Soldering/brazing a boiler.

Okay, I will check what burners are available from the hardware store but it is difficult to find anybody in these places who knows anything about what they are selling. Sometimes I get lucky if it is an ex-tradesman, but usually any questions are met with blank stares !

Is 3/8'' BSP standard for all brands ?

Edited By Brian John on 19/11/2014 09:30:45

If the piston on your little wobbler is a bit loose, take it out and turn a bit of a groove just a bit below the crown of the piston, and wrap a twisted bit of Teflon plumbers tape in the grove, put it all back together, it probably won't go faster, but it will have more power.

In the 4 or 5 wobblers that I'v built, the cylinders have been built up using tin lead solder. The pistons made by drilling, and tapping, and the con rod screwed in, except for the little one where the piston/con rod are one piece stainless steel.

Ian S C

Ian, Brian does not have a lateh yet.

The Sievert stuff is not 3/8" BSP nore is my Bullfinch so no and I doubt your Mapp gas torch has 3/8" BSP on it, probably 7/16x28tpi

I have ordered some more brass rod 7/32''  to have a go at making my own piston but without a lathe it could be difficult. How do you find the EXACT centre of the piston in order to drill it for the con rod ? I have tried doing it by eye but do not even get close. There must a be a trick or a tool to do this ?

The other problem is damaging the outside of the piston when you hold it in a vice prior to drilling and tapping.

Edited By Brian John on 19/11/2014 10:26:40

Edited By Brian John on 19/11/2014 10:27:28

<<How do you find the EXACT centre of the piston in order to drill it for the con rod ? I have tried doing it by eye but do not even get close. There must a be a trick or a tool to do this ?>>

Measuring for the centre of a circle the manual way is a centre finder.. a tool that is simply an angle around 90degs with a ruler edge that bisects that angle. Mark from several points around the circumference to allow for inaccuracies of the tool. Woodturners use a cheap plastic device or an engineers combination square set.

I needed to make some simple thumbscrews recently without access to lathe but I do have a bench pillar drill of dubious accuracy. To bypass marking for a centre - The solution I came up with was to drill a hole in a scrap of timber clamped to the drill shelf the diameter of the large end, drop a piece of stock into the hole and drill the centre hole without adjusting anything but the drill bit change. My fit was tight enough to get away with it or you may need to glue the stock in to stop it spinning. Most glues will soften with heat.

Jason, yes he does, as far as the grove in the piston, even if he only has a hand drill, if you can Brian fit the piston in the drill chuck, and get to work with a file, whole models have been built this way, just a bit difficult mounting a hand drill in a fixed position so you can crank with one hand, and file with the other. Must try it in practice.

Ian S C

There are no grooves or piston rings on this cylinder. I will turn the piston down in the drill until it fits the cylinder as you described. I have already done such things a few times. Who would have thought there were so many uses for a cordless drill ?

Yes, the hole in the timber should work. I was also think of putting the piston in a piece of 1/4 inch tubing (or the closest fit) then drilling down into that with a close fitting drill bit until I made a mark dead centre.

I have spent all morning at the hardware store and  BOC Gas talking about torches and burners. Here is what I intend to buy to solder the boiler :

handle BK2119

hose BK8179

neck tube and full flame burner BJ2146

ultra pin point burner (for small fittings) BJ8842

Plus an LPG 1.25 kg gas cylinder as used for camping.

**LINK**

All up it is about $140.

Edited By Brian John on 20/11/2014 12:55:14

Edited By Brian John on 20/11/2014 12:59:35

Hi BJ,

I emailed Midwest as you had some difficulty and they advise that the boiler is SOFT SOLDERED, hope this helps

Info

Lofty, if you look back through the thread somewhere you will see that Brian wants to use the boiler to practice his silver soldering, that is why he is doing it that way.

Really jason? I also saw that he tried to contact Midwest without success.

Only trying to be proactive.

Thank you for that email address ; that will be useful.

Yes, I need to practise my silver soldering/hard soldering. I assume that Midwest mean for the boiler to be soft soldered because they recommend cleaning the metal thoroughly before fluxing and soldering. I gather from recent advice that there is no point to cleaning the metal prior to hard soldering as the large amount of heat involved oxidises the metal anyway so cleaning it is a waste of time.

NOTE : I will clean the metal anyway

Brian, don't know where you got that idea but you do need the metal to be clean. The areas covered by the flux which is applied before you start heating will be protected and not oxidise.

Have a read of CuP's best practice and see what it says about cleaning

What ever you finally decide, don't forget that you cannot silver solder if there is any trace of soft solder near the joint.Soft solder, ie lead/tin, can be used after silver solder.

Jason : I have read it. Please read the section on joint cleanliness. Am I reading this wrong ? It says cleanliness at room temperature is unnecessary.

Gordon : there is no soft solder involved at all.

At what point does soft solder become hard solder ? What is the difference between the two ? Is it the silver content or the melting point ?

Edited By Brian John on 21/11/2014 12:48:24

Brian, you would not want to try and solder a piece of copper that has been knocking around under the bench for 20years or had been heated to leave a heavy oxcide layer on it without cleaning first.

On the other hand you don't need to go to clinical levels in an oxygen free enviroment to make sure the surface is not contaminated.

Basically you want a bright copper to the eye, the flux can then cope with the rest.

So taking your boiler as an example if you soldered say the bottom on and then went back later to do the top you should be acid cleaning between the two, if you tried to do it without cleaning you will get into trouble.

600degrees C is about the change over, melting point

Edited By JasonB on 21/11/2014 13:01:22

As I mentioned above, I WILL be cleaning the metal regardless of whether it is necessary or not.

Yes, the main joints (top and bottom) of the boiler will be done in two stages. Then the chimney in two stages. Finally the filler plug and steam outlet will be added to the top of the boiler. I am hoping that the pinpoint burner will produce enough heat for this last job without melting the already soldered joints of the boiler and chimney.

Edited By Brian John on 21/11/2014 13:17:34

Today I made the first attempt after purchasing the correct equipment. In the photos below you can see the full flame burner I used to silver solder the base of the boiler. Beside it you can also see the medium burner which I will use to solder the fittings (steam outlet and safety valve/filler plug). Tomorrow I will do the top of the boiler and the next day will be the chimney. I may do both the top and bottom of the chimney in one go...not sure yet.

Everything seems to have worked well but there is a lot of heat. It uses a surprising amount of solder (expensive stuff). I am worried that when I try to solder the chimney it may melt all my previous work.

I gave the soldered parts a wash in water then into the citric acid pickle for one hour before taking some photos. I have put it back in the pickle now. The solution has turned blue : has all the citric acid been used ie. should I mix a fresh batch and leave it overnight ?

NOTE : I did not solder in the kitchen I have a small courtyard outside the apartment.

Edited By Brian John on 06/12/2014 02:34:43

Edited By Brian John on 06/12/2014 02:41:51

Here is another photo of the new equipment showing the full flame burner attached to the handle. I have vented all the gas from the hose. I have been told that it is now safe to store it in this position....comments anybody ?

That looks a very good joint for a first attempt, the solder has flowed very nicely around both sides of the joint.

When you come to do the other joints just position the boiler in such a way that everything is supported and then you should not have too much of a problem with previous joints. Also once silver solder has melted it needs more heat to melt a second time so you should be OK.

Some people prefer to place a few short lengths of the silver solder rod around the joint as that can be a bit more economical but I prefer to just feed in the stick once the job is upto temperature.

Yes fine to store like that, if you are not going to be using it for a period of time then I would take the hose off the canister just so its less bulky to store.