View Full Version : suggestions on how to bend aluminum rod

05-24-2013, 09:05 AM
I would like to make an aluminium dock,, similar to these, http://www.naylorsystems.com/docks.html, http://www.soderbloom.com/docks.html, the kind that roll in and out each year. I have purchased the aluminium for the webbing (1/2" solid bar) and the angle (1 1/2" x 1 1/2" x 3/16"), based on what I saw as products currently available. I initially, was going to cut the rod into the appropriate length to form the web and then just weld each joint up. I have seen commercial docks done both with pieces like this and with the rod bent to form the web, so one piece.

If I wanted to bend the rod, any suggestions on a fairly simple jig? I was picturing a flat 1/2" steel plate with some rollers and a lever or some other bending force. I have an old pneumatic cylinder but not sure it would have enough power under shop air. The rod seems pretty easy to bend. I want it to be fairly consistent for a nice appearance so I think the jig is the way to go. I am debating whether it is worth it for this project or to just go with pieces. I am thinking, from docks I have looked at, a 10" web would suffice. Any suggestions?

Since I am not CAD wise, here is a crude drawing of what I am thinking. The question is how to move the bending roller (gotta be a better name for this...forming roller..? ;-) )


05-24-2013, 09:24 AM
I don't think you should clamp the end of the rod.
If you do the bend point changes as the rod gets pulled in
Leave both ends free to move.

05-24-2013, 09:38 AM
Wouldn't a cheap metal bender from HF be easier, or maybe even just a conduit bender?

05-24-2013, 11:05 AM
800miner, I thought that maybe the bent end (I would be lifting the rod out and moving it to the left after each bend) might be pulled back slightly, distorting my previous bend so that by clamping it, the free moving end would be pulled in, only.

JoeEM, I don't know, never used the HF bender or anything like it. I think I know the one you mean though...http://www.harborfreight.com/bench-top-bar-and-rod-bender-38471.html ? It looks like it might....

I have used a conduit bender but I would think it would be hard to bend a 20 foot rod as consistently as I want, that many times without missing on some bends. I am not sure a conduit bender goes that small, does it? What is the OD of a 1/2" conduit?


05-24-2013, 12:11 PM
A larger DiAcro bender (#3 or #4), set up with 1/2" dies, would make short work of this job.
The one major issue I see is the amount clear space needed when working with 20' lengths.

Pic of #4 DiAcro with 3/4" X .065 wall 6061-T6 "test pretzel". The same set up will work with aluminum bar stock.



05-24-2013, 12:46 PM
Wow! That is a serious bender...;-) Probably a little more than I need..., although it looks like fun..:-)

I will experiment and see what I come up with. As always, working on other projects and trying to gather info on the next one. This is the next one.

Thanks all

05-24-2013, 12:51 PM
I built a bender some time ago. It is in the archives somewhere.

This is it:


05-24-2013, 12:52 PM
Wow! That is a serious bender...;-)

You need a serious bender if you're serious about accurate bending, eh.


05-24-2013, 02:23 PM
Thanks Evan. As mentioned in that thread, very nice work.

I was thinking a one time project but now I think I might want a bender too.....I should quit coming here...too many ideas!! ;)


05-24-2013, 02:33 PM
I really think the Harbor Freight unit would do a very nice job, with a bit of patience and lay out work, for not a lot of money.

05-24-2013, 05:34 PM
I think the OD of the 1/4" conduit is just over 1/2". The length of the rod doesn't really matter with those if you do the bending outside but yes it would take some practice to get the bends all the same. Still, it's not like it's one pull and done. You can bend a bit and look and if it's not far enough you can bend some more. Same with the cheap HF bender. They sell two - a compact and a benchtop. They're the same price but one (I think it's the one you didn't link to) has the concave dies that a rod would sit in. The other either has straight (for flats) and concave, or just the flats. Evans shopmade one looks pretty cool too. I thought I'd seen plans in a back issue of one of the metalworking mags - HSM or PM. If you want to make one and can track down an article # I've probably got the magazine and can mail it to you if it's from the last 10 years or so.

Mr Fixit
05-24-2013, 08:08 PM
The diameter of bend for a 1/2" steel headed conduit bender is 7.5" and a aluminium head is around 10" diameter, if this is enough they will make quick work of the job, a used one at a garage sale or craig's list should be very cheap. Here is a link to how the benders work. http://www.gardnerbender.com/pdf/instructionmanuals/conduitbending/b-0040_bender_how_to_guide.pdf If you are trying to bend the whole 20' length in one piece you may need to use something else but the pic's you show are 1 V up and 1 V down so I think you can make each one seperately and weld into place.
Good luck on the project and keep us updated when it gets going.

Mr fixit for the family
Chris :)

05-24-2013, 08:27 PM
1/2" aluminum should be easy to bend. I would set up a V block in my arbor press and just start bending away. Mark all your bend points first than just go down the row. If no sort of press a hefty vise may even be enough but the V-block would have to be bigger.

Forhire pictured this jig in his arbor before. Would work just fine for the round bar.


