Soldering Piano Wire

Lindsay G
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Soldering Piano Wire

Postby Lindsay G » Mon Jan 30, 2017 12:47 am

Its been a few weeks since I progressed the Roundhouse for Burntisland 1883, but that's about to change. One area that I need to finish is the smoke vents - all 15 or was it 16 of them? Etchings have been arranged for the pyramid-shaped caps that topped off the vents but whilst waiting their arrival I need to attach the supports to each vent. This gives an idea of what I'm talking about with 2 vents and supports temporarily in place :

Vent Supports.jpg
Vent Supports.jpg (127.03 KiB) Viewed 4859 times

The roof is rather exposed and is hinged to gain access to the interior. There is the chance of the supports being damaged or at least mis-shaped so I bypassed brass and nickel silver wire in favour of piano wire that I reckoned should be able to withstand heavy-handed abuse. However, I'm having trouble in getting a good solder bond between the wire and the brass tube. A few waggles and they come adrift on all but the odd one or two. The support is a one-piece item formed in an angled U shape with the bottom side of the U soldered to the rear of the brass section. I've given the wire a good clean and roughened surface with a file and course W&D to give a good key, used virtually all colours of Carrs flux (I think orange might be the odd one out), solder from 144 up to 224, and heat up to 400 degrees - I haven't as yet used my gas soldering iron or blow torch yet. I can't find a combination that's foolproof.

Is there a secret to soldering piano wire, or should I ditch it and go for an alternative metal wire?

Lindsay

Terry Bendall
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Re: Soldering Piano Wire

Postby Terry Bendall » Mon Jan 30, 2017 8:12 am

Lindsay G wrote:Is there a secret to soldering piano wire,


I have never tried but given that both parts are really clean - use a glass fibre brush and suitable flus and solder, I would have thought that it would be possible to get a decent joint. One way, if you can, would be to drill a hole through the brass tube, pass the wire through to give a mechanical fixing before soldering. If your gas torch will get the metal hot enough then silver soldering, would be an alternative. Easy Flo silver solder melts at about 650 degrees C.

Terry Bendall

Philip Hall
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Re: Soldering Piano Wire

Postby Philip Hall » Mon Jan 30, 2017 8:25 am

Piano wire is awkward stuff to solder as you have found out. La-Co flux was recommended to me for steel a long time ago and seems to help, and I have used it on the odd occasion I have had to solder steel wire.

Philip

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Will L
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Re: Soldering Piano Wire

Postby Will L » Mon Jan 30, 2017 9:38 am

When I read the title, my immediate reaction was "don't". On mature reflection you could try bending the wire so it goes round the three outside edges of the vent, rather than just the inside edge, giving you get is more of a mechanical joint nor relying on the strength of the solder joint.

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jon price
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Re: Soldering Piano Wire

Postby jon price » Mon Jan 30, 2017 9:51 am

This may be heretical for those wedded to solder for any metal joint. If you arrange a metal tube inside the stack, long enough for a sliding fit, then run the piano wire through the wall into the tube you could use araldite. The wire inside the tube will provide a bond that would be almost impossible to break without destroying the stack.

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Re6/6
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Re: Soldering Piano Wire

Postby Re6/6 » Mon Jan 30, 2017 12:33 pm

Philip Hall wrote:Piano wire is awkward stuff to solder as you have found out. La-Co flux was recommended to me for steel a long time ago and seems to help, and I have used it on the odd occasion I have had to solder steel wire.

Philip


I agree Phil. I've successfully used 'La-Co' for some time now for this purpose.
John

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Will L
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Re: Soldering Piano Wire

Postby Will L » Mon Jan 30, 2017 1:09 pm

Will L wrote:When I read the title, my immediate reaction was "don't". On mature reflection you could try bending the wire so it goes round the three outside edges of the vent, rather than just the inside edge, giving you get is more of a mechanical joint nor relying on the strength of the solder joint.


