Atlantic's works: 3D printed J21 interlude concluded?

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Atlantic 3279
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Re: Atlantic's works: J21 continues

Post by Atlantic 3279 »

After a slightly frustrating session of trimmimg bits of, checking, finding that I'd either trimmed not enough or too much, then either trimming more or sticking pieces back on, I eventually felt I was somewhere near to the intended result and that I could add two small tongues of 0.25mm plastic to the underside of my "bunker conversion piece" to complete the tops of the tank arms at the front. I also added a 0.5 mm strengthening layer to the back of the boards that close off the front of the coal space between the tank arms, and cut out an approximation to a shovelling hole. Compared to the black Hornby Q6 tender, and the pale grey un-modified print, my converted trial piece now looks like this:
DSCN0703.JPG
The tool boxes will be able to sit apart more effectively on the final version once I've trimmed inside the side cornices more thoroughly.

What I can't quite decide now is whether I've trimmed a shade too much from the front edge of the top sheet, exposing a little too much of the coal space in front of the toolboxes, and making it necessary to fit those boxes tightly against the front of the upper coal plate. I could easily add back a thin slice of plastic to give the boxes a marginally deeper shelf on which to sit. Opinions of the knowledgeable would be most welcome.
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Atlantic 3279
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Re: Atlantic's works: J21 continues

Post by Atlantic 3279 »

Pending final thoughts on the correct appearance for the front of the tender, I've turned my attention to the coal rails. Paul's print includes a set of course, so if you are happy with those they only need painting.
I chose to look at the possibility of alteration for a combination of reasons. The one photograph of which I am aware showing one of these locos in my home area features No 289 at New Holland, probably around 1932, and its tender clearly has added coal rails, giving a total of four around the coal space and three around the water filler area. If I could succeed in making a suitable full set in stiff brass wire it is likely that they would be stronger than the printed resin ones. Additionally, I might be able to produce square rear corners rather than rounded ones, as well as arranging for the rails to curve down and terminate in a slightly different position near the front of the tender, so as to agree more closely with my interpretation of photographs I've seen of these tenders.

I began by having a go at producing a spacing gadget for the rails. A drawing had given me the impression that if I made the rails from 0.7mm brass wire and spaced them using 0.45mm brass wire then the height would come out about right. I therefore assembled this selection of pieces of wire on two layers of double sided tape on an offcut of card:
DSCN0708.JPG
The L shaped bits would eventually act as the spacers for the rails. The middle three are 0.45mm wire, the outer two are 0.7mm for greater strength / stiffness. The straight pieces are all 0.7mm wire ensuring that the spaces between the upright legs of the L shapes are wide enough to accept 0.7mm rails.
A good application of solder was used to hold the whole lot together.
DSCN0709.JPG
Another layer of card (as a bit of a heat shield) wrapped in double sided tape was added over the solder, and I could then position some coal rails, with front curves pre-formed, something like this:
DSCN0710.JPG
After carefully adjusting positions of the rails to line up the curves using a good photograph of the right type of tender as a guide, I could then solder the first of a series of uprights across the rails. It rapidly became obvious that is is easiest to tin the full length of each rail, and the wire that is to form each upright, and that the uprights can be held, positioned and soldered most easily if they are initially of greatly excessive length. After each upright was added, the "tool" could be moved along the rails to a position adjacent to the intended next upright. One of the snags I encountered was the effect of heat on the double sided tape, which was supposed to be holding the rails in place for soldering, as its adhesive tended to melt and lose its stickiness in the heat. Anyway, after not too much sweating and profanity, compared to some of my performances, I currently have these completed sets of rails and uprights, trimmed to more or less the right dimensions.
DSCN0713.JPG
The remaining challenges now include:
1. Forming the lower parts of the uprights to fit into suitable drilled holes inside the top edges of the tender print, with the rails correctly "stepped out" to sit above the very edges of the cornices.
2. Trimming to final length and filing a mitre to get neat square rear corners without gaps.
3. Soldering the rear corners without damaging the 3D print or ruining the carefully spaced soldered joints already made on the rails.

It should be fun!

Once they are fitted and the rear corners soldered, I can glue some "plating" inside the rails around the coal space.
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Re: Atlantic's works: J21 continues

Post by mick b »

Graeme
Like this one ?,a Dave Bradwell version.
fullsizeoutput_38e3.jpeg
fullsizeoutput_38e4.jpeg
fullsizeoutput_38e5.jpeg
fullsizeoutput_38e6.jpeg


Dimensions

Tender Tank front to Coal Plate/Divider 16mm

Tanks 9mm wide note rivets all round the top curve curve

Rear 10mm from rear to Coal plate/Divider

ToolBoxes 12mm wide x 6mm deep

Mick
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Re: Atlantic's works: J21 continues

Post by mick b »

fullsizeoutput_38e7.jpeg
Everything is straight , the Camera lens was having fun !!
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Atlantic 3279
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Re: Atlantic's works: J21 continues

Post by Atlantic 3279 »

Thanks Mick, those are very useful. There's a bigger gap revealing the coal space in front of the toolboxes than I would have imagined. The dimensions are handy to know. The tanks fronts are not as wide as 9mm on the printed version, the side sheets being thicker than metal ones of course, limiting the internal space. I'll check the coal plate positions against those figures, and against scaled photographs. "Confirmation", if a model can confirm anything, of that short horizontal handrail on the rear, may lead to me adding one of those too. I'd only seen the backs of the larger, more modern tenders in photographs, and the rear handrails on those had made me wonder whether the older, smaller tenders were similarly equipped.

