Darwinian Posted February 3, 2012 Share Posted February 3, 2012 OK here goes, my first attempt at a thread of my own in this section.In between the day job, family and so forth I'm building a Gibson kit of a GWR 850 pannier tank that I purchased at the York show about four years ago.To start off here is the progress on the chassis. I've never been entirely happy with wiper pickups so thought I'd try doing what Triang used to do!Chassis spec is therefore:Sprung using supplied system (another experiment as a change from beams).Small Mashima motor mounted on Branchlines multibox (40:1 I think, I did this over a year ago).Plunger pickups one side.Wheel rims shorted to axles using Martin Finney etched shorting wires on the other, giving a live chassis.Gibson wheels (I section spokes) fitted using a GW wheel press.Underside of boiler represented to hide mechanism. I pinched this idea from the high level kit for the 57xx chassis.Here is the early running chassis. I just built it according to instructions with the axleboxes built up in situ and much to my surprise it ran smoothly!Last week I added the brakegear. Twice because I put the pull rods outside the wheels to start with and cursed when the cranks hit them . A quick check in Russells books and on the instructions helped me to realise they go inside the wheels on these tanks. So the chassis looks like this now. Sorry about the camera shake on the close up shot.I'll post more when I get the time. Starting this might encourage me to finish the job before another year has passed .Adrian. Link to post Share on other sites More sharing options...
N15class Posted February 4, 2012 Share Posted February 4, 2012 This 850 builds into a lovely loco. I did a saddle tank one, from the days before Alan got hold of them. There is a photo in my gallery. I made it to EM gauge. I look forward to seeing more. Link to post Share on other sites More sharing options...
Castle Posted February 4, 2012 Share Posted February 4, 2012 Hi Darwinian, Well done on a first thread - I have just done the same myself! The chassis looks great and I look forward to seeing this little pannier develop. The 850s were nice locos that exuded their period either in pannier or saddle tank form. It is such a shame that one wasn't saved as we would have had an Armstrong loco to look at today! They lasted until the 1950's so they came very close ... All the best, Castle Link to post Share on other sites More sharing options...
Darwinian Posted February 4, 2012 Author Share Posted February 4, 2012 Thanks for the comments. Here are some rather gllomy pictures of early stages in the construction of the body. To get the join between panniers and cab aligned I soldered a thick piece of Nickel silver fret waste into the end of the tanks and drilled and tapped it 10BA. Corresponding slightly oversize hole in the back of the cab accepted 10BA bolts to hold everything aligned while I soldered the two components together into a single unit. Prior to this the opening in the boiler underside was extended so that the verticle joint with the chassis part of the boiler falls behind the front springs. Main body parts: The first big problem arose when fitting the assembled superstructure ot the footplate. With the valve cover box at the front it was about 1.5mm too long to fit between the raised buffer beam tops . I got around this by taking the front off the pannier tanks and filing back the edge of the whitemetal component until it was very thin. I then reduced the back and front of the valve cover box as well. Finally the buffer beams came off the footplate and a pice of scrap fret was carefully fitted behind each to move them slightly further away from the footplate etch. Hopefully it isn't too obvious. The footplate bolts to the main superstructure at in the smokebox and under the cab. A dash of grey rattle can primer showed up where there were still gaps around the tank joints. These have now been filled and I'm now at the stage shown below. Wonder how i can improve the fit of the dome. Didn't notice that gap around the back before . Hope to get some more detailing done now that half term is approaching. Adrian Link to post Share on other sites More sharing options...
RMweb Premium Siberian Snooper Posted February 4, 2012 RMweb Premium Share Posted February 4, 2012 Hi Adrian I have one of each in the to do supply of unbuilt kits, I like the progress you are making, they are nice little engines. Cheers SS Link to post Share on other sites More sharing options...
Darwinian Posted February 12, 2012 Author Share Posted February 12, 2012 Some more, if slow progress on the 850. I was distracted on Friday evening making a jig to bend up the G shaped handels for GWR coaches. What I thought would be a half hour job took three times as long . Apart from fettling work done so far and fitting the steps to the tank front the main progress has been making the cab roof and adding some details to the footplate. The roof is a fully etched component so is ridiculously thin. I cut a square of brass sheet and laminated it to the underside of the roof, using 120 degree solder, after rolling both to the correct profile (simply done using a parallel knife handle on my thigh). Then mounted the whistles. These were lost wax rather than turned and had a right angle pipe to fit into the cab front. On this engine they are mounted on the cab roof so I snipped off the tail pipe as close as possible and then cleaned up by putting the whistle into a mini drill and gently filing, with a fine needle file, as the drill spun the component. Here's the result: I have also fitted the handrails over the front steps (not all locos had these steps) the reversing rod and a shelf to support the tool box. The latter isn't included in the kit but without it the toolbox will not fit over the edge of the smaller part of the splasher. I had to cut a gap in the shaft across the frames because a wire to the pickups has to slide through as the body is fitted to the chassis. Hope fully it won't be obviuos in the gloom under the tanks. A bit more cleaning up is still required. Then it's on with the small details, lamp irons and so forth. Adrian Link to post Share on other sites More sharing options...
