Building a B12

[gowest]

RAF

Have just seen your drawings and like the idea must give it a go

[96RAF]

Lateral thinking employed...

I just scribbled out a sketch and took a photo of it, which I can upload. sorry,about not being able to crop it.

I wasnt criticising the state of the loco Gowest, merely noting that live steam is a tad messier than electric. Anything this small on live steam has to be in good working order else it wont operate properly.

Rob

[gowest]

RAF

yes can be a bit oily but that's half the fun I take it you run live steam so must know the format but maybe should have given it a good clean before the photo.

 I also have some other much larger live steam 7 1/4 engine and you know when the oil is doing its job when you get a ring of oil on the top of the chimney.

[96RAF]

@Gowest

No unfortunately I dont have any live steam, but my son's ex father-in-law ran a couple of gas-fired large garden scale live steamer outside his house and that was great fun. I think they were Roundhouse models.

 

They were manual so you had to be nimble to keep them under control, but he was looking at R/C upgrades.

 

I would have loved one of those beautifully made engines, but the cost was a tad out of my (justifiable) budget.

[96RAF]

RAF

Have just seen your drawings and like the idea must give it a go

 

Further thoughts...

the con rod locking pin may have to be two pins to hold the big end block in alignment if the crank webs wont suffice to maintain alignment and the pin or pins could be simple split pins. Ditto the driver axles combined horn block locking.

 

Twin cylinders...if there is limited space within the frames for suitably sized side by side cylinders could you stack them vertically and articulate the con rods to cater for the horizontal offset.

[gowest]

lots to think about here like the conrod idea will start machining one out and letsd see what happens the cylinders will have to be side by side as the Hornby valve system has only one type of assembly

[gowest]

Here are a couple of pictures of my GWR Rail motor under construction some year ago which show the Hornby standard layout of the cylinders and valve assemble.

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Starting at the cylinders and working our way up 

The square brass block with the 4 screws is the cover to the valve which is a rotating disc the picture below shows this with the cover removed. The next square brass part with 4 screws is the oil tank cover with the large oil filler screw which is also steam exhaust the right hand end of this part has the regulator assembly and the silver part is the regulator cover and supper heater unit with the small copper pipe from the safety valve not pictured here.

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with the brass cover removed from the valve unit and the valve and spring you can see the valve port face with the small holes that lead down to the cylinders and the large hole in the centre for the valve drive shaft.

as this like full size 2 cylinder engines is a double acting engine there are 4 ports 2 for each cylinder  the steam is applied to both sides of the piston. so if we are to use the Hornby parts we must configure this B12 in the same way with the inside cylinders.

[RB51]

@ RAF & GW

 

I think you may well find that there are more than a couple of folk enthralled - I've never read a thread with so much enthralledness. I am not able to comment on the process as I have no idea about engineering (on any scale) but it is certainly a good read. I look forward to more.

 

R-

[walkingthedog]

Without doubt the most interesting thread on the forum. 

[96RAF]

@GW

thanks for the pictures and the explanation.

I can see that to have stacked cylinders would mean a total rework of the rest of the mechanism, not really an option.

Rob

[gowest]

/media/tinymce_upload/a5bf783391c78663596523b8edb8d524.jpgHi Rob 

the thing is that you asking the question and me finding the pictures has pointed out a new problem which is the cylinders of the Hornby A3 are wider than the B12 and the 4 fixing holes which you can see in this picture are hanging in fresh air?

but as the top part of the cylinder with steam passage ways in has not been made yet ( keep putting that bit off) it could be made wider to accommodate this or cut off the 4 little feet and fix it some other way 

as for the rest of the readers here that have left comments I really want this one to run but it's in the lap of the gods unless granddads looking down and his mates. 

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[96RAF]

@GW

Anyway you could make the cylinder block and that silver valve part as one lump.

 

Making the cylinder/valve chest as one would obviously mean some odd port drillings that would would have to be partially blocked off where there is overdrilling.

 

Maybe slot the side frames to allow max possible cylinder width, only a couple of mm I know but Every little helps.

 

Rob

[walkingthedog]

Could you not use the holes and long bolts in the silver part to clamp it to the cylinder block or is there not enough space. 

[RB51]

........ as for the rest of the readers here that have left comments I really want this one to run but it's in the lap of the gods unless granddads looking down and his mates. 

 

Hold on GW - I'll send some of my lot to pay you a visit. Not one good engineer amongst them, but you never know.

 

I'm sure you'll figure it out between you.

 

R-

[gowest]

Roger B

who said something about if you give some monkeys a typewriter and a load of paper in time they will type the complete works of William Shakespear?

im getting a large input of ideas and that's a good thing as one or two look good even the longer screws is an idea and no doubt there's going to be many more as the job goes on

even engine designers had there problems seeing a program on steam the early days yesterday on BBC2 touched on the use of sand to help the engine get a grip this idea from the steam days was carried over to the electric sliding door stock back in the 1950 the ran out of Liverpool Street but in some cases caused problems with the earth return as a layer of sand insulated the wheels from the track very dangerous should you be touching the coach and standing on the ground.

but thanks to all that post here and will give all your idea some thought.

