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Post by Jim Scott on May 31, 2012 13:56:41 GMT
I agree entirely with Miken on this. When I became an apprentice toolmaker almost 50 years ago it was regarded as almost a ‘rite of passage’ that you would replace the old vicejaws with your own hardened and ground ones. If for some reason you had to get extra purchase then you could use paper, thin card or zinc sheet, or in desperation, coarse emery cloth with the rough side to the work. I found that red fibre jaws were pretty useless for any purpose at all after a few days of use. All of my workshop vices, both hand and machine, are ground dead flat and square.
Incidentally, it was also very common for hammer faces to be finely smoothed and polished. I remember my father (a sheet metal worker) having a set of planishing hammers so finished which gleamed when they caught the light.
Jim S
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Post by Jim Scott on May 21, 2012 8:55:30 GMT
Hi doubletop
I don’t know that fibre glass tape is the best heat insulation for model boilers, this was surpassed decades ago by the older silica based materials (Refrasil etc) and more so by the newer ceramic materials. The latter is not expensive for the amounts required for our relatively small boilers. Personally I wouldn’t consider anything other than ceramic matting, even if it were free. However, it is a relatively friable material which is more fiddly to apply than tape, but on the other hand it can be ‘moulded’ to some extent.
The following is from the catalogue of ‘the well known model engineers suppliers from Long Eaton, Nottingham, UK’. (No interest in this company apart from a satisfied customer).
Boiler Lagging High temperature (1200 deg C) ceramic matting in 2mm or 3mm thickness 20” wide, cut length to your requirement
Boiler lagging 2mm (0.08”) thick £2.30 per ft Boiler lagging 3mm (0.12”) thick £3.30 per ft
Regards
Jim S
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Post by Jim Scott on May 10, 2012 15:10:48 GMT
Hi Paul
Quote: “Let’s also not forget that a superheater is there to increase efficiency, a loco will run without one and do the job without a problem. Generally the biggest problem with saturated locos is seeing where you are going in cool/cold weather especially if you wear glasses”.
This is very true. The efficiency angle is up to the individual owner but the latter point concerns me most as many of our club drivers wear glasses (including me) and most others tend to wear some form of eye protection. ‘Essential ‘ may be overstating the point but we have seen on occasion simultaneous operation of multiple locos on both raised and ground level tracks. This has led to a general realization that we do need to see where we are going, especially during the Autumn/Winter months when locos have been be run in the dark.
Julian I have seen many superheater failures of the return bend type element, invariably made in copper with the failure close to the brazed joint. However I have never seen a failure of a similar stainless unit. Has anyone else, if so are details available? Note that stainless steel superheater elements are available via a well known model engineering supplies company in Nottingham and I also recall an individual advertising in ME a while back supplying ss welded spearhead return bends. (Can’t remember his name though, -Paul?)
For spearhead returns, 20 or 22swg stainless steel of any weldable grade will be satisfactory, 316 for preference. Tungsten/inert-gas (TIG)welding is generally regarded as the most suitable process. One method is to cut both tubes at an angle to form a sharp arrowhead form, weld the joint then bend back parallel. Another is to pre-bend each end slightly and cut to leave a close fitting joint with both tubes parallel and about 1/16” apart. A competent TIG welder can weld through this small gap.
If you’re going to fit stainless steel return bend superheaters you really should really take advantage of the better material properties by inserting them as far as possible into the firebox.
Jim S
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Post by Jim Scott on May 9, 2012 19:19:56 GMT
Hi Julian Our club experience is that superheaters are pretty well essential. My superheaters are as per Martin Evan’s original radiant design, ie with great clumsy blocks of stainless steel TIG welded to thin gauge stainless tube. Once again these were made a long time ago, mid 80’ I would think, the only recent work was to extend the (too short) elements by silver soldering copper extensions which also allowed the tight bends from the wet header to actually be made. I will use them as made because they don’t appear to interfere too much with the firebox arrangement. However, I suspect that all new super heater elements made for/by club members will be TIG welded spearheads in stainless steel. Folk will then have the option as to how much they want to put into the firebox. Incidentally, I was very wary of silver soldering the copper extensions. The bronze transition pieces were joined to the stainless tube using argobraze 56 (see www.jm-metaljoining.com/pdfs-products/Argo-braze%2056.pdf) Crevice corrosion can be a real problem with stainless combinations, I once had a lightly stressed, easyflo no2 joint in good quality ss/ss fail completely at the interface, albeit some years later. Not on any model engineering application I hasten to add. The bronze to copper joint can of course be silver solder I’m not a fan of co-axial superheaters either, but only in as much as they were not fitted to my 1880 protoype. Jim S
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Post by Jim Scott on May 1, 2012 19:08:59 GMT
Hello John
Like Julian, I’m trying hard to produce a reasonably accurate Terrier, as indicated in a previous post to this thread. However, my continuing valiant attempts to make a ‘silk purse’ from Martin Evan’s ‘sows ear’ requires construction compromises which may forever be a source of irritation. But it is a mid 1960’s design though and this should be kept in mind.
