Smoke deflector beading

[Deleted]

I'm building the Modelworks Britannia and I'd like to add half-round brass beading around the edges of the smoke deflectors. I did this successfully around the top of the coal bunker, but that was brass and mainly straight edges and I was able to soft-solder the beading to it with very good results. The smoke deflectors are 1.5mm steel, with tight curves - see photo on my website at www.britanniabuilder.co.uk/kit18.htm . I've never tried silver-soldering and I'm afraid that I may end up with lots of unsightly blobs. Would it be safer to fix it with Loctite? Also, how do I bend the half-round beading around the tight corners while keeping the flat side flat?

Regards,

John

[baggo]

Hi John,

You should be able to soft solder the beading onto the steel so long as you clean it well and use an appropriate flux such as Bakers Fluid or Carrs Black label. It may be easier to put the bends in as you go along i.e start with a straight bit and solder the beading on up to the next bend, then form the curve by hand until it matches. Solder the bend and then carry on to the next one etc. You will probably have to keep tapping the beading flat as you form the bends as it will try to twist. You may have to anneal the beading first if it's too hard to bend easily.
Probably worth having a trial run on a scrap bit of steel before you tackle the real thing!

John

[Deleted]

Hi John,

Thanks, I didn't realise that steel could be soft-soldered - I'll get some Baker's Fluid and give it a try. Actually I think the steel is zinc-plated (not that I want to restart that debate!), but I guess that won't make soldering any more difficult? When annealing the brass beading to soften it, is it sufficient to heat it red hot and let it cool fairly rapidly in air, or does it need to be cooled more slowly? Will repeated heatings make it softer?

Regards, John

[baggo]

Hi John,

The zinc plating will probably take the solder better actually! I notice however that the handles etc. have been brazed to the deflectors so perhaps they are not plated?

Take care not to overheat the beading if you do need to anneal it. A dull red should be plenty hot enough then just let it cool naturally. If you heat it to bright red it may melt! (It's better to do the annealing in the dark as it's much easier to see the colour). How well the beading anneals will depend on the type of brass used. Some extruded brass does not anneal very well, if at all.

Repeated heatings won't make it any softer than just one. The idea is to change the grain structure of the material and that should happen on the first heating.

John

[Jason]

Hi John,

I have been soldering half round brass beading onto my Duchess tender which is also Zinctec with out any problem. For the tight curves I found it easier to half cut into the bead to allow it to bend with ease, a bit like flexi MDF and then filling the cuts with solder.

Regards,

Jason

[Deleted]

John, I'm not certain that the steel of the smoke deflectors is zinc-plated - it seems to have some sort of coating, which has discoloured around the brazed areas, but it's not the same light grey as the other zinc-coated platework. I guess it doesn't make too much difference either way.

Jason, thanks for the tip about cutting into the beading on the corners. I'll do this if I need to.

One further question - one of the copper cups brazed behind the handhold cutouts on the smoke deflector has been positioned a bit off-centre. I could send it back to Modelworks to adjust, but can I try just heating it with a blowtorch to melt the joint and push it into the correct position, without further flux or solder, in the same way that I could with a soft-soldered joint? The strength of the joint is not critical. I guess there's no harm in trying.

Regards, John

[mott]

Hi JJ, You have received lots of good advice. You can silver solder Zintec quite easily and it you need a strong joint thats the way forward, other than that soft solder or even COMSOL which is higher temp soft solder should do the business. The guidance on annealing is is very good, though I had never thought of "doing it in the dark". Mott

[baggo]

jj said:

One further question - one of the copper cups brazed behind the handhold cutouts on the smoke deflector has been positioned a bit off-centre. I could send it back to Modelworks to adjust, but can I try just heating it with a blowtorch to melt the joint and push it into the correct position, without further flux or solder, in the same way that I could with a soft-soldered joint? The strength of the joint is not critical. I guess there's no harm in trying.

Hi John,

You could try moving it but it may not be that easy to remelt the solder or braze. The problem is that when you solder or braze metals, the solder/braze absorbs some of the parent metal and forms a new alloy that usually melts at a higher temperature than the pure solder/braze. It would probably be easier to get a new cup from Modelworks (or make one yourself), file or grind the old one off, and then fasten the new one on with soft solder as Mott suggests.

John

[Deleted]

Hi John,

I managed to remove the mis-aligned cup with the blowtorch, and cleaned it up and then silver-soldered it back into the correct position using Easyflo 2. My first attempt at silver-soldering, and it doesn't look too bad. I've also bought some Carr's Green Label flux and will try using this to soft solder the brass beading to the steel smoke deflectors - I chose the green label because it claims to work on steel and brass, whereas black label just mentions steel.

Regards, John

[Deleted]

I've successfully annealed the brass beading and started to soft-solder it to the steel smoke deflectors (which are definitely not zinc plated). It bent round the 10mm radius corner without needing to cut into the beading. The Carr's Green Label flux works well. See photo at www.britanniabuilder.co.uk/kit18.htm#label1 . Thanks for all the advice.

Regards, John

[Jason]

A very neat job John, and I agree it finishes the edge off nicely!!

I found with the Zinctec on my tender the solder adheres much better if a grind the Zinc off leaving the steel exposed.

Jason

[Peter W.]

jj said:

I've successfully annealed the brass beading and started to soft-solder it to the steel smoke deflectors <snip> The Carr's Green Label flux works well.

John, which solder did you use ?

Peter W.

[baggo]

Nice job John. Glad it worked out ok

John

[Deleted]

Peter,

Just an ordinary reel of 1.2mm 'Draper Solder Wire' from a DIY shop that I've had lying around for years - apparently it's 60/40 tin/lead. I'm not even sure if lead is still legal? The Carr's catalogue lists a bewildering choice of solders for different applications, but this seems to work OK for me. The thin wire definitely helps to avoid getting too much solder around the beading.

Regards, John

[Phil Sutton]

A proper job,John.

Phil

[Peter W.]

John,
Many thanks for the information on your flux and soft solder
combination. I haven't done any soft soldering yet, but I'll
have to do some 'bodywork' some day ! ( I hope )

Glad your work turned out so well.