Bending brass tubing - help!

Weaver · August 20, 2011, 01:35:49 PM

Okay, I'm trying to make a couple of helicopter exhaust pipes, which bend outwards with slash-cut ends. I've got some K&S brass tubing of the right size and I've got some K&S benders (springs, basically). The benders won't fit over the outside of the tube as recommended (it's too big) but the biggest one wil fit fairly close inside it.

Trying to bend it cold is a no-no: it's just snaps. The bender instructions recommend heating it and bending it slowly. Tried that, and it just creases on the inside of the bend. Running out of ideas and tube now.

Any input?

Steel Penguin · August 20, 2011, 01:41:06 PM

the only spring benders ive seen were used interanly ( admitidly this was on 18mm copper water pipe) as the spring supports the pipe internaly and stops it creasing, but it does mean that you have a min rad.

$:-\$ a thought stikes, could you do the 1st part / bend, in bar turn down the end and slip a short length of tube over the end, to give the impresion of tube??

deathjester · August 20, 2011, 02:25:31 PM

How about finding a local car spares shop that makes replacement brake pipes - they will be able to do it with out creasing.

GTX · August 20, 2011, 02:27:24 PM

Try heating it first (as described) as this should anneal the metal. Then once cool, fill the tube with water and with one end blocked, freeze it. Once frozen try bending. The ice inside should provide some support to the tubing.

Regards,

Greg

kitnut617 · August 20, 2011, 02:45:05 PM

I would try using aluminum tubing, bends far easier. And put the spring inside. Another way is to pack it with sand.

Green Dragon · August 20, 2011, 02:56:05 PM

Only method I've heard of is Kits one, filling it with sand. Only done it on copper water pipes myself but it worked every time.

Paul Harrison

kitnut617 · August 20, 2011, 03:20:15 PM

There is this tool (and other similar types like it)

http://www.alltradetools.com/catalog/general-purpose/263-648485-heavy-duty-tube-bending-pliers.html

Or, just go to the hardware store and rumage through all the different pipe elbows that can be used for copper plumbing. You could cut two exhausts out of one elbow (maybe more)

rallymodeller · August 20, 2011, 05:30:30 PM

Here's something that I've tried, and it seems to work pretty well: plug one end, fill the tubing with a mixture of water and dish soap, and freeze them. Once frozen, they can be bent around a jig and should not kink. This technique is used by makers of brass instruments (trumpets and so forth). Then let them melt and there you go. Saw it done on "How It's Made" and had to try it right away on some 1/8" ID tubing that I had. What do you know, it worked OK!