And in pursuit of some nice model detail, it might pay to think how the prototype was constructed, they wouldn't have soldered the supports to the inside edge of the flue either.

dal-t
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Re: Soldering Piano Wire

Postby dal-t » Mon Jan 30, 2017 4:02 pm

Will L wrote:
And in pursuit of some nice model detail, it might pay to think how the prototype was constructed, they wouldn't have soldered the supports to the inside edge of the flue either.


But did they really need to have the roof hinge on the prototype?
David L-T

garethashenden
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Re: Soldering Piano Wire

Postby garethashenden » Mon Jan 30, 2017 4:40 pm

The guitar wire sold by Dart Castings for AJ couplings may work for you. It is spring steel wire, but it has a coating that makes soldering quite easy. http://www.dartcastings.co.uk/mjt/2476.php

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Will L
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Re: Soldering Piano Wire

Postby Will L » Tue Jan 31, 2017 7:20 pm

dal-t wrote:
Will L wrote:
And in pursuit of some nice model detail, it might pay to think how the prototype was constructed, they wouldn't have soldered the supports to the inside edge of the flue either.


But did they really need to have the roof hinge on the prototype?


Not sure that's relevant. Lindsay's original idea (below) was not strong enough regardless of the handling issue, in part because of the soldering problem, but partly because it was totally reliant on the strength of a single solder joint under tension, never desirable. Nor did it bear any relationship to the way the prototype would have been made.
stacka.jpg
stacka.jpg (32.36 KiB) Viewed 4580 times

My quick original thought was simply to wrap the support wire round the vent, which would be much stronger, not to mention mechanically more satisfactory because it was not reliant on the strength of the solder joint for anything other than keeping the wire in the right place. But still bearing no relationship to the prototype.
stackb.jpg
stackb.jpg (27.48 KiB) Viewed 4580 times

By then I started to wonder if the way the prototype would have done it had anything to teach us. Again the first though I had was that a collar, that the support wires threaded through, would be necessary in full size. Mechanical superior again and if the collar is soldered to the vent pipe without any need to solder the wire to anything.
stackc.jpg
stackc.jpg (30.16 KiB) Viewed 4580 times

But then I began to wonder how could a real live blacksmith make that. So then I though what a practical real size arrange would be like. This is my attempt but there are a number of ways that it might be done so a blacksmith could have produced the bits. A little research may produce a picture that show us how it was done, but failing that If you start from a prototypically practical way of attaching the supports, a model version might well be possible that is strong enough to resist handling and would also provide a nice bit of model detail, rather than something you hid under a layer of paint.
stackd.jpg
stackd.jpg (36.1 KiB) Viewed 4580 times

Lindsay G
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Re: Soldering Piano Wire

Postby Lindsay G » Tue Jan 31, 2017 10:50 pm

Will,

Are you trying to shackle me to this roundhouse for the remainder of the year!?!

Don't ask how long it took to make the double-laminated ply body and roof - the latter with a part-detailed timber-supported interior (a la Derby roundhouse of similar vintage), only for some sod in our group to produce an image, not seen before by any of us, of a part dismantled roundhouse at Burntisland......exposing an all steel or iron framework with no internal pillars - wood interior now completely stripped out! (Thankfully, the ply is robust without the framing). Nor ask how long it took to scribe the stonework. Then there was a wee interlude whilst I introduced myself to Arduinos and programming (last time I programmed was within a DOS environment!) to prototype the control of everything.

Now I've got 28 leaded windows, 16 vents, half round brass tube guttering to wind around the roof, umpteen downpipes, roof windows and external roof cladding (the original may have been tiled, can't see it myself, but that's just a huge no-no anyway), detailed interior for everything that will be seen on the public viewing screen, then on to the working turntable, opening doors, lighting, et al (where another or others in the group will take over with their superior electronics knowledge).

So, I don't think I can face overly detailed vents. There will be too much on the go for punters to notice them at exhibitions but there are photographs and magazines to consider (not to mention the readers of this thread that will now be eagle eyed to see the outcome). Actually they might have had only a single support each, existing images are thin on the ground - the earliest being 1914, and it was build 60 years before that, with our period half way between them (I'm eagerly awaiting another sod to produce a further faded photograph).

