Tank building

ian1954 Sat Sep 14, 2013 10:36 am

This post may get a little confusing as it includes a few hints on what to do and at first sight - a successful build turned into an abject failure!

Why build your own? To maximise the space available, end up with pipes where to want them and how you want them.

I needed this tank to proceed with building the KK Radian so that I can continue the "Cox Flight Contest". The tank is a prerequisite for building the fuselage.

Here it started. Careful measurement - just cut a length of card and bend it to shape.

Tank building Radian11

Then cut a strip of brass. Easy peezy so far!

Tank building Radian12

Use the bent bit of card as a template

Tank building Templa10

The carcass is ready to test fit

Tank building Radian13

Now ready for soldering. I had used all my resin cored soft solder and so went to buy some more. You can only get "lead free" soft solder and I thought it wouldn't matter.

Tank building Radian14

Butt joints with a fillet as usual

Tank building Radian15

File and grind the edges, soak in citric acid to clean ............. et voila!

Tank building Radian16

Even though I say it myself - it looks impressive but ..................

..............................

I tested it and it leaked like a sieve. Blocked off all except one tube, attached fuel pipe and blew into it under water. Bubbles everwhere! I have never experienced leaks on this scale before!

I resoldered and on the next test the bubbles, lots of them came from different places! I suddenly realised the this solder wasn't up to the job!

The original solder I used had a noticeable difference between the heat needed to melt the fresh solder and to re melt soldered joints. Here there was little difference. I also had trouble tinning the joints. The solder preferred to blob rather than flow to an even layer.

The result of my efforts to cure leaks.

Tank building Tankdi10

DISASTER!!!! This was a couple of hours thrown away. Not amused!

To be continued ..............................................

ian1954 Sat Sep 14, 2013 2:37 pm

After the last disaster, I adopted another technique by folding over the edges to increase the soldered area rather than rely on butt joints.

This is not my preferred method for tank building as, although the result is stronger, it adds a little more weight and is time consuming.

Started by building the carcass (as before but a more complex shape) and then cutting out the sides following the shape of the carcass but a little larger.

Roughly folding over the edges ready for the next step.

Tank building Sig_hu16

Then I use Polymorph - it is a granualar plastic after placing in hot water can be moulded and shaped. It sets solid as it cools.

Tank building Sig_hu17

I use this to fill the carcass

Tank building Sig_hu18

and then slice it flush

Tank building Sig_hu19

By filling the cracass, it can be used the neaten the folded edges with a little hammer and then they can be filed neatly ready for soldering with a nice tight fit.

When this is finished, the carcass is popped in hot water and the Polymorph push out (it can be reused many times)

Tank building Sig_hu20

This time I only inserted one tube to test for leaks. After tinning, all that should be required is a slight pressure to make a good joint with minimal filling.

Another disaster - bubbles everywhere which no amount of resoldering cured.

How annoyed was I? Extremely!!!!!!!! Now many hours buidling a tank. The time should have been measured in minutes!

This is what the tank looked like when I gave up with it - Well not exactly! It is a pink colour because I threw it in the citric acid and left it there over night!

Tank building Tankdi11

Today, I started again - I need this tank to start the Radian build!

This time - butt joints - and silver solder. Expensive solder but 40 minutes start to finish.

The new "lead free" soft solder I bought has ben cast aside. It is definitely not for tanks!

There were no leaks on testing

Tank building Sig_hu21

and a perfect fit!

Tank building Sig_hu22

JPvelo Sat Sep 14, 2013 3:54 pm

Man you do some beautiful and impressive work.

Jim

**Cribbs74** Sat Sep 14, 2013 4:08 pm

Dang Ian! Talk about perseverance!

Good job, I find brass hard to solder. I do use rosin core flux and lead solder, I have to get the brass very clean and quite hot for it to flow. I also use paste flux as well.

Ron

pkrankow Sat Sep 14, 2013 4:56 pm

Needed more volume did you?

Impressive is the truth.

Phil

fit90 Sat Sep 14, 2013 8:24 pm

Beautiful work. If you are able to go a little hotter I bet brazing could be really effective. I have never brazed copper or brass before but it looks like it should work depending on what kind of stick you use. That tank looks beautiful!

chubbyellowcat Fri Nov 01, 2013 5:01 pm

i'm knew too this....what brand of "silver soder" are you using and where can I get it ? thanks for the illusttrations Smile

ian1954 Fri Nov 01, 2013 5:36 pm

chubbyellowcat wrote:i'm knew too this....what brand of "silver soder" are you using and where can I get it ? thanks for the illusttrations

I use Easy-flow silver solder - I have a stock of it but it has Cadmium in it and is no longer sold.

I always bought my solder from www.cupalloys.co.uk .

For tanks you can use soft solder but make sure it is not lead free.