I must say this before having tea that even at work some engineers were very good and some were terrible and one day a group of us were trouble shooting a small problem and one such less than great engineer was at the table and my friend said "two heads are better than one even if one is a sheeps head"

[walkingthedog]

Sheeps head and engineer makes me think of Isambaaaard Kingdom Brunel.

[Bulver]

I am fascinated by the skills displayed here, what a fantastic project.  I am looking forward to you solving the myriad problems that crop up.  Rob's comment regarding your skills is spot-on, and he is no slouch either, is he?  Best wishes in completing this lovely model

Rod

[gowest]

Rod

Yes just seen his layout with the LEDs on the track and the station layout and as someone said very neat wiring like the sheep bit if this forum carries on like this maybe we should turn it in to a book as we have quick witted people amongst us that make for some light releaf postings.

[gowest]

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Now for the connecting rods these will be machined from 1/16” brass To start with two pieces of brass about the right size are soft soldered Together then painted in marking out ink the distance from the end of the piston rod to the centre line of the axle is worked or in my case guessed at as there are unknown items that will come into the equation no doubt further down the line and the thing that needs my utmost attention is will inside cylinders run?

 

With the profile and hole centres marked out it was put in the mill and machined to the size marked out its at this point you do not want it to move under the milling cutter as has happened to many a machine operator and the work piece is then scrap.

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Here you see the two parts still soldered together and the milled profile finished.RAF96 Posted a drawing on the forum page which I have reposted showing his idea for the connecting rod assemble and as it looked better than my idea and it only had one screw not 2 and was also more like the type of assemble used in steam

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Engine construction I decided to give it a go so this single hole had to be drilled right through the big end before it had this square section milled in place this would be easier and maybe keep the hole in line. Later this hole would need to be re drilled through the bearing block then drilled out to a taping size of  1.2 mm and hopefully leaving enough metal so it would look ok 

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In the picture here is the first drilling operation and as the connecting rods are still soldered together they might help keep the hole a little more easier to drill.

The next part would be to mill out a slot in the big end of the connecting rod just like his drawing.

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Once set up in the mill a small milling cutter of 1/16” was used to pass through the big end of the con rods down to a marked line.

Now the connecting rods can be unsoldered and cleaned up and the old unwanted solder removed.

The very small bearing end cap would need to made next and made a good tight fit after which with out it moving the hole in the connecting rod can be drilled and then re drilled to the finished size and finally taped 1.2 mm and a screw to keep it all in place. With the screw holding everything in place the big end assembly was drilled .70 mm and then opened out to 2 mm the size of the crank pin.

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 There you RAF 69 as per your drawing and I am pleased that it turned out as good as it has.

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This picture shows it in position on the cranked axle it is a little on the tight size but as a mate at work would say “that just the newness”

[RB51]

Amazing! R-

[96RAF]

Looks good GW, now just got to get those pesky cylinders within the available frame space.

 

Just a thought - has anyone ever used oval cylinders.

Rob

[gowest]

Hi Rob

yes I once had a 1949 Vauxhall that had oval cylinders it used more oil than than petrol.

[gowest]

2 axle boxes need to be made to fit the bearings in these were machined from brass bar and made as the drawing.

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The hole in the axle box brackets are made a knat’s appendage under 6 mm so that the bearings can be a good press fit and it was made with a shoulder to locate in the frames and Protrude passed the surface of the frames by about ten thou. The axle box brackets were held in place with 3 1.2 mm screws

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Starting with some brass bar in the lathe the shape soon came into being and looked like it was going to work.

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In the picture here you can see the 2 brackets and one with its bearing I place they will need the fixing holes drilled in them and the bottom section filed flat.

Now might be a good time to fit the parts that have been made together just to see what it is looking like.

I must tell you this Full Steam Ahead was on the TV Thursday night which you may have seen and they explained about the use of detonators on the track to warn on coming trains. My father once told me that back in the 1950’s on a wind swept winters night at Bethnal Green station London that the porter was having trouble getting the fire in the ladies waiting room to draw up so an old trick this chap had was to throw a detonator on the fire this would loosen the soot up the chimney and help the fire burn up but in the mean time a little old lady had gone in the waiting room to warm her hands by the fire not many minutes had passed and a loud BAG was heard so off went the porter to build up the fire but was shocked to see the little old lady covered in soot and shaking, dad said it took all the staff to clean her up and cups of tea to calm her down.

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The frames had to be lengthened so that the cylinder block could be fixed in the frames in I hope about the right position.

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The red line is just a rough guess to show just how much too long the cylinder is and will have to be cut down at some stage.

Now the middle axle needs to be made up again with bearings and all assembled in a one piece brass housing like the drawing.

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[walkingthedog]

It's like watching a really exciting TV series. Look forward to the next episode.  

[96RAF]

The seemingly impossible is starting to come together. Good work GW.

 

Looking at the red line on the cylinder block, I presume it was made overlength  but when cropped is still within the stroke length of the crank else that would invoke a remake with shorter throw, not something you want to do at this stge.

 

What is not apparent in general viewing of these photos but obvious when you read the drawings is how small all these bits and pieces and their attaching screws are, which makes it all the more remarkable.

 

Rob