I seem to have got my modified toolbox sizes right anyway.
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Re: Atlantic's works: A needlessly complicated D7?

Post by mick b »

Normally just a "rail" no knobs normlly used on NER engines . The NYMR J27 is the same , sadly they have stuck two steps on the rear as well , totally wrong for in period.
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Re: Atlantic's works: J21 continues

Post by nzpaul »

Atlantic 3279 wrote: Thu Jul 22, 2021 9:31 pm
The remaining challenges now include:
1. Forming the lower parts of the uprights to fit into suitable drilled holes inside the top edges of the tender print, with the rails correctly "stepped out" to sit above the very edges of the cornices.
2. Trimming to final length and filing a mitre to get neat square rear corners without gaps.
3. Soldering the rear corners without damaging the 3D print or ruining the carefully spaced soldered joints already made on the rails.

It should be fun!

Once they are fitted and the rear corners soldered, I can glue some "plating" inside the rails around the coal space.
Fun (noun)... Amusement, enjoyment.

Ex...Graeme was having fun burning his finger tips whilst soldering coal rails. :lol:

J21 is looking very nice and worth the extra fun you're having.

Paul
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Atlantic 3279
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Re: Atlantic's works: J21 continues

Post by Atlantic 3279 »

All of my finger ends are still in good order and the (by now accursed) tender for the J21 is at last in almost its final condition, bar brake pipes and coupling hook. I have more details of the method to add to these notes, plus the final dimensions of that bunker insert for anyone who might be interested, but I have neither the time nor the willpower to post up that information tonight. I'll try to add it tomorrow. In the meantime, a couple of images will suffice, and will no doubt give somebody the opportunity to tell me, with great certainty, that my chosen parallel shank NER style buffers were extinct by the 1930s and I should have fitted the tapered type...
DSCN0719.JPG
DSCN0721.JPG
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Re: Atlantic's works: J21 continues

Post by mick b »

See here for the correct rear top lamp iron .

https://www.52fmodels.org/accessories

They are the ones centre/right of the photo . NER liked to do thing slightly different !!

Excellent job on the Coal Rails !!
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Re: Atlantic's works: A needlessly complicated D7?

Post by kimballthurlow »

https://www.lner.info/forums/download/f ... =24426&t=1

Ah.. what a beautiful thing that coal rail jig is.

Kimball
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Re: Atlantic's works: J21 continues

Post by Atlantic 3279 »

mick b wrote: Sun Jul 25, 2021 10:23 pm See here for the correct rear top lamp iron .

https://www.52fmodels.org/accessories

They are the ones centre/right of the photo . NER liked to do thing slightly different !!

Excellent job on the Coal Rails !!
Thanks Mick. Yes, I'd noticed from the big drawing in Hoole for the later tender, and from the best photos, that the NER had a special top lamp iron. I decided to be satisfied with something that would simply carry a lamp.
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Re: Atlantic's works: J21 continues

Post by Atlantic 3279 »

kimballthurlow wrote: Mon Jul 26, 2021 1:22 am https://www.lner.info/forums/download/f ... =24426&t=1

Ah.. what a beautiful thing that coal rail jig is.

Kimball
Thanks. I suppose the creation of that jig is one of the benefits of having enough time these days to think about how to make a tool to suit the job, rather than feeling that I just have to get on with it straight away and struggle through the difficulties.
In hindsight, a much longer card base coated with double sided tape might have made it easier to use, giving firmer and more lasting control of the positions of the wires during the soldering process.
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Re: Atlantic's works: J21 continues

Post by Atlantic 3279 »

Here are some of the promised (or threatened) details of the methods I used.

The first task was to create some bends in the supports for the coal rails so that the rails would sit in the right places when the supports were pushed into drilled holes in the tank top. Gripping the rails with pliers, tightly onto each support as I bent it, so as not to strain / snap the delicate soldered joints or distort the rails, I made the bends to size "by eye" at first, but then checked suitability by offering each section up to its location and tweaking the bends to suit.
DSCN0717.JPG
Once I was reasonably satisfied that the rails would actually fit, I decided to start the attack on the second printed tender shell that Paul had kindly sent me. With its additional permanent and temporary additional bracing that I had left in place until this point, it must be said that this print was much freer of distortion than the first on had been. Some of the upper extremities of the additional, permanent, internal, upright braces for the sides had to be trimmed back slightly as I cut out the unwanted sections of the top deck and made clearance for inserting my substitute bunker, but nothing caused any real difficulties and I don't expect the little material I removed from the braces to compromise the stability and rigidity.
Interestingly, when I inserted my bunker, I found it a looser fit than it had been in the first printed shell, and the "tongues" of thin plastic at the front, already trimmed and shaped, didn't cover the tank fronts quite so well. I then compared the two prints side by side and realized that the second one was a shade larger all round than the first. The fit of the bunker did however become much more acceptable when I simply added a layer of 0.25mm plastic to the face of the printed rear bunker slope. I've been in touch with Paul regarding the size change, and I gather that this is a consequence of "light bleed" into adjacent areas in the resin because of using increased exposure time in the printing process for the sake of more rigidity.

