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Building a B12


Go_West

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Well reporting back on the new electronics, as they say do you want the long answer or the short answer.

The short answer is it don’t work. It was ok for a short time and then died so switched to a larger device which can take 2.5 Amps and I know this works as I have used it before but it will mean making a new PCB as it’s a little larger component.

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The new SSR is the white coloured component hanging off the board with the smaller black SSR on its own.

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The board under test with the engine and with this new 2.5 Amp SSR things worked ok but more testing must take place on the track in steam and as my track has one or two dead spots this will show if its going to be any good or not.

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R&D stands for Roughly Don't work but have no fear as we speak the new drawings done and tomorrow will build a new PCB and there's no garrentee it will be the final design.

As long as it works just a little it would mean that I can do some steam and track testing which is what I'm really pushing for as its still not done any work as a steam engine yet. This could all take place over the weekend So stand by.

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Second time around and a new PCB ready to have its components soldered in place some times I think will I ever get this (what ever I’m working on) work as with most of us things are set against us and it all gets that bit harder to over come some thing I say this as I once had a plastic flower that died.

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So this is the. I was going to write final PCB but that might be a bit premature so ill just say the second design and looking at it if I have a problem with the size I could always make it at least half the size by fitting some of the parts on the other side of the PCB making it double sided.

Moving back onto the engine I do have a problem connecting the regulator/whistle to the electric motor gear assemble as there are a lot of parts in the way like the safety valve and pipe work so have come up with this idea of a cable a bit like on a bike. This consists of an outer cable and a solid inner spring wire passing through it. I will need to make 2 brackets to fix the out cable ends to and hope there is not too much drag that might stop it from working properly.

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This is the cable which I hope will be able to drive the valve back and forth

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Hope fully you can make out the cable fitted to the regulator arm it will run the other side of the whistle and copper pipe and become ridged once it has its 2 brackets screwed in position.

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I don't suppose the whistle could be shortened so it fits somewhere else to give you space for the control wire Ken.

 

Or lateral thinking bend it into a U-shape.

 

Obviously shortening it would affect the toot pitch, even to the point that only dogs could hear it.

Rob

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Hi Rob

a very good point Rob about the whistle I may remove it for testing and think about it position and size later as for a shorter whistle I think it can be made smaller by shortening the brass tube but by adding a larger diameter box section or tube the sound pitch can be set within normal hearing range which will need testing to acheive the right sound and size.

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Steam Tests

The engine was a little front heavy with all the brass parts so far in front of the main drivers so the front boggy had to be made in a way that would carry some of this weight and allow the engine to sit level on the track and distribute the load more evenly over all the wheels.I made up the front boggy from the kit but had bought some Hornby bogies from that action site and the one that fitted perfectly is pictured here. It looks like it came from a GWR Castle class engine.In the picture you can see the spring which carries the load by supporting the engine from under the cylinder block.

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The front end of the frames has a bracket fix to it which carries the fixing point to the boggy frame and allows it to turn in two positions. The only thing that needs changing is it has 2 guard irons in the front of the leading wheels which will need removing as the irons on the S69 are on the front buffer beam of the engine once the front boggy was fitted the steam tests could start.

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As we have no tender yet for this engine an A3 tender was pressed into service and the complete set up was placed on the rolling road.

There’s no oil filler yet for the oil tank so the 4 screws holding the small oil tank cover was removed and some steam oil placed inside and the cover replaced.Water was add to the tender and the engine left to heat up after a bit the tender safety lifted not the engines valve so a fault there to look at but this meant that we had a good head of steam and with some rotating of the wheels it was not long before it burst into life be it a bit jerky so it was left to run and 2 more steaming’s and it was running fine.

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What would happen on the track ? oil and water tank were refilled and onto the track the engine went and once again the wheels went round and off the engine went.

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It was left to travel round for a good 15 minutes then a coach was added and off the train went once more. Still pulling with out any problems more coaches were added and still the train steamed around the track even on the more difficult section which is up hill and on a curve so makes it much harder to drive and means the engine has to work harder to complete that part of the track unlike when it enters the tunnel which is down hill and less steam is required to complete the loop along this part of the track.

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 All in all the very good, the times I’ve wondered if this inside cylinder layout and cranked axle was going to work at all. Just the finer points of the model need to be completed and check it fits in the body. So have open my bottle of best scotch in calibration of a successful  test run (video to follow)

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That is good news indeed Ken and such progress definitely deserves a large scotch.

 

How does the body fit look, will the chassis bits all go in and leave room for cab detailing, etc.

 

Next step I suppose is the tender and trying to get max volume into the boiler without sacrificing any of the tender detail.

Rob

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Hi Rob

i did try the body and need to make some changes as it will not fit properly also can get the engine to run backwards and the safety valve is set too high but all I'm hoping is just tweaking have made a video of the steam testing if you click on the link.

ken

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That looks good on the move Ken and it pulls real well considering its a bare bones chassis at the moment and there were leaves on the line. The front bogie tracks nicely as well.

 

What do you reckon could be the cause of the reversing problem, slightly misdrilled valve chest maybe or servo not fully ranging. I don't suppose you have to be far out to cause problems.

