East Barnet Joint Stock - a workbench

[Chas Levin]

Here's a C12 photo that shows a few useful details very clearly: the mass of pipework under the rear LH corner (which I think accounts for the second pipe visible under the same corner of the N2 photo series, as discussed above), the spark shields (I didn't have this photo when I was doing them), the 'Thistle' cylinder lubricators, the boiler side handrails ending at the smokebox with a separate short one on the upper area of the smokebox door, the difference in 'beam underside to piping gap' between the front and rear areas of the SH piping (the front part is right up against the buffer beam's lower edge, whereas the rear part is suspended well below the drag beam, I would estimate by 1.5 times the pipe width, possibly to allow for the pipe joint visible there, a joint I plan to replicate with a Markits crankpin washer) and cab doors:

 

I picked up a rather useful Mainly Trains detailing etch from Wizard while ordering some other things, which has some quite attractive looking cab doors...

Edited May 15, 2022 by Chas Levin

[Chas Levin]

On 08/03/2021 at 21:46, Chas Levin said:

I'm also planning some sort of pinning of the whole of each piping run under the valances...

So, how practical is it to use the 0.4 mm wire pinning system on the piping? The reason it appeals is partly my habitual belt-&-braces urge to prevent future detailing causalties by fixing things as securely as possible (especially in an area where things get handled, like the footplate sides); partly concern that if I try to fix the piping by soldering the strapping to the outer valance surfaces, heat passing along the tubing might mess up the alignments of some of the elbow joints (I know you don't think this likely David, but I suspect you're a much more confident and experienced solderer - is that a word? It is now! - than I am); and partly fear of ending up with excess solder around those very fine strapping bands (and the 4 thou copper strip from Hobby Holidays is certainly fine).

Here's a quick test run: first, a flat filed on one side of some 0.8 mm tube and a 0.45 mm hole drilled and slightly elongated parallel to the length of tube. The piece of 0.4 mm wire (equal to the inner diameter of this tube) has a small 90 degree hook at the end, to give it extra hold:

 

Next, the small hooked end of the wire is inserted into the hole and wiggled into the tubing so it stands perpendicular (or near) to the tubing:

 

Followed by a quick touch with the iron:

 

With some cleaning up the tube surface should be flat and the wire can go through a corresponding hole in the valance and be bent and soldered against the inside surface (with the tuing clamped to prevent the end of the wire that's inside it from shifting). I reckon with three or four of these the pipe run should be pretty secure (given that it'll also be held at each end where it joins the sections that go under each end beam) and with no unsightly solder along it.

 

Whether I'll be able to do the same with the SH pipe on the other side - where the elbows will be 0.8 mm but the main run will be 0.7 - remains to be seen...

Edited May 15, 2022 by Chas Levin

[Daddyman]

Good idea, Chas. This will be stronger than other ways of fitting. The difficulty will be lining the holes in the valance up with the pins; if they don't line up, the pipe will appear bent; you may have to ovalise the holes...  Just one thing, I'm not sure about bending the wire behind the valance: that will put stress on the tube at the point where it is most fragile (where you've drilled it). However, when I've done this I've drilled the tube right through (for more purchase, I think - but your hook might obviate the need for that), so my tube was more fragile.

 

For the 0.7 tube, you will be wrapping the Hobby Holidays copper wire around your tube and then clamping it into a "tail" at the back of the tube; what about trying to file that "tail" into a sort of pin shape, which you can then insert into holes in the valance. The tail-which-is-now-a-pin will be fragile off the loco, but easily strong enough once on. Another possibility is to put a twizzle of 0.193 brass wire hard up against the copper strip so that when soldered and dressed, strip and twizzle appear to be one; file the "tail" off the copper strip before doing this, and insert the "tail" on the twizzle into a hole.   

 

Your first photo looks very like the one I was going to send you of how to make your own smokebox door darts; you just need another hole at right angles to take the other handle: 

 

 

 

Edited March 11, 2021 by Daddyman

[Chas Levin]

On 11/03/2021 at 07:47, Daddyman said:

Good idea, Chas. This will be stronger than other ways of fitting. The difficulty will be lining the holes in the valance up with the pins; if they don't line up, the pipe will appear bent; you may have to ovalise the holes...  Just one thing, I'm not sure about bending the wire behind the valance: that will put stress on the tube at the point where it is most fragile (where you've drilled it). However, when I've done this I've drilled the tube right through (for more purchase, I think - but your hook might obviate the need for that), so my tube was more fragile.

