RMweb Premium t-b-g Posted January 5, 2020 RMweb Premium Share Posted January 5, 2020 5 hours ago, CF MRC said: One couldn’t sleep easy in one’s bed knowing that a lamp iron was missing from the tender inside front sheet. So I fitted one. i also reduced the size of the sandbox horizontal linkage. Tim You win Tim. I give up trying to find things for you to add Unless you want to go for the second fire iron bracket for a full house! You can just make out our recently departed mutual friend Roy in the background so it was worth showing the photo for that alone. 1 Link to post Share on other sites More sharing options...
RMweb Premium CF MRC Posted January 5, 2020 Author RMweb Premium Share Posted January 5, 2020 Good point Tony. I had forgotten about that. The fire irons might actually offer some protection to the front cross. Tim Link to post Share on other sites More sharing options...
RMweb Premium CF MRC Posted January 6, 2020 Author RMweb Premium Share Posted January 6, 2020 A few details at the back and the second fire iron support. Tim 6 6 Link to post Share on other sites More sharing options...
RMweb Premium t-b-g Posted January 7, 2020 RMweb Premium Share Posted January 7, 2020 Gorgeous! (The tender, not you Tim!). Link to post Share on other sites More sharing options...
sej Posted January 7, 2020 Share Posted January 7, 2020 On 09/10/2019 at 13:16, CF MRC said: The GNR N2 failed to proceed on Copenhagen Fields at Fareham last weekend. It was made by the great Denys Brownlee and has run for 30 years, probably covering many hundred of real miles in that time. It is very rare for me to have two engines on the go at once, but I thought this deserved a ‘12 hour chassis’ - so it jumped the queue. On examination, I found that the 1/16” axles were worn by 0.1mm. They were put in a step collet and have been re-profiled to 1.5 mm diameter. On looking closer I also noted significant wear on the coupling rod pins. Denys had used remarkably thin (for him) steel for the rods and it had ‘cut in’. The new rods will be made twice as thick. The chassis has been made with brass frames and tapped acetal spacer blocks. The frames were separated from the blocks and one sweated to two pieces of brass to act as a pattern for the replacement chassis. The old holes were located using an equivalent size drill upside down as a plug fit in the drill press, with the frames held accurately in a vice on the X - Y table of my mill - drill. Once the location was correct, the drill was used correct way up to make the hole. The axle holes were drilled by dead reckoning, using the table to set the coupled wheelbase (the rods will be made the same way). Once all the holes were made, the new chassis was filed up to shape using the old one as a pattern: the image shows the three pieces still sweated together. I am fairly confident that I will be able to re-use some of Denys’ acetal spacers. It would be appropriate to keep as much of the original as possible. Tim Thanks for that Tim, I've always wondered how to exactly position drills into pre-existing holes...and there you go! Cheers Simon Link to post Share on other sites More sharing options...
RMweb Premium CF MRC Posted January 7, 2020 Author RMweb Premium Share Posted January 7, 2020 You’re welcome Simon. I try to put hints and tips into these posts that may not be immediately obvious unless you’ve been there... Tim 1 Link to post Share on other sites More sharing options...
RMweb Premium CF MRC Posted January 20, 2020 Author RMweb Premium Share Posted January 20, 2020 I spent a pleasant weekend at the London Model Engineering exhibition whittling some styrene on the MRC demonstration stand. All it has to do now is cast OK. Tim 7 1 7 Link to post Share on other sites More sharing options...
Caley Jim Posted January 20, 2020 Share Posted January 20, 2020 That's a b****y big shovel that's sitting in the fire hole! How does the fireman manage to manipulate that? Jim 2 Link to post Share on other sites More sharing options...
