RMweb Gold chris p bacon Posted April 6, 2018 RMweb Gold Share Posted April 6, 2018 If you go back a bit you will see a plastikard mock up Dave built checking fit etc. Ah....but motion is a bit of a 'wing and a prayer' as I couldn't make it up in plastic to try......I think it will work.... I'll send you some bits soon as I've nearly done with the etch and most things left are WTC 5 related rather than Shannon. 1 Link to post Share on other sites More sharing options...
RMweb Premium AdeMoore Posted April 6, 2018 Author RMweb Premium Share Posted April 6, 2018 Ah....but motion is a bit of a 'wing and a prayer' as I couldn't make it up in plastic to try......I think it will work.... I'll send you some bits soon as I've nearly done with the etch and most things left are WTC 5 related rather than Shannon. Wing and a prayer Dave, I still have the faith you’ll do it, as for me perhaps the connection rods are surplus to requirements! Inside motion anybody! Or some cheat representation maybe! I’ll see soon. The bits Dave your most kind but no rush as you can see, progress is quite slow. Cheers Ade Link to post Share on other sites More sharing options...
RMweb Premium AdeMoore Posted April 6, 2018 Author RMweb Premium Share Posted April 6, 2018 (edited) Is there enough clearance thus far behind the cylinder crosshead on this tiny prototype? Worth considering now while you are assembling the coupling rods. I would suggest that the thickness of those rods will give you problems later on, especially once you put the retaining bushes on the forward crank pins. Paul A. Paul quote from the instructions remember we are talking 7mm here not 4mm I’m building.However, the front wheels present difficulty, with the crosshead moving exactly across the area where the crankpin nuts want to be! One solution I use is fairly 'low-tech', but effective. Substitute a 10BA screw for the 12BA supplied, grip the top-hat bearing in a pin vice and tap 10BA. When assembling the front crankpin, put the top-hat bearing on back to front so the flange part of the top-hat lies outside the coupling rod boss, thereby eliminating the need for a washer and nut. By carefully eliminating excess clearances and thinning the bearings flange, by rubbing on wet & dry, a neat (almost) flush fitting crankpin results. In practice, the brass bush can be wound onto the screw until any slack is taken up and then retained with a spot of varnish or Loctite 242 Nutlock, which is a low-strength locking fluid that will allow removal, at a later date. Umm food for thought I’ll probably see what Dave does then see where it takes me. Edit to remove text, added by mistake. Edited April 6, 2018 by AdeMoore Link to post Share on other sites More sharing options...
N15class Posted April 6, 2018 Share Posted April 6, 2018 And if you countersink the front coupling rod hole the crank pin bush can be flush to the coupling rod. Even more space, and prototypical. 1 Link to post Share on other sites More sharing options...
doilum Posted April 6, 2018 Share Posted April 6, 2018 And if you countersink the front coupling rod hole the crank pin bush can be flush to the coupling rod. Even more space, and prototypical. In this game, every thou counts. The secret is not to focus on one component, but to look synoptically at the whole mechanism. Slimming a thou of each face usually works better than taking three from one of them. 1 Link to post Share on other sites More sharing options...
N15class Posted April 6, 2018 Share Posted April 6, 2018 I agree that it needs to be looked at as a whole, but thinning a coupling rod from 3 or 4 layers down to 2 or 3 layers will give you a 0.020" extra without any undue weakness. Better than making the back of the crosshead too thin. 1 Link to post Share on other sites More sharing options...
