Monday 30 April 2012

Saturday session

The non-stop rain in Hertfordshire meant that I was largely confined to home this weekend, apart from a spell in the garage to continue painting the floor, and a spin on the SS up to the garage where my car is, as I had to choose the colour of new carpets to go in it.

So on Saturday I had the opportunity to do a little more work on the Coffee Pot.  And what a joy it was, as the design quality of the kit showed itself again.  Below are a few pictures showing what I mean:

To make fixing the cab handrails easy, Chris has designed in a cross-brace that goes across the entire cab opening.   This means that there aren't tabs or flaps that can get bent earlier in construction, and the whole thing strengthens the cab whilst it is being assembled.

You then insert 0.4mm wire through holes at the lower end, and then solder it to the cross-brace.  As you can see, cutting the wire overlength, and then soldering it (messily but strongly) on the side away from the cab means that it is securely fixed.

And  this is the end result.  I'd already done the other side of the cab.  The cross-brace was first snipped in the middle with my best Xuron sidecutters, and then the remains of the cross-brace trimmed back.  The final touch was a few strokes with a fine needle file to round off the edges.  Looking at it in close-up, this one isn't quite perfect, as the rear rail comes in slightly at the end.  I always forget to use things like scraps of wood to set handrail depths so that they are absolutely parallel :-/

Next steps involve the buffer beams.  These are cast whitemetal, which has three benefits.  Firstly, it adds weight in a really useful place on the model.  Secondly, it allows for the proper prototype construction of steel-timber-steel to be replicated.

And thirdly, it allows for some really crisp rivet detail to be incorporated.  This just wouldn't be as fine  if the whole buffer beam was a single casting.  Just have a look at the detailing that is on the _rear_ of the bufferbeam.  This would hardly be noticed when the model is completed, and yet it is there...

Then it was time to put on the outward facing overlays to the castings.  To do this, and make sure that they were in exactly the right place, I pre-tinned the etched brass and and held it in place using miniature clothes pegs.

 From a sightly different angle you can see how the sandwich construction of the bufferbeam is faithfully reproduced.  With the etching held securely in place, all that I had to do was to place a drop of flux at the edge and flash some low melt solder around it to fix it firmly in place.

This was helped by being able to stand the model vertically in my foam cradle, which grips it just firmly enough to be used as a "third hand" and unlike a vice means that there is no risk of accidentally damaging it by crushing the model.

Finally, the cast whitemetal dumb buffers were fitted, which gives more useful weight, and the whole thing was given a comprehensive clean to remove the excess flux.

I'm really pleased with the session's work.  Next, it's on to the boiler and tank fittings...


Tuesday 24 April 2012

Watchmakers' work

Apologies for the delay in posting - Blogspot seems to have had a funny couple of days :-(

One of the things that I really love about High Level Kits is that they are such fiddly things to build.  Not difficult, certainly not badly designed, but containing such a  level of detail that it really pushes the boundaries of your skill levels to do the job properly.

Last night was like that.  After a long and tough week at work, which meant that I wasn't able to join friends in either Hay on Wye or Wakefield for the weekend, for various other reasons as well, I determined that last night was going to involve some modelling.

The next thing on my list of instructions (I'm on page 7 out of 18, and this is for a kit that is under 8cm long!) was to fit the clips that hold (what I think are) the sandbox operating rods.  These clips go under the saddle tank, and are soldered to it.  Here are a couple of pictures of the work completed:

They are each made from a single small piece of etched brass, soldered in place and then bent over to form a clip. However to give you some idea of the size of the part, and the level of detail that is built into these kits, when you bend the half-etched part of the clip over, to ensure that it takes the correct shape you use a piece of 0.4mm wire as a former!

After this, there were a couple more brackets to be fitted to the front of the tank, and a couple of valves to be mounted on those, and it was finally fitted in place and soldered to the bunkers and smokebox. And as you would expect from everything that this kit has been so far, it fitted together perfectly...

A quick wash down with lashings of ginger beer, or rather Carrs Acidip, and a trip through the ultrasonic tank to clean it up, and it was looking lovely :-)


Sunday 8 April 2012

Tank shaped...

Here's a quick update of the completed (but not yet detailed) tank.  Not annealing the side panels and bending them in the approved manner doesn't appear to have affected the end result:

And here is the tank in place in a trial fit on the locomotive:


Friday 6 April 2012


Both metal, and the rules :-)

But more of that later...  First of all, this is how the saddletank has gone together so far.  It's a very clever design idea.  First you build a stout subframe that will keep everything square, and then you put the top and sides in place.  These are held in place with etched tabs whilst you solder it together, and then file the tabs off after all is done.

This is the subframe assembled with the panel of the tank top already in place.  This is located over vertical tabs which have been filed off leaving just the faintest of traces.

