TFW’s workshop

[Caley Jim]

Not sure whether to model the tender brakes. 

Waaaaay back in the dark ages when I built my first 6-wheeled coaches I decided not to model the brake blocks as they would be hidden behind the lower footsteps - I thought.  When I had finished the coaches and compared their side on view with the drawings, something didn't look quite right.  The overhang between the outer wheels and the headstocks was too long.  I checked and double checked all the measurements, but they were spot on.  Eventually I realised that the brake blocks made the wheels look 'fatter' and filled part of the space between the wheels and the headstocks, making the overhang look smaller, so the brake blocks had to go in and they 'corrected' the 'look'.  Since then I've always fitted brake blocks, no matter how 'hidden' they appear to be.  Just a thought!  Might be worth it to make a stunning model even better!  It's like your tender front detail.......

 

Jim

[nick_bastable]

stunning 

 

I have been lucky enough to catch Copenhagen Fields twice once at the GJLC when I was unlucky enough to present my own meager effort opposite it  and at the AGM a couple of  years back, on both occasions I was able to appreciate it without the bustle of a "normal exhibition"  hopefully I will catch up with Lord President  at the DJLC 

 

Nick

 

[CF MRC]

Realised after looking long and hard that I hadn’t put in the rear two brake hangers, so these should keep Jim happy (very important that). These make a big difference and, frankly take away from the need for the brake shoes themselves, which are tucked up well behind the frames. Ironically, the brakes themselves, being attached to the body, are not part of the internal chassis and so the advantages of split frame pick up don’t work here.

 

 

Exhibition maintenance on our locos on CF is a constant battle against fluff, not always helped by brake shoes. The engines can attract enough of the stuff over a weekend to set a Hotpoint tumble drier on fire.

 

Tim

[CF MRC]

The cylinder drain cocks and pipes are very obvious on a P2, launching themselves forwards to join up eventually with the front guard irons, as was also the case on the A4s, as built. Quite sensibly, they were shortened in BR days. On LP they were made from a length of 0.25 phosphor bronze wire folded back on itself and silver soldered together (with silver solder paste) over about 15mm length. This produces a nice strong length of double ‘pipe’ that is also resistant to soft soldering temperatures.

 

 

These were then bent up to shape to enter the drain cocks themselves, which were made from small brass tubing that was a plug fit into holes already drilled in the bottom of the cylinder casings. The control link was a short length of nickel silver strip, bent at ninety degrees at the front to represent the rest of the linkage. The pipes really do swing right out at the front to clear the pony truck on tight curves.

 

 

The pipes were soft soldered onto the front guard irons and a little bit of epoxy used to secure them into the cylinder: I wasn’t going to waft a soldering iron near that lot at this last stage. At the same time, the bearing cover for the front brake cross shaft was fitted in the chassis, behind the cylinders.

 

 

Now for the RHS. The bits are made, but it will have to wait while the epoxy sets. These pipes really help to join up the font end of the engine; without them, it looks a bit like Jimmy Edwards without a moustache (only a few on the forum will remember him).

 

Tim

[Caley Jim]

....... These pipes really help to join up the font end of the engine; without them, it looks a bit like Jimmy Edwards without a moustache (only a few on the forum will remember him).

Whack O!

 

Jim

[CF MRC]

Finished off the other set of drain pipes this evening. The two photos show the clearance between the pipes and pony wheels. Should be OK, unless the engine damages the pipes in some minor misdemeanour: as often happens with miniature live steamers.

 

 

Shorting out isn’t a problem, of course, because of split frame pick up. The insulating PCB between the cylinders and the outer cover/valence is pretty obvious in these views.

 

Tim

[CF MRC]

Can you tell what it is yet?

 

 

Tim

[Atso]

Can you tell what it is yet?

Tim

Brakes????

[Caley Jim]

Brakes????

Yep! I reckon he's going to slice it up to make brake blocks and their hangers.

 

Jim

[Atso]

Yep! I reckon he's going to slice it up to make brake blocks and their hangers.

Jim

Slice? Looks like it started off as eight layers sweated together...

[CF MRC]

Give the boys a coconut!

A pattern in styrene was made to fit on the brake hanger pivots to check the size.

 

This then needed to be copied eight times in 20 thou nickel silver. To make eight pieces, a strip was tinned, folded up, and then squeezed together in the vice and re-heated to join up the layers.

 

This block was then drilled with two 0.5mm holes for the hanger and push-pull beam pivots.