John_Hughes Posted April 7, 2018 Share Posted April 7, 2018 Which is what led me to the template. Once the coupling rod holes have been opened up they have lost that precision. Many years ago, I invested in John Ahern's classic book and soldered frames together before drilling. I still have the twisted wreckage. It took thirty years to gather the confidence to return to scratch building frames. Each has to find their own preferred method by absorbing other people's ideas. My scratch building tally stands at five chassis, including two pairs of same class locomotives. One refinement is to leave the frame blanks over length, drill 1mm location holes in the diagonal corners and then drill a 4mm hole close to each end. The frames can then be fastened down with a small wood screw. John Ahern's opus - I have a copy to which I refer surprisingly frequently - is certainly a useful book to have, but astonishingly he nowhere refers to the need to make the coupling rod centres precisely match the wheelbase, let alone give any suggestions as to how this can be done. Perhaps this is why the Madder Valley line reputedly didn't run as well as it looked! I'm very much of a jig-man myself, starting with the rods - in fact getting them completely finished in case continued working affects them in any way - and using them to establish the axle locations. Is this less accurate than clamping the blank rods to the blank chassis and drilling pilot holes through both at the same time? I'm not sure that it is, though many people recommend that way of doing things. It's surprising how drills can drift as the various holes are opened out to the final dimensions, and to ream out an axle hole to something over 1/8" when you're starting with a No. 72 drill or similar is something I'd rather not have to do. But we all develop - or borrow - techniques that work for us; there's no absolute single right way. 1 Link to post Share on other sites More sharing options...
RMweb Premium AdeMoore Posted April 26, 2018 Author RMweb Premium Share Posted April 26, 2018 (edited) Posts not loading all content try again. Give up! Edited April 26, 2018 by AdeMoore Link to post Share on other sites More sharing options...
RMweb Premium AdeMoore Posted April 26, 2018 Author RMweb Premium Share Posted April 26, 2018 (edited) No better! Edited April 26, 2018 by AdeMoore Link to post Share on other sites More sharing options...
RMweb Premium AdeMoore Posted April 26, 2018 Author RMweb Premium Share Posted April 26, 2018 Right been a while, been ill again and another hospital stay but back to it! First Dave of Chris P Bacon Sandy fame has been more than generous he posted me his spare etches from his excellent build here http://www.rmweb.co.uk/community/index.php?/topic/57208-sandy-gn-lnwr-or-bre/page-29 what’s more he wouldn’t take any payment for anything even the postage. Quote “It's yours for Gratis..Freebie...Nuffink...even if you only use a few bits as for me it's the fun of the build” Thank you again Dave. So the coupling rods were being a pain as many suggested they would! Binding up the wheels lost my mojo a bit to get it sorted, I could of moved on to something else but even the cylinders and cover plate relied on the spacing of the connecting rods to make them. Perhaps I should of done the footplate, never mind Daves delivery was the answer to my prayers, laminated his etches first time I’ve ever soldered a laminated etch part. Checked the centres um as tight and perfect as my rough ones. I still liked them so much more I moved on and spread the bush holes. No one will notice those holes will they 5 Link to post Share on other sites More sharing options...
RMweb Premium AdeMoore Posted April 26, 2018 Author RMweb Premium Share Posted April 26, 2018 Photos ended up in reverse order and captions gone can’t fix it! So chuffed to get a nice rolling chassis with coupling rods! Video here of the 3F pushing Jane along! Here she is ready to fit Daves fine etches of the connecting rods. Cruel close up photos. Last two photos. 4 Link to post Share on other sites More sharing options...
RMweb Gold chris p bacon Posted April 26, 2018 RMweb Gold Share Posted April 26, 2018 That's really good, it also goes to show that the spacing you've done for the axles is accurate, as we both took the measurement from the same drawing. There's still a fair bit left to scratch build but those bits will give you a bit of a 'leg up' Link to post Share on other sites More sharing options...
RMweb Premium AdeMoore Posted May 10, 2018 Author RMweb Premium Share Posted May 10, 2018 Bit more done, Jarred off reducing bush length on the crankpins for a tighter clearance, in the end thought flip this I’ll never get it done and left em as they came. Below in the lead up to that the journey to it. First 0.5mm shim added to coupling rod boss to give a measurement of bush length. Then finding a way to hold bush for filing down so blummin small duster or magic cloth in this case helps retain it when dropped instead of pinging off if used over a hard surface. Below in pliers no resulted in a squashed bush. Helping hand no good either won’t hold tight or square. In the end surgical tweezers did the trick but I had it slightly off square. I then realised a cocktail stick in the end and sanding on emery cloth was the answer, but over did it and made it flush with coupling rod. No gap to connecting rod. So ditched that and put together as is and will widen the cylinder spacing to suit. Next started on cylinders and tried a cheap set of snips on some 0.25mm brass worked ok ordered some expo magic scissors going to try them also for £3.50. Pritt sticked on paper template. All comments gratefully received. 3 Link to post Share on other sites More sharing options...