 

For the 0.7 tube, you will be wrapping the Hobby Holidays copper wire around your tube and then clamping it into a "tail" at the back of the tube; what about trying to file that "tail" into a sort of pin shape, which you can then insert into holes in the valance. The tail-which-is-now-a-pin will be fragile off the loco, but easily strong enough once on. Another possibility is to put a twizzle of 0.193 brass wire hard up against the copper strip so that when soldered and dressed, strip and twizzle appear to be one; file the "tail" off the copper strip before doing this, and insert the "tail" on the twizzle into a hole.  

 

Yep, lining up the holes will be key, I'd already realised the great importance of that in this case. Ideally you'd want to mark the holes on the valance with the piping in place, resting against it, which of course you can't do.

I'm considering a couple of options, such as cutting an accurate template of the valance in clear thin plastic card, temporarily fixing the piping to it (as if it were fixed to the valance) and drilling through the plastic card from what would on the loco be the inside of the valance, just enough to leave a mark on the piping to locate the holes for the pins, then using the same template with the piping removed to locate the holes on the valance. The difficulty will be maintaining the accuracy through those manoeuvres.

Another possiblity might be to fix the pins in the piping first and then use the technique of a dab of paint on the ends of the pins which marks the valance when the piping is offered up. I'm not sure that in this case though, given the small scale of the parts and the flexibility of the piping, that method would be accurate enough.

Your idea of combining the HH copper strapping with the fixings is one I've thought about but I'm not keen on. I'm keen to preserve as clean and pristine an appaearance as possible for the strapping and I suspect that applying the necessary heat to use them as part fo the fixings will end up flooding them with solder, which would be difficult to clean up well without damaging them as that copper strip is so thin.

There's room to have four fixing pins alongside the strapping, with (hopefully) enough separation to avoid previous soldering being disturbed as each stage progresses - I've marked it in the photo below, where red is the strapping (ignoring the larger red mark on the right-hand end, which marks which end is to the loco front) and blue the fixing pins:

 

I'm going to think about this for a day or two; in the meantime, I've made a start on the SH pipe elbows, in 0.8 mm:

 

They're not much more fiddly than the vac ones in 0.9, though even so small a difference as 0.1 mm is perceptible.

 

Thank you for the smokebox door dart suggestion: when I get to the smokebox door, I'll post a photo of the Markits ones and you can see what you think. From memory (it's a few months since I looked one) it's a three or four-piece assembly, with a central tapered pin, a flange and the two arms (darts?) and I thought it looked quite good - here's one on my J9/10 from last year - though if I use another I might thin the arms down so they sit closer to the door when viewed in profile like this:

Edited May 15, 2022 by Chas Levin

[Daddyman]

Good luck with all that, Chas. The paint dot might work, though I suspect you'll end up ovalising the holes whatever you do... 

 

The only decent finescale door dart I've seen is Dave Bradwell's casting. All the others are grossly overscale. Here's a scratchbuilt one: 

 

 

[Chas Levin]

11 hours ago, Daddyman said:

Good luck with all that, Chas. The paint dot might work, though I suspect you'll end up ovalising the holes whatever you do... 

 

The only decent finescale door dart I've seen is Dave Bradwell's casting. All the others are grossly overscale. Here's a scratchbuilt one: 

 

 

Yep, I think you're right and holes will indeed end up oval! Well, as long as the piping ends up in the right place that's fine, and you certainly won't be able to see the holes afterwards.

Yes, over-scale smokebox darts are a worry. That's a very fine-looking one on the front of a very fine-looking loco: one of yours?

Interesting the way the buffer housings are let into the footplate (ref our recent discussions about standpipes) - I don't think I've seen that before. Is it an NER thing?

[Daddyman]

1 minute ago, Chas Levin said:

Yep, I think you're right and holes will indeed end up oval! Well, as long as the piping ends up in the right place that's fine, and you certainly won't be able to see the holes afterwards.

