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Woes of the hard soldering.

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MW26/06/2016 17:22:14
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And hard being the operative word.

I made a boiler shell to one of tubal cain's designs however, i'm fairly new to fiddling around with sheet metal, joins and fillets and although it's sound and rigid it looks pretty beaten up and crinkly for what should be a nice round cylinder and i'm not really sure what to do about it.

I'm so ashamed of it i'm kinda nervous of the idea of even posting a picture of it because of all the stick i'd get from the steam fans and solderers.

Anyway i did anneal it before i worked on it and that was fine (bar the scaling) and tried using brass brazing rod but it doesn't melt very well under the heat of the butane/propane torch and the silver solder worked much better but now i've run out.

Should i just scrap it and try again?

Michael W

Edited By Michael Walters on 26/06/2016 17:23:31

JasonB26/06/2016 18:38:37
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Scaling on the surface will clean off with pickle and not worth trying to solder it unless it is completely clean.

Brass brazing rod really needs oxy to get it hot enough and the phosphorous in teh rods does not go well with coal fired boilers.

Really depends on how bad it is as to whether you start again or see if you can save it or use for practice. Not sure why the tube should look beaten and crinkly or did you roll your own? If teh flange edges looked crinkly its quite common to skim them down to a nice fit in the tube.

MW26/06/2016 18:59:42
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Thanks JasonB,

Yeah i tried to roll my own around a hardwood former and i followed Tubal Cains method of making hinges, but they kept popping out either side of the seam so it got beaten up a little bit. In future i'd go with riveting the two sides together and then soldering as a neater way, i guess it's a good practice, wouldn't have known that otherwise. The hinges are too prone to popping open when you hammer it together. I could just buy some tube tbh.

Yeah i thought the brass wasn't melting too well, yet the silver solder does. Where could i get some pickling fluid?

It is pretty strong but just looks awful at the moment, i may just try to carry on and see where it gets me, so long as i get a working steam engine i'm not too fussed for a first attempt. I'll post the pictures on here when i've got to a decent stage, the cost of the materials makes retries expensive.

Michael W

JasonB26/06/2016 19:14:39
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I use the dry crystals that most of the ME suppliers will have for copper/brass & bronze, think mine came from Chronos. On the larger fabrications and for steel brick/patio cleaner works well and also shifts the HT5 flux but not an acid you want to keep in the workshop so do it and keep it outside, builders merchant will have that in 5lts.

MW26/06/2016 19:30:35
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Yeah, i've seen some crystals on "the bay", it sounds far safer that sulfuric acid, which the less i have to do with the better. Pretty inexpensive too.

I would warn anyone thinking of trying this to be careful of whats considered "silver solder" jeweler's use a soft solder which, i don't think is suitable for brazing. What you need is the stuff that melts at around 600C as a "hard solder", it's not cheap but the 40% silver content is more economical than the 55%.

Michael W

JasonB26/06/2016 19:39:33
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Jewelry solder is a hard solder generally melting between 700 and 800deg depending on exact composition and is usually sold as "Easy" "medium" and "Hard" with easy being in teh lower temp range and hard getting up towards 800deg. It also looks more silver in colour so is a better colour match. You can also get ones that match gold and platinum better.

J

Michael Gilligan26/06/2016 20:04:08
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Michael,

Jason [predictably enough] is correct.

... There are 'jewellers' of many kinds.

For disambiguation; you might find this page from Cookson Gold useful.

MichaelG.

Edited By Michael Gilligan on 26/06/2016 20:05:45

fizzy26/06/2016 20:17:22
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Using 40% silver is just asking to make things difficult. You will find the extra expense of 55% means a much nicer, easier job which doesnt end up in the bin. Sure I use 40%, but only with oxy.

MW26/06/2016 21:19:26
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Thanks for the tip, but i think i'll wait and see.

Michael W

Neil Wyatt26/06/2016 21:19:54
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I have a large bottle of SUMA SCALE which works very nicely as a pickle for me. Blimey! £31 - £59 for 5 litres! I got mine for £7 at the Bullring Market.

W5 kitchen descaler also works well,

Neil

MW26/06/2016 21:30:47
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Just goes to show you can still find a bargain in unlikely places.

Michael W

MW26/06/2016 21:41:39
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Sorry for DP, but i also have a proxxon mini power tool/dremel type, i may try using it tomorrow to grind out some of the worse fillets from the brass brazing and clean it up a little bit whilst waiting for some more soldering supplies.

See if i can also iron out some of the kinks and dimples in a gentle manner, if it wont go i wont force it though.

If theres some time left i can return to the lathe to make some of the valves.

By the way if you're wondering what surface i'm using i made a miniature hearth out of a couple of 9" x 12" "vermiculite" bricks and wood screws, the off cut i have left over i use as a spacer to lean work pieces on at different angles.

For anyone thinking of trying this, i keep a bucket of water nearby for quenching and fire safety in case anything goes awry. 

Michael W

 

Edited By Michael Walters on 26/06/2016 21:49:26

MW27/06/2016 16:49:34
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Hi again, I've tried to clean it up a bit so i can take a picture, (i dont do WIP shots because its too hard) it's only from my phone.

boiler1.jpg

Theres a couple more on Misc. of my album but i wont put it here because i dont want to photo spam.

I cleaned up the body with a wheel on my lathe and tried to make it a little rounder, i will need to redo some of the joins when some more solder comes and pickle the debris out of the inside. It probably shows i've never done this before.

Michael W

Howi27/06/2016 17:35:06
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Oh! Dear........

I hear more men are taking up knitting these days  ( only joking )

 

MW27/06/2016 18:08:10
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It's ok,

I'm not offended.

Michael W

fizzy27/06/2016 18:39:24
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Hi - im a bit confused, what do you mean by boiler shell? Is it a boiler or a boiler cover perhaps?

JasonB27/06/2016 18:57:25
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A bit more crinkley than I was expectingsurprise

Probably best not to waste any more silver solder on it, the joint gaps are likely to be too big in places and you may have a job getting it really clean especially if you have been beating on it with a surface covered in scale as teh scale will have been driven into the surface.

Which of TC's designs is it meant to be? Polly?

J

MW27/06/2016 19:19:31
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Yeah it's polly, It seems there are only a few places where theres still some holes needing to be covered. The main seam is ok, The solder has penetrated both sides. I was going to put another disk inside the boiler to "double wall the ends.

The boiler shell is the exterior of the boiler. I think i'm going to soldier on.

Michael W

JasonB27/06/2016 19:29:49
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You should really have flanged endplates on that as they give a greater area for the soldered joint.

You will have a job soldering a thickening disc on the inside and won't be able to see if the solder joint is good. It is also not needed as the central flue acts as a stay to support the flat area, that is unless you have used thinner coppper than spec.

Fizzy this is the actual boiler for a "Polly" which is a simple vertical centre flue design.

MW27/06/2016 22:24:39
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Yeah, i think if i had another go i would've deviated from his design slightly by riveting the shell together and flange the end plates, his methods are designed to hide the joints so that everything is flush but it needs an expert hand to do it right. And for a beginner maybe not a great way when you're being guided blindfolded.

I've used his sizes of copper 22G for the end plates and 24G for the wall so 0.6+0.7 respectively. I'm going to keep following onto the chimney after this and then fault find the joints by filling them up and checking for leaks.

If i've got some spare brass left i might be able to do a little bit of window dressing banding around the outside of the tube ends. I don't think it's irredeemable it's just a venture into the dark. Besides i've hardly got somewhere yet. Just wanted to try something new.

Michael W

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