What's new
What's new

Making a tapered aluminum tube

implmex

Titanium
Joined
Jun 23, 2002
Location
Vancouver BC Canada
Hi Laukejas:
I would not cut it with a plasma cutter; I would cut it with a portable circular saw running in a home made timber frame to guide it and with a thin kerf, anti kickback blade.
If you are going to TIG or MIG weld it, your cuts will have to be clean so you cannot lubricate the blade with anything you can't dissolve away again with acetone or some other solvent (like water!).
Best for welding if you cut dry but that may be impossible.
You may try ordinary cow's milk and then wash the aluminum thoroughly with a hose and running water...try on a test piece first.
Use your wooden sawing frame as a compression rig too, so you can close the sawn joint(s) with clamps, ready for welding.
If you're careful you won't catch it on fire.
Use the same rig with a little wooden sled for your welding rig, so the weld(s) are easier to do.

For your oven you only need 200 degrees Celsius, so ordinary building bricks loosely stacked into a long box shape and buried in a trench with sand, on top of which you can build a long charcoal firepit should work...the hardest part will be to gauge the temperature and rake the coals around to keep from overheating it in localized spots, so you have to make your trench wide enough that you can rake the coals away from the roof of the brick box if the interior is getting too hot.
Ten hours of tending the fire will be tedious, but old time potters and brickmakers did it so you can do it too.

You may have to get something that will melt at the proper temperature; Tempil sticks are the industry standard for these kinds of things, but you may not have those in Lithuania, so maybe old plastic bottles, or toothbrush bristles or something can be found that melts at the proper temperature.
Do a test run of the kiln before you put in your mast so you're sure you've learned how to control it decently.

The rest is hand work with a file to dress the weld(s) and some patience.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
 

GregSY

Diamond
Joined
Jan 1, 2005
Location
Houston
I did a bit of online browsing and a 3" OD aluminum pipe (6061 Extruded) with a .125 wall will run you $404 and that is without any taxes or shipping. Let's assume there was a place selling it close enough to pick up in person and you managed to get a 'good' price....you still be over $300 out the door. Even if you just wanted flat plate of 12" x 20' x .125", it wouldn't be cheap.

I like the comment that round masts are old news...partly because it would make your job easier if it were ovoid in shape.

If you could make a form that looked like half the mast in cross section (a 17 foot long form, something like a trench cut into a long slab of oak), you could use some old Lithuanian craftsmen* to hammer form a piece of aluminum to match it. Once you had two halves, weld them together and you'd have the tapered mast.


*I have no doubt there are countless old European craftsmen sitting in pubs and in dark basements. 20 years since they'd picked up a hammer. They'd have names like Lazlo and Pyetr and however you say 'Stinky' in Lithuanian. You'd have to first endure being shunned and beaten until they accepted you wouldn't be giving up. Finally, you'd say something that would appeal to their sense of pride and they'd show up at your door one evening with hammers in hand. Only this time, instead of beating you with the hammers, they would being pounding the aluminum into shape.
 

surplusjohn

Diamond
Joined
Apr 11, 2002
Location
Syracuse, NY USA
I find it hard to belive that someone isnt already doing this in aluminum. Light poles. Sailboat masts etc. Spining? Swedging? But like many others are saying i would be looking at carbon fiber. We know that capability is available. It also seams that Lighting protection would figured out already. Embeded wire or what ever
 

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
My idea - not sure how realistic - is to take a 70mm x 3mm tube, split it lengthwise with a V-shaped gap. This gap would be near-zero width at the point where the taper starts (around 1m above the bottom end of the tube),and then gradually get wider towards to the top. Then, the idea is to press the tube with clamps so that the edges of this gap would come into contact, and then weld them together again. The difficult part would be clamping this tube with sufficient force and precision.

Not such a bad idea.
You going to apply heat on the areas that get stressed when forcing the halves together? Apply a little force at the bottom and apply heat then work your way up.
Or do tack welds as you go. Alternate the welds on each side as you go.

