How to bend tubing

Here I show how to bend aluminum tubing. This is basically documentation of how I built a new bow rail for my sailboat.

Step 1 Build the jig

Here (2nd image) I trace the curve that I want on some scrap lumber. This scrap will be used to build the bending jig. I'm just using a couple of old 2x4's. You wood should be somewhat thicker than the diameter of the tube you wish to bend.

Comments

[Evox_Rider]

I have been looking for alternatives to buying conduit benders (they are not cheap...and I am...lol).  Would doing a jig like this, but for a small 3 or 4 inch radius work for 1/2" conduit? or would it kink?

[GreyBird]

I use a spring to bent PVC Conduit. For long pipes I attach a rope on the one end and shove it down the pvc until it is in place. My spring was inexpensive. Hope this helps.

[PaulE]

 I think it should work ok.

Just pull very hard and go slow. You keep the conduit very tight against the jig.

[Evox_Rider]

 I was thinking if it does kink, to try and make a groove in the edge of the half circle part to match the conduit (thinking to maybe mount the full circle into the drill press and use it as a makeshift lathe)

[Punkguyta]

I bend metal with my hands.

[jongscx]

yeah? well I do it with my mind...

[NinjaBear]

So? ... I can do it without my mind

[gossumx]

Well, it can bend itself without me.....

[jayeshshinai]

its so easy, i make someone else do it for me..

[shopfoxBB6]

you are all bending it the easy way, tubing was just flat strips of sheet metal before I started bending it into cylinders...

[jayeshshinai]

it was so easy...ilet u do it ...(nothing personal^, just goes wid flow)

[Murdok]

If you are super concerned with getting a smooth rail, fill the rail with sand and close both ends. When you bend the tube it won't kink or deform.

[rwhorton]

I have had a little experience bending tubing, as I was a band director who "dabbled" in instrument making in my early years.

I successfully bent brass tubing using molten lead (which I reheated and removed later) inside the tubing. If you are not trying a real tight curve, then this should keep kinks from forming.

Another way I have seen, but never tried, is to freeze water in the tubes, and then bend them. (Saw this on T.V.) I imagine you could place your pipe into a freezer, as long as it will fit.

[dlfynrdr]

I want to make a bicycle handlebar like the one shown in this pic. Would this be a good technique to do it with? Can anyone suggest what thickness of aluminum to use? Thanks, in advance

[corrysoccer16]

One thing you might want to try to do is to fill it with something.  Brass instrument companies do this to prevent collapsing the tube.  They use a bees wax and tar mixture i am sure you can find a recipe online for it.  But at this point you may just want to do what another person posted which is just cut another pair of drop handle bars.

[sedague]

I recently watched an episode of 'Factory Made' on the Science channel. They made the bends in a brass trombone by filling the brass tube with liquid and freezing it. The ice core kept the tube from collapsing. I don't know if this would work in this case since more force would be required to make the bend than is needed for the brass tube.

[Fujitsa]

Why not try something more different? like go for a shape that no one else has! and show off your coolness!

[kg6gfq]

Probably easier to find a set of old drop bars and apply a hacksaw.  They won't look exactly like this, but bending tube to that shape, especially with this method, seems like it could be tricky. 

[Rishnai]

It would definitely be a cost-effective way to do it, but beware about getting enough force to make the bends out by the grips. You'll have to bend with a longer tube and then cut to length for sure. Also, getting that compound bend (down and then real near to it, towards you), will require careful bracing when you build your jig. I learned that the hard way when I was bending conduit to run electricity to my swamp cooler and had to make some funky bends like that. I did the actual bending a different way, but I found I had to build a bracing jig all around the bend I had just made and then begin my next bend. It was the only way to keep the angle inact, and have a stable force to bend against. As for aluminum thickness, unless your old handlebars have collapsed in some way, use that thickness. Otherwise, I would use electrical conduit. It's cheap, handy, and relatively easy to bend. I wouldn't use it for apehangers or if I was going to put a lot of weight on my hands while I ride, but for that style, conduit should be fine.

[jcmaner]

if you fill the conduit with sand it will not kink

[idostuff]

Making some custom handlebars for my road bicycle... Would there be any advantage to using BOTH sand and water inside the tube?