**RknRusty** Fri Nov 01, 2013 8:55 pm

That's what I want to learn how to do. I'm an expert at electronics soldering, but have no experience with this sort of project. What about 60/40 rosin core solder, would it work, or would I be wasting my time by not going with silver solder?

Rusty

Ken Cook Sat Nov 02, 2013 5:13 am

Rusty, 60/40 is all I ever used and I used paste flux in addition. I do however solder my pipes inside and out including end caps. Ken

ian1954 Sat Nov 02, 2013 6:13 pm

60% tin and 40% lead will be OK.

I was struggling with the lead free which is why, in this case, I silver soldered.

It is difficult to find anything that isn't lead or cadmium free in the UK but, last week, I managed to track down Tin 62%, Lead 36%, Silver 2%. It melts at 179 deg C, flows and "tins" nicely and will be ideal for tank building.

Silver soldering needs a bit of practice - the minimum temperature is 610 deg C and it doesn't gap fill.

If you normally solder wires and electrical components and only have a sub 25watt iron - it would be better to step up to a 60 watt.

roddie Fri Dec 06, 2013 2:11 pm

ian1954 wrote:60% tin and 40% lead will be OK.

I was struggling with the lead free which is why, in this case, I silver soldered.

It is difficult to find anything that isn't lead or cadmium free in the UK but, last week, I managed to track down Tin 62%, Lead 36%, Silver 2%. It melts at 179 deg C, flows and "tins" nicely and will be ideal for tank building.

Silver soldering needs a bit of practice - the minimum temperature is 610 deg C and it doesn't gap fill.

If you normally solder wires and electrical components and only have a sub 25watt iron - it would be better to step up to a 60 watt.

Hi Ian, Thanks for linking me to this thread for my tank build. I had read it previously a while ago. There are since; some new comments/questions/answers that I find VERY Helpful.

As you know; Lead-free solder is for Plumbers... who have to use it by law, in potable water systems... it has no other practical use IMHO...

I have the 60/40 solder (.031") and also the 62/36/2 (2 being Silver... in .022" dia.) both are rosin-core. I also have x5 one-pound spools of "Kester 24-6337-7601" (63/37... in .031"/.8mm dia.) that I got out of the recycle-bin at work, when the company went in compliance with ROHS requirements. Here's some specs on it.

http://www.janelonline.com/kester-wire-no-clean-cored-solder-sn63pb37-p/kester-24-6337-7601.htm

So.. I have lots of "soft-solder" options. I recently bought a tin of "Rubyfluid" petroleum-based paste-flux. It is stated to be superior for soldering Brass, Copper, Tin, Steel and Stained-Glass work... and also states NOT for electrical use. Do you have any experience with it?

Thanks again Ian,

Roddie

ian1954 Fri Dec 06, 2013 2:45 pm

roddie wrote:
ian1954 wrote:60% tin and 40% lead will be OK.

I was struggling with the lead free which is why, in this case, I silver soldered.

It is difficult to find anything that isn't lead or cadmium free in the UK but, last week, I managed to track down Tin 62%, Lead 36%, Silver 2%. It melts at 179 deg C, flows and "tins" nicely and will be ideal for tank building.

Silver soldering needs a bit of practice - the minimum temperature is 610 deg C and it doesn't gap fill.

If you normally solder wires and electrical components and only have a sub 25watt iron - it would be better to step up to a 60 watt.
Hi Ian, Thanks for linking me to this thread for my tank build. I had read it previously a while ago. There are since; some new comments/questions/answers that I find VERY Helpful.

As you know; Lead-free solder is for Plumbers... who have to use it by law, in potable water systems... it has no other practical use IMHO...

I have the 60/40 solder (.031") and also the 62/36/2 (2 being Silver... in .022" dia.) both are rosin-core. I also have x5 one-pound spools of "Kester 24-6337-7601" (63/37... in .031"/.8mm dia.) that I got out of the recycle-bin at work, when the company went in compliance with ROHS requirements. Here's some specs on it.

http://www.janelonline.com/kester-wire-no-clean-cored-solder-sn63pb37-p/kester-24-6337-7601.htm

So.. I have lots of "soft-solder" options. I recently bought a tin of "Rubyfluid" petroleum-based paste-flux. It is stated to be superior for soldering Brass, Copper, Tin, Steel and Stained-Glass work... and also states NOT for electrical use. Do you have any experience with it?

Thanks again Ian,

Roddie

Ruby fluid is ideal - especially for tinning brass or tin. It is slightly acidic which is why it isn't recommended for electrical work. The solder runs more freely with Ruby Fluid and you get a thinner layer and use less solder.

roddie Fri Dec 06, 2013 3:28 pm

Thank You again Ian... That's what I was hoping for. I've been dragging my feet doing research... Reading

to the point where I have holes in my shoes. Your "5 minutes; to finish my tank(s)"... will take me 5 HOURS! Wink

the "procrastinating" Roddie

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