Deleted on Oct 22, 2016 0:16:57 GMT
Oh...sorry I misread what you were saying Julian...thought you was talking about the buffers themselves....sorry, no idea why the difference...not at the PC right now so can't check my reference pictures...
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Post by Deleted on Oct 22, 2016 8:44:31 GMT
Your observation has intrigued me, Julian, I've been digging through my reference pictures to see if I can spot when this may have changed if indeed it has as I agree they do look different. I'm beginning to think, though, that either Jim is right and it's a trick of the light or this particular buffer may have had some sort of repair. I am convinced though that the buffer as drawn by Don is correct, I have looked through many pictures and they all look sharper edged than what the right-hand buffer suggests today. That includes from built up to at least 1994, the Wembley exhibition photo's in particular, show the buffer shape well as they are unpainted, same shape when Pegler bought her in 1963 too and both looking identical, so who knows what the true story is, as I said I was intrigued by your observation, very interesting... BTW she had a complete new buffer beam made for her last restoration, first in over 50 years, I have no info on whether the buffers were worked on or not. regards Pete
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pault
Elder Statesman
Posts: 1,497
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Post by pault on Oct 22, 2016 9:50:38 GMT
Hi A possibility for the difference is that the two buffers were cast at different workshops from different patterns. There is a fair probability that the patterns although made from the same drawings could have βlocalβ differences. These local differences were often as a result of the old pre grouping rivalries. Doncaster and Darlington even had slightly different shades of apple green because of this.
The other thing is in this day and age we expect everything to be made exactly to a highly detailed drawing. In those days some things were left to the discretion of the craftsman and should a pattern be damaged it would not be out of the realms of possibility that it would be slightly changed as part of a repair.
Regards Paul
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Post by nick952 on Oct 22, 2016 10:33:57 GMT
Hi Pete,
Lovely work and in particular the work on your Crank Axle. I'm about to start on the crank axle for my castle and it's the only part that concerns me about the whole engine(as I've not made one before), but your build has given me a couple of ideas.
The rubber/steel stack is I think, called an Elastomeric Spring.
Nick.
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Post by Deleted on Oct 22, 2016 10:55:18 GMT
Hi nick
Thank's for your kind words...I was also very wary of making the crank but it was pretty straight forward, in the end, I did take it slowly though. The real test however won't be known for some time yet, fingers crossed it will pull a heavy load without any problems. Your mention of the rubber/steel stack reminded me to go and check what Don had written, especially as the word 'elastomeric' didn't ring any bells. Don states that the discs were, from what I can tell, all bonded together in a mould and were called 'Spencer springs'.
I look forward to following your progress with the castle, lovely looking locomotives...
Regards
Pete
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