mbrown
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Post by mbrown on Nov 6, 2021 19:24:54 GMT
Wrapper SheetsA bit of workshop time today saw the flanged plates trimmed to length and the firebox inner and outer wrappers bent to shape. IMG_20211106_173734 by malcolm brown, on Flickr On the wall behind is the drawing of the full size loco's boiler, blown up to 1:9 so that it is correct size for the model. The wrapper sheets were reasonably straightforward. I didn't make wooden formers as some do, as the shapes are pretty easy. But I did use my home made bending gadget which is a length of bedstead angle, a couple of 1/4" studs and a length of 1/2" round bar. IMG_20211106_171255 by malcolm brown, on Flickr Here it is being used to trap a length of 3.5" steel tube around which I bent the outer wrapper. Doing this with the copper in "as received" hardness meant that it sprang out to just the right 4" inner radius although I then annealed it once to get a really good fit to the backhead and barrel. IMG_20211106_171518 by malcolm brown, on Flickr I have also drilled holes through the V of the angle in such a way that the bar can be tightened down to draw a plate into fairly tight bends. I used it that way on the firebox inner wrapper. IMG_20211106_172726 by malcolm brown, on Flickr More tomorrow, I hope. Malcolm
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mbrown
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Post by mbrown on Nov 7, 2021 18:50:58 GMT
Tubes and Tubeplates
On we go with the boiler.... First job this afternoon was to make a little gadget copied from someone else's thread on this forum (sorry, can't remember whose) to put a bead on the end of each tube to stop them falling through the holes in the tubeplate. It consists of a small former, turned to fit inside the tube and a roller which is brought up against the tube to form the ridge. IMG_20211107_163803 by malcolm brown, on Flickr With the tube end well annealed, and holding the tube lightly in the right hand, it worked well on the 7/16" dia small tubes. IMG_20211107_163841 by malcolm brown, on Flickr It was less happy with the 18g flues, so as there was plenty of thickness in them, I used the alternative approach and turned a few thou off a short length at the firebox end, cutting the holes in the tubeplates to match. Next up were the tubeplates and I did these the usual way, marking out the tube layout on the firebox former and drilling through at 1/8" then using the former to spot the holes in the tubeplate. For drilling the tube holes, I ground up an old 7/16" drill, by hand, to the profile recommended by Alec Farmer in his book. Used with cutting oil and a slow speed, it does the job very nicely. IMG_20211107_173207 by malcolm brown, on Flickr So, after doing the same on the front tubeplate, cutting the flue holes with a Cone Cut, and countersinking the tube holes roughly with a 9/16" drill, we have the tubeplates done. I also cut the various holes in the boiler barrel for the dome and bushes. IMG_20211107_182312 by malcolm brown, on Flickr It will soon be time to start sticking it all together.... Malcolm
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mbrown
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Post by mbrown on Nov 13, 2021 18:28:02 GMT
First heat - and a bit of a blooper...First job today was to solder the dome and bushes into the boiler barrel. All went smoothly and most of the solder stayed where I wanted it. On the side furthest from me in the brazing hearth, I was a little unsure that the joints were filled as they were hard to see, so I added "just a little more" solder and of course that led to a run down the side of the barrel. Nothing much, but impossible to hide. Now everyone will know it isn't a professionally built boiler!! This is the good side... IMG_20211113_163001 by malcolm brown, on Flickr I then spent a lot of time fitting the throatplate to the barrel, trimming the firebox wrapper to shape and then fitting that to the barrel and throatplate. Here it is, fixed with about six 8 BA steel screws and nuts. IMG_20211113_180552 by malcolm brown, on Flickr I took a lot of trouble to make sure everything lined up nicely. Unfortunately, after looking at this picture I realised I had put the throatplate and wrapper on the wrong end of the barrel.... Various rude words followed, but I was relieved I had spotted it before starting the braze-up. So apart it all had to come.... It shouldn't be a disaster. All the screw holes come well within the barrel extension beyond the tubeplate and in the overlap with the smokebox. If I want, I can plug them at the same time as fitting the tubeplate, but they won't affect the integrity of the boiler. But I am kicking myself, both for wasting precious workshop time and for nearly ruining the job. The moral is, don't press on when you are tired... as I was after a hard week and a morning rowing with a crew who are fitter than I am! There's always tomorrow to put things right. Malcolm
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mbrown
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Post by mbrown on Nov 14, 2021 19:26:24 GMT