However, having said all of that, I will be taking on board some things you and others have said - not sure which yet, but must make my mind up before the etched tops arrive. Since the original posting I Googled the same matter and there seems to be a lot of aero modellers soldering this stuff for landing gear and control wires, both of which will be subject to far greater stress. Perhaps filing the wire flat on both sides would give a larger surface area for soldering on one side, and the representation of a flat strip riveted to the vent on the other, at least I don't then have to throw away 16 shaped supports that have all been through a temporary fitting. Must get my thinking cap on.

Thanks all for the replies. Cheers,

Lindsay

P.S. I'd also like to progress Barnton.

P.P.S. I see Screwfix sell La-Co flux. I'll purchase some when I visit later this week - in connection with fitting a new kitchen to a daughter's flat - and with a second daughter flat-searching, what chance to getting back to progress Barnton or Burntisland?

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Penrhos1920
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Re: Soldering Piano Wire

Postby Penrhos1920 » Tue Jan 31, 2017 11:02 pm

Don't use normal solder, e.g. 188oC. There's a special solder. We used 175oC or something like that at work when soldering to steel and special brown flux. Not the aluminium solder that carrs do
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Lindsay G
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Re: Soldering Piano Wire

Postby Lindsay G » Wed Feb 01, 2017 12:03 am

Hi Richard,

I've already tried Brown flux (which (I think) is pretty high on the acid front and good enough for stainless steel), but it made no difference to other fluxes. To me it's down to the type of steel used in piano wire - I've soldered many a joint on Burntisland's steel track without problem (with black flux), but piano wire seems to me a dirty type of steel that needs to be abraded clean just like brass, but with a lot more effort (maybe I didn't apply enough effort). Accept that this is a personal, and probably off-beam, maybe well off-beam, impression.

Lindsay

Terry Bendall
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Re: Soldering Piano Wire

Postby Terry Bendall » Wed Feb 01, 2017 8:03 am

Will L wrote:But then I began to wonder how could a real live blacksmith make that


This seems the right approach to me. Look at the prototype and model what you see - at least as far as possible. However I think Will's idea of riveting the straps to the vent may not have worked. For something of that size the rivets would probably be put in hot, and therefore the head would have needed support whist the rivet was formed over. Difficult with something of this size. It is more likely that nuts and bolts would have been used and the bracing strap could then have been put in place one the vent was in position on the roof.

some years back I was looking at the steel roof trusses of a fairly old building - built around 1910 or so. One half of the each truss had riveted joints - the other half was bolted together. Why? One half was small enough to be made in the workshop and then moved onto the site. No riveting facilities on site so the other half had to be bolted together. :)

Terry Bendall

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Le Corbusier
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Re: Soldering Piano Wire

Postby Le Corbusier » Wed Feb 01, 2017 8:21 am

Apologies ... a bit off topic I know but - .... I've always thought riveting was used over bolt construction because bolt technology had not developed sufficiently? If bolting was an alternative at the time, then why was it not used universally at that time .... or alternatively, why is it used universally now and riveting (at least on structural steelwork in buildings) is obsolete?
Tim Lee

billbedford
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Re: Soldering Piano Wire

Postby billbedford » Wed Feb 01, 2017 11:05 am

Rivets were used because they were much cheaper than bolts.
Rivets were mainly replaced by welding, which was cheaper again and made for lighter structures.
Bolts are preferred over rivets in present structures because bolts can be made from a higher spec material, and be kept more consistently to spec than hot rivets.
Bill Bedford
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Le Corbusier
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Re: Soldering Piano Wire

Postby Le Corbusier » Wed Feb 01, 2017 11:12 am

billbedford wrote:Rivets were used because they were much cheaper than bolts.
Rivets were mainly replaced by welding, which was cheaper again and made for lighter structures.
Bolts are preferred over rivets in present structures because bolts can be made from a higher spec material, and be kept more consistently to spec than hot rivets.


Thanks

Tim
Tim Lee


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