Your photos show some excellent manufacturing of various components, in particular the motion plate which, had you not said, I would have said was a precision casting.
Are you modeling a particular prototype? I note you have made up buffer supports which presumes it was modified for motor-train operation, ie with the raised buffer height.
Although some time away yet the thought of joining yourself and Julian for a ‘Terrier’ get together is very appealing.
Jim S
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Post by Jim Scott on Jun 30, 2011 23:33:08 GMT
Julian Thanks for including the photo of the 10 ton truck - it will look good as a tender.
Slidebars. I too wanted to fit the channel type but the relief required to clear the links etc precludes this. Alignment of the slidebars during assembly depends on some very careful machining beforehand, both on the rear cylinder cover and the motion plate. In fact Martin Evans suggested making dummy slidebars in mild steel first to check for correct fit before replicating same with silver steel. I eventually made some provision for slight adjustment at both supporting points.
A quick note re the valve spindle bushes on the steam chest. Redesign these to be removable, ie with flange and securing studs, then you will be able to install the buckle and valve spindle in one piece, easier than joining them in situ. And of course they could be made to look more to prototype...
Stroudley livery? Painting is at least a year away but I'm already halfway through Chris Vine's book....
Don Bill's animated diagram shows a horizontal engine, crankshaft on left, cylinder on right. As I understand it, he is measuring link rotation clockwise/anti-clockwise from the link true vertical position. I will look at the Wallace and other sims again though, as previously I wasn't sure about the terminology used.
Glad I'm not starting from Julian's position, although he will undoubtedly be very pleased to have a 'designer' valvegear arrangement. Could put his selling price up!
Jim S
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Post by Jim Scott on Jun 29, 2011 21:37:36 GMT
Julian It hadn't occured to me to check the overall widths etc, probably because I built the frames almost 40 years ago (slow builder!). I had realised though that the smokebox dia was too small, and no attempt had been made to represent the flat-bottomed appearance as per the original unrebuilt locos. My intention re lubrication is to fit a hydrostatic type with the tank under the footplate. Could be interesting... Would be interested in details of you LBSC 10-ton truck at some later date.
Don I may have misunderstood, but the Hall Sim reports link swings in full forward gear as: anticlock -24.9, clockwise 34.7 degrees. However, as most of the valvegear components had been built exactly (and in the case of the eccentric rods, incorrectly) as plan before I discovered your book, my only variables left were valve adjustment on its rod, the link suspension offset and the eccentric positions. The table of cutoffs looks reasonable though; I look forward to the results of your evaluation of Julian's layout.
Jim S
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Post by Jim Scott on Jun 29, 2011 9:39:58 GMT
Hello from yet another 5" Terrier builder. (No 83 Earlswood, 70% complete, modelled circa early1890's so as to retain the condensing gear and Stroudly livery). In reply to your questions 1 My alternative boiler shell construction was to roll from 13 SWG sheet (which I already had).The boiler is now complete and tested. Note that the bottom water gauge fitting as specified could leave the firebox crown uncovered with water still showing in the glass! Modern practice in our club is to fit rod stays to the crown instead of plate stays. 2 If I were to do my wheels again I would N/C or laser cut them from solid steel. The spokes on the original loco wheels were quite thin and almost rectangular section (possibly forged?) and the castings look overscale. 3 No real problems constructing the valvegear but I'm not quite finished this bit yet. Try inputting the info into Prof Hall's simulator, from which I optimised the link suspension to point to be 0.061" ahead of the link centreline. Link swing does seem excessive though at ~ 60 degrees. (Any comment Don?). 4 I have still to make the safety valve. I believe Gordon Smith's designs were published in EiM. 5 I'm also trying to make a true representation using Martin Evans plans and consequently there are many changes/additions. One early frame headache was the size of the frame lightening holes; I believe these were both the same depth in the original loco. Martin reduced the depth on the front one to accomodate the crosshead pump mounting. Also, look at the 'Metro' notes as there were some changes of materials specified. I concur with Don's comment re better materials for the valvegear linkages as some items are quite fine when kept to scale. Try 'Portrait of the Terriers' by Handel Kardas for some accounts of operating full size Terriers. Also, this youtube clip spurred me back into action when in the doldrums a few years ago: www.youtube.com/watch?v=JM30VZAeLA4&feature=relatedFinally, some good ideas on Norman Barber's build site but I have yet to look at Alan Stepney's 'Site of Correction'. I'll do it when I'm not thinking about model engineering... Keeep up the good work! Jim S
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Post by Jim Scott on Apr 17, 2010 20:32:29 GMT
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