Yes, over-scale smokebox darts are a worry. That's a very fine-looking one on the front of a very fine-looking loco: one of yours?

Interesting the way the buffer housings are let into the footplate (ref our recent discussions about standpipes) - I don't think I've seen that before. Is it an NER thing?

Yes, my D51, Chas. The buffer thing was a feature of some early NBR tank engines. 

 

That's a very nice finish on your J-thingummybob! 

 

[Chas Levin]

The 'might-have-been' LNER Express Parcels Thorneycroft is through the paintshop, though I see from some of the photos that the matt varnish on the tilt top wasn't quite dry - either that, or it was out in the rain overnight at the yard:

Edited May 15, 2022 by Chas Levin

[Compound2632]

On 07/03/2021 at 19:00, Chas Levin said:

Very interesting, thank you Stephen, makes a lot of sense. Is it also the case that signals in general decreased in size over a similar period? I have the impression that earlier signals were taller, with more repeating posts, but were gradually scaled down and subsumed into the landscape somewhat...

I don't know generally but the LNWR went in for some very tall signal posts that became rather less tall when renewed by the LMS. On the other hand, the Midland, which was also RH drive, didn't have many tall posts.

[Chas Levin]

9 minutes ago, Daddyman said:

Yes, my D51, Chas. The buffer thing was a feature of some early NBR tank engines.

 

Oh, excuse me, NBR locos are not familiar to me (though I'll learn a little about one or two when I get to an LRM Drummond R Class 0-6-0 in my pile ). Beautifully clean looking work...

That buffer/footplate style is actually quite puzzling. Surely it's less work to have a one-piece straight edged footplate and have the buffers fully below it, as is more commonly seen? It must have been quite a bit of extra work to do what they've done there, so I wonder what the perceived advantage was?

 

9 minutes ago, Daddyman said:

That's a very nice finish on your J-thingummybob! 

 

Thank you, simple Halfords matt black rattle-can, which to be honest I think is on rather too thick: over-applying paint is something I'm still learning to avoid!

Edited March 12, 2021 by Chas Levin

[Chas Levin]

5 minutes ago, Compound2632 said:

I don't know generally but the LNWR went in for some very tall signal posts that became rather less tall when renewed by the LMS. On the other hand, the Midland, which was also RH drive, didn't have many tall posts.

Hm, further interesting knowledge, thank you!

I have a book on the history of GNR signalling so I'll have a look through and see what it says about heights...

[Daddyman]

13 hours ago, Chas Levin said:

Oh, excuse me, NBR locos are not familiar to me (though I'll learn a little about one or two when I get to an LRM Drummond R Class 0-6-0 in my pile ). Beautifully clean looking work...

That buffer/footplate style is actually quite puzzling. Surely it's less work to have a one-piece straight edged footplate and have the buffers fully below it, as is more commonly seen? It must have been quite a bit of extra work to do what they've done there, so I wonder what the perceived advantage was?

These were just a slightly longer R Class, with a bogie for tighter curves. 

 

Your R will have the same buffer / b. beam arrangement; it's common on small-wheeled locos as the footplate is lower than the height the buffers need to be. You see it on Manning Wardles, Pecketts, and the Brighton terriers. 

[Chas Levin]

7 hours ago, Daddyman said:

These were just a slightly longer R Class, with a bogie for tighter curves. 

 

Your R will have the same buffer / b. beam arrangement; it's common on small-wheeled locos as the footplate is lower than the height the buffers need to be. You see it on Manning Wardles, Pecketts, and the Brighton terriers. 

Oh - of course, I should have remembered that the R Class 4-4-0 became the D51, because I read up about them when I was deciding which one to build, as both versions are in the LRM (ex-Riceworks) range: is yours the LRM one?

I decided to go with the 0-6-0 as it would be an easier build, having read about 4-4-0 / 0-4-4 balancing subtleties, though if I were buying it now I might feel more ambitious .

 

Thank you for the explanation about smaller wheeled locos with lower footplates, which makes perfect sense: I felt sure there must be a reason for something that clearly added complication to the designing and building processes.

 

[Chas Levin]

The two long piping runs now have their strapping - thank you again David for the Hobby Holidays recommendation: that 4 thou copper is, as you said, just right!