RMweb Premium AdeMoore Posted May 10, 2018 Author RMweb Premium Share Posted May 10, 2018 Making up Daves etched connecting rods. Making a jig from deheaded track pins. Note long nosed pliers to hold them by, easy to hammer in then. Drilling for the bush size. Cleaned up done, 2 Link to post Share on other sites More sharing options...
N15class Posted May 10, 2018 Share Posted May 10, 2018 I find the easiest way to file crank pin bushes is to push them into the coupling rod hole from the front, then put the whole lot on the bench with the outside face and flange on the down side. File off the bush until you have the length you require. Filing from the the back helps if you slip the front remains undamaged. You would be better opening out the hole with a broach or tapered reemer. A drill bit even if it's backed off is likely to snatch and bend your rod. You seem to be progressing nicely. Half the battle is doing it slowly and finishing before going onto the next stage. 1 Link to post Share on other sites More sharing options...
jdb82 Posted May 10, 2018 Share Posted May 10, 2018 (edited) Agree with using the broaches - drill bits can leave the hole slightly elliptical which can cause binding. Make sure your broach is sharp though, or these too can snag. Here speaks the voice of recent experience! N15class gave me a good piece of advice - if it's throwing up lots of burr, it's not sharp enough! Shame I didn't think of that before I bent my coupling rod through 90 degrees ;-) I'm enjoying following this thread - good work! Edited May 10, 2018 by jdb82 1 Link to post Share on other sites More sharing options...
doilum Posted May 10, 2018 Share Posted May 10, 2018 Bit more done, Jarred off reducing bush length on the crankpins for a tighter clearance, in the end thought flip this I’ll never get it done and left em as they came. Below in the lead up to that the journey to it. First 0.5mm shim added to coupling rod boss to give a measurement of bush length. ACF0EA4F-A279-4E89-85FE-632365C3F391.jpeg83B15A14-DD2A-4875-8A20-FE6F50A5F4F6.jpeg 3AD9D419-32C4-4AF5-A99A-58F43076DC9C.jpeg Then finding a way to hold bush for filing down so blummin small duster or magic cloth in this case helps retain it when dropped instead of pinging off if used over a hard surface. 2C71E4C3-61B3-4751-8378-D829793743B0.jpeg Below in pliers no resulted in a squashed bush. 7E98C628-2CFC-4831-AA1E-D04E87C796BF.jpeg 380EDA88-BEC5-45F9-B458-0EF22D643CDC.jpeg Helping hand no good either won’t hold tight or square. 71EAE345-4B2C-4E25-BD5D-DDEBBFD39B46.jpeg In the end surgical tweezers did the trick but I had it slightly off square. ADFC51B3-B307-48CA-A6ED-883E03E7481D.jpeg I then realised a cocktail stick in the end and sanding on emery cloth was the answer, but over did it and made it flush with coupling rod. No gap to connecting rod. So ditched that and put together as is and will widen the cylinder spacing to suit. DE33B667-237A-4EAA-B08D-421E981B8EB4.jpeg Next started on cylinders and tried a cheap set of snips on some 0.25mm brass worked ok ordered some expo magic scissors going to try them also for £3.50. Pritt sticked on paper template. 0F2B9744-0C71-4FD0-B925-F88B744BA80F.jpeg 02C9C493-96E7-4264-84F9-E072E9374E8F.jpeg All comments gratefully received. It is surprising what can be cut with a decent pair of kitchen scissors 1 Link to post Share on other sites More sharing options...
RMweb Gold chris p bacon Posted May 10, 2018 RMweb Gold Share Posted May 10, 2018 Looking good. When you plan and mark out the cylinders make sure you mark from the rods to get the cylinder position. When I drew the etches I took the measurements from the drawings and even allowing for the rods and pins it was still tight, so had to rework the cylinder positions. She has very little clearance but it can be done. Apart from fitting the motor and box in the boiler/firebox, you're on the hardest part and doing well Link to post Share on other sites More sharing options...