Reminds me how fire ladder trucks get built. The chassis starts out with long half-box beams ([) lined up on a long jig with hydraulic arms. Ensures everything is straight.
On yours I would map out a TIG welding route so that the sequence causes the least amount of warp.
 

Ries

Diamond
Joined
Mar 15, 2004
Location
Edison Washington USA
If you cut your tube into only 2 pieces, and then weld back together, it will bend more easily in one axis (say, east/west) than in the other (north/south). I cant imagine that is good. Which is why you should probably do 3, or even 4 pieces.
I still think the vid shows 3 slits- probably because of the built in sail track, so 4 wouldnt fit.

Welding full length tig welds, even if its just 2 of em, is time and material consuming. It should be done while its clamped to a buck, so it doesnt warp too much.

As for hose clamps- you saw, in the video, that press brake, right? Probably a hundred tons.

Have you ever broken a hose clamp?
I have, its not actually that hard. And it happens at way less than 100 tons.
What usually happens is the thin stainless sheet just bends at the slots, so turning the screw doesnt tighten the clamp.
I would think something more like custom jaws for a vise. Or a bunch of vises.
Those vise grip pliers with the chain would be an intermediate step- not as good as a press or a vise, but better than hose clamps.
Also, aluminum loads up conventional grinding discs pretty much immediately. When I grind aluminum, I use these brown grinding wheels that are made just for aluminum. They cost more, and I have to special order em. Then I use zirconia flap discs for final cleanup. Sometimes I do file, them, with a special large spacing, curved cut file made specifically for aluminum. Which also is more expensive and harder to find than a standard file. But it works.

Me, I have a pretty well equipped DIY shop- no cnc mills or 100 ton press brakes, but plenty of welders, saws, plasma table, rolls and benders.
And my general rule of thumb is it costs me about 3 times the amount to make one of something as it costs to buy one mass produced one.
Thats the amount I charge a customer, because it has to include money for labor, insurance, utilities, rent, taxes, filler rod, abrasives, blades, shielding gas, and so on.
Its NEVER cheaper to make one, yourself, with a few tools, than it is to buy one from a factory.

I know you may be able to make one, for very little, if you dont factor in any cost of labor.
I have a friend who built a functioning ultralight airplane with a hang glider he bought used at the goodwill for 25 bucks, and a lawn mower engine he got for free on garbage day. But thats not very common...
 

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa
Not such a bad idea.
You going to apply heat on the areas that get stressed when forcing the halves together? Apply a little force at the bottom and apply heat then work your way up.
Or do tack welds as you go. Alternate the welds on each side as you go.

Reminds me how fire ladder trucks get built. The chassis starts out with long half-box beams ([) lined up on a long jig with hydraulic arms. Ensures everything is straight.
On yours I would map out a TIG welding route so that the sequence causes the least amount of warp.

....Just think of all that TOXIC plasma DROSS you'll be putting on the ground, and the TOXIC
Aluminum oxide SMOKE (White powder) your putting into the air.....:ack2:
Let's not forget about all that Argon you releasing, and UV radiation too.
 

GregSY

Diamond
Joined
Jan 1, 2005
Location
Houston
Yes....you'd be doing us all a favor if you just ate a salad instead of trying to make anything. Use a wooden fork made from reclaimed wood.
 

rogertoolmaker

Cast Iron
Joined
Jan 3, 2016
Hi,

I am quite new to machining and metal work in general, and I'd like to ask for some advice about making a round tapered (cone shaped) aluminum tube. The tube in question is meant to be a mast for a sailboat, 5.5 meters in length, 70 mm in diameter at the bottom, gradually tapering to around half of that (35 mm) at the top. Tapering is done in order to save weight, which is important for sailboat stability - every gram counts. Wall thickness of said tube would probably be 3 mm.

Shape requirements are pretty relaxed. The tapered profile does not have to be perfectly round - it can have some teardrop shape, although the closer to the round, the better to resist sideway bending forces.