[drevt]

Great instructable! I have two questions though: I am looking at making mtb bars, out of steel preferably, and I'm wondering if a) it would be possible to bend steel using this method, and b) would it be possible to make a jig that would allow the middle section of the handlebars straight for ease when fitting it onto the stem (sort of like these )?

[sti390]

What is the max size of pipe(diameter) I'm able to bend it over the jig?

[Rishnai]

Without heat? I guess that depends on how sturdy your jig mount is, how strong you are, and how thick the walls on your chosen tubing are. Of course, if you get some tubing home and find you can't bend it, heat with a propane torch (don't light your jig on fire) and then bend. Make sure you evenly heat everything that you want to have bent evenly, and the sky's really the limit.

[PaulE]

Not sure. I used 3/4 inch tubing. I would guess that as long as the jig is bigger that you would be ok. Honestly, this was a one off kind of thing (I was simply making a new bow rail). I am very surprised at the amount of discussion.

[Scott Dallesasse]

How about just going and buying the right size conduit bender?

[Paulcet]

Conduit benders are fixed-radius, but with the wood form it can be any radius you want, even varying radius.

[DiamondBack]

a conduit bender bends pipe. While you can get aluminum pipe, this how-to talks about bending tubing. If you were to attempt to bend tubing in a pipe bender, you would end up putting a serious kink in the tubing - rendering it unattractive, and useless But, doing this rail WITH conduit, and the conduit bender, might be a viable alternative. Polish it up with 2-3 grades of emery cloth, and it could look quite attractive

[PaulE]

If I were doing more than one little thing, I would wholeheartedly agree. However, the bow rail only required 3 bends in one piece of tubing. Using scraps in the garage seemed the way to go.

[bethehammer]

Add a torch and this is a good way to bend steel tubing/pipe also...

[sdallesasse]

Great subject. From experience I can see that you are on the right path. You have almost everything component that is included in a commercial tubing / conduit bender. You have the shoe / form and the hook / scrap block. The only thing you need is a follow bar. Some sort of item to squeeze the tubing to the form / shoe to keep it from kinking. In hand benders this is accomplished by using the ground / floor. I think that if you wanted to use your jig that is pictured, all you need is a reinforced slot that would be parallel to the jig and justwide enough to allow the tubing to fit. Then you would need some sort of metal bar that you could pull along this slot to squeeze the tubing to the form.

[pojken]

I've seen how trumpet guys do it - they fill it with water and then freeze it. Problem is, how would you freeze it unless it's winter outside. Any how, that's another alternative if you're looking for one.

[Cabofixe]

I just wanted to make a clarification on here. The trumpet guys don't use water because it freezes into ice and isn't bendable. Also pure water expands when it freezes and can crack or break tubing when it freezes. They use a soap/water mixture because it can still bend. And doesn't expand as much.

[handymann]

you can bend it just as effectively by packing the aluminum tubing with sand tightly packed into the inside of the tubing, then do the rest as the instructions say

[PaulE]

good idea. When its not winter (or if you're in Florida like me) I bet you could dump some dry ice on it and wrap it in visqueen or a similar plastic for a few minutes.

[Ribs]

Why would you want to fill it with anything at all? wouldnt that just make it harder to bend?

[ELF]

Because when you bend it, the "outside" (blue line) of the curve has to be longer than the "inside" (green line). If you don't fill it, it will of natural reason deform in the profile (red circles) when you bend it... This may cause collapse, which is what I THINK is what they mean by kink. Illustration 1 is of a tube bent with something filling the inside of the tube, to force a constant volume, and thereby force the tube to stay in shape. illustration 2 is of the tube without filling. Notice the red profile cut half-way. Hope that helps :)

[Ribs]

Thanks a lot that makes more sence now. and it is kink i think.

[such_momjeans]

The Ghost in our old house frightens the kids when they get up to pee in the middle of the night. I made lighted paths from their rooms to the bathroom that they can turn on from bedsides, should nature call...

[bub4280]

The brass wind instrument makers used pitch to fill the tube prior to bending. Easier to find and cheaper than wood's metal. low cadmium content, too. Nice earthy smell, too.