Progress With the Fiddly Bits

I said I would do updates on progress with the Townsend Hook kit as it gets closer and closer to the 7mm NGA Convention.

Here is the latest news:

Test prints of all the parts that will be brass castings have been completed in standard resin.  These are shown to the left and I have sprayed them yellow so that they look a bit brassy.  They are still on the printers support frames in this first picture.

Next part of the plan was to use these to dress up a body with these parts.

There is a nest of piping that connects all the cab valves together which will be easier to install when they are done in brass. The resin, particularly on that Christmas tree of a cab valve, is quite fragile.

Townsend Hook has Salter balance safety valves now whilst William Finlay has pop valves. There will be castings for both varieties in the kit.

In another example of me not knowing when to quit the loco has clear glass for its single gauge glass!

The firebox print has holes in it and there will be a bit of clear plastic in the kit to represent the glass. (Its actually a small bit of fibre optic)

Now I have hideously enlarged the image I can see I should have added handles for the top and bottom cocks on the gauge glass!

Now, while I pack the car for Doncaster Show, the printer is on with producing the waxes for the castings

Playing Trains & New Models

It had  been the plan that my next jottings would have been about my trip to Wales driving trains at the last bank holiday but, as is often the case, having skived off for a few days I came back to a load of catching up that precluded sitting at the PC and writing for pleasure. I’ll include a bit about that trip at the end [so you’ll either have to read the rest – or scroll to the bottom].

The thing that is filling all my time at the moment and causing more than a little anxiety is the plan to launch our new Townsend Hook Body kit at the 7mm NGA Convention in less than two weeks. When we made that public, it looked like we had loads of time but with the date approaching its looking incredibly tight.

Until Friday it looked like the critical item were going to be the brass castings. I had a bit of a panic when I phoned the caster to discuss timescales and the first thing he said was, “I’m on holiday next week”.  Anyway, a cunning plan was hatched that actually gives me next week to get the waxes done.  Taking advantage of the 3D printer we’re doing things a bit differently.  Traditionally, you made a master, they made a mould from it, in that mould they poured wax and made many wax replicas of your master and added runners, made a ceramic mould around the waxes, burnt the wax out and poured molten metal in.  The new way is to print the multiple waxes using a castable wax resin in the 3D printer.  That sidestepped that critical item, at least for now.

Having done the design for the parts in CAD the first thing to do was to print them in ordinary resin (cheaper) to make sure they print and fit the model when done. Attempt 1 showed some opportunities to improve the designs and attempt two printed them successfully.

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Challenging Commissions

I do like a challenge!

I find the repetitive stuff in building model railway items the hardest just from a motivational point of view. I guess I get bored easily and need to be challenged to keep me interested.

This one was certainly a challenge! In more ways than one as it turned out.

The commission was to make an model of an original Spooner bogie to 16mm scale. The first challenge was converting ancient blue prints that didn’t tell you all the information into a modern CAD model.  Only heavily modified descendants of the original Spooner bogie exist so looking at them only helped with clues rather than providing something that could be copied. At the very least they have been modified to include brake gear which wasn’t even an optional extra on the original. There have been changes to the suspension as well over the years.

I use SolidWorks for my CAD so a full solid model was created in the CAD comprising of many individual components then put together in an assembly drawing to see if it all fitted together.

Now here’s a thing. When drawing a pen and ink blue print you can draw a line any length you like and write a dimension on it and no one says a thing. (well, the bloke on the shop floor might call you names but then he’ll just build it how he’s always built it.)  3D CAD wants the dimensions , wants them to be right and gets cross with you if they are not. Often it refuses to go any further until you do get them right, or at least work out a lie that its happy with.

Now the thing with the Spooner Bogie is that it has a spherical centre and then a secondary suspension arrangement that takes some of the weight off the centre with a sort of spring in a cartridge arrangement which bears on castings on the inside of the frames.

Sorting the design out was the first challenge, then it was on to making it. Many of the parts were to be 3D printed on my new 3D printer.  Learning to use that was the second challenge as this was the first real job to be done on it. It was quite a steep learning curve with more than one false start whilst the boundaries of what is possible were tested.

My printer is a Formlabs Form 2, a proper production machine rather than a hobby machine, and probably the closest you can get to a desktop printer at the moment.

Its still not straightforward with the prints having to be cleaned and then cured but it us developed to the point where its a process in which you don’t have to touch the resin or the wash.  Its still messy with uncured resin and buckets of Propanol swilling about.

Eventually the process produced a load of printed parts to which then had to be added metallic parts and then the whole thing assembled. Trying to turn and thread 14BA suspension bolts generated some poor language!

Also practical assembly resulted in some mods and some reprints.

 

Eventually it all went together. It was then painted and weathered and a bit of display track made for it.

Just a quick note on weathering. It’s weathered to show up the details and to mimic the way it catches the light. I was asked if I was going to paint it black just as I finished it. I was not impressed!  On the other hand if I had painted it gloss black I could have missed half the details off as they wouldn’t be seen.

Anyway, here are two pictures of the finished item. You decide if it came out alright

 

 

 

Applauding Excellence

Just the other day I received some pictures that I have to share with you.

These are some photos sent to me by one of my Australian Customers, Roger Hill, and show his model of a Darjeeling B Class built from an EDM Models kit.  He’s made a superb job of it and its great to see a completed model. So often I send kits out and then never hear of them again. Statistics suggest a significant number end up unbuilt in a cupboard so its great to see a finished one.

Better still its a prize winner having gained first place for steam loco’s at the 2019 Australian Narrow Gauge Convention.

 

The astute amongst you will not there are two certificates. The second is a First Place for Photography – Prototype won with this shot.