I am exploring options on how to manufacture such a tube, considering that there are no such tubes readily available for purchase (yes, I have looked up flag poles, street light poles, etc., but they are never the right dimensions).

I have considered making a "stepped" reduction in diameter (making this mast from sections of different diameter aluminum tubes that slide inside one another, like a fishing pole), but the required overlap between these tubes to have sufficient strength in the joints overcomes any weight savings of the tapering, making overall weight even higher. Additionally, these "steps" would create a lot of inconveniences when raising and lowering sail on the boat.

My idea - not sure how realistic - is to take a 70mm x 3mm tube, split it lengthwise with a V-shaped gap. This gap would be near-zero width at the point where the taper starts (around 1m above the bottom end of the tube),and then gradually get wider towards to the top. Then, the idea is to press the tube with clamps so that the edges of this gap would come into contact, and then weld them together again. The difficult part would be clamping this tube with sufficient force and precision.

Can anyone comment on this, do you believe this is a realistic approach to turn a round straight tube into a tapered tube? If not, can you suggest any alternatives to make tapered aluminum tube that are possible to do with typical DIY tools? I have angle grinders, welding equipment, 1 ton hydraulic press, a lathe (not large enough for 5.5m long tube, though!), and some other typical equipment, but no special machinery for this task.

Any idea may lead to an idea that is workable. Make Split Tapered Dies in sections Reducing the taper diameter with each size. Decrease as moving up the shaft. Press the end of tube into the dies, one after another until the shaft is to size. It would require about 20 to 30 tons of force.

Roger
 

crossthread

Titanium
Joined
Aug 5, 2004
Location
Richmond,VA,USA
This may sound nuts to some of you but about thirty years ago my dad and I made a mast for the dingy he towed behind his sailboat. The mast was eighteen feet long. We made it out of a piece of straight and naturally tapered bamboo. We bought some rolls of 3" fiberglass tape and dragged them through a five gallon bucket of resin as we rotated the mast and wrapped it top to bottom. I can't remember the exact dimensions of the tape but it was quite thin, almost like denim material. The whole thing was extremely light and strong. It never gave us a problem and we used it to haul groceries and fresh water from shore. Cost of materials at the time may have been twenty bucks for the tape and resin.
 

Tony Quiring

Titanium
Joined
Nov 5, 2008
Location
Madera county california usa
If you can cut and weld...

Start with material full diameter.

Build a track guide for lack of better term that is long enough to support a moving portable tool.

Make a carriage to hold a circular saw and another to hold a router.

Do the complicated math to determine the cutting angles to make lengthwise cuts to remove the required material to allow for reducing the diameter.

Imagine the sheet metal ducting with complicated bends used to change duct sizes.

The router first forms the bevels where the material will come together.

The circular saw will make the final cut to remove the wedges.

With strap clamps, radiator hose clamps or other devices to pull the material together and fixtures to hold it you tack weld as you go to create final shape.

Come back and weld in spots to minimize heat until done.

Same track system and be used with router to trim above surface weld material.

Sent from my SM-G781V using Tapatalk
 

GregSY

Diamond
Joined
Jan 1, 2005
Location
Houston
Bamboo is a very interesting material.....it's not a wood but it's often lumped in with wood because it's so strong and tough...it's tougher than a lot of woods. Light, too. I'm told that in many Asian cultures, bamboo is referred to as a 'bastard of a plant'.
 

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
Bamboo is a very interesting material.....it's not a wood but it's often lumped in with wood because it's so strong and tough...it's tougher than a lot of woods. Light, too. I'm told that in many Asian cultures, bamboo is referred to as a 'bastard of a plant'.

Try removing a bamboo hedge and all the roots.
 

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
Like it or hate it. Eiffel Tower like.

Aluminum rods of a small diameter arranged around circular plates that gradually decrease in diameter until the top is reached. Maybe spaced every 18 inches.
Each plate has a locating half circle or maybe a full circle. Use a index tool for that.