Satisfied with the "dry" fit of the new bunker I then bonded it thoroughly in place using quick-setting epoxy.

The amended final length of the main top-piece of the bunker was 41.5mm, i.e. trimmed back at the front to expose some of the coal space. The length from its rear edge to the front edges of the channel for the coal was however 43.5mm, i.e. the coal chute projected 2mm further forward than the main top sheet.

Once the epoxy had hardened I thought about the front and rear coal division plates on top of the structure. Both would need to be taller to suit the four coal rails I intended to have, and they would look neater if made new from single pieces of plastic rather than as extensions grafted on to the lower original plates. Also, the front one was no longer need to hold the tank sides straight and parallel since my bunker top was now doing that. Hence I trimmed away both plates and all of the printed coal rails. It was then a fairly easy matter to drill the holes for the new coal rail supports and insert those for a proper trail fit.
DSCN0715.JPG
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Re: Atlantic's works: J21 continues

Post by Atlantic 3279 »

After some more manipulation of the dry-fitted coal rails, filing mitre joints at the rear, and re-soldering to the uprights where joints had gone "ping" during the struggle, I was happy that the fit was as good as it was every likely to be. I'd been thinking about the order of subsequent jobs, and concluded that the best thing to do at this stage was to take the rails off again and tin the mitred faces in order to make the soldering up of the rear corners in situ as quick and easy as possible. I kept the nearby uprights firmly gripped on to the rails with pliers as I did the tinning. I also filed flats on the inner faces of the rails where the plating-in of the rails would be required. The cleaned and fully prepared rails could then be put back in place.
I decided that it would aid the correct alignment of the rear corners if I fixed each set of rails in the nearest approximation to their final positions before I tried to solder the joints. I used a piece of 0.45mm wire under the bottom rail to get the correct spacing from the cornice as I pushed each upright in turn fully home in its hole, checked that the rails were looking straight and square, then applied a tiny drop of cyano-acrylate super-glue around the exposed part of upright in contact with the tank cornice and around the hole. After soldering the corners, I intended to add epoxy to the uprights inside the tank too, but at this stage I wanted to give myself some remaining hope of breaking them free and having another go if absolutely necessary.
In order to get the quickest, cleanest, sound joints at the rear corners of the rails, I obviously applied flux, but I was concerned that even if I was very quick the solder might bridge the gaps between the rails and that my iron might over-heat the corner of the resin print. I therefore slotted narrow strips of thin card between the rails leaving just the very corner of each exposed, and put a larger piece of thin card under the bottom rail to shield the resin. With a thin even coating of nice bright solder on a clean hot iron tip, and a prayer, I then managed to make the joints and only a reasonably small amount of mess to clean off!
I'd be very surprised if it were possible to solder the corners accurately with the rails off the model and then get them into place without breaking the joints again.
For the plating behind the coal rails I cut pieces of 0.25mm plastic to size for each section, checking that each one was a good fit and would rest its bottom edge neatly against the cornice before I even thought about putting any glue near it. I then found that with the tender lying on its side I could put each piece quite quickly and accurately in position on the exposed back face of the rails on the lower side, with the aid of needle-nosed tweezers.
I was therefore able to use some super-glue that had originally been runny and quick setting but which had thickened slightly with age, initially putting a series of tiny spots on the backs of the rails, then having just enough time to position the plastic correctly before the glue took hold. I then drew little droplets of additional super-glue around the edges of the added plastic, sealing them firmly to the cornice, the uprights and the top coal rail. Once finished it all cleaned up quite nicely with a file, scraper and abrasive paper.
With the side plating all in place it was easier than it might otherwise have been to add the new front and rear division plates. Once I had cut them to size and shape I was able to use ordinary slow-evaporating styrene solvent to initially stick just their outer edges to the plastic side plating. This made it fairly easy to adjust the new plates to be square, upright and in just the right places before gluing their lower edges to the tank top. In the case of the rear plate I used super glue rather than solvent at the bottom edge, owing to the dissimilar materials, and I suspect it would have been difficult to get it "just so" all in one shot...
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Re: Atlantic's works: J21 continues

Post by Woodcock29 »

Its looking good Graeme.
I presume you'll be fitting a short central horizontal handrail on the rear?
Andrew
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