Outer boiler shellIt didn't take long to reassemble the throatplate and wrapper at the correct end of the barrel... Once it was all screwed together and I could be sure the joints were all well pulled together, each screw was removed in turn, the holes opened out and countersunk, and each screw replaced with a 3/32" copper rivet. A long time ago, someone gave me a short piece of Easyflo foil - too small to do much with - and it has lain around the workshop for at least a couple of decades. I decided to make small washers out of it to put under each rivet head. Getting at the inside heads when the boiler is red hot isn't all that easy, and this ensured a neat ring of solder around each inside head. IMG_20211114_155028 by malcolm brown, on Flickr The it was out to the hearth and get it all hot. Using a 2" burner on my Bullfinch torch, it didn't take long and the solder flowed nicely. Too nicely, in some places as - as I usually find - the flux runs and the solder follows it. So there are silver runs down the outside to the wrapper, but that will mostly be in the area of the stays so will ultimately contribute to sealing them, I hope! IMG_20211114_175218 by malcolm brown, on Flickr Although some of the joints don't look very full of solder, there are neat fillets on the other side of the joints, so penetration was good. I can always put a little dab on that bottom rivet when I come to do the stays. And here is the shell mounted on the frames for the first time. Propping up the rear by 1/16", where the foundation ring will sit on top of the frames, brings the boiler dead level - which is correct as the foundation ring sits on a bronze slipper and I now know that this will be just 1/16" thick as designed. The stain on the barrel is because the acid in my pickle tank needs topping up - I can't immerse the middle bit of the boiler at present. IMG_20211114_175401 by malcolm brown, on Flickr By close of play today, I had got the firebox tubeplate and wrapper together with screws, pending replacement with rivets, and the tubes sit nicely in place. IMG_20211114_173930 by malcolm brown, on Flickr Soldering that up will have to wait for next weekend. Best wishes Malcolm
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mbrown
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Post by mbrown on Nov 20, 2021 18:48:46 GMT
Foundation ring, firebox and tubes.I have never been entirely happy with the usual way of making foundation rings from square copper bar and then filling the gaps at the corners with slivers of copper hammered in, In particular, the corners of the inner firebox, where there is always a bit of a radius on the corners of the tubeplate and door plate, present problems of that sort. I thought it was worth trying something better... So, for the front section of the foundation ring, I machined a piece of 1/2" x 1/4" copper bar to be a neat fit over the firebox tubeplate at the bottom. IMG_20211120_140251 by malcolm brown, on Flickr Then, with a 3/32" slitting saw in the lathe, I cut two short slots to accommodate the firebox wrapper sheet where it butts up against the tubeplate. IMG_20211120_140547 by malcolm brown, on Flickr The outside of this piece was then fitted carefully into the inside of the throatplate, ensuring that the centres aligned. IMG_20211120_141716 by malcolm brown, on Flickr There may be a little fitting to do as the solder fillets around the tubeplate will need to be taken account of, but I think this is a much better solution than trying to plug the gaps in an ad hoc way. I will aim to do the same with the rear foundation ring, and the sides can then be filled in with 1/4" square bar. Then it was time to assemble the inner firebox and tubes and silver solder the lot. It all went well and there is a good fillet of solder around every tube on both sides. IMG_20211120_162901 by malcolm brown, on Flickr IMG_20211120_162918 by malcolm brown, on Flickr Tomorrow I will do a reheat and get some more solder into that top corner where the flange didn't fully bed down onto the wrapper. There is a good fillet on the other side, but the gap is unsightly and leaves a nagging doubt that I would rather deal with straight away... Best wishes Malcolm
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oldnorton
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5" gauge LMS enthusiast
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Post by oldnorton on Nov 21, 2021 10:12:24 GMT
Very interesting to watch your progress Malcolm. I do like the heavy angle iron and stout bar to achieve large radius bends. I have made a few bending jigs in the past but nothing like that before. Simple and obvious once first seen, thank you Norm
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Gary L
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Post by Gary L on Nov 21, 2021 17:19:04 GMT
Very interesting to watch your progress Malcolm. I do like the heavy angle iron and stout bar to achieve large radius bends. I have made a few bending jigs in the past but nothing like that before. Simple and obvious once first seen, thank you Norm Yes, it works well, and unlike rolling, on long bends you can apply pressure to the middle of the ‘stout bar’ to prevent it bowing. Worth noting that professionals use this method too, but prefer channel to angle, because ‘springback’ prevents you achieving a full 90 degree bend otherwise. Spread heavy vinyl or similar across the channel or angle to prevent scoring of the work. Gary
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mbrown
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Post by mbrown on Nov 21, 2021 18:20:43 GMT
Thanks Gary,
I do have a length of channel which I have used in this way - specifically to bend up the doubler plate at the base of the dome which needed to be a close fit to the boiler barrel.
