Atlantic's works: Portable layout update

[Mercator II]

Looking good Graeme, hope it goes easier for you, am taking notes for my variant/s

Where are you planning to add the pour spout and vent holes?

oOo

Brian

[Atlantic 3279]

I think the shape may suit the simple method of pouring resin in to the outer mould, to slight excess compared to final necessary volume, then lower the plug/lid piece into it.

I might just bevel the horizontal element of the that internal rebate first, to discourage air bubbles from hiding in the rebate.

[Atlantic 3279]

Good-o. Postie has just brought me some more rubber to play with.

[Mercator II]

Good-o. Postie has just brought me some more rubber to play with.

Watch out 'Mrs Atlantic'!!!

[Atlantic 3279]

Mrs Atlantic liked the rubber, 'cos it was pink.....

[earlswood nob]

Good morning all
I watch this thread with interest, but I'm not sure if my great-nephew would like me pinching his Lego set (he's the only one I now who has one).
I suppose one could use plastic boxes, if found in the right sizes.

Everytime I visit the model shop in the great wen, I look at the shelves of casting resin/mould rubber etc., and wonder about trying some.
It's a good job that I visit the "Hoop and Grapes" afterwards, not before, as everything is a good idea after a few pints.

Earlswood nob

[Atlantic 3279]

You can make the moulding box from plastic, wood, metal, shiny card etc. so your great nephew's lego need not be requisitioned for this obviously more important use.

I find that many things seem like a good idea after a couple of hours in the White Hart....

[Atlantic 3279]

As with any new mould that I've tried, the first casting or two in this one provided me with instruction rather than perfect results, but I've managed to turn both into good tender bodies, learning a fair bit along the way. As my resin supplies are now rather low too, I'm glad I didn't struggle to a greater extent. I'll try to post notes and pictures tomorrow.

[Horsetan]

Good-o. Postie has just brought me some more rubber to play with.

Is it inflatable

[earlswood nob]

Good morning all
Thanks for the info, I wouldn't need anything large, as I am merely interested in copying boiler mountings, smokebox doors, etc., which are getting harder to source.
I shall keep my eyes open for useful mould containers.
I don't think today is going to be my day, as the 8 key on my keyboard packed up working (raisin from bagel jammed it) and Automatic radio controlled clock didn't automatically change like it should (needed new battery).
I shall have to tread very carefully today.
Earlswood nob
PS. A Great Northern tender (A,B, or D type) in resin would be a popular item for followers of this forum. I was looking at the D3, yesterday, and there were five different tenders (variants of A,B, or D type).

[Atlantic 3279]

B type on the "to do" list.......

[Atlantic 3279]

Initial mould separation was very encouraging, with razor-sharp definition of detail and no unwanted voids due to trapped air bubbles.

With the three-dimensional nature of the top/core piece of the mould clearly visible, I realised that the added bosses would never be reproduced in resin unless I created some breather holes above them to let air out as the resin level attempts to rise.

[Atlantic 3279]

Howzat for surface texture reproduction:

That was the first casting, quite pleasingly free of air bubbles around the lower edges given that as soon as I had inserted the core piece into the partially resin-filled outer mould it was obvious that my estimated volume for the resin mix was a little low - there was hardly any resin overflow, which is usually essential in order to "sweep out" the air bubbles


Erm......

In thickening the sides of the master I had done the right thing, but I was wrong in assuming that the rear was thick enough as it stood. The lower part of the rear broke as I tried to extract the casting from the mould. In order to avoid repetition, I took a slice of rubber off the rear of the core piece so as to thicken the rear wall on its inner (unseen) face.

More problems: The bosses inside the body were poorly formed or entirely absent, and there were air pockets in the front footplate area, partly due to the low volume of resin but also (I suspected) suggesting inadequate size of the breather holes that I had created. I enlarged them before trying a second casting.

[Atlantic 3279]

Getting there, on that modified Hornby u-frame shown earlier. This is that first casting with the broken rear repaired using superglue and a couple of layers of plastikard as internal strengthening pieces. I'd also filled the voids in the front footplate area by adding some extra resin while the casting was still in the outer mould.

[Atlantic 3279]

Mods to create the streamlined version.

The beadings were simply filed off and rubbed down to a good finish. The top front fairing was produced in stages. Firstly the top of the front plate was filed down towards its edges, but not in the centre, so as to create a tighter curve with notches near the copings to accept the added fairings in a way that would achive a final flush-fit. I then added a strip of 20 thou plastic, 2.5mm wide and about 28mm long across the top curve of the front plate, and some strips about 10mm long x 3mm wide under the front ends of the side copings. Part of the width of the side strips protruded within the bunker space, creating a legde or rebate onto which the top layer of the fairings could be bonded. I then added two triangles of plastic and some fill-in pieces to form the top layer of the fairing to roughly the right shape. With all firmly bonded I filed in the correct curvature of the edges. The resultant front plate and fairing are correctly higher in the middle than is the front plate on either a 1928 tender or on the revised post-war streamlined version.

Having noted previously that this resin does soften more effectively than does styrene sheet in hot water, I decided to have a go at straightening the curves in the front side sheets rather than cutting these off and replacing them. I cut them free of the fottplate at the bottom using a coping saw before I tried to manipulate them. A fairly quick dip of the relvant part of the casting in nearly-boiling water is more than enough to soften the material, and pressing it between two rulers/straight-edges does a reasonable job of straightening the curves. There are snags however. Complete freedom from distortion id very difficult to attain, hence there's a little filler in my finished example, and some well filed-down areas. Also, the straightened resin retains "plastic memory2 and it is hard to prevent one side shhet from curling again as heat is used to straighten the other. Reinforcement layers bonded to the inner faces of the straightened sheets are therefore vital if simple ambient temperature changes are not to wreak havoc with the model in future! For speed in this case I used two 20-thou plastic layers as they won't be highly visble when the loco is in use. However, a neatly shaped layer of say 15 thou metal sheet would give a neater result for those who like to examine the details on the fronts of their tenders, and I suspect that with no beadings to preserve or re-create, it would be just as easy to hack of the old curved pieces and replace them in plastikard , using the metal layer behind to brace the joint.

As well as the fill-in pieces around the edges of the front footplate area, to suit the widened gap between the straightened side sheets, this picture reveals a repair patch under the middle of that running plate. That's because I'd broken it due to clumsy handling whilst doing my modifications.....