The horizontal tabs are left in place as they are used to locate the side panels of the tank.

This is the tank subframe from underneath.  The plate with all of the holes in it acts as a reinforcing piece for the assembly.  The multitude of holes is to enable you to easily solder it in place.  I used an RSU to join them together, so it was less relevant for me, but if you are using a conventional iron, then you can flood solder through the holes.

Now this is where I started bending the rules, as well as the metal.  Normally Chris's instructions in High Level Kits are absolutely spot on, and indeed they come with a sizeable health warning not to alter them and try to do your own thing.

However when it came to shaping the complex S-curve  that makes up the sides of the tank, I felt a little nervous.  The instructions state that you should anneal the panels prior to bending them.  I'm never comfortable at my ability to anneal brass evenly, and to the right extent.  Added to the facts that the panels themselves are already half-etched, and that I was not confident that the completed sides would not accidentally pick up dents in the softened metal, and alternative approach was needed.

So I started off by putting the gentle curves at the top of the tank in by pressing the metal around a largish diameter metal rod on to the mouse mat on my desk.  Then I clamped the panel against the rod in my modelling vice, and used a further rod to gently ease it over, as in these pictures...

You can also see the gentle bend that I put in at the top of the tank from the pressure on the mouse mat.

Well, this may not be the recommended way to form the curves in the tank but I seem to have got away with it.  This is the first panel fitted into place on the tank, and held in place only by the locating tabs.

I've now done the second side panel as well, and maybe later tonight I'll get chance to solder them in place.


Great balls of solder...

Or rather, very tiny ones...

After the arrival of my vials of solder from Hong Kong, I couldn't wait to try them out.

This is the top of the saddletank of the Coffeepot about to be soldered into place.

- position parts for soldering on the RSU (which is why it is all silvery - that is tin foil used as the negative terminal)
- apply spot of flux using pipette bottle
- apply single 0.7mm ball of solder using tweezers
- place RSU probe, and press [on] switch

Zap...  and a very neat join with no cleaning up required.  I like this :-)

If anyone else is thinking of ordering these solder balls, I'll just confirm that for 4mm, the 0.7mm size seems just right.  Anything smaller is just too damn fiddly to manipulate easily, although I can see that "pouring" them into place will work well in certain circumstances with the very smallest size.


Wednesday 4 April 2012

The right tool...

Every so often, having the correct tool for the job makes life so much easier.

The otherwise excellent instructions from High Level for their Coffee Pot kit refer to using a piece of wood to bend the inner of the saddle tank squarely up.  Or you can do as I did and use a Hold-And-Fold tool.  

Very easy, very accurate, and you should get perfect straight bends.  It's one of those "investment tools" that you don't use every day, but when you do, you reflect on just how easy it makes things...


Monday 2 April 2012

Eastern promise

One of the joys of the internet is that it makes all sorts of things available to you from all sorts of sources, that you possibly never even knew existed before...

When returned on Friday from a business trip to Singapore, I found a package waiting for me...

Lots of pretty coloured stamps on the outside!  It was the contents of it that I was really interested in.

First up was a set of electronic tweezers.  These (apologies for the rather blurred shot) are unusual in that they have plastic tips on them so that they don't short out electronic components. I was curious what they would be like.  

They don't have as fine a point as I expected.  However the fact that the tips are made out of plastic will make them very useful when I file grooves in the ends of them to pick up what came out of package next...

These are an assortment of small - that is a one pound coin for size comparison - glass vials containing balls of solder.  I went for a "trial pack" which contains different size balls of sizes 0.75mm, 0.45mm and even 0.3mm.  And there are 10,000 of each size in each vial!

When I saw these, I was amazed at the possibilities for really precision, clean soldering either using a conventional iron or more likely an RSU.  These offer a really precise way to get as much or as little solder in the joint as you wish.  I have no idea what they are used for in the electronics industry, yet to me they offer lots of possibilities.

And finally to the real reason why I had been browsing on Ebay:

Small pipette bottles.  For the last couple of years, Tim Watson has used these during his soldering tutorial at Missenden to hold flux.  They allow it to be dispensed in a much more precise way than the traditional mucky paintbrush.  Even Tim says that these are getting more scarce for him to find through his chosen trade of dentistry, so I thought that I'd have a look and see what the internet could throw up.

These cost not-a-lot each, and I got four of them.  Each one comes with a variety of different sized nozzles so I'll see what gives the best control.  And they should be a lot less messy when the inevitable happens and they get knocked over on the workbench!

What was perhaps even more impressive was that I ordered these last Sunday before I left, and they were waiting for me on Friday when I returned home.  That's a turnaround time that many dommestic businesses can struggle to meet.  It just reflects the impeccable service culture that I have found all over Asia.