I made my angle-based bender many years ago in the days when the budget was tight and I had to use what I could find. My mother threw out two old beds with steel angle frames, which I claimed... One became my loco building stand which is glimpsed in various pictures on this thread - the other has gradually been used up on numerous projects over the years, but one bit was rapidly transformed into the bender!
I wish I could find some more iron bedsteads going begging, but the model engineers and scrap men seem to have snaffled them all....
Malcolm
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mbrown
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Post by mbrown on Nov 21, 2021 19:00:14 GMT
Bushes and other BitsLess progress than I hoped today - partly because I started later than usual and forgot how early it gets dark. My brazing hearth is out of doors and I really ought to rig up an exterior light of some sort... Anyway, I successfully re-soldered the upper corner of the inner firebox which now has a very neat fillet on both sides. Unfortunately, in the course of the reheat, one of the bottom corners where the wrapper meets the tubeplate began to "spring" slightly and that will need another heat to put right next weekend. It shouldn't be difficult, but three heats to do a job that should have been completed in one is a bit annoying. All my boilers have involved something going not quite according to plan - it is always been remediable so far... I also finished turning the remaining bushes for the backhead and front tube plate. On the backhead, there is the usual regulator bush and, on the left, the lower water gauge bush and on the right the two bushes for the try-cocks fitted to the real loco and quite prominent. I don't know yet if I will (be able to...) make them work. The three small blind bushes are to fix the fire hole assembly and I shall need to make the backing plate at least, so that I can locate the bushes from it. The fire hole is to scale size - it's quite a big opening on the full-size loco which is handy in a model. IMG_20211121_170258 by malcolm brown, on Flickr On the tubeplate, the central bush has a recess for the wet header which seals onto the steam pipe with an O ring. The header is then clamped down by a strong-back held in place by two 2 BA studs which screw into the smaller bushes on either side. I have used this method on Lyn and on the Burma Mines loco and it works well. The top water gauge fitting is an elbow which allows the fitting to be mounted quite high up. Here it is on the prototype, and you can see it is not a right angle fitting but more of a 130 degree angle. The backhead (on the real thing and the model) has a very generous radius all around and the fitting will screw into this. (The radius, however, is obscured by the right angle edge to the cleading!). dsc_3121ztkiv by malcolm brown, on Flickr I made it by turning and drilling a length of bronze, screwing one end and adding a flange at the other. The angle was obtained by sawing out a Vee almost through the material and folding it in until the correct angle was achieved. As the gap wouldn't close entirely because of the thickness of the saw blade, I wrapped a length of 20g copper wire around the gap. When it was all soldered up with high-melting point silver solder, the wire was then filed back to smooth it off. IMG_20211121_170647 by malcolm brown, on Flickr The angle doesn't really show in the picture, but I couldn't get it to sit still in any other posture! So now I have the outer shell and the inner firebox and tube assemblies, and here they are with the internal dry pipe temporarily assembled. The manifold bush it comes off will be soldered in at a later stage. I can't do much more until the work so far has been approved by the Boiler Inspector. It may be a few weeks before we can meet up. There are various bits to do in the meantime, although the exciting stuff (assembly, staying etc.) will come later. IMG_20211121_181016 by malcolm brown, on Flickr Best wishes Malcolm
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jma1009
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Post by jma1009 on Nov 23, 2021 0:14:13 GMT
How nice to see the front foundation ring section of the method I use.
I add steps to the ends to avoid a butt joint with the foundation ring sides, and holds things in position.
Very nice work, Malcolm, and a pleasure to see on here.
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mbrown
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Post by mbrown on Nov 23, 2021 0:59:39 GMT
Many thanks Julian - in engineering (model or otherwise) most bright ideas turn out to be unoriginal, don't they! It is perfectly possible that I noted your method from your Stepney thread and absorbed it subconsciously before "reinventing" the idea.
If by "steps on the sides" you mean a vertical step to lodge the side member on, that sounds like a very good plan. My side members will have to reflect the angle changes of the foundation ring, which is parallel to the frames for an inch or so at the front and back but angled in between. So some way of keeping them from tilting even a fraction will be very handy. The parallel bit at the front sits on top of the frames so must be level in every respect.
