Oswestry Works

Locomotive works diorama in 4mm

Tag: experiments

No.9000 – Back to Black

Considering the benefits 3D printing gives when tackling something like the top feed and sandboxes, there is still a good deal of traditional modelling required to integrate them into the model.  The sandbox pull rods have given me a few hours of amusement trying to solder them (mental note: now might be a good time to look into etching some!); the casing for the top feed pipe, where it runs up the side of the boiler, was equally challenging.  I’d originally tried used masking tape to replicate the thin metal that encases the pipe, but I didn’t get very good results.  Having some time away from the problem was what I needed and this morning I realised that tin foil would be perfect for the job.

Shaping tin foil around the top feed pipe

2 hours later I was still battling with the umpteenth strip of tin foil, having tried and failed with 3 different methods for accurately shaping it around the wire.  The final method which worked well enough was to bend some wire around another Dukedog boiler, take an inch long strip of tin foil about 2.5mm wide, tape one end to the boiler/wire and then smooth the tin foil down the wire making sure it shaped to the wire.   Then using a flattened end of a cocktail stick you can tease the tinfoil gentle into the wire.  Even at that stage the process is fraught with danger, as slightly too much pressure with the cocktail stick tears the tin foil.

Shaping tin foil around the top feed pipe

With that fiddly task completed I turned attention to the front of the loco.  No.9000 was one of a few class members that had a lamp iron on the smokebox door, another nice fiddly task to challenge me.  The lamp iron on the smokebox door would need to be quite fine so as not to jar with its surroundings, so I decided to use Shawplan Extreme Etchings Lamp Brackets as these are a lot finer than the Mainly Trains etch.   Iain Rice’s Etched Loco Construction was my guide for folding the etch into shape, not as tricky as I thought but still a testing task with the Hold’n’Fold.   To keep things the same I replaced the other lamp irons and for variation fitted a new smoke box dart.

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With those jobs finished the last task tonight was to mask and then coat with Halfords black primer.  This wasn’t quite as straight forward as with the Pannier as the open cab has fantastic detail which needed preserving.  A few layers of Tamiya masking tape did the job but for me it still takes a bit of a leap of faith when using maskol.  This time however I’m completely sold on it, it worked great used directly on the cab windows and peeled off easily after starting with a cocktail stick.

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Of course once the primer is on then the niggles start to show.  The top feed has an unsightly gap where it meets the boiler that I’d forgot to tackle, I think I’ll have to try some modelling putty and another coat of primer.  Anyways, that’s it for now, I’m waiting on the numbers still so No.9000 will go back into the queue.  I think it might now be time to blow the dust of the High Level Chassis for No.5726! I’m booked onto the Loco building course at Missenden in March, so I think making a start on the kit now would be good and I’ll take a Comet Manor and Mogul chassis’ to Missenden as I imagine they will be quite a lot harder.

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Experiments with Spot-HT Resin

Other B9 Creator users have had some impressive results usingSpot-HT resin, in particular for small highly detailed components.  The main difference with this resin to the proprietary B9 resins is that you cannot use it for casting, it is also much less viscous which should mean that it settles quicker.

I’d just about enough life left in the layer of PDMS for another print, so today I tested printing some detailing components using Spot-HT.   The test parts I’ve roughly drawn up in Sketchup, some will need a little more work depending on the results of the print.  The test pieces were:

  • 4x Pannier tank rear steps
  • 1x Top feed for 74xx
  • 12x GWR Whistles pairs and mounting bracket
  • 14x Steam heating hose cocks

Spot-HT Test Print components

First up, the steps have come out really well, with a thickness of 0.5mm they look just right.  The rivet detail has come out nicely but I will probably increase the size next time round.  There is some flash to remove from the edges of the steps, due to the positioning on the build table.  Another thing for next time is printing these small components on a sprue. They were a devil to get off the build table without damaging! That said, this material is pretty tough even before curing under UV light.

The whistles have lost quite a lot of their detail but I think this is down to the clouding of the PDMS.  However, the small nut on top of the whistles has printed really well, considering its 0.25mm wide its pretty amazing!   The steam heating hose cocks also look pretty good, with the addition of a turned brass pipe and handle made from 0.4mm handrail wire.  However both these items are slightly overscale, I’ll have to get the micrometer out next time and make them more accurate!

Spot-HT test prints

5726 with 3D printed steam heating hose cock

For now that’s it for printing.  I’m waiting on my spare vat to return from the USA as its being fitted with a replacement for PDMS called Nuvat, developed by Evert on the B9 Creator forum (details here).  This new material should last a lot longer than PDMS.