Rob

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Hi Rob

i think it's one of 3 things one the valve shaft and drive rod are too tight the web block that hold the adjusting screws are too thick and need filing down or it just out of the setting range and needs adjusting will need to correct this and one or two other bits that need attentio. Once this is corrected and the whistle fits and works and it all fits in the body along with the electronics which I'm still not happy with  then it will be the tender to build. And fit out.

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So the steam testing went ok apart from the fact the engine never went backwards but that’s a easy thing to fix (he said) .

Rob asked does the body fit on the chassis no it don’t the problem was that the valve housing is about 2.5mm too long and will not go in the smoke box, it also leaves the steam exhaust out let not directly under the engines chimney so the only way these 2 faults can be corrected is to make the valve housing smaller so that it does not project out in front so far.In this picture you can see I've removed the valve housing just to see if there were any other problem but glad to report the chassis fitted fine.

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The housing was set up in the lathe and both side had a millimetre or two machined off and also just ground off part of the valve spring to reduce the pressure on the rotating valve.

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You can see from the 2 pictures here the difference in the S69 chassis and the A3 chassis with the shorter valve housing and the new larger oil tank set more to the back of the valve unit on the S69 chassis.

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Now looking in the front of the engine smoke box with the door remove you can just see how all the space has been used up.

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With these changes out the way the engine looks like its getting to the last stages of the loco build.

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And a cab with room for a crew the back head of the boiler will have to be made from sheet brass as the one in the kit is a solid casting about 5mm thick so will not fit properly.

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Hi Ken, I've just caught up and watched the video. That looks great - and to think you built it! I am truly in awe. I'm sure you will soon fix the one or two little niggles that remain, you seem confident anyway. 😀 You must be chuffed (sorry). R-

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RogerB

Chuffed is about right there was a time when i thought that this engine was not going to run at all let along pull coaches to discribe the building of somthing like this and show the work as it goes along is a bit of a commitment what maybe a better way to go would be to build it first and if i works then write about it. but there you are dont lets get too steamed up about it.

NEXT THE TENDER.

 

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The boiler of the tender was going to be made from scratch and rather than go straight into building one in brass and maybe having trouble with the fit this time I made a boiler to the drawing here but on my 3D printer this way the fitting of the boiler could be check out and then if all was well a metal one could be made to the same design.

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Then the brass body need some of the metal inner parts removed so that the space can be used for the water tank  or primary boiler. It is hoped the heater wires can be in terminated in the front of the tender unlike the A3 and A4 which will leave space for a LED as a rear lamp.

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The drawings for the tender give a rough idea as to what I think is going to be the best way to utilise the space but as with all developments no doubt it will change as things progress.An auntie of mines father did drive steam engines like this doing the boat train runs from Liverpool street station to Harwich which is what they were design for. He did also take the King and I think our Queen to Sandringham my father said that they would paint the buffer heads of the locomotive with white paint and the cab roof, if he gave them a comfortable ride and didn’t shake them up to much he would get an extra 15 shillings for the trip that’s nearly a pound. I think this S69/B12 kit was £120.

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Looking at the 2 tenders you can see just how small the GER one is against the A3

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Could the filler cap go on the stepped notch Ken, like the real thing, then there is a void at the top of the main boiler part for steam to fill, or would you lose too much water volume, given the available volume is marginal for the target running time.

 

The coal load could be well humped to cover the extended height of the boiler outside the tender body lines.

Rob

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Hi Rob

yes as you say it would look good using the filler as the full size engine but as you also say the run time would be shortened which needs to be 30 minutes so can we afford to loose space to steam rather than water? What I should have done and still could is when steam tests were being conducted was to see how long the engine would run on one filling of water? 

When these engines were being designed weight and overal length were considered as parts of the network would not take too heavy a locomotive and turn tables were not built large enough to take too long an engine so this engine was built with a small tender of some 3700 gallons it did have a water scoop so could pick up water on the move but I think it was the coal space that was sacrificed for more water as a steam engine used more water than coal and when test runs with the engine were carried out it was found to be good on coal. Later the network under the LNER was up graded to take heavier engines, an old pilot friend of mine the flew 4 engined Sterling bombers in WW2 said that the air ministry insisted that Shorts of Belfast must not make the wings longer than 95 feet as they would need to go in the hangers which had a set door way opening so this restriction effected the planes overal performance and as it turned out the planes were always dispersed far away from building and each other making them harder targets In the end.

its a fact of life that engineers have problems just building items but when the paper pushers set there requirements then life becomes much harder.

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@Rog

The boiler in the tender is a pressure vessel so it needs to be the best shape to take the pressure.

 

Round is good, square is not, unless it has radiused corners and internal stay braces to take the loads.

 

If you take a cube and pressurise it it tries to become a sphere.

Rob

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Rog and Rob

You have both got something yes a square water tank will hold more water and yes when pressure builds up the sides will blow out of shape straining the joints and may even explode. But if you look at the design of a belpare boiler it can consist of 7 flat plates to makeup the boiler and all these have to be stayed to with stand the pressure. If we use a square boiler and this has a working pressure of 30 psi it only has 6 flat side and if these are all stayed on all 6 side it should not be a problem. So Rog has some thing and as we are stuck for space and the final look of the tender Rog idea I think can be made and work successfully so will build one and see what can be achieve. 

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