 

Here's a close-up of the close together pair in the middle of the vac pipe run; they've been done with 188 solder, in hopes of discouraging movement during later soldering operations:

 

Still a little more tidying up to do (the right-hand one of that pair needs a hair taking off the bottom where the end of the strip wraps around) but overall I think they look quite effective. I considered trying your idea about incorporating a twizzle of a very fine wire with the strapping and turning those into the fixings, but I wanted to make sure each piece of strapping was as clear and evenly seated as possible and that was fiddly enough, without trying to hide a piece of wire too, so I went ahead just with the copper strip.

 

I'm still mulling over the fixings, so the next job I think will be to look at the rear frame ends and what happens to the pipe runs there - and how the rear coupling will fit in with those arrangements...

Edited May 15, 2022 by Chas Levin

[Daddyman]

16 hours ago, Chas Levin said:

is yours the LRM one?

Erm, I think I ended up being able to use 4 or 5 bits from the kit, yes. 

 

16 hours ago, Chas Levin said:

having read about 4-4-0 / 0-4-4 balancing subtleties

It's not a problem with 4-4-0 tank locos as the tanks allow lots of weight to be put over the drivers. 

 

Your strapping looks very neat. What was the problem with shaping the "tail" of the copper strip? I've never tried it, but thought I might one day. But I think it should be possible to drill 0.7 tube for 0.4 wire, especially if you nick the point on the back of the pipe where the drill needs to start, and drill right through then dress after soldering. 

 

Re solder melting, and your question to Will on the S4 forum, on your side you do also have that peculiar quality of soldered joints which no book I've ever seen mentioned: namely, that soldering done a few days ago will be much less likely to melt and de-solder than soldering done a minute ago. There seems to be no metallurgical explanation for this, and it may even go against the laws of the universe, but empirical observation confirms again and again that it is a truth (albeit one not universally acknowledged). So de-soldering may be less likely than you think... 

[Chas Levin]

8 hours ago, Daddyman said:

Erm, I think I ended up being able to use 4 or 5 bits from the kit, yes.

Oh dear - had I better not ask? I'm curious though, because I'll be building the 0-6-0 version...

8 hours ago, Daddyman said:

It's not a problem with 4-4-0 tank locos as the tanks allow lots of weight to be put over the drivers.

Oh, yes, of course, good point.

8 hours ago, Daddyman said:

Your strapping looks very neat. What was the problem with shaping the "tail" of the copper strip? I've never tried it, but thought I might one day. But I think it should be possible to drill 0.7 tube for 0.4 wire, especially if you nick the point on the back of the pipe where the drill needs to start, and drill right through then dress after soldering.

Thank you. The problem with shaping the 'tail' of the copper strip was in preventing it affecting the flatness of the rest of the strip where it went round the piping, so I felt I'd rather keep the strips separate to the fixing.

For drilling the holes for the fixing wire pieces, I plan to drill only through one side, because I suspect that if I drill right through, no matter how good a job I try to do of dressing and covering up the hole where it emerges on the front of the pipe, the holes may still be visible in what would otherwise be an unblemished run of pipe, especially when the light hits it.

I'm going to do some more test smaples, with different lengths of hook on the ends of the wires, to see how well it will work, and also to get practice at the process before risking it on the actual pipe runs.

9 hours ago, Daddyman said:

Re solder melting, and your question to Will on the S4 forum, on your side you do also have that peculiar quality of soldered joints which no book I've ever seen mentioned: namely, that soldering done a few days ago will be much less likely to melt and de-solder than soldering done a minute ago. There seems to be no metallurgical explanation for this, and it may even go against the laws of the universe, but empirical observation confirms again and again that it is a truth (albeit one not universally acknowledged). So de-soldering may be less likely than you think... 

That's very interesting: I have noticed exactly that too! And I've also not come across any mention of it in books, but I have read mention of needing to "re-activate" the solder on previous work. I've found something that could be described as that, where old solder takes a little more heat and physical movement to flow.

I would assume that solder is a little like glue, in that it continues 'going off' for longer than appears, so it can be re-worked more easily shortly after use but then sets more fully over a longer time...

[Jol Wilkinson]

2 hours ago, Chas Levin said:

Oh dear - had I better not ask? I'm curious though, because I'll be building the 0-6-0 version...