For a made up jig I would also think the (also pictured by someone else earlier and everyone copied them including me) "cheap and fast bar bender" kind of deal would work.





05-24-2013, 08:28 PM
Someone elses version.

05-24-2013, 10:31 PM
Simple,efficent bender for small rods,even does the gauging-

Isn't this what your looking for?

I had to bend some 1/2 aluminum rod for a job awhile back,depending on alloy and bend radius the rod may have to be annealed.with 6061T6 the tightest 90* bend I could achieve was a 1.75" radius.After annealing I managed 1-1/4 and it was much easier to bend.

05-24-2013, 11:59 PM
Isn't this what your looking for?
http://www.youtube.com/watch?v=jnhWM-Vfl9E&feature=fvwp&NR=1I was going to suggest something like that (alittle simpler set-up for a "one-off" job)..... Use a cheap Harbor Freight bender bolted to a bench and then trace out the angle and sink a lag bolt (or something - two blocks of wood cradling the bar, what ever)... you would just have to get the first bend correct and then after that just make sure when you flip to bend that you are flat.

05-25-2013, 12:26 AM

Toggle clamps (just to convey an idea, this link was the first google result) - http://www.carrlane.com/catalog/index.cfm/27025071F0B221118070C1C512D020609090C0015482013180 B041D1E173C3B2853514258

http://i1284.photobucket.com/albums/a570/iMisspell/bender_zpsb245b0b9.jpg (http://s1284.photobucket.com/user/iMisspell/media/bender_zpsb245b0b9.jpg.html)


Paul Alciatore
05-25-2013, 02:35 AM
After looking at your drawing I think you are trying to bend at three places at once. This has some undesirable consequences. The first half bend, where you show a clamp, is probably OK by itself. The middle bend will start at one point on the clamped bar and move along it as it gets deeper. In all, it will probably move several inches by the time you get to the complete point. This means that you will be first bending it at one place and then another and then another, etc. AND, you will be expecting it to straighten at the points that are already bent. At the third point, on the right, you will be moving along the rod at twice the rate of the middle bend but it will be a smaller bend so I am not sure if it will be better or worse than the second bend point.

Putting it all together, you are at least doubling the effort by making the full middle bend and the two other half bends. In addition, the unbending of already bent areas will only increase the effort needed. It will probably increase the effort to 3 times or more of what is needed for a single bend. All-in-all, it is a bad set up.

I would suggest bending only ONE place at a time. This means that you will need more room to allow the unbent length to swing in a wide arc, but a lot less effort will be needed. And it will be a lot more accurate in locating the bends. Here is a suggested layout for a shop made bender for this job.

http://img.photobucket.com/albums/v55/EPAIII/TrussBender_zps7b7818b9.jpg (http://smg.photobucket.com/user/EPAIII/media/TrussBender_zps7b7818b9.jpg.html)

The first bend at the end of the rod will need some kind of clamp. Rollers are not needed for the fixed pins but a roller on the lever arm is a good idea. And the pins and roller do not need to be grooved for the rod's radius if it is a solid rod. These grooves are only needed when bending tubing. You will get a little distortion, but for this application it should be acceptable.

The lever arm with the roller only needs to be made of metal (steel) for a foot or two past the roller. Then a wood extension handle will be strong enough past this point. I have bent 3/8" steel re-bar using a fixture made from two 2x4s and a gate hinge. It worked just fine for the purpose but was not accurate enough for this job.

After the first bend at the end, the clamp is removed and the rod is flipped over. The bent end is hooked on the second, left-most pin and it is again bent around the right pin. A clamp to hold it down between these two pins may be desirable. For the third and subsequent bends, the rod is flipped over each time and bent as before until you get to the end or last bend. It should go fast.

Another advantage of doing one bend at a time is you will be inducing less stress to the bar. The bending and then unbending of the areas of initial contact in your scheme will produce stress in those areas and perhaps some stress cracks which would weaken it. Not good for a structural element. By bending it one place at a time and eliminating the unbending you will minimize these stresses and better preserve the original strength of the bar.

Also, by hooking the rod over the two pins for each subsequent bend, the bends will automatically be the same distance apart. This will greatly increase the accuracy and repeatability of the parts you are making. And it will require almost no time to get this accuracy and repeatability. Just flip, bend, repeat.

Looking at my drawing a final time, I think that the roller should be a lot closer to the second pin to keep the bends tight and prevent the rod from bending between the pin and the roller.

05-26-2013, 10:30 AM
Agreed, making three bends at once may be too much. I will have to experiment. All great comments....Thanks to all. When I get going, I will try to post some feedback.

Alistair Hosie
05-26-2013, 05:05 PM
Evan and rode to ruin well you guys have a great set up yhere I have alittle one I never yet used for plumbing as most stuff here is plastic now. Alistair

05-26-2013, 05:42 PM
For this sort of job it isn't going to matter if the properties of the aluminum are somewhat diminished by heating. You can easily bend that size of rod even by hand if it is first softened with a hand propane torch. It doesn't need to be fully annealed. If heated to about 600 degrees it will bend like taffy while hot. You could hand bend it around a die of any shape and size without cracking or noticeable spring back. Once it cools it will gradually regain much of its strength within a few days to a couple of weeks. With a propane torch you don't need to worry about melting it either. It can't supply enough heat to take it that high considering the high heat conduction of that size rod.

