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Laminating flat brass/nickel silver etches.


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Hi All

 

I am currently building a couple of Alan Gibson 850 kits, the footplate's are thin brass etch, which despite my best efforts buckled whilst soldering up the first one. In an attempt to rectify it, I used some clothes pegs (wooden) to hold the bits together and put it in a baking tray and slapped it in the oven for 15 minutes at gas Mark 5 which is about 200deg C. I then had a quick squint, which showed that I had got rid of most of the buckling, so I have done the second one in the oven. I applied some Carrs179 solder cream to the edges of the lower laminate and added the top laminate, ensure that all the mating edges are properly flat and apply the clothes pegs and put the entire ensemble in the baking tray and place in the top of the oven and start it up, after about 15 mins have a look, if all appears to be well put it back in and switch the oven of and allow it too cool naturally and hopefully you should have a wrinkle free footplate. Mine is cooling while I type this.

 

I hope this may be of use to other kit builders.

 

I will take a picture of the oven baked article when it has cooled down.

 

SS

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Interesting idea though I'm not sure about the domestic's view on use of an oven exposed to fumes from fluxes. I don't get much of a problem with laminating parts and for small items really prefer higher temperature solders. Nothing worse than laminating a grill on the side of a body then have it slide as the body is soldered up.

 

Not quite sure about the slow cooling idea though. I was always told don't open the oven door while cooking as you will let all the heat out. I believe that brass loses temperature very quickly.

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The footplate pieces are quite large in some areas and decidedly less in others hence the uneven expansion causing the distortion.

 

I don't think the small amount of flux in the solder cream is a problem. My oven is gas and has ventilation in it, there was no noticable smell when I entered the kitchen to check on it or on opening oven door. I think there is enough metal in the baking tray to prevent rapid cooling of the etched parts and I certainly was not going too touch it too find out as the tray was hot enough through the glove.

 

I lined the baking tray with tin foil and there was no sign of any residue on it.

 

I don't think the domestic authorities will find out that I have used the oven, after all it's not like sticking siezed car parts in there to get them apart, like me and me dad did when we had problems with them, when mum was at work or out shopping.

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An alternate solution is the use of a (redundant) electric frying pan. This has been documented in the model press and a member of our society has been successful using this method.

 

Cheers,

 

David

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Here are a couple of photos.

 

A top view

post-9897-0-25511900-1468267659_thumb.jpg

 

It looks as if I was not fastidious enough in making sure that the two parts were properly mated.

 

The underside.

 

post-9897-0-61242200-1468267647_thumb.jpg

 

I will now have to ponder on how too close the gaps, without distorting the rest of it.

 

 

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SS

 

You could try using a selection of miniature' crocodile' clips, hair clips and the slightly larger metal spring clips, obtainable from 'Rolson' or other suppliers. Place them all around the item and add a cream type flux like Power Flow or Copalux. Then, using a flame torch, waft it over the item until it all settles down to where it should be. I think this way you can have better control over the amount of heat you want and where you want it. Don't forget to use a flame proof surface, not the usual MDF!!!!

 

Good luck

Sandy

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SS

 

You could try using a selection of miniature' crocodile' clips, hair clips and the slightly larger metal spring clips, obtainable from 'Rolson' or other suppliers. Place them all around the item and add a cream type flux like Power Flow or Copalux. Then, using a flame torch, waft it over the item until it all settles down to where it should be. I think this way you can have better control over the amount of heat you want and where you want it. Don't forget to use a flame proof surface, not the usual MDF!!!!

 

Good luck

Sandy

 

 

Thanks Sandy, I will give it a go later.

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There is a problem with using gas torches on laminated brass. The heat is considerably greater than the typical soldering iron and when used on very thin brass the brass is annealed very easily. I would not take the route of trying to effectively unbend the brass in that way. The crocodile clips even if well sprung might not work well as you are expecting the spring in the clip to be powerful enough to close the gap and un-distort the brass. The forces in the clips will be pressing on the rear of that brass as well as on the buckled bit so there is not a clear outcome.

 

Stepping back: were both parts tinned fully before bringing together? I'm also not convinced about the application of solder paste solely round the edges, I would not do that (though I do use a RSU for this type of work) and when using solder paste, I always put the dots of paste towards the centre of the laminate, the solder then flows out to the edges. Placing it round the edges leaves an air pocket in the middle to expand.

 

Laminating brass is straight forward but has a few potential traps. Once fallen into one of them the way back can be difficult. This is why best practice is to apply heat from the middle of the part and work outwards squeezing the solder/air/flux sandwich to the edges, the heat expanding the brass from the centre outwards.

 

1. remove the buckled laminate completely (may take you back further), clean off all solder on both parts, flatten the bucked laminate (may involve annealing and hardening the brass), start over.

2. Is the buckled brass actually visible, if it can only be seen by viewing from under the loco then just use filler and forget it.

 

Having said that take heart, I think the only main reason it didn't work was not enough clamps. It does get easier, honest :D

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I like the idea and will take note of the pitfalls, as I have several Gibson kits in the to do pile.

 

brass layer laminations are nothing peculiar to AG kits (or even brass kits) many/most kit designers use detail laminations at some point or other. rivet detail is common. Small ones are not the problem. The issue arises in particular where the laminated area is large or where the parts can have uneven heat transfer.

 

It is not only laminations, any long thin strips of metal eg valences can buckle easily due to uneven heating.

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Arthur K gets round this problem by having holes etched in the hidden laminations to allow access with the soldering iron in more central areas. It has worked well on the kits of his that I have built.  It's been a while since I looked at an AG kit, but might it be an idea to make a few strategically placed holes in the hidden bits yourself during construction? It won't help the OP here, of course - but it may help others.

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I have also had some difficulty with laminating.  My solution is to tin both pieces using an iron.   Then tack one corner together for alignment.  Add a little flux.  Position on a flat aluminum or stainless plate(or iron frying pan) on stove top gas burner.  Put an insulating sheet over and add weights.  Keep the burner going until a scrap of test solder forms a bead.  Shut off burner and wait to cool or put damp sponges on corners.  My result has been an evenly soldered, flat surface with little chance of error on my part.  Have used on loco frame sides.  When I subsequently solder spacers, etc., the immediate area where I am working melts and then re-cools without disturbing flatness.

I had previously tried pre-tinning and then resistance with a blunt carbon probe.  This deformed a thin(.008") Finney overlay for an O scale tender top.

John Hutnick

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I do think we are making out the process as being something of a horror when in fact it isn't. Like so many things in kit construction there are things that can go wrong but they can generally be overcome and only a case of learning how to do it with confidence and experience.

 

Some extraordinary solutions being proposed. Perhaps those of us who do these things on an every day basis are wondering what all the fuss is about or have forgotten what it was like to do it the first time. Or, perhaps on the rarer occasion it happens to us we just roll on to the solution and think nothing more of it.

 

Holes are a good idea where large areas are being laminated, and the concept is certainly not new, but this is not a solution to the problem and where not designed in to the kit can involve a great deal of unnecessary time and effort. Not all laminations are put on a flat surface, more often being applied to a 3D progressing build (as in the example of the OP).

 

Resistance soldering is both a useful and dangerous tool. It has the potential at the wrong setting to vapourise the metal or more typically punch a hole through it. It nearly always heats the metal to well beyond the annealing temperature but in a very localised position. Yet in the right hands it can be used to solder white metal to brass (never white metal to white metal).

 

Of course there is always the option (it pains me to say it , as it is a cop out) of gluing the laminates on. Most laminates are non-structural. But then if you take that route and give in the fear of doing it will not go away.

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