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Here is Part 7 - I'm afraid it is a bit of a marathon...

I'm starting to add the frame spacers. Things take a bit longer as I put the first one in the wrong position! On the plus side, it means I get to show you how to correct such a mistake.

 

https://youtu.be/ylBEBvq4TvA

 

The footage for the next 2 parts is in the can (8 = Erecting the frames, 9 = Simpson springs), but I probably won't have time to edit it until after the weekend.

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It was really good to see Andy making progress with his Jubilee at our 2mm group meeting on Thursday evening. John also showed us a part-built example which "only" needs its valve-gear assembling...

I didn't take any pictures, but perhaps the builders may be persuaded to upload one or two?

 

Anyway, it has taken a little longer than I'd hoped to get back to this, but here at last is part 8, where I finish off the spacers and assemble the main frames:

 

https://youtu.be/9hUC260cWK8

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Yet another excellent installment Nick. I've attached a picture of the little fold up frame assembly bobbins that come with all Bob Jones kits, they really are useful. As you can see I've modified one set so they can slip over a bearing without being trapped once the frames are soldered up.

 

I have a spare unassembled set - see photo -  so if anybody wants them they are yours for an SAE. PM me, first come first serve.

 

Jerry

 

post-1074-0-91090100-1530432793_thumb.jpg

 

Edit to say that the frame spacer etches have been claimed

Edited by queensquare
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Yet another excellent installment Nick. I've attached a picture of the little fold up frame assembly bobbins that come with all Bob Jones kits, they really are useful. As you can see I've modified one set so they can slip over a bearing without being trapped once the frames are soldered up.

 

I have a spare unassembled set - see photo -  so if anybody wants them they are yours for an SAE. PM me, first come first serve.

 

Jerry

 

attachicon.gifIMG_05161.JPG

 

Edit to say that the frame spacer etches have been claimed

 

I am not sure how you can use these on frames unless they have the frame extensions with a hole in to do the alignment, as Bob's kits all do.

Surely the modeified one will space the frames the correct distance apart (if you have single thickness frames) but cannot actually do any aligning?

 

Chris

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I am not sure how you can use these on frames unless they have the frame extensions with a hole in to do the alignment, as Bob's kits all do.

Surely the modeified one will space the frames the correct distance apart (if you have single thickness frames) but cannot actually do any aligning?

 

Chris

 

The 1.5mm axle steel and external bobbin type retainers hold the allignment - I have the old Association ones with a grub screw. I've quickly mocked up what I mean in the photo on one of Bob Jones chassis which is destined for another 3F. This shows the frame extensions Chris refers to which means normally you would put the temporary spacers at the ends whist soldering up the frames so wouldn't neccesarily need my modified spacers. They come into their own with scratchbuilt chassis which dont have the frame extensions although there is of course no reason why they cant be included and, particularly with small tankies, it would probably be beneficial to do so.

 

 post-1074-0-32029500-1530449902_thumb.jpg

 

Jerry

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A final picture which shows my full armory of spacers and bobbins which take into account different thickness frames, different types of spacer etc - you cant have too many!

One of my modified Jones assembly spacers is seen propped up above the axle. Because the p/b bearing is proud of the frame on the inside simply enlarging the hole in it is no good as it would be trapped - hence the slot.

 

When I dug out the 3F chassis bits I noted that there was another set of Jones etches there so if anybody else wants some pm me

 

Jerry

 

post-1074-0-17828900-1530451598_thumb.jpg

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Part 9 is here at last, where I'm demonstrating how to attach the tender drawbar support bracket to the rear frame spacer without unsoldering it from the frames...

 

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Hot on the heels of Part 9 comes Part 10, in which I finally get round to making the Simpson springs.

 

Incidentally, there is a wire works in Wokington called Simpson Springs. Forget Northern Wire - this would make a great lineside industry. Then there's the Simpson Spring bottling plant in Massachusetts...

 

https://youtu.be/hthbUxasRhs

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Simpson springs are usually delivered in one of these

 

post-25077-0-05443800-1531342787_thumb.jpg

 

Jim  :jester:

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These videos are great - thank you for taking the time to do them!

