Woes of the hard soldering.

[JasonBModerator @jasonb]

The flanged bottom plate is fitted flange outwards so when the 4 holes are drilled and tapped they only go through the outer boiler barrel and the flanged edge of the bottom plate so will not "breach" the water space.

Not sure what you are getting at with the chimney. It needs to extend from just below the bottom plate to well above the top plate. The hot gasses from the burner below pass up the chimney and it acts like an element to heat teh water as well as the hot gasses hitting the bottom plate of the cylinder

Edited By JasonB on 14/07/2016 12:57:04

[MWParticipant @mw27036]

Thanks for the 3D image, i couldn't picture it in my head but now it's clear. The drawing i'm looking at seems to show the bottom almost double walled but now i understand it isn't

So does the chimney pass straight through the boiler, isolating the water contained from the inner wall of the chimney? I notice you have a center hole on that bottom plate? Ah the second image has appeared, i see that it does isolate the tank entirely. Thank you very much. 

Michael W

Edited By Michael Walters on 14/07/2016 12:59:12

Edited By Michael Walters on 14/07/2016 13:00:08

[MWParticipant @mw27036]

Just another question, my steam pipe is quite small, i have 2mm bore, T.C recommended 1/8th is this too small for this boiler?

Michael W

[JasonBModerator @jasonb]

That Brass boilered 10" loco you saw, was it the boiler or the cladding you were looking at. As my unpainted traction engine woul dlook like it had a brass boiler to the untrained eye

[JasonBModerator @jasonb]

1/8" pipe would be refering to OD so yours should be OK

[MWParticipant @mw27036]

Ok thanks for the help.

It looks simply marvelous, Jason. Must've taken a while to build? So much detail! I bet you love catching people out when they ask if it's brass! 😛

Michael W

[PeroParticipant @pero]

Keith

Thank you for your response. I have been mulling this one over in my mind for some time without reaching any conclusion. I became quite good at silver soldering very small joints in stainless steel when making fittings for radio control racing yachts but haven't yet attacked the bulk of a boiler. I think my largest efforts to date are on 20 mm plumbing fittings using 15% silver rods. These were all successful so I think now is the time to step up to a 50 mm boiler!

A bit far to get to the shows (I am in Perth, Western Australia) but I may take up your kind offer to phone if I get into difficulties.

Regards

Pero

[Steve WithnellParticipant @stevewithnell34426]

Posted by John Olsen on 14/07/2016 04:34:52:

Since Mamod have been known to make entire boilers of this general size and class from brass, I don't think it is going to be of great concern if the end caps for this one happen to be brass. It only needs to work at low pressures, so the temperatures are low and any dezincification will only occur very slowly.

[MWParticipant @mw27036]

I wonder if anyone does metal "spinning" or thinning to make a boiler or chimney, where a disc of metal is spun on the lathe and rubbing tools are used to shape it over a mandrel, musical instruments such as trumpets and horns are still made this way.

I believe brass jackets for bullets are also "stretched" to shape too. 

Michael W

Edited By Michael Walters on 14/07/2016 20:05:10

[JasonBModerator @jasonb]

I spun the shiny steel end cover on this TE cylinder.

Press tools seem more common for flanging boilers than spinning

Edited By JasonB on 14/07/2016 20:31:36

[MWParticipant @mw27036]

Very nice indeed, the results look good, perhaps if i needed to use sheet metal in future i could machine a die form for the arbor press i use for broaching.

An update anyhow,

This is the new boiler with the end plates now soldered to the tube, holes for the chimney, steam pipe and valve have been made and 4 shallow threads sunk into the shoulder of the end plate, this is what it looks like after i pickled it in a solution and tumbled it with stainless shot, i haven't done any polishing or finishing to it yet and i'm definitely impressed with the results. The great thing about it is it will also clean up the inside of the tank (for now).

There was one downside in that i would advise anyone considering tumbling with pickling to cover or plug the threads! i ended up with shot imbedded in the recess, luckily i was able to get it out by spinning a grinding bit over the top of the ball as it spun round it gradually reduced in size enough for it to come out with a sharp tap against the bench.

The theme for this week seems to be getting things stuck and finding a solution!

Michael W

[JasonBModerator @jasonb]

Certainly a big improvement over the previous effort.

Couple of points for future reference.

You have a lot of solder on those joints, any saving you had hoped to make by using 40% solder has been well and truely negated by the amount used. Most likely reason is that you have not got things hot enough for the sollder to flow freely, another disadvantage of 40% is it needs more heat and does not flow like 55%. Combine this with your tight joints and you won't have got it to flow well into the actual joint so have ended up with more of a brazed joint rather than silver soldered.

Another tell tale sight of it not being hot enough is the lumpy surface of teh solder, once properly heated it will flow like a liquid and just leave a very small even fillet.

If you are pickling it enough you should not need to tumble it, just a quick rub with a scotchbrite pad or wire wool when it comes out should have it looking like the first pic of the unsoldered pipe. Also don't try polishing until all soldering is complete.