N15class Posted May 10, 2018 Share Posted May 10, 2018 Agree with using the broaches - drill bits can leave the hole slightly elliptical which can cause binding. Make sure your broach is sharp though, or these too can snag. Here speaks the voice of recent experience! N15class gave me a good piece of advice - if it's throwing up lots of burr, it's not sharp enough! Shame I didn't think of that before I bent my coupling rod through 90 degrees ;-) I'm enjoying following this thread - good work! I did forget to say a drill bit with two flutes also tends to drill 3 cornered holes. 1 Link to post Share on other sites More sharing options...
PenrithBeacon Posted May 10, 2018 Share Posted May 10, 2018 ... You would be better opening out the hole with a broach or tapered reemer. A drill bit even if it's backed off is likely to snatch and bend your rod. ... Broaches have their usefulness but they make a tapered hole, so not so good for a bearing. Best to use a reamer but these small ones are dreadfully expensive. If they can't be afforded then use a broach from both sides of the workpiece alternately. https://eileensemporium.com/index.php?option=com_hikashop&ctrl=product&task=show&cid=645&name=hss-hand-reamer-2-0mm&Itemid=189&category_pathway=1050 1 Link to post Share on other sites More sharing options...
RMweb Premium AdeMoore Posted May 10, 2018 Author RMweb Premium Share Posted May 10, 2018 Looking good. When you plan and mark out the cylinders make sure you mark from the rods to get the cylinder position. When I drew the etches I took the measurements from the drawings and even allowing for the rods and pins it was still tight, so had to rework the cylinder positions. She has very little clearance but it can be done. Apart from fitting the motor and box in the boiler/firebox, you're on the hardest part and doing well Cheers for that Dave, the template for the cylinder block has been widened from the dimension of the rods. I made it look so professional there you didn’t notice 1 Link to post Share on other sites More sharing options...
RMweb Premium AdeMoore Posted May 31, 2018 Author RMweb Premium Share Posted May 31, 2018 Slow progress been gardening/outdoor weather! Of late a small bit more done this evening. Scratch building is pretty slow compared to popping an etch out a fret and cleaning up. But very satisfying. Not a great standard but hopefully I can make the motion work. Filing up the cylinder covers. Trying out piston cover on the cylinder cover. Folding up cylinder block, just to see how it looks. Drilling Prep to drll to piston hole size. Using the back cover as a template to drill the front cylinder cover. Filing vee’s to aid folding. Test fit prior to fitting brass tubes and soldering up. Any comments appreciated. 2 Link to post Share on other sites More sharing options...
RMweb Gold chris p bacon Posted May 31, 2018 RMweb Gold Share Posted May 31, 2018 Only question I can think of, did you mark up the piston rod holes against the rods ? I found that the clearance was really tight with the slidebars and crankpins and had to ease them out again. I'm now waiting for some etches for 'Little England' which was the other locomotive on the Sandy & Potton. 1 Link to post Share on other sites More sharing options...
RMweb Premium AdeMoore Posted June 2, 2018 Author RMweb Premium Share Posted June 2, 2018 Only question I can think of, did you mark up the piston rod holes against the rods ? I found that the clearance was really tight with the slidebars and crankpins and had to ease them out again. I'm now waiting for some etches for 'Little England' which was the other locomotive on the Sandy & Potton. Dave yes I measured off the frames to the centre of the connecting rod 7mm. Massive I know but that because the crankpin bushes I gave up on make it that. Am I right with that is that what your asking?Looking forward to Little England is Shannon running on the layout yet? Cheers Ade 1 Link to post Share on other sites More sharing options...
RMweb Premium AdeMoore Posted June 2, 2018 Author RMweb Premium Share Posted June 2, 2018 (edited) Another question on those darn crank pins, should the bushes be tightened against the wheel and therefore the coupling rod rotates around it or somehow the bush is fixed in the rod and the bush rotates on the crankpin? This is the way my mind says it should be but I can’t fathom with what’s in the pack how it can be achieved? It’s a Markits pack for romfords. . Edit to say what’s in the kit 6 x crankpins, 6 x bushes and 6 nuts. Any help very greatfullly received............ Cheers Ade Edited June 2, 2018 by AdeMoore Link to post Share on other sites More sharing options...
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