 

This was then filed up in the vice.

 

And then a lot more filing.

 

Next stage will be to separate them, file in the brake shoes and then make the rest of the rigging. More to follow....

 

Tim

Edited February 4, 2018 by CF MRC

[bécasse]

That's funny, Tim, I would have done it like that too, folding up tinned strip and pressing it in a vice. The only thing that I would have done differently (from experience) is that I would have made TWO identical black plastikard patterns and put one at either end of the block before filing it up - it makes it much easier to ensure that one is filing evenly and the plastikard patterns take minutes to make.

[CF MRC]

I can file more accurately than I can make two styrene patterns David; the drills are the main way to determine shape and act as filing indicators. Also, the plastic patterns probably wouldn’t have survived being held in the vice at such a small size.

 

Tim

[CF MRC]

Final filing and shaping of the brake blocks and hangers required the use of some nice safe-edged Vallorbe escapement files.

What can’t be seen is the finger nail that would be holding down the brake block.

 

Each block was made to fit a particular pivot, as my chassis drilling wasn’t that accurate.

 

They tuck snugly into place on the wheels and definitely fill the space well, helping to hide the overscale flanges. There is no way I could have made this engine with scale size wheels: the brake gear would have been impossible to fit.

 

Sorting out the cross beams and rigging should be straightforward. Before that, I’ve got to do the other side - they will, of course, be quicker to make; but it’s also good to give the eyes a rest from time to time.

 

Tim

Edited February 5, 2018 by CF MRC

[richbrummitt]

Would the flanges be closer than touching if you had used scale size across the treads?

 

How will you secure the brakes in place? Soldering that close to the wheels scares me for the integrity of the tyre material. Of course I could be patient because all will be revealed, I'm sure, but I thought I'd ask.

[Caley Jim]

.....How will you secure the brakes in place? Soldering that close to the wheels scares me for the integrity of the tyre material. Of course I could be patient because all will be revealed, I'm sure, but I thought I'd ask.

My guess is solder paint and a quick touch with a hot iron, using a slip of paper to space the brake block from the wheel. (At least that's how I would do it, but then I was just a humble GDP, so who am I to second guess a Prof?)

 

Jim

[CF MRC]

 

Does that answer your first question Richard? Not a sharp image, but the wheels are nearly touching. To accomodate scale wheels the chassis and body would have had to stretch as the wheelbase is touching the cylinders or ashpan at the ends, so compromise is the order of the day. The brake blocks are constrained inwards by a shouldered bolt; I’m still thinking about fixing strategy.

 

 

Tim

[richbrummitt]

My concern with Jim's suggestion would always be the tyres, which I have had rusting problems with in the past.

There appears to be a little forming on the RH wheel in your final photo. Since I have always polished the tyres in the lathe before starting assembly bit still worry about it. How do you manage this?

Yes. The picture shows what you described regarding wheel size well. The 6'8" GWR 4-6-0s present a similar problem.

[CF MRC]

I use phosphoric acid flux in minute quantities in this sort of application. A bit of spit will also neutralise any residual acid, (it’s alkaline) if washing in water is not an option. Also a smell of oil can act as a rust inhibitor.

 

Tim

[richbrummitt]

Agreed, however lubrication is likely to impinge traction. Maybe that's less of an issue with the mass you have built into this particular engine.

[CF MRC]

The oil is only there when soldering. Even Lord President would object to slippery wheels. Wouldn’t want to do a Blue Peter!

 

Tim

[CF MRC]

I made the first of the brake assemblies today. Basically consisting of thin double sided PCB with a brass pin soldered across and gapped. The assembly is gently sprung over the brake hanger pivots.

 

The cross beam was also strengthened by a piece of shim brass on the other side to span the insulation gap: this will have the push/pull rods soldered to it to allow the brakes to be held in the ‘off’ position.

 

Before mounting in the engine the whole lot was chemically blacked.

 

Afraid these photos are desperately cruel.

 

Tim

Edited February 9, 2018 by CF MRC

[Caley Jim]

Afraid these photos are desperately cruel.

 

Another button we need. 'disagree'!

 

Jim

[bécasse]

Another button we need. 'disagree'!

 

Jim

 

I suspect that Tim meant that the photos were cruel to all those of us who, despite having the best tools and lots of experience, can't quite manage to model things that small that well.

[CF MRC]

Well, no actually, David. I may be arrogant, but hopefully not that bad. Cruel enlargements.

 

Tim