Atlantic's works: Portable layout - Ground Signals Again
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- Atlantic 3279
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Re: Atlantic's works: MS&LR Class 2, LNER D7 4-4-0 in resin
Here are the three parts of the completed mould for running plate + splashers + cab sides. As will be evident in one or two other images too, auto-adjustment to colours has done wonders for what had been poor contrast in images of pale pink moulds, but the effect on the colours is horrible...
What the two tone rubber does show is a nice reminder of the fact that, before pouring the bulk of the rubber for the main outer mould, I had ensured that the crankpin cut-outs in the splashers filled properly, one side at a time, with the master and mould box lying on one side. Those cut-outs were of course also closed off by thin shuttering on the inside faces, before the first of the rubber was poured. The image also shows the many breather (air release) holes that I cut out of the rubber once it had cured, allowing resin to fill all spaces.
The cab core piece fits in like this, having to go in very quickly once a small amount of resin has been introduced to fill the deep recesses that form the upper parts of the cab sides. It is such a tight fit that it proved difficult to extract after casting, without causing damage, until I made two relieving cuts in the rear of the outer mould. The length of the mould, plus those relieving cuts, does make the sides as well as the rear end susceptible to spreading under the weight of liquid resin and the pressure caused by pushing the core piece into place. A simple clip cut from stiff card keeps everything braced. The outer mould having been produced with a sloping top in order to avoid un-necessary use of extra rubber, it is of course necessary to support the mould on a rigid sloping base when pouring in the resin.
The two strikingly different shades of pink in the rubber are not due to poor measuring mixture ratios. I changed to a new batch of rubber part-way through making the D7 moulds, and its catalyst is much less strongly coloured than the previous one. The fact that it comes from a different supplier is probably irrelevant, as I've seen just as much variation between batches from the same supplier. Cost was my reason for trying a new source.What the two tone rubber does show is a nice reminder of the fact that, before pouring the bulk of the rubber for the main outer mould, I had ensured that the crankpin cut-outs in the splashers filled properly, one side at a time, with the master and mould box lying on one side. Those cut-outs were of course also closed off by thin shuttering on the inside faces, before the first of the rubber was poured. The image also shows the many breather (air release) holes that I cut out of the rubber once it had cured, allowing resin to fill all spaces.
The cab core piece fits in like this, having to go in very quickly once a small amount of resin has been introduced to fill the deep recesses that form the upper parts of the cab sides. It is such a tight fit that it proved difficult to extract after casting, without causing damage, until I made two relieving cuts in the rear of the outer mould. The length of the mould, plus those relieving cuts, does make the sides as well as the rear end susceptible to spreading under the weight of liquid resin and the pressure caused by pushing the core piece into place. A simple clip cut from stiff card keeps everything braced. The outer mould having been produced with a sloping top in order to avoid un-necessary use of extra rubber, it is of course necessary to support the mould on a rigid sloping base when pouring in the resin.
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- Atlantic 3279
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Re: Atlantic's works: MS&LR Class 2, LNER D7 4-4-0 in resin
The non-ideal mould for the tender soleplate that I mentioned a little earlier:
The outer mould for the boiler, which has to split along the bottom centre line of the boiler in order to allow the projecting base of the cast smokebox to be extracted:
Here it is with the (inverted) core piece. That core piece has a "plinth" at the firebox end, which functions in the same way as the plinth I used in the running plate mould, controlling the depth to which the core piece is inserted, and since it is trapezoidal in shape it cannot be put in the wrong way round. The conical tip engages with a conical depression at the smokebox end of the outer mould, ensuring centralization of the core piece and even thickness of the cast boiler walls. That is essential for even, adequate strength and to ensure that the small boiler can sit centrally over a motor of reasonable size.
The interlocking stepped contours of the rubber I created on each side of the split, by careful arrangement of thin shuttering before poring the rubber, plus supporting clips cut from stiff card, keep the split closed when resin and the core piece are introduced into the mould.
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- GCR O4 2-8-0 'ROD'
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Re: Atlantic's works: MS&LR Class 2, LNER D7 4-4-0 in resin
Thanks for sharing & showing the process
I do still get enjoyment from reading your work and methods
Hope the casts go well
I do still get enjoyment from reading your work and methods
Hope the casts go well
oOo
Brian
Garage Hobbit!!
Modelling in 00 on my heritage line, very GCR inspired
Brian
Garage Hobbit!!
Modelling in 00 on my heritage line, very GCR inspired
- Atlantic 3279
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Re: Atlantic's works: MS&LR Class 2, LNER D7 4-4-0 in resin
Thanks Brian.
Here's an almost complete set with varying amounts of flash still attached to the minor parts. The big bits of course have been cleared of flash and of many attached "rods" of resin formed in the breather holes of the moulds, so that they will fit together. The full sheet of flash that covered the space between the splashers obviously had to be removed with care, to avoid damaging the splashers themselves, and so as to leave nice neat edges. the same goes for the smaller sheet covering the cut-out in the underside of the boiler barrel and the skirt of thin flash that was present around the lower edges of the firebox. Should anybody wish me to add closer views of the castings, I have the necessary images ready.