RMweb Premium t-b-g Posted January 20, 2020 RMweb Premium Share Posted January 20, 2020 1 hour ago, CF MRC said: I spent a pleasant weekend at the London Model Engineering exhibition whittling some styrene on the MRC demonstration stand. All it has to do now is cast OK. Tim How many of the model engineering folk passed by muttering about your sanity? Most of them won't ever have seen components that small for anything in their lives. Link to post Share on other sites More sharing options...
richbrummitt Posted January 20, 2020 Share Posted January 20, 2020 40 minutes ago, Caley Jim said: That's a b****y big shovel that's sitting in the fire hole! How does the fireman manage to manipulate that? Jim Might it be a spare from a 4mm version? 1 Link to post Share on other sites More sharing options...
gr.king Posted January 21, 2020 Share Posted January 21, 2020 11 hours ago, CF MRC said: I spent a pleasant weekend at the London Model Engineering exhibition whittling some styrene on the MRC demonstration stand. All it has to do now is cast OK. Tim Cast? Purely for single-piece strength, and added weight if in heavy metal? Or are you now making preparations for building a fleet of locos with similar cab fittings? Link to post Share on other sites More sharing options...
RMweb Premium CF MRC Posted January 21, 2020 Author RMweb Premium Share Posted January 21, 2020 (edited) 4 hours ago, gr.king said: Cast? Purely for single-piece strength, and added weight if in heavy metal? Or are you now making preparations for building a fleet of locos with similar cab fittings? It’s a pattern for investment casting, Graeme. A one off. Will certainly add useful weight in the right place. One 9P is enough! Tim Edited January 21, 2020 by CF MRC Link to post Share on other sites More sharing options...
RMweb Premium 65179 Posted January 21, 2020 RMweb Premium Share Posted January 21, 2020 It's the 9Qs which you'll be building a small fleet of then presumably ;-) Simon Link to post Share on other sites More sharing options...
RMweb Premium CF MRC Posted January 22, 2020 Author RMweb Premium Share Posted January 22, 2020 (edited) The only other GC engine that could grace CF would be a Director, Simon. That is exceedingly unlikely now we have Valour on the way. I’m also not sure that I really like their proportions. Tim Edited January 22, 2020 by CF MRC Link to post Share on other sites More sharing options...
RMweb Premium 65179 Posted January 22, 2020 RMweb Premium Share Posted January 22, 2020 (edited) Tim, There are actually quite a few other GC types that made it to KX in the period covered by CF, but, given that another Pullman or a Cleethorpes/Grimsby special isn't really representative of the broader picture, I think that Valour is an entirely fitting representative of the GC. All the more so given the intended purpose of the real loco and the quality of your workmanship on the model. Simon Edited January 22, 2020 by 65179 Link to post Share on other sites More sharing options...
2mm Andy Posted January 22, 2020 Share Posted January 22, 2020 (edited) 10 hours ago, 65179 said: Tim, There are actually quite a few other GC types that made it to KX in the period covered by CF, but, given that another Pullman or a Cleethorpes/Grimsby special isn't really representative of the broader picture, I think that Valour is an entirely fitting representative of the GC. All the more so given the intended purpose of the real loco and the quality of your workmanship on the model. Simon To illustrate Simon's point about other ex-GC locos appearing at KX, another photo from the camera of my late grandfather; this one has recently been digitally restored by Steve Armitage who has also added the caption and copyright information at the bottom. I don't know if this would be within the time period on CF? Andy Edited January 22, 2020 by 2mm Andy 2 Link to post Share on other sites More sharing options...
RMweb Premium CF MRC Posted January 23, 2020 Author RMweb Premium Share Posted January 23, 2020 Cracking picture, Andy, but not as pretty as a 9P, in my opinion. Modelling ‘typical’ means that one GC engine is enough for CF. Tim 1 Link to post Share on other sites More sharing options...
