Overclockaholics Forums - Guide: Brazing a Braided Flex Line

Figured we could use one with pictures!

Parts:
From www.under-the-ice.com;
Braid, flex, and ends, as well as two 7/16" pipe joiners

http://img695.imageshack.us/img695/6992/dscn2159.jpg

Process:
We start with the end stubs, careful prepration of these makes the entire process much easier. Start by cutting the length into two pieces, I prefer to make one longer then the other. That way an access can be added to the longer to purge and pressure test without making you cut TOO near later on.
http://img691.imageshack.us/img691/8936/dscn2160c.jpg

So now we have two stubs;
http://img705.imageshack.us/img705/2176/dscn2161.jpg

Deburr then, this also removes a restriction. Your pipe cutter might not have a piece, so go get the tool; deburr every pipe ever. It's a great way to get btter results.
http://img689.imageshack.us/img689/5492/dscn2162.jpg

And test fit, should be able to fit snugly.
http://img69.imageshack.us/img69/5787/dscn2163.jpg

Sometimes it doesn't fit perfect though, or theres a flange on the flex, I use needle nose to widen and "reflange". This also scrapes at it a bit and raws up the metal for later brazing.
http://img69.imageshack.us/img69/8351/dscn2164e.jpg

Ta da! She fits!
http://img69.imageshack.us/img69/9016/dscn2165u.jpg

Here's what I use. I had a access with 3ft of 1/8" tubing on the end, I brazed it into the longer stub, crimping a bit around it. Attach it to your purging kit.
http://img24.imageshack.us/img24/4639/dscn2166fq.jpg

It helps to use a vice, really helps, that way you can hold the work out and balance it. Do not clamp near the heating point though or it will suck up the heat.
http://img64.imageshack.us/img64/6726/dscn2167s.jpg

Tune your torch in (acetylene here) and go for it, start by heating the inner pipe right before it meets the flex and once red move over the flex. The flex is a bit thinner walled so you don't want to melt thru.
http://img691.imageshack.us/img691/4605/dscn2168r.jpg

Apply the rod. Since these are copper alloys, I use 15% Harris phos' rods. Apply the rod at the joint, on the flange made with the needle nose and up onto the first ridge. This prevents cracking of the flex at this point later. When you start brazing, and applying the rod, move the torch over the flex pulling the filler in.
http://img691.imageshack.us/img691/359/dscn2169.jpg

Make sure your purging gas is running for that, and check if your holding pressure with your finger after. (Obviously on the unbrazed side!)
http://img21.imageshack.us/img21/6387/dscn2170j.jpg

Do the other side.
http://img709.imageshack.us/img709/3351/dscn2171.jpg

Doesn't she look nice?
http://img31.imageshack.us/img31/8851/dscn2172u.jpg

Little wet rag, and check for any holes
http://img36.imageshack.us/img36/5579/dscn2174m.jpg

Time to clean her a bit so you can add the flex. I use a wire brush end in my drill. Clamp her in tight for this.
http://img97.imageshack.us/img97/1262/dscn2175.jpg

Now to stretch the braid. Run it over the length, and I pull it an INCH past the flex joint. This again helps for brazing, reduces the chance of hurting the flex joint, and prevent cracking the flex line later.
http://img36.imageshack.us/img36/406/dscn2176db.jpg

Slide a coupling over. Then pull it backwards with the flex so that it hits the flex itself and stops.
http://img96.imageshack.us/img96/9392/dscn2177w.jpg

Push the braid through till its level with the end of the coupling.
http://img191.imageshack.us/img191/2321/dscn2178.jpg

Mount it in the vice, your going to be using a bit of rod here and you want it to pool inside the coupling so let gravity help you by bending it upwards.
http://img36.imageshack.us/img36/5806/dscn2179.jpg

Light her up!
Here's how the heating goes;
Take the torch to the coupling till its red, then go to the inner pipe. Do not point the torch inside the coupling, youll melt the braid and it will pull away. Get the inner pipe red and then move the torch so that it is perpendicular to the inner tube and connector and is heating both. Apply the rod with gravity downwards inside the two, starting with the inner pipe.
http://img36.imageshack.us/img36/4683/dscn2180l.jpg

Now this looks good, don't forget the purging gas when your doing this though!
See how it fills inside the cup, the braid is inside the filler.
http://img97.imageshack.us/img97/1259/dscn2181.jpg

Do the other one the same, and then give her a clean up!
Remember when you do the other to pull the braid tight, you don't want it loose. If it goes past an inch on your flex, cut it. You do not want loose braid!
http://img31.imageshack.us/img31/366/dscn2187u.jpg

Not too shabby.
http://img190.imageshack.us/img190/2264/dscn2188k.jpg

Now to pressure test. With the open end, crimp it, and just quickly braze the end shut. To do this cleanly, run the purging gear while your heating it up, and quickly kill it and apply the rod, throw the wet rag on it. The nitrogen will stick around long enough without blowing the filler out.
http://img192.imageshack.us/img192/2871/dscn2189p.jpg

Turn up the regulator! 300 psi for 6 hours and she's good. I've pressure tested to 600 psi without issue.
http://img189.imageshack.us/img189/3886/dscn2190q.jpg

Hope that helps!