 

Without wanting to spoil a future instalment, do I need to take anything off the axle muffs to make space for the Simpson Spring?

 

Thanks

Simon

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Part 11 is a bumper episode, featuring the assembly of the bogie frames and fitting the bogie pivot to the main frames.

 

https://youtu.be/R3mtfKhrc7c

 

 

Another excellent installment Nick. Can I make one suggestion. I suspect that when soldering in the bogie pivot the main heatsink is the metal vice its in, not the casting.A couple of little slips of ply cheeks in the vice to insulate the metal jaws from the frames would do the trick.

 

Keep them coming, looking forward to the next installment.

 

Jerry 

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One of our first exercises in metal work class at school was to make a set of voice grips out of aluminium sheet to protect the workpiece from the serrated jaws of the vice. I now have a set made in card to prevent the 'heat sink' effect. If/when they get a bit charred it's a simple matter to make a new set.

 

Jim

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I suspect that when soldering in the bogie pivot the main heatsink is the metal vice its in, not the casting.A couple of little slips of ply cheeks in the vice to insulate the metal jaws from the frames would do the trick.

 

That's a good thought, Jerry. The pivot and the spacer I was soldering it to are separated from the main frames and vice jaws by the double sided PCB insulation pads. I had assumed they wouldn't transfer heat that well, but being so thin, maybe they do.

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After an enforced break of a few weeks while I selfishly went on holiday, I'm getting back in the swing of things with Part 12.

I'm on to the tender chassis now. I've heard lots of advice that says you should start with the tender, but I find them so much less exciting.

Anyway, this part is really the warm-up (call it a revision class if you like!), before I tackle the part of this kind of tender chassis which frightened me for years...

 

https://youtu.be/ytGQFlFFu0w

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These videos are great - thank you for taking the time to do them!

 

Without wanting to spoil a future instalment, do I need to take anything off the axle muffs to make space for the Simpson Spring?

 

Thanks

Simon

 

Hi Simon,

Please accept my apologies for having left it a month before replying to your question - I didn't notice it before I went on holiday.

The short answer is "yes"!

You will need to reduce the length of your muffs anyway to fit between the bearing flanges. By how much depends on how much side-play you require for a given axle.

For the sprung axle, I use a digital caliper to measure the distance between the springs (without squashing or otherwise distorting them), then subtracting the amount of clearance I require. This would be a few thou if I just want a running fit without sideplay.

I can't give an ideal muff length, as each one needs to be made to fit its location.

The process of fitting wheels to the frames can squash them in slightly, and your carefully measured running clearance may turn into a tight fit which binds. If this happens, you can always "tweak" the frames out a bit. You'll see me doing this in Part 13 which I'm about to upload. Chassis building is part science, part butchery!

I should be getting round to fitting muffs between springs in 3 or 4 episodes' time.

 

Nick.

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After the warm-up act of part 12, here comes part 13 - and a double-length episode to boot.

 

This time I'm fitting the pivoting platform to the tender frames, and amongst the usual broaching of holes and soldering, there are plenty of new techniques to discover. We'll have our first dealings with a muff, do some glueing, and use a mini-drill.

 

You'll probably know by now that I own a watchmaker's lathe, and I'm not afraid to use it... however, it is a luxury rather than a necessity in 2mm modelling. (Having said that, I would not now be without mine.)

Since the purpose of this series of videos is to encourage people to join in, I will endeavour to show alternative methods for the jobs I would normally do by default on the lathe. In part 11 there was the option of buying a bogie pivot instead of turning one, but we've reached the point now where we do have to start making things...

 

https://youtu.be/Ovydc5KT5yY

 

Next time I'll be preparing the wheels ready for fitting...

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Part 14 is here, in which the wheels are prepared by fitting the crank-pins and balance weights, and de-burring the spokes.

There's also a minute or so  in the middle where I drill some holes to represent the hollow axles most Jubilees ran with... Sorry but I absolutely had to use my lathe to do it. You can close your eyes for that bit if you like!