I do still need to cast some inside-bearing sub frames for the tenders, for those who might want such things. Fortunately, the same one that suited the GNR tenders I used with K2 and J6 models will suffice so I don't need to make a mould for that part. I also need to consider whether to produce some resin side frames to suit the four-coupled part of the chassis, with suitably shaped edges and reasonable surface details, for those who are not averse to use of resin for frames. That would leave builders needing to add only suitable frame spacers, brass bearings (set in place accurately using a suitable choice of coupling rods and jig axles), wheels, axles, motor, gearbox, stubs of stiff wire on which to mount the resin brake shoes, a representation of the yokes and pull rods, plus a means of attaching that part of the chassis to the body. ALTERNATIVELY, I could just supply a paper template for the necessary frame shapes...
For those interested in copying my arrangements so that the front of the loco actually rides on the bogie (with pin in slot to allow lateral movement too) and so that the four coupled unit is free to tilt slightly to follow undulations in the track without un-necessary losses of electrical pick-up, the images below show how I arranged for that freedom to tilt.
Seen from the side (my choice of well-forward motor position, but it would fit within the firebox if mounted more typically to the rear of the leading wheelset): A view revealing the strong brass strip fixed across the top of the chassis. This protrudes laterally not quite as far as the inside faces of the coupling rods. A hole is drilled in each projecting end, just large enough to clear a slim screw. The slim screw passes up through the hole in the brass into a hole that is drilled in the appropriate position in each side of the running plate, between front and rear splashers. If possible the hole in the resin should be tapped, although screws will bite in an un-tapped hole of just sufficient size in the resin. The correct positions for the holes in the resin are ringed in red in the image below. the casting is thick and strong in these areas, and holes in these EXACT positions ensure that the screw tips emerge above the running plate inside the edges of the firebox, while their heads remain accessible from below even when the brake shoes are fitted. The trick when mounting the body onto the four-coupled unit is NOT to tighten these screws quite fully. This keeps the components in close alignment but allows the necessary tilting / rocking to take place.
Here's an almost complete set with varying amounts of flash still attached to the minor parts. The big bits of course have been cleared of flash and of many attached "rods" of resin formed in the breather holes of the moulds, so that they will fit together. The full sheet of flash that covered the space between the splashers obviously had to be removed with care, to avoid damaging the splashers themselves, and so as to leave nice neat edges. the same goes for the smaller sheet covering the cut-out in the underside of the boiler barrel and the skirt of thin flash that was present around the lower edges of the firebox. Should anybody wish me to add closer views of the castings, I have the necessary images ready.
I do still need to cast some inside-bearing sub frames for the tenders, for those who might want such things. Fortunately, the same one that suited the GNR tenders I used with K2 and J6 models will suffice so I don't need to make a mould for that part. I also need to consider whether to produce some resin side frames to suit the four-coupled part of the chassis, with suitably shaped edges and reasonable surface details, for those who are not averse to use of resin for frames. That would leave builders needing to add only suitable frame spacers, brass bearings (set in place accurately using a suitable choice of coupling rods and jig axles), wheels, axles, motor, gearbox, stubs of stiff wire on which to mount the resin brake shoes, a representation of the yokes and pull rods, plus a means of attaching that part of the chassis to the body. ALTERNATIVELY, I could just supply a paper template for the necessary frame shapes...
For those interested in copying my arrangements so that the front of the loco actually rides on the bogie (with pin in slot to allow lateral movement too) and so that the four coupled unit is free to tilt slightly to follow undulations in the track without un-necessary losses of electrical pick-up, the images below show how I arranged for that freedom to tilt.
Seen from the side (my choice of well-forward motor position, but it would fit within the firebox if mounted more typically to the rear of the leading wheelset): A view revealing the strong brass strip fixed across the top of the chassis. This protrudes laterally not quite as far as the inside faces of the coupling rods. A hole is drilled in each projecting end, just large enough to clear a slim screw. The slim screw passes up through the hole in the brass into a hole that is drilled in the appropriate position in each side of the running plate, between front and rear splashers. If possible the hole in the resin should be tapped, although screws will bite in an un-tapped hole of just sufficient size in the resin. The correct positions for the holes in the resin are ringed in red in the image below. the casting is thick and strong in these areas, and holes in these EXACT positions ensure that the screw tips emerge above the running plate inside the edges of the firebox, while their heads remain accessible from below even when the brake shoes are fitted. The trick when mounting the body onto the four-coupled unit is NOT to tighten these screws quite fully. This keeps the components in close alignment but allows the necessary tilting / rocking to take place.
Most subjects, models and techniques covered in this thread are now listed in various categories on page1
Dec. 2018: Almost all images that disappeared from my own thread following loss of free remote hosting are now restored.
Dec. 2018: Almost all images that disappeared from my own thread following loss of free remote hosting are now restored.
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Re: Atlantic's works: MS&LR Class 2, LNER D7 4-4-0 in resin
Excellent description of the process for creating the moulds Graeme.