Oh, yes, of course, good point.

Thank you. The problem with shaping the 'tail' of the copper strip was in preventing it affecting the flatness of the rest of the strip where it went round the piping, so I felt I'd rather keep the strips separate to the fixing.

For drilling the holes for the fixing wire pieces, I plan to drill only through one side, because I suspect that if I drill right through, no matter how good a job I try to do of dressing and covering up the hole where it emerges on the front of the pipe, the holes may still be visible in what would otherwise be an unblemished run of pipe, especially when the light hits it.

I'm going to do some more test smaples, with different lengths of hook on the ends of the wires, to see how well it will work, and also to get practice at the process before risking it on the actual pipe runs.

That's very interesting: I have noticed exactly that too! And I've also not come across any mention of it in books, but I have read mention of needing to "re-activate" the solder on previous work. I've found something that could be described as that, where old solder takes a little more heat and physical movement to flow.

I would assume that solder is a little like glue, in that it continues 'going off' for longer than appears, so it can be re-worked more easily shortly after use but then sets more fully over a longer time...

I can't say that I've ever found that solder matures with age, like a good wine. 70 degree definitely undergoes some sort of transformation when used with white metal, probably some sort of "alloying" that significantly changes its characteristics. The interaction between 145, etc. and brass or nickel seems less apparent, possibly because the alloying is at literally molecular levels at the interface surface.

 

 

[Chas Levin]

4 minutes ago, Jol Wilkinson said:

I can't say that I've ever found that solder matures with age, like a good wine. 70 degree definitely undergoes some sort of transformation when used with white metal, probably some sort of "alloying" that significantly changes its characteristics. The interaction between 145, etc. and brass or nickel seems less apparent, possibly because the alloying is at literally molecular levels at the interface surface.

Hello Jol, I hadn't thought of comparing it to a good wine: "Mmmmm, I'm getting notes of tin and lead, with just a hint of bismuth; a little immature - perhaps best laid down and used for soldering in 2026..."

 

But seriously: when you've gone back to re-solder or adjust something previously soldered (assuming you'd have done this on occasion) do you find that solder even a few days old is slower to flow than fresh solder from the reel?

 

Mind you, it occurs to me whilst writing that - and visualising it - that one important difference is that anything already in place on a model has a (possibly) large heatsink attached to it (the model) which would lengthen the time taken to reach melting point, whereas fresh on the reel its mass is tiny, which might be a factor. Yet I've still noticed the same thing whilst working on these piping lengths, when a piece has needed re-positioning and where the mass of the workpiece is very small: it appears to take more heat and for longer to melt the older joint.

[Daddyman]

13 hours ago, Chas Levin said:

Oh dear - had I better not ask? I'm curious though, because I'll be building the 0-6-0 version...

Part of the problem was that the kits don't cater for the locos after the 1908-11 reboilering, when the boiler was raised 3 inches on both classes (despite the assertions of the LNER diagrams that they remained at 6'3" centres - a point only made in print in the NBRSG journal article on the class; even Yeadon, for all his obsession with boilers, misses this). For us building these kits, this makes many parts unusable: the smokebox front, the tank fronts and the smokebox wrappers; the tanks also need modifying to fit the higher boiler. Then there was a change to the cab sides at some point, when the door aperture was narrowed to the same width as the handrails (I'm not sure when this happened, and no one else seems to have noticed it - even the NBRSG articles on the classes make no mention); this seems, from looking at Yeadon, to have happened to the J82s too (possibly when they were still NBR property). So that makes the cab sides in the kit unusable. There are other "issues" with the kit, but these are the main ones. 

13 hours ago, Chas Levin said:

For drilling the holes for the fixing wire pieces, I plan to drill only through one side, because I suspect that if I drill right through, no matter how good a job I try to do of dressing and covering up the hole where it emerges on the front of the pipe, the holes may still be visible in what would otherwise be an unblemished run of pipe, especially when the light hits it.

There's nothing to worry about there, Chas - any such joint would be absolutely invisible; that's the beauty of working in metal. 