 

https://youtu.be/CNC-h_ErL0c

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Really enjoying this series Nick, thanks for taking the time to do it.

 

Can you spell out the name of the material you are using as a soldering pad and offer a source at all?

 

Many thanks

 

John

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Can you spell out the name of the material you are using as a soldering pad and offer a source at all?

 

Hi John,

It is called Trespa.

Henk Oversloot first brought it to the attention of the 2mm Virtual Area Group as a potentially useful material back in 2005.

I got a few small squares of it shortly afterwards for free by requesting samples from their website: https://www.trespa.com/en-gb/exterior-panels

It looks like the facility to request samples on-line is still there.

The company did contact me to follow up my request, and seemed quite happy that I just wanted to experiment with the material for use in building model railways.

 

Nick.

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Thanks Nick, a request has just been sent in.

 

Now about my having Benny Hill music stuck in my head ........ ;-)

 

John

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Part 14 is here, in which the wheels are prepared by fitting the crank-pins and balance weights, and de-burring the spokes.

There's also a minute or so  in the middle where I drill some holes to represent the hollow axles most Jubilees ran with... Sorry but I absolutely had to use my lathe to do it. You can close your eyes for that bit if you like!

 

https://youtu.be/CNC-h_ErL0c

Sorry to ask, but I need to clarify in my mind, am I correct, you're saying the balance weights are in identical positions on both sides in relation to the spokes not as I've been doing as mirror images side to side?

Brillant set of video tutorials though. You should publish as a DVD when the set is complete.

Oliver

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Sorry to ask, but I need to clarify in my mind, am I correct, you're saying the balance weights are in identical positions on both sides in relation to the spokes not as I've been doing as mirror images side to side?

Balance weights are there to balance the mass of the coupling rods and motion, so they are in the same position relative to the cranks on the wheels of each axle.  They are usually a different size, and sometimes in a different position, on the driven axle as there they are also balancing the mass of the connecting rod and the valve gear etc., whether that be inside or out.

 

Jim

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Balance weights are there to balance the mass of the coupling rods and motion, so they are in the same position relative to the cranks on the wheels of each axle.  They are usually a different size, and sometimes in a different position, on the driven axle as there they are also balancing the mass of the connecting rod and the valve gear etc., whether that be inside or out.

On the Jubilee, the balance weights were different on all 3 axles. They are 3 cylinder engines, and the middle cylinder drove onto the front axle. Some of the balancing of this was done with extended crank webs, and the rest with the weights on the wheels.

With a steam locomotive, there are two sets of forces to balance - the rotational forces (i.e. the eccentric weight of the big ends of the connecting rods + coupling rods + crank pins going round) and also the reciprocating forces (i.e. the weight of the connecting rods and other bits going back and forth).

Balancing is therefore a compromise, with different "hammer blow" being measured in various places (wheel, axle, rail, and engine as a whole). If you balance out completely one set of forces, you can add to the other.

3 cylinder engines are interesting in this respect. The reciprocating forces are easier to balance as they are more nearly opposite each other than on a 2 cylinder engine.

A jubilee flying along at 70mph would experience very little hammer blow overall for the engine, but each rail would be pounded with over 8 tons five times each second.

 

This is probably too much information, when a simple "sorry, but yes, you've been doing it wrong" would have answered Oliver's original question!

 

Not one to know when enough's enough, however, the other closely related thing to worry about is which side of the engine "leads" - i.e. when you quarter the wheels, which side leads the other by a quarter turn.

Most British 2-cylinder engines were right-hand lead, but I've recently realised I've got this wrong on my "Coal Tank"... do I pull it to bits to make it correctly left-hand lead?

But then 3 cylinder engines aren't quartered at all, they're "thirded" (ish - unless it's a compound - it gets very complicated!)... though I'm not sure that anything other than quartering would work well on a 2mm model.

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........ but I've recently realised I've got this wrong on my "Coal Tank"... do I pull it to bits to make it correctly left-hand lead?

Does it matter?  Are you going to operate the loco with a mirror behind it so that folk can see both sides at once?   :dontknow:

 

Jim

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