View Full Version : Swaging

Skip Ellis
01-01-2011, 04:18 PM
I'd like to connect some 1" alum tubing and/or emt with like material. What's the easiest (cheapest) way to enlarge an end for a slip fit that can be soldered or brazed (or even set-screwed)? I've seen a hammer operated gizmo like a punch that's in my budget - has anyone used one of these for small production numbers?

Mr Fixit
01-01-2011, 04:42 PM
Hello Skip,
They make a tapered tool like a cone that if you have a lathe you can turn one real easy. Refrigeration repair techs or someone in that line of work may have one you could use. Also they are sometimes at garage sales in junk boxes because nobody nows what they are for. Be careful soldering EMT it is galvanized and puts off poisonses gases you should use mild steel tubing instead to be safe. Good luck on the project. EMT does have couplings that are set screwed but the overall size is larger.

Chris :)

Mr. Fixit in the Family

01-01-2011, 05:04 PM
For the record. Yes, Galvanized = zinc = bad fumes when welding, and maybe even at soldering temp.
However, the only person iv heard of dying from it, Left a whole bunch of galvanized plate in his shop oven and.. stuck around for a few hours.
It can make you feel quite ill if you do enough of it, But we'r talking hours of work on it.

If you just do it outside, quickly, then leave the area, You should be fine.
If you have more then a peice or two to do, I highly recommend getting out the respirator, And limiting exposure to the fumes as much as you can.

01-01-2011, 05:38 PM
This is as good as any I've seen for expanding pipes for a slip, clearance or "welding"/brazing/silver-soldering fit as the "feel" and "creep" are very good.



Mine has all the formers for the usual run of copper pipe (nominal diameter) from 1/4" to 1".

I anneal the pipe before expanding it and again during expanding if I feel it getting "harder".

Getting a really good brazed/silver solder joint is quite fast and easy whether in a vise, on the bench, down a hole or trench or in a wall or with just a relatively short stub.

It was expensive in dollar terms when I bought it (new) but given my need at the time, it has paid for itself many times over.

I only use it when I don't have a preformed sleeve, reducer, bend etc as expanding will reduce the pressure capacity of a pipe. Generally, only going up one "step"/size is OK.

I don't like swaging/flaring a cone or a "bell" and then silver soldering it to the end of plain pipe as it is likely to fracture. I only use the flaring tools for "compression" fittings.

01-01-2011, 05:51 PM
If you want to make tubing larger there is a thing that works like an expandable collet. If you want to make it smaller you need a swaging machine. If your only doing a few parts make couplings in the lathe solder them on.

I am putting up a 30 ft TV antenna with 1 inch EMT conduit. I connected all the pieced together with EMT conduit couplings. On top of each coupling sets a flat washer with 3 holes drilled in it for steel cables. 3 cables attach to each flat washer so I have 3 flat washers and 9 cables to hold the tower up. All the cables go to 3 stakes in the yard. Antenna is on top the tower is touching the ground so it is grounded for lightning. Coax 50 ft long to the TV in the house. I am picking up 40 channels on the antenna. All are digital HDTV and it is all FREE. I am getting 8 channels that are all movies some channels have no commercials. The weather channel, NPT and more great stuff all 40 miles away. It beats the heck out of paying $$$$ for cable TV or satellite TV.

The Artful Bodger
01-01-2011, 07:53 PM
If I want to expand the end of a light gauge metal tube this is what I do, for example to expand the end of a 1" external diameter steel tube to 1" internal diameter.

I get a bit of flat steel strap, 1/4" or so thick and grind the end until I have a width of 1" (the required internal diameter) then I bend the end at right angles. If I want 1/2" of expanded length I will make the turned over bit a trifle longer than that. This will be the tool and I grind the sharp edges off getting them as smooth as possible without getting too excited about it.

This task requires holding the steel tube firmly so I drill a hole through a block of wood than cut the block in half so that I have two pieces I can put in the vice to hole the pipe very firmly.

I slightly flatten the end of the tube about, for about 1" and flat enough so that the tool will go into the end of the tube.

The tube is firmly clamped in the vice between the blocks of wood then I put the tool in and start to work it back and forth in a rotary motion. This action will stretch the pipe and after expending the energy equivalent of about 3 weet-bix the job is done.


(Yes, I know a picture is worth a thousand words etc....:) )