 

11 hours ago, Chas Levin said:

Mind you, it occurs to me whilst writing that - and visualising it - that one important difference is that anything already in place on a model has a (possibly) large heatsink attached to it (the model) which would lengthen the time taken to reach melting point

The heat sink is no different from when you attach it to the model, so I don't think that works as an explanation. To be honest, the explanation doesn't really matter: this characteristic of soldered work is something that you and I have both noticed (I've taken advantage of it again this morning, working on something soldered a couple of weeks ago). 

 

[Jol Wilkinson]

11 hours ago, Chas Levin said:

Hello Jol, I hadn't thought of comparing it to a good wine: "Mmmmm, I'm getting notes of tin and lead, with just a hint of bismuth; a little immature - perhaps best laid down and used for soldering in 2026..."

 

But seriously: when you've gone back to re-solder or adjust something previously soldered (assuming you'd have done this on occasion) do you find that solder even a few days old is slower to flow than fresh solder from the reel?

 

Mind you, it occurs to me whilst writing that - and visualising it - that one important difference is that anything already in place on a model has a (possibly) large heatsink attached to it (the model) which would lengthen the time taken to reach melting point, whereas fresh on the reel its mass is tiny, which might be a factor. Yet I've still noticed the same thing whilst working on these piping lengths, when a piece has needed re-positioning and where the mass of the workpiece is very small: it appears to take more heat and for longer to melt the older joint.

 

Chas,

 

I tend to avoid having to rework a model after a period but that's possibly because I usually build the kits as supplied as "layout models" and, as LNWR locos changed relatively little over time I usually don't often find things that were altered. 

 

I have on occasion had to remove/adjust parts that don't go right first time and have found that the RSU is sometimes the best tool for the job. I think that re-melting already applied solder does require more heat. When applied fresh the solder is already at melting point and tends to more readily run into the fluxed joint "carrying" the heat with it (a rather poor layman's explanation of what I believe happens). When heating an already formed joint you have raise the whole area to a sufficient temperature to break the molecular bond. 

 

Looking at soldering stations online, many used in the electronics industry also include hot air guns for re-working. Is that because a hot air gun, like a blow torch used by plumbers, raises the temperature of the area soldered to  the correct temperature quickly, rather than relying on heat "flow" from a single point?

[Chas Levin]

13 hours ago, Daddyman said:

Part of the problem was that the kits don't cater for the locos after the 1908-11 reboilering, when the boiler was raised 3 inches on both classes (despite the assertions of the LNER diagrams that they remained at 6'3" centres - a point only made in print in the NBRSG journal article on the class; even Yeadon, for all his obsession with boilers, misses this). For us building these kits, this makes many parts unusable: the smokebox front, the tank fronts and the smokebox wrappers; the tanks also need modifying to fit the higher boiler. Then there was a change to the cab sides at some point, when the door aperture was narrowed to the same width as the handrails (I'm not sure when this happened, and no one else seems to have noticed it - even the NBRSG articles on the classes make no mention); this seems, from looking at Yeadon, to have happened to the J82s too (possibly when they were still NBR property). So that makes the cab sides in the kit unusable. There are other "issues" with the kit, but these are the main ones.

Oh, Ok, that's reassuring from my point of view, in that I'll be happy to build a version that the kit caters for. You're operating at a higher level of authenticity than I am - is that the right word? I hope you know what I mean - I mean it as a compliment, not as a criticism!

Is your D51 finished and if so, would you consider posting some pictures? Quite understood if not - I never know whether it's OK to ask that or not. Or, if you've already put some up somewhere, please would you post a link?

Actually one of the main reasons I bought the kit - and the LRM J65 - is because they were originally Iain Rice's kits. I learnt a huge amount from his books on building and detailing and very much enjoy his wirting style and the general atmosphere of his writing, so I thought it would be nice to build something he'd designed...

13 hours ago, Daddyman said:

There's nothing to worry about there, Chas - any such joint would be absolutely invisible; that's the beauty of working in metal.

At school, we had to choose between woodwork and metalwork and I chose woodwork, because I was a little nervous of metal and the tools and techniques - wood seemed easier, more 'friendly', somehow.

In recent years, as I've got more used to working with it, I've learnt what amazing things you can do with it and I absolutely love working with it, but I'm still very much learning what you can and can't do with it.