I used to follow your Stepney thread avidly - it would be good to see it resumed....(hint, hint)
Best wishes
Malcolm
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mbrown
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Post by mbrown on Nov 27, 2021 20:20:56 GMT
Backhead and FiredoorModel Engineering ought to be an all-weather activity, but the high winds, rain and cold today have made it difficult to do much that involves the outdoor brazing hearth. I managed to get a bit more solder into the bottom corner of the inner firebox wrapper to be sure of that joint, but then beat a hasty retreat back to the relative warmth of the workshop.... The backhead bushes I turned last weekend looked too large. I hadn't measured them when I visited the loco at the WEM in 2019 but all the flanges on the boiler were either 150 mm, 120 mm or 100 mm dia. I had assumed the water gauge flanges to be the larger size but decided to turn them down to a scale 120 mm and the try-cock bushes to a scale 100 mm which look much better. They are made so that they stand well out from the backhead but are flush with the inner surface of the plate. That helps keep the waterway as wide as possible whilst leaving enough thread for the fitting. I cut out the firehole with an Abrafile (what a pity you can't get them any more...) and decided to make up the fire box door assembly as I shall need it to spot through the holes for the fixing bushes. It all mounts on a small steel plate which fits around the top right hand corner of the fire hole. IMG_20211127_170545 by malcolm brown, on Flickr Here is a picture of the door and its operating mechanism in full size. There is a third stud to fix the back plate but it is hidden behind the operating latch. DSC00462 by malcolm brown, on Flickr I started making the door itself from an oval of 1/4" BMS, starting to get the dished shape with an angle grinder then files, then emery cloth. I haven't yet got the dishing quite right so that job will continue tomorrow before adding the hinges etc. IMG_20211127_170630 by malcolm brown, on Flickr The boiler work itself will continue once I have the Boiler Inspector's verdict on the work to date. Meanwhile I will try to finish the fire door as it is quite an interesting little project in it s own right. Malcolm
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Post by Deleted on Nov 27, 2021 20:39:15 GMT
Just caught up on your boiler Malcolm, superb work sir...
Pete
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mbrown
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Post by mbrown on Nov 27, 2021 21:31:54 GMT
Many thanks Pete. It is, of course, a lot smaller and simpler than the boiler for a 5" g Gresley Pacific! But as I do a boiler on average every 10 years, it can still be challenging. I wish I could get over my tendency to add "just a little bit" more solder.... I might be able to avoid those unsightly runs. But once they are there, one can't do much about them....
Best wishes
Malcolm
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Post by Deleted on Nov 27, 2021 21:39:12 GMT
Many thanks Pete. It is, of course, a lot smaller and simpler than the boiler for a 5" g Gresley Pacific! But as I do a boiler on average every 10 years, it can still be challenging. I wish I could get over my tendency to add "just a little bit" more solder.... I might be able to avoid those unsightly runs. But once they are there, one can't do much about them.... Best wishes Malcolm From what I understand, to much solder is better than too little. A boiler that looks too neat with little solder to see may not be a sound boiler.... Pete
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mbrown
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Post by mbrown on Nov 27, 2021 21:42:37 GMT
It's a Goldilocks situation.... not too much, not too little - just right. Only I always overdo it "to be on the safe side"....!
Malcolm
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Post by Deleted on Nov 27, 2021 21:58:01 GMT
It's a Goldilocks situation.... not too much, not too little - just right. Only I always overdo it "to be on the safe side"....! Malcolm As the saying goes, better safe than sorry.... I'm only going by what Paul told me when building mine, he's a big fan of using lots of solder.
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Post by steamer5 on Nov 28, 2021 9:31:42 GMT
Hi Malcolm, Looking good, still enjoying the build...one question though bushes at fullsize of 1500 to 1000mm would be a bit on the large size, guess you managed to get an extra "0" in there?
Cheers Kerrin
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mbrown
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Post by mbrown on Nov 28, 2021 9:37:33 GMT
Hi Kerrin,
I don't "think naturally" in metric so your post made me stop and think.
You are quite right, of course! I must go back and edit my post ..
Best wishes
Malcolm
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Post by ettingtonliam on Nov 28, 2021 11:39:20 GMT
Malcolm I'm in the same situation as you - I only build a boiler every 10 -15 years, and my hearth is outside. I tend to overdo the solder as well, the only downside, apart from extra cleaning up, is the cost of the stuff! Locomotion's boiler has a cylindrical firebox, so that at least lets me off all that firebox staying. Probably no more boiler work now until the spring, I should have done more in the summer!
Your boiler is looking good so far.
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