Darwinian Posted February 19, 2012 Author Share Posted February 19, 2012 Detailing is now the order of the day. Here are some shots of progress with the "face" of the loco. I use small staples (an Ian Rice tip from years ago) for lamp iron material which seems to solder quite well with 120 degree solder. They are already flat and have one bend already done for me. The Gibson smokebox door handles have been modified slightly with a fine needle file to flaten the profile of the "knob" end front to back and make it more cylindrical too. I realised when I took the photo that I've left off the top lamp bracket so will have to remember to do that when I do the bunker ones. I spent ten minutes looking for the lance cock casting after it pinged out of my tweezers onto the carpet. Amazingly I did find it again. Perhaps I should have bought a lottery ticket . Adrian Link to post Share on other sites More sharing options...
Castle Posted February 19, 2012 Share Posted February 19, 2012 Hi Adrian, This is coming along very nicely - keep up the good work! I would like do do a Gibson kit someday as they look great. Perhaps when the heap of bits, ideas and potential that is destined to become 4709 is more advanced I can justify one in the collection... All the best, Castle Link to post Share on other sites More sharing options...
Darwinian Posted March 11, 2012 Author Share Posted March 11, 2012 I've not had much time to work on the little pannier recently however progress is being made on the final details. I've never been very good at getting the front handrail right and this one is particularly tricky as it has a straight bit along the top. After much fiddling and fettling this is the best I could manage. I searched through the frets loking for the front guard irons and not finding any looked at pictures of the real thing. It didn't have any, just extension pieces fitted to the front brake hangers. I've yet to fit these, something that probably should have been done whilst assembling the brake gear. The bunker rear has also had it's ironmongery added using small staples again. Once again I forgot to do the top lamp iron Hopefully I'll be able to finish the detailing soon and get on to the painting. Just nicely timed as the weather starts to improve as i do my painting outdoors. Thanks for looking. Adrian Link to post Share on other sites More sharing options...
Castle Posted March 11, 2012 Share Posted March 11, 2012 Hi Adrian, That's going really well! You have got to the stage where it all looks very multi coloured / multi material and in a way I find it quite cathartic to get that coat of primer on it to even it all out as it allows the picture in your brain to begin to match what you have on the workbench! I am glad to see that you too are a user of the ultimate in well ventilated spaces as well (weather permitting). Well, it is what is says on the cans... I am also glad I am not the only one who forgets the proverbial 'top lamp iron'. When I did my model of Churchward Mogul No. 5322 I completely forgot both spare lamp irons on the side and only noticed when I started weathering it, having reminded myself to be careful around them, and realised that the darn things weren't there! Sometimes you can look and look at something only to find you missed the stunningly obvious... Taking the pictures for my thread I have found really useful and it enables you to be positively self critical. Something that can only go to improve anyone's modelling. Keep going - I look forward to seeing this little gem finished! All the best, Castle Link to post Share on other sites More sharing options...
Darwinian Posted April 15, 2012 Author Share Posted April 15, 2012 Just an update to confirm that I haven't given up. Other pressures on my time and the recent miserable weather have slowed down progress. The loco now sports pre1928 GWR green (precision enamel) and black (Halfords rattle can) but the green finish is not as good as I would have liked. My airbrush technique has obviously got a bit rusty. I am applying Humbrol gloss coate by brush to see if I can get an acceptable finish to apply the lettering. Chassis has recieved a single coat of Precision paints frame grime. Will update with photo's when I have a chance and some sunshine to take them in. Adrian Link to post Share on other sites More sharing options...
Darwinian Posted April 24, 2012 Author Share Posted April 24, 2012 Well that didn't work out too well! It seems that glosscoat over precision enamels is not a good idea. The paintwork acquired a nice fine crackle effect. This happened to me with humbrol satin varnish on my rebuilt P1 but isn't too noticeable under the grime and from a normal viewing distance. This time it was worse. I'm sure I've used Humbrol acrylic varnishes over precision paints in the past without any problem. Oh well, time to find some Nitromors and an ice cream tub, at least the footplate is looking OK. Anyone got any recomendations as to what varnish will be OK? Adrian Link to post Share on other sites More sharing options...