13 hours ago, Daddyman said:

The heat sink is no different from when you attach it to the model, so I don't think that works as an explanation. To be honest, the explanation doesn't really matter: this characteristic of soldered work is something that you and I have both noticed (I've taken advantage of it again this morning, working on something soldered a couple of weeks ago).

Yes, agreed. I'm still curious though - I'll let you know if I discover anything further. I find soldering absolutely fascinating and not a little bit magical; even though I understand the theory of it, I still can't quite believe it actually works!

[Chas Levin]

12 hours ago, Jol Wilkinson said:

 

Chas,

 

I tend to avoid having to rework a model after a period but that's possibly because I usually build the kits as supplied as "layout models" and, as LNWR locos changed relatively little over time I usually don't often find things that were altered. 

 

I have on occasion had to remove/adjust parts that don't go right first time and have found that the RSU is sometimes the best tool for the job. I think that re-melting already applied solder does require more heat. When applied fresh the solder is already at melting point and tends to more readily run into the fluxed joint "carrying" the heat with it (a rather poor layman's explanation of what I believe happens). When heating an already formed joint you have raise the whole area to a sufficient temperature to break the molecular bond. 

 

Looking at soldering stations online, many used in the electronics industry also include hot air guns for re-working. Is that because a hot air gun, like a blow torch used by plumbers, raises the temperature of the area soldered to  the correct temperature quickly, rather than relying on heat "flow" from a single point?

I too would want to avoid reworking things later on - I was thinking more of when something that is installed during a later part of a build involves disturbing previous work (though I reliase that this probably happens much less when you're a more expererienced builder!). Or, a situation where you're adding something on top of something else. For instance, on this C12, I was soldering the half-etch smokebox wrapper over the circular smokebox piece (I can't remember the correct term for it) that had already been soldered over the front end of the boiler. I'd imagine in that case though that the boiler acts as sufficient heatsink to prevent earlier work moving.

From time spent working in the Service department of my employer (where audio equipment is repaired and serviced) the main use I've seen for hot air guns is where what needs de-soldering is either too small to be accurately done with an iron, or where multiple small joints need to be melted simutaneously. For instance, we sometimes deal with IC chips that have 50 or more tiny legs (and the whole chip is not much more than an inch square) and in that case, a heat gun is used to melt the joints on all the legs simultaneously so the chip can be lifted off. Delicate business, controlling the area affected by the hot air. And needless to say, chips removed that way are being removed bacause they've already failed - because subjecting them to that amount of heat would probably cause failure in itself - and the object is to save the rest of the board and install a replacement chip.

13 hours ago, Jol Wilkinson said:

When applied fresh the solder is already at melting point and tends to more readily run into the fluxed joint "carrying" the heat with it (a rather poor layman's explanation of what I believe happens).

I'd say that sounds like a very good way of describing it actually .

[Daddyman]

9 hours ago, Chas Levin said:

Actually one of the main reasons I bought the kit - and the LRM J65 - is because they were originally Iain Rice's kits.

 

Well, that's one of the "issues" - I really don't appreciate the irony of having to use Rice's work-arounds for dodgy kits on one of his own kits! For example, in the book he complains about single-ply coupling rods, but what did I find in the kit but... single-ply coupling rods! Then there's the footplate, made of an underlayer with fold-down valances and a top layer, but none of the holes and slots in the two layers line up! 

 

It's another model I finished, primed ... and then immediately took to pieces again! Too many "issues" adding up to an unsatisfactory model. I've since cut out a new footplate and valances and am working up from there. I've only really got new tanks to do but it's got shunted down the queue a bit. It's the kit on which I learnt never again to rely on slots and tabs; instead, all my tank engines and tender bodies get a 15 thou baseplate (Judith-Edge-style) bolted to the footplate, with all tank sides and cab sides soldered to the edge of that. That way, you're sure to avoid wavy tank sides and to get a consistent distance between footplate edge and tanks/cabs.    

 

Happy to let you (or anyone else) see photos of models in private but I have a rule about not posting photos of completed models on RMWeb. 

 

[Pebbles]

Before starting the J65 get the GER Society/ John Gardner drawings. 

[Chas Levin]

32 minutes ago, Pebbles said:

Before starting the J65 get the GER Society/ John Gardner drawings. 

Thanks - I will do