I'm still hoping to use my spare Cotswold F1 milled brass chassis, after suitable modification in mine but would get a full set of parts including chassis parts. I expect the etched Mainly Trains 6'6"+6'6" tender inner chassis should fit the tender. These are available from Andrew Hartshorne at Wizard Models, not far from you. I've used these in GN A type tenders.
Thanks
Andrew
I'm still hoping to use my spare Cotswold F1 milled brass chassis, after suitable modification in mine but would get a full set of parts including chassis parts. I expect the etched Mainly Trains 6'6"+6'6" tender inner chassis should fit the tender. These are available from Andrew Hartshorne at Wizard Models, not far from you. I've used these in GN A type tenders.
Thanks
Andrew
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- GCR D11 4-4-0 'Improved Director'
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Re: Atlantic's works: MS&LR Class 2, LNER D7 4-4-0 in resin
We haven't had a "photo epic" from you in such a long time - welcome back Graeme!
Many thanks for taking the time and trouble to put the pictures and descriptions on here. They're incredibly useful, and very much appreciated...
Many thanks for taking the time and trouble to put the pictures and descriptions on here. They're incredibly useful, and very much appreciated...
Re: Atlantic's works: MS&LR Class 2, LNER D7 4-4-0 in resin
Thank you. 'Proper Modelling'!
I hope the MSl/GCR deserve you!
I hope the MSl/GCR deserve you!
- Atlantic 3279
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Re: Atlantic's works: MS&LR Class 2, LNER D7 4-4-0 in resin
I'm glad I haven't wasted the effort with the pictures. I could have put up rather more, but I'm already concerned about swamping our host's data storage arrangements.
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- Chas Levin
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Re: Atlantic's works: MS&LR Class 2, LNER D7 4-4-0 in resin
Definitely a far from wasted effort on the picture front: each one speaks a thousand words so you must be into 5 figures by now - in fact I make it just under 20K in the last three days!
I agree with Andrew, very good description of the mould process. It's something I've not yet tried, so this sort of detailed portrayal is invaluable: thank you.
I agree with Andrew, very good description of the mould process. It's something I've not yet tried, so this sort of detailed portrayal is invaluable: thank you.
Chas
Re: Atlantic's works: MS&LR Class 2, LNER D7 4-4-0 in resin
Excelent work Graeme , well done.
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Re: Atlantic's works: MS&LR Class 2, LNER D7 4-4-0 in resin
Very impressive!
- Dave
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Re: Atlantic's works: MS&LR Class 2, LNER D7 4-4-0 in resin
Brilliant work as usual Graeme
- Atlantic 3279
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Re: Atlantic's works: MS&LR Class 2, LNER D7 4-4-0 in resin
Here's a brief return to the main frames of the four-coupled drive unit I mad last year. Front is on the left in this view. With wheels off this side, the frame profile is visible, which as far as I can tell from the only drawing I've been able to view is correct. Note the rather artistic curvature of the lower edge of the frames between the axles, with (I presume) the flat-bottomed ash pan showing below that curve. Note also that the curved cut-out is not mid-way between the two axles, it is offset towards the front.
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Re: Atlantic's works: MS&LR Class 2, LNER D7 4-4-0 in resin
The loco looks great, I agree with all others about how good this looks.
The Gcr / mslr modelers are certainly enjoying watching the build.
Richard
The Gcr / mslr modelers are certainly enjoying watching the build.
Richard
- Atlantic 3279
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Re: Atlantic's works: MS&LR Class 2, LNER D7 4-4-0 in resin
On and off, over the course of the last couple of days, I've been test building a set of the D7 castings. One thing I noticed along the way, with the particular boiler casting I was using, was that when I first tried it on the running plate it appeared dead level at the top, but where the bottom was visible between the base of the smoke box and the leading splashers, it appeared to slope subtly, as if the barrel had a very slight reverse-taper. The more I looked at it, the less I was able to believe that it would go un-noticed when the model was finished. So after some Vernier measurements I made a cut in the base of the boiler and inserted a strip of plasticard, which sorted things out nicely.
I also had to thin down the tender soleplate on its upper face, near one corner, as it was visibly too thick along the edge, suggesting that the two halves of the mould had failed to come together as tightly as they should have done in that area. Otherwise, the parts have gone together quite nicely so far. I've left some of them off for the time being to avoid damage, to preserve access, to facilitate painting, or to give a better view of what's what in photographs.
I've deliberately included this picture to show the arrangement of the steps for the tender. Unlike those for the loco, which are a complete set in each case and which need to be provided with some sort of reinforcement where they fix to the running plate, the tender has each set of steps split into two parts: The upper, shaped, part of the backplate plus a reinforcing piece to carry the lower parts of the steps are cast integrally with the tender soleplate. The treads for both steps, and the face of the backplate between the two treads, form a separate small casting that has to be stuck in place. These small castings are HANDED too, because the sweeping curve of the backplate starts quite low down...
Most subjects, models and techniques covered in this thread are now listed in various categories on page1
Dec. 2018: Almost all images that disappeared from my own thread following loss of free remote hosting are now restored.
Dec. 2018: Almost all images that disappeared from my own thread following loss of free remote hosting are now restored.