[TowerTalk] How do I cut aluminum pipes?

[Roger (K8RI)]

>
> On Dec 7, 2007, at 1:06 PM, Alex Malyava wrote:
>
>> Is it enough to use regular hacksaw and sand the edges or there is
>> some
>> fancy tool like pipe cutter used in plumbing?

When it comes to cutting aluminum tubing a lot depends on the size and 
alloy.

>
> Fastest way to cut aluminum tubing, if you have a machine shop, is to
> use a band saw. With a proper blade, you can roll the tubing across
> the table and it cuts quickly.

I prefer this method, but it does have the likely hood of the saw grabbing 
the tube and spinning it.  This can grab fingers, or gloves and if the tube 
is very long cause the end to whip around.
Use a fine blade and a fairly high speed near the top end of the range for 
cutting Aluminum.  Get a good, firm grip on the tube with both hands and let 
the blade cut lightly while rotating the tube in the opposide direction of 
the blade movement against the tube. Make sure the blade is sharp, and is 
not loaded with Aluminum.  That is a big problem cutting soft aluminum.


>
> The second best way is to use a quality tubing cutter. Use a good one,
> and you can cut a tube of any size in a couple of minutes. A poor one
> will spiral down the tube.

OR heavily depress the end of the tube forming  a vert deep burr. It's not 
uncommon to find the outside of the radius is of a smaller diameter than the 
nominal, inside tube diameter which leaves a very sharp edge after 
deburring. It also leaves the tube shorter than expected.

Go slow using a good tool with a sharp cutter. resist the urge to add much 
pressure on the tool by overly tightening the cutter. Tighten just enough to 
feel the increase in pressure and spin the tool around the tube a coule of 
times until the pressure is gone, then add a bit of pressure and repeat.

>
> A hacksaw will work, but it's really hard to get a clean, square cut.
>
I either hold the tube in a fixture I can use for a guide, or cut a 1/16th" 
long and slip it inside a metal block with a hold drilled to give a good fit 
on the tube. I then use a fine file to square the end.
For larger tubes I wrap electrical tape around the tube to use as a guide. 
This gives a fairly straight cut, but it'll still need to be squared off 
with a file and then deburred.

> After the cut, be sure to dress it with either a deburring tool, or
> round file or half-round file. Don't go wild with the files, as it
> will take off a lot of aluminum in short order. You're just trying to

Use one of the chain sharpening files that have a very fine cut. Leave the 
file almost parallel to the inside of the tube when deburring. As Bill says, 
do easy as you can remove a lot more metal than you should.

> break off the burr. A sanding sponge, or a sanding block covered with
> very fine grit sandpaper can also be used to dress the outside edges
> of the cut.

I much prefer emery cloth as it doesn't shed like sand paper.  If you are 
fitting tubes together a single errant grain of  sand can end up causing the 
tubes to bind.

73

Roger (K8RI)
>
> Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
> Quote: "Not within a thousand years will man ever fly!"
>             -- Wilbur Wright, 1901
>
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