Best way to split a seam in small Al pipe

[Jack Olsen]

I've got a 48" length of 1/2" diameter aluminum tubing (with 1/16" wall) that I would like to find a way to cut a lengthwise seam in. The goal is to open it up slightly at the seam and then re-compress it into a teardrop-like profile -- an aerodynamic shape.

I've been trying to think about the best way to make a straight cut through the stuff. I will need two 18" lengths, in the end. So if cutting it to size first would help, that's on the table too.

Here's what I'm talking about.

 

[Hawk]

Make a jig to run it on a table saw. Very carefully. Or use a dremel with a cutting wheel.

 

[kazlx]

If it were me, I would probably make two 18" sections of wood that form a clamshell, then just screw them together and run it down a table saw. Could easily make the halves with a table saw and a router with a 1" half round bit.

Basically like this, tube blocks used for frame building:
http://www.paragonmachineworks.com/cgi-bin/commerce.cgi?search=action&category=TB07

Edit: You could probably just make like 4 different blocks instead of one piece and line them up enough to push through a table saw.
http://www.instructables.com/id/Wood-Tubing-Blocks/

 

[Capt J.D.]

If you have access to a table saw and a rip fence: fasten length of tubing at both ends, to a piece of wood such s a 2x2 of the same length or a little longer. You may have to drill a hole in both ends of tubing to make sure it won't turn and screw / bolt it to the wood.
Using a very fine blade, and the rip fence with the distance to the centre of the tubing, and height less than where the bolt / screw passes thru the tubing, make your cut.
( it works with long dowels)
hope this helps.

 

[Capt J.D.]

the above folks were faster typers than me..

 

[-Brent-]

For 36" I'd almost be inclined to pony up the $ for some streamline tube.

Other than that, pressing it came to mind, first.

 

[rsanter]

If it was me I think I would try to do it without splitting the pipe.
If you could make a couple of rollers that defined the final profile and then run it through the rollers squeezing a little more each time I think you can get the shape you want and not have to split the pipe at all
Look up ring roller or bead roller. You will only need 2 wheels, not 3 to roll between.
You can use oak and turn the profiles on a wood lathe. To make sure you don't break out the sides of the wood you will want some steel discs on the outside of the wood rollers or make the rollers about 6 in wide so there is enough meat there to support it.

Another option is that if you can turn the profiles in steel,or aluminum rollers that will fit my bead roller you can come use it or send the stuff to me

Bob

 

[Jack Olsen]

Simple was best. Or at least quickest. Thanks!

 

[Guster]

Now to anneal it so you can press it without cracking.

 

[dr_clyde]

I was all ready to suggest a slitting saw on a horizontal mill, but it appears quick and dirty was what the doctor ordered. Nice.

 

[EdT]

Jack,
This could work if your application is not structural and just for streamlining. http://www.ksmetals.com/32.html

 

[-Brent-]

Jack, how did it come out?

 

[Jack Olsen]

Like much of my work: ugly but viable.

Here's the basic shape. After this, I used the sander to bring the trailing end to more of a point:

Why all the trouble? This graphic shows why I'm concerend with putting two extra rods up into the airflow.

Installed:

And the weight of the pair of struts:

I'm going to fill the open seam with some sructural adhesive for the sake of increased strength. I don't think it's essential, given the forces involved. But it can't hurt and I've got the stuff on hand.

 

[sqznby]

I think it looks great. Nice work

Here's a place that has a pretty good selection of tubing for your aerodynamic needs
http://www.aircraftspruce.com/catalog/mepages/4130streamline.php