Darwinian Posted June 20, 2012 Author Share Posted June 20, 2012 Finally after a prolonged lay off due to pressures of work I've had time to attack the little 850. The failed paintwork was stripped, the rather unsightly moulding lines on chimney and dome addressed and all the bits that fell off during paint stripping put back on. It is now awaiting a final coat of satin varnish to seal in the transfers and take off the gloss varnish shine. In the end I used Windsor and Newton gloss varnish which seems to spray quite nicely. The slightly orange peel finish is not apparent at actual size. This is a fairly small loco. Left hand side: Right Hand side: The main assemblies are only placed together so the alignment of the under boiler will be improved once it's all bolted down. I'm quite pleased with this one so far . Adrian Link to post Share on other sites More sharing options...
N15class Posted June 20, 2012 Share Posted June 20, 2012 A coat of varnish will bring everything together nicely. Looks much better now. Link to post Share on other sites More sharing options...
Darwinian Posted October 14, 2012 Author Share Posted October 14, 2012 Something of a hiatus has been reached, Although it ran well enough the ride height was about 1.5mm too high. I tried everything I could think of but the little loco just isn't heavy enough to compress the springs in the hornguides . I'll have to have a think. Might have to strip down the chassis and try CSBs instead . In the meantime I'll get on with something else. Link to post Share on other sites More sharing options...
buffalo Posted October 14, 2012 Share Posted October 14, 2012 Looking back over the topic, I can't see any mention of adding extra weight. On a small model like this, I would expect to have to fill the tanks and probably some of the boiler and bunker with lead just to get reasonable traction, let alone compressing any form of springs. That said, my experience of the Gibson sprung hornguide is limited to a couple of occasions when I've assembled some (both plastic and metal types) and chucked them back in the packet because I reckoned there were easier, less fiddly, solutions. My understanding (please correct me if I'm wrong) of the Gibson system is that they are not a real suspension system. The idea is that the springs should be fully compressed with the ride height set using the screws. The springs then function only to control a wheel that dips below its normal running height, hence the very soft springing. As I don't have any on a loco to test how much weight is needed to deflect the springs, I've just taken a single assembly out of the packet and tested it on the scales. I found it needed around 15gF to compress it fully (a little under 2mm). Surely, without added weight, the unsprung weight of the 850 is more than 90g? Perhaps you have a problem with one or more of the guides sticking, or you haven't adjusted the screws sufficiently? I'm surprised that it is running 1.5mm too high as there is very little more travel available in the Gibson guide. Nick Link to post Share on other sites More sharing options...
Darwinian Posted October 14, 2012 Author Share Posted October 14, 2012 Looking back over the topic, I can't see any mention of adding extra weight. On a small model like this, I would expect to have to fill the tanks and probably some of the boiler and bunker with lead just to get reasonable traction, let alone compressing any form of springs. That said, my experience of the Gibson sprung hornguide is limited to a couple of occasions when I've assembled some (both plastic and metal types) and chucked them back in the packet because I reckoned there were easier, less fiddly, solutions. My understanding (please correct me if I'm wrong) of the Gibson system is that they are not a real suspension system. The idea is that the springs should be fully compressed with the ride height set using the screws. The springs then function only to control a wheel that dips below its normal running height, hence the very soft springing. As I don't have any on a loco to test how much weight is needed to deflect the springs, I've just taken a single assembly out of the packet and tested it on the scales. I found it needed around 15gF to compress it fully (a little under 2mm). Surely, without added weight, the unsprung weight of the 850 is more than 90g? Perhaps you have a problem with one or more of the guides sticking, or you haven't adjusted the screws sufficiently? I'm surprised that it is running 1.5mm too high as there is very little more travel available in the Gibson guide. Nick Maybe it wasn't quite as bad as I imagined but I could definately get movement to the correct buffer height by pressing down on the body. I tried adjusting the stops upwards anyway but the little bolts had corroded (flux and steel just don't mix I guess) and a couple sheared off. I don't have the loco to hand at the moment but it isn't all that heavy as only the pannier assembly is white metal. I was reluctant to add any more weight for fear of exceeding the capabilities of the small Mashima motor. Now the damage is done as I hoiked the springs out of the front and rear boxes and doubt if I could get new ones back in. (Note to self, must do better at waiting until the feeling of irritation has gone). Oh well we live and learn. I'll find a solution no doubt, eventually. Adrian Link to post Share on other sites More sharing options...
N15class Posted October 14, 2012 Share Posted October 14, 2012 A white metal body should be more than enough to compress the springs. Also for a running point of view should need no extra ballast. All the white metal 0-6-0's I had would out perform the prototype without extra weight. From what I can remember the AG springs were very light. You must keep all steel parts covered in oil and away from the soldering. I would also change steel screws for brass. Only fit the steel screws, springs etc when everything is clean and painted. If you have to use steel screws it is worth blueing and oiling them. Link to post Share on other sites More sharing options...