J

PS make sure you have a valve/feed hole in teh top plate when you come to solder the chimney into place so fumes can get out

[Ian S CParticipant @iansc]

MichaelW, saddly we only had the one meal work night class, 6 weeks, I spent most of my time there instructing on the lathes and shaper (the teacher was one of the main pupils). I also helped some of the others with soft soldering, and silver soldering. Only one didn't work, and I got it a few years later.

Ian S C

[MWParticipant @mw27036]

A little side track but for those of you interested in dezincification;

These are a couple of german mauser shell casings pulled out of a trench in france. I got them because when i was out walking i noticed a half sunken tractor that was coned off in the middle of a field. Nothing happened but i went back a few days later and noticed the local farmer had rounded up some labourers who had taken the tractor out and dug an enormous trench. Next to it a pile of wet sloppy mud that was probably 10feet high. The tractor had fallen through a sink hole which happened to be a buried bunk area, luckily the driver was unharmed because the metal roof and supports stopped it sinking any further. Inside the trench the beds and framework were still intact, these shells were loosely wrapped up in a cloak under one of the beds, one of the labourers hauled it up and it burst open on the field and i asked if i could take a couple with me. The germans were clearly recycling their brass. They were slightly brownish in appearance and i cleaned them up when i got them, but there was no signs of any verdigris or "dezincification" to the brass or on any of the shells for that matter. So why in a rain sodden piece of earth for nearly 100 years, it did not suffer any separation? The trench was completely waterlogged. Could it be a different amalgam they used for their brass or simply preserved by luck?

Michael W

Edited By Michael Walters on 15/07/2016 14:05:58

[JasonBModerator @jasonb]

I doubt it got to boiling point in the mud.

This is why its generally said brass is OK for steam fittings ABOVE the waterline of the boiler, as I said earlier teh softer brasses like the cartridges would have been made from also contain less zinc than the commonly used hard brass that we buy for machining.

Verdigris is oxide so needs oxygen, the bottom of that waterlogged trench would be a bit like a bog and I'm sure you have seen how that can preserve bodies for 1000s of years

Edited By JasonB on 15/07/2016 14:12:41

Edited By JasonB on 15/07/2016 18:25:56

[Speedy Builder5Participant @speedybuilder5]

Hi Jason – what language have you got your computer set up for ? Tongue in cheek of course!
I have just read a book about the Last Australian Postman of the outback where he said that cartridge brass was used for brazing.
BobH

[Clive HartlandParticipant @clivehartland94829]

Maybe the area where the cases were lying was not acid but alkaline, clay soil is benign I believe. I have opened boxes of ammo and found cases dezincified in storage. Airtight boxes! I might suggest the the cartridge brass is suspect at manufacture as it goes through a lot of manipulation and pressure forming. Also there are some nitro powders (Cordite) that can affect a case from the inside causing head seperation or longitudinal splitting on firing.

Clive

[Ian S CParticipant @iansc]

Some primers on WW2 .303 ammunition can cause corrosion around the base of the cartridge case.

I'v used cartridge brass for brazing.

Ian S C

[MWParticipant @mw27036]

Ok, so i've "soldered" the chimney today, i cut the brass tube to length,faced off, countersunk and cleaned it up for a good fit with some grit paper between centres. The tube was positioned with a steel spacer so that the fit was just below the bottom of the tank, the top was done first, i chose a bigger burner tip this time and heated for longer because i understimated the thickness of the brass, it's not a clean job but it's completely melted and the joints are sound.

Interestingly the tank filled up with water through the valve hole as i quenched it, i held it up and it held the water fast. There were no leaks as far as liquid is concerned which i suppose has to be a good thing all things considered, next i'll make the valve and fit the steam pipe. Then onto the firebox.

Michael W

[John OlsenParticipant @johnolsen79199]

There was some mention of pickling earlier, but I don't think anyone mentioned citric acid, which should be available in packets at your local supermarket. It is safe to use and does a good job.

Incidently you don't actually need to quench the job, you can just leave it to cool naturally. It doesn't matter too much either way, since copper and brass won't go hard on you like some steel might, but putting very hot things into water can cause hot splashes.

A good check for leaks is to plug any holes while it is cold, then put it into warm water and watch for tiny bubbles to appear. Even better, if you adapt a bicycle valve to fit the safety valve hole, you can put a little bit of pressure on with a bicycle pump. Give it a good pickle first, since pinholes may be blocked up with flux. Usually you will be able to see places that might be dodgy, eg if the silver solder has run well and left a smooth fillet then there is probably no problem.

John

[Ian S CParticipant @iansc]

You will get the citric acid at the home brew shop cheaper, and in larger packets. Also at a supplier of agricultural chemicals, although there you might get a 50kilo sack offered to you.

[MWParticipant @mw27036]

Yes, thankyou it's good to know what the mysterious powder actually is! that way i can get more than a few teaspoons full.

Thanks,

Michael Walters

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