Solder for an all Copper Pot Still

[myles]

I have been doing a bit of experimenting and have come to the conlusion that copper phosphorous brazing rods are great for parts of the still that are not going to get really hot. Condensers etc as they dont need flux and are easy to use.

Am wondering about the pot builds though. I currently use mostly 56% Silver solder (Cadmium free) with a melting range of 620 - 650 degrees centigrade. I use some 49% Silver solder with a higher temp range for 2 stage solder operations.

There is no doubt that these give good strong joints on both copper and stainless steel, but for all copper builds are they over the top? I would not like to use soft solder on a boiler, but is there a lower temperature option than the 600 degree Silver solders?

I am currently building a tapered lyne arm from a 2" 1.2mm wall thickness, copper tube and am having real trouble getting the 3' length up to soldering temperature. For the silver solder that I am using, the joint has to be at the red hot stage to melt the solder.

I am currently improvising a forge to heat the entire length of pipe, to the point where my MAP torch can provide enough extra heat to get the joint up to temperature.

I have been thinking of using 0.9mm copper sheet to build a double boiler variation of a Pint style pot, and that will pose the same problem.

For those of you that have already done an all copper build, what sort of solder do you use? Are you using hard solder or are you using something in between, with a lower melting point, but higher than tin based soft solder? Or are you in fact using soft solder? Please coment.

[Husker]

I am not sure of your concern about tin based soft solder. Most all copper stills are going to be riveted for strength and then 'tinned up' for sealing. As long as you do not boil dry, it should not come close to reaching temps that will cause solder to flow. I do not believe the temp will go much above the boiling point of your water/ethanol mix that is boiling at the moment. I would think 5% or 10% silver solder would work just fine, and be pretty easy to flow with direct MAPP heat.

H.

[squidd]

Myles,

Have to agree with Husker.

However, if you still want the BTU's, oxy-acetylene is probably an easier (for me anyway) course of action than a forge.

HTH

[Husker]

I bought an oxy acc a couple years ago, and I would NOT want to do any large copper sweating with anything less than that. It has such a nice LITTLE flame, i.e. very accurately ONLY heats what you want it to, and does so without carbonizing a LARGE section of your copper. When working with 2", I think it works so much better.

People use MAPP all the time to do 2", but I find the little flame of the oxy torch works so much cleaner.

H.

[HookLine]

I use 2% silver braze rods (coz they are cheap), and as long as you have enough heat to do it they work fine.

[myles]

Thanks for that everyone. I suspect I have fallen foul of some clever advertising ploy from the people selling the high percentage silver solder. Sure its good stuff, but it looks like its really not needed in this application.

[heynonny]

I have an ox/acet torch but I purchased a propane regulator and use my acet 'rosebud' (used for heating large areas) with my still propane tank and the ox bottle. One can heat a large area quickly. I use 'Hobart' 'Blockade' hard solder (used in air conditioning soldering) Its good at filling gaps if one is a mite sloppy, , , hey

[Husker]

How much cheaper in the long run, is using propane vs acet? I know a propane bottle (20lb), is about $15 to fill, and the ACC is much more. Just wondering how fast you draw down that propane?

I might look into that type setup. acet IS an overkill. Fun, but certainly much more heat than you 'really' need to properly work copper.

H.

[Rebel_Yell]

You'll like the propane for dealing with copper pipe...

http://www.cousesteel.com/AndysPlace/PropaneAcetylene.html

[HookLine]

Thanks for that link, Rebel. Good info.

[Husker]

I agree, good info link.

However, I think I will stick with O2/Ace for the actual braze/soldering. There is one huge missing part of propane/O2. That is the CO2 shield you get with acetylene. From this reading, that is lacking in the propane/O2. However, I think heating for annealing, and some other purposes I have, it would work great, and be much cheaper. Sounds like it actually has much more actual thermal power, just a little less temp, and little more O2 use, and lack of the CO2 barrier.

But certainly useful, if all I need is a fitting and new torch tips. Cutting with propane also sounds very interesting, as cutting will suck a bottle of acetylene dry in no time at all.

H.

[heynonny]

VERY interesting link, Rebel, thanks.
Another thing about acet for heating. Those acet tanks are full of it looks like cotten stuffing from an old sofa because the bottles are (not completely)fulled with liquid acetone which when the acetelyne is introduced under pressure, the acet is absorbed by the liquid acetone. This is a MUCH more stable way of storage as gaseous acetelyne is rather unstable. I dont reccomend this , but if one lays a bottle of acet on its side and uses it welding /cutting one sees tiny whiteish specks in the flame (depending on size of bottle/amount of gas being consumed) This is the liquid acetone coming out with the acetelyne. Doing a lot of cutting really requires a large size bottle as one needs a greater (internal)volume to supply adequite gas for cutting/heating. When I bought my propane regulator I also bought my acetelyne rosebud tip (It was cheaper than, and, they had one on the shelf)
Also I think most of us (correct me if I'm wrong) use propane for heat, so theres that tank, and believe me, propane is WAY cheaper than acetelyne. -hey-