Darwinian Posted October 15, 2012 Author Share Posted October 15, 2012 A white metal body should be more than enough to compress the springs. Also for a running point of view should need no extra ballast. All the white metal 0-6-0's I had would out perform the prototype without extra weight. From what I can remember the AG springs were very light. You must keep all steel parts covered in oil and away from the soldering. I would also change steel screws for brass. Only fit the steel screws, springs etc when everything is clean and painted. If you have to use steel screws it is worth blueing and oiling them. Thanks for that suggestion, I'll try to remember to do it next time. Fortunately this evening I have managed to extract the hornblocks by unbending the wire retaining hasp. I had some Gibson plunger pickups which appear to use the same springs so I replaced the springs I'd ripped out. Now all I need to do is re-quarter the wheelset I had to disassemble and check the body weighting to get the loco to sit level. If I remember I'll see what the body actually weighs and let you all know. Of course i'll also have to remember to get some replacement springs for the plunger pickups too, just in case I want to use them. Adrian Link to post Share on other sites More sharing options...
Darwinian Posted October 16, 2012 Author Share Posted October 16, 2012 A quick check on the scales reveals that the loco body weighs in at 125g. There is easy movement ion the hornguides so I don't know why this isn't enough. The body is front heavy because the cab and tank are etched brass so it sits at an angle. That made the height problem worse at that end. I'll experiment with weighting the body to see if it sorts out the problem. Adrian Link to post Share on other sites More sharing options...
N15class Posted October 16, 2012 Share Posted October 16, 2012 If there is plenty of movement in the guides it is purely down to weight. I am surprised it is too light. I would add just enough to compress the springs to get the ride height right. Being sprung the traction will be better than one with a rigid chassis. So it actually does not need to be eo heavy for equal pulling power. Link to post Share on other sites More sharing options...
buffalo Posted October 16, 2012 Share Posted October 16, 2012 A quick check on the scales reveals that the loco body weighs in at 125g. There is easy movement ion the hornguides so I don't know why this isn't enough. The body is front heavy because the cab and tank are etched brass so it sits at an angle... There's something wrong here. 125g plus around 20g for the frames (not wheels, axles, motor...) should give an unsprung weight approaching 150g. This is more than enough to fully compress six of these little springs. You mention them being the same as used in the plunger pickups so they are the same as the ones I tested. Is something snagging because the back is higher than the front and the hornguides are not woking freely? ...I would add just enough to compress the springs to get the ride height right... Peter, see my earlier post. So far, no one has corrected my assertion that the bearing blocks are meant to rest on the bump stops (the screws), not be suspended on the springs. Bizarre, perhaps, but that's how I've always understood they are meant to work. The springs are just too soft for effective sprung suspension. Nick Link to post Share on other sites More sharing options...
Darwinian Posted October 16, 2012 Author Share Posted October 16, 2012 Buffalo, I believe you are correct about the ride being intended to be on the stops. I've been having a little play with the model and if i press down on the front or the rear end the springs can be compressed by 1mm or so. Immediately that I let go the loco pops back up again so i guess there isn't too much catching. I had thought the centre axle might be a problem because squeezing in the gearbox made everything a bit tight across the frames and it does not move quite so freely (I'm working in OO) however the centre axle tends to sit a bit higher if anything so it's not causing all of the problem. I'll have to do some more investigating when work allows. Off to the Peterborough show this weekend as it's not so far from me as most. Adrian Link to post Share on other sites More sharing options...
N15class Posted October 16, 2012 Share Posted October 16, 2012 Buffalo I would say that the hornblocks should be sitting against the adjustment screw, with the centre wheel screws about 0.5mm above the blocks. Link to post Share on other sites More sharing options...
Darwinian Posted April 24, 2013 Author Share Posted April 24, 2013 I cannot believe how long it has been since the last post on this. My little 850 still has the chassis as built and the ride height is coming out about 1mm too high, This doesn't interfere with the couplings or cause any problem with the buffers on adjacent vehicles so I'll live with it. The plunger pickups on the one side were found to be jamming and noit sprining back enough when the wheels moved away from the frames on curves, leading to erratic running. I've supplemented them with conventional phosphur-bronze wire wipers and the running is now pretty good. I nearly had a disaster with the weathering as the Humbrol "Super" enamel thinners are more aggresive than I'm used to and nearly took off too much paint when i wiped the body over to give the impression of some cleaning being done. Weathering was simply Precision paints frame dirt lightly blown on with an airbrush from the side and slightly below, then the same but with a dash of matt black to make a nice sooty greyness, sprayed on from above. Sides and cab windows were then lightly cleaned using a cotton bud dipped in thinners and then largely dried (see comment above). Adrian Link to post Share on other sites More sharing options...
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