05-26-2013, 07:54 PM
If it hasn't been mentioned yet, use an aluminum alloy that lends itself to bending, like 5052. 6061 alloy doesn't like to be bent.

05-26-2013, 10:25 PM

05-27-2013, 12:47 AM

Some like the cheap one (http://www.amazon.com/QLT-MARSHALLTOWN-14739-Rebar-Bender/dp/B000KKWXVO/ref=sr_1_1?s=hi&ie=UTF8&qid=1369629266&sr=1-1&keywords=rebar+bender) and replacing the upper/point wheels bolt with a longer one bolting the whole thing to a jig might be nice, you would be able to bend in both directions with out having to flip your work over (and lot of your work is already done/machined for $25 bucks).

06-04-2013, 12:58 PM
Well, I made some progress on this project. I had a piece of 1/2" steel plate around so that would form my base. The rod material is 6061 1/2" aluminum and jmarkwolf says it does not like to bend. Yep, found that out! I was showing a friend, discussing improvements and the rod snapped!

With this first prototype, I have a couple of issues I am off to address today.

1 Very hard to bend, even with lever. I am digging into the rod (I can see the burr and resulting flat on the rod after bending), as I do not have any bearings in place yet.

2 Snapping it today shows the bend radius is too tight (1 " diameter pivot) so will increase this. I have to go google what minimum, thinking 2" at least, if not 3"..?

3 This jig does cause the swinging of the pieces, which I was trying to avoid but the concept works well so I may just live with it for now. I realized I have my little backhoe sitting there so have access to a hydraulic system. I just need to add a length of hose and some quick couplers. Kind of handy option anyways to have around. For now, I will leave it manual.

4 The wire feed alum gun works really well so I am wondering why I have it in my head I have to bend instead of cut a bunch of pieces.....? I think bending will look better. What would you's do?

The parts

http://i1359.photobucket.com/albums/q786/ShawnR6/Aluminium%20bend%20jig/IMG_2278_zpsa1ad5a26.jpg (http://s1359.photobucket.com/user/ShawnR6/media/Aluminium%20bend%20jig/IMG_2278_zpsa1ad5a26.jpg.html)

Set up for first bend, swing arm to the left, then install block shown in next photo, then swing right.

http://i1359.photobucket.com/albums/q786/ShawnR6/Aluminium%20bend%20jig/IMG_2279_zps61e5ff39.jpg (http://s1359.photobucket.com/user/ShawnR6/media/Aluminium%20bend%20jig/IMG_2279_zps61e5ff39.jpg.html)

After two bends, rod has to be removed and flipped. Starting with a 20 foot pieces, it gets awkward. The hydraulics and doing all bends at once without swinging excess material back and forth is appealing....I have to go back and reread the comments about this.

http://i1359.photobucket.com/albums/q786/ShawnR6/Aluminium%20bend%20jig/IMG_2281_zpsb6a6ce92.jpg (http://s1359.photobucket.com/user/ShawnR6/media/Aluminium%20bend%20jig/IMG_2281_zpsb6a6ce92.jpg.html)

At least it works....albeit needs some upgrades. The pivot is getting sloppy though as I had to beef up the welding, then ground some, so the new pivot will be larger and better done and I think the bearing installed on the arm will make a large difference in required force.

http://i1359.photobucket.com/albums/q786/ShawnR6/Aluminium%20bend%20jig/IMG_2282_zps1dd0fd5b.jpg (http://s1359.photobucket.com/user/ShawnR6/media/Aluminium%20bend%20jig/IMG_2282_zps1dd0fd5b.jpg.html)

06-04-2013, 01:14 PM
If it hasn't been mentioned yet, use an aluminum alloy that lends itself to bending, like 5052. 6061 alloy doesn't like to be bent.

You'll find that 5052 is normally only available in plate and sheet. For bendable extrusions (rod, pipe, angles, etc.) you need 6063 alloy. Annealing 6061 is a lot of extra work and will leave you with material that's pretty weak...

06-04-2013, 01:17 PM
I already have the material, 6061, so will have to make due with it. But, are you suggesting that simply cutting the pieces to length and welding to the angle may be better than bending? I know one dock manufacturer's product that I looked at had pieces forming the assembly versus one continuous piece. Maybe that is the difference, material.......mmmmmmm


06-04-2013, 01:29 PM
Looks pretty good so far!
I would recommend that you increase the radius to 1 1/2" to 2" and mount a ball bearing to the lever. This will eliminate the gouging of the material and reduce the effort of making the bend.
The big swing is pretty much unavoidable when bending long lengths...........be careful, you could put someone's eye out!! :p


06-04-2013, 01:43 PM
6061 is a heat treatable alloy. When annealed it will slowly age harden back to at least half of the original strength. It won't go all the way because part of the strength is due to work hardening when extruded. Even so, it will be plenty strong. It will be welded anyway which is the same as annealing in the HAZ. As I previously posted, heating will make