Atso Posted January 23, 2020 Share Posted January 23, 2020 (edited) 23 hours ago, CF MRC said: The only other GC engine that could grace CF would be a Director, Simon. That is exceedingly unlikely now we have Valour on the way. I’m also not sure that I really like their proportions. Tim Not necessarily Tim, http://shedbashuk.blogspot.com/2016/01/kings-cross-1933-1951.html Interesting to note an B2 and B7 at King's Cross shed on the 29th April 1933 (OT: there are a couple of D49s listed too!). 25th May 1935 shows two A5s (some where based there), a B4, an N5 and an O4. Finally, the 27th February 1938 finds a solitary B2 representing the former GCR. Some spotter notes that I have covering 1935-36 shows a B2, two B3s, two B4s and a B7 being copped between King's Cross and Hadley Wood. Furthermore, the RTCS green series states that C4 got transferred to Cambridge between April 1936 and April 1938 (Yeadon's states this too), which was used mainly on the slow trains to King's Cross and occasionally the buffet express (although this was rare due to a 40mph speed restriction on the loco between Cambridge and Hitchin). Edited January 23, 2020 by Atso 1 Link to post Share on other sites More sharing options...
RMweb Premium 65179 Posted January 23, 2020 RMweb Premium Share Posted January 23, 2020 Sorry Tim. I didn't mean to set a hare running! Simon 1 1 Link to post Share on other sites More sharing options...
RMweb Premium Popular Post CF MRC Posted January 28, 2020 Author RMweb Premium Popular Post Share Posted January 28, 2020 (edited) As promised some time ago, the styrene back head pattern was sacrificed to make a metal substitute, using investment casting. The pattern was mounted on a casting cone with wax, sprued into the back of the pattern in a non critical area and angled to give optimal metal flow. A cristobalite investment was used. The casting ring is lined with an aluminio-silicate tape to allow expansion of the investment on heating. The vacuum mixed investment slurry is poured into the ring taking care to avoid air bubbles on the pattern. The cone former is removed and the ring then placed in a furnace at 600 deg C to burn out the styrene and wax pattern. This also expands the investment to compensate for the shrinkage of the cooling alloy. The metal used is a high copper (80%) brass alloy - “students alloy”. It has a liquidus at 1015 deg C and is heated in an induction furnace. The cast button can be seen and, once cool it is broken out of the ring. The moment of truth is when the casting is divested using grit blasting. The sprue was cut off and the casting then polished with glass bead blasting. It is a amazing how the casting picks up all the faults in the original pattern! There will be some extra details added to the back head casting such as the firebox door and seat backs. Apologies for the rather long post, but I thought it might be of interest to see some of the technical aspects of ‘lost wax’ casting. Tim Edited January 28, 2020 by CF MRC 8 7 11 Link to post Share on other sites More sharing options...
RMweb Gold queensquare Posted January 28, 2020 RMweb Gold Share Posted January 28, 2020 Looks excellent Tim but I'm not sure I'd want that poured in my fillings - looks a bit hot to me! Jerry 1 Link to post Share on other sites More sharing options...
gr.king Posted January 28, 2020 Share Posted January 28, 2020 But just think of how durable it might be. Link to post Share on other sites More sharing options...
RMweb Premium CF MRC Posted January 28, 2020 Author RMweb Premium Share Posted January 28, 2020 Gold is a beautiful and durable restorative dental material, but is used less and less these days. Don’t worry, Jerry, it is generally fitted as an indirect solid restoration. However, cohesive gold (leaf) could be malleted into a cavity - I wish I could say I had done some, but it had completely fallen out of favour in the UK by the time I graduated. If this casting had been made of gold it would have put some useful weight where it’s needed. The casting fits perfectly, but I am currently working on a signal gantry for CF, so final finishing will wait a while. Tim Link to post Share on other sites More sharing options...
Caley Jim Posted January 28, 2020 Share Posted January 28, 2020 Are you going to get the pipework copper plated, or does the lab no longer have the gear for that now that copper band impressions are no longer used? Jim 1 Link to post Share on other sites More sharing options...
RMweb Premium CF MRC Posted January 29, 2020 Author RMweb Premium Share Posted January 29, 2020 No real need Jim. It’s quite a warm alloy as it is. I used to like using compo, copper rings & copper dies for inlays: Cecily has one that is now 42 years old. Tim Link to post Share on other sites More sharing options...
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