Would be a lot of welding but the design offers less resistance to the breeze. Very simple to bolt mast to boat and plenty of attachment points for the
sail and other rigging stuff. Would it be lighter or heavier? Weaker or stronger? If I knew of a modeling program I would suggest one. :cryin:
 

boslab

Titanium
Joined
Jan 6, 2007
Location
wales.uk
Bamboo is a very interesting material.....it's not a wood but it's often lumped in with wood because it's so strong and tough...it's tougher than a lot of woods. Light, too. I'm told that in many Asian cultures, bamboo is referred to as a 'bastard of a plant'.
When I was in school, aeons ago, one of the subjects was botany, one of the questions in a test was about bamboo, it’s a grass not a wood like deciduous or coniferous, that surprised me but there we go, my floors are bamboo, I must say I like it but by shite it can give you a mighty splinter laying it, I got one well over an inch and a half long, like a bloody needle, long even fibre, it’s scaffolding tube for tower blocks in Japan, makes my toes curl to see it but it can take more punishment than steel.
Mark
 

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
When I was in school, aeons ago, one of the subjects was botany, one of the questions in a test was about bamboo, it’s a grass not a wood like deciduous or coniferous, that surprised me but there we go, my floors are bamboo, I must say I like it but by shite it can give you a mighty splinter laying it, I got one well over an inch and a half long, like a bloody needle, long even fibre, it’s scaffolding tube for tower blocks in Japan, makes my toes curl to see it but it can take more punishment than steel.
Mark

Every 12 inches or so the is a circular plate inside, easily identified on the outside. Contributes to the strength.
 

henrya

Stainless
Joined
Jun 25, 2008
Location
TN
This may sound nuts to some of you but about thirty years ago my dad and I made a mast for the dingy he towed behind his sailboat. The mast was eighteen feet long. We made it out of a piece of straight and naturally tapered bamboo. We bought some rolls of 3" fiberglass tape and dragged them through a five gallon bucket of resin as we rotated the mast and wrapped it top to bottom. I can't remember the exact dimensions of the tape but it was quite thin, almost like denim material. The whole thing was extremely light and strong. It never gave us a problem and we used it to haul groceries and fresh water from shore. Cost of materials at the time may have been twenty bucks for the tape and resin.

Naaahhhhhh…

Can’t do that - its practical, functional, easy, and cheap. The OP wants aluminum even if he uses $500 worth of electricity and welding rods and untold labor.
 

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa
Like it or hate it. Eiffel Tower like.

Aluminum rods of a small diameter arranged around circular plates that gradually decrease in diameter until the top is reached. Maybe spaced every 18 inches.
Each plate has a locating half circle or maybe a full circle. Use a index tool for that.

Would be a lot of welding but the design offers less resistance to the breeze. Very simple to bolt mast to boat and plenty of attachment points for the
sail and other rigging stuff. Would it be lighter or heavier? Weaker or stronger? If I knew of a modeling program I would suggest one. :cryin:

How much torsional resistance ?
localized buckling ?
 

Milland

Diamond
Joined
Jul 6, 2006
Location
Hillsboro, New Hampshire
And with a design like that, you'd have to add a dedicated slider track, no way could you get good sail up-down (I'm sure there's a nautical term for it) with such a structure otherwise.
 

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
The design is thought up from thinking about Bamboo. The cross-section has a disk every so many inches. Easily seen as rings on the outside.

My choice is getting a tube and cut two segments. Weld together. Would have a airfoil shape.
I would not try this myself because I am not welding aluminum every day. Takes an expert to make it look sanitary.

The two sharp edges are melted into each other probably using a light touch. I don't know about MIG, but it only works by adding material.
With TIG you can just heat the sharp edges together with no added rod. After all that then just hand file or carefully belt sand until the
airfoil looks smooth.

What welding process would a professional welder use?
Is it better to use MIG and load up the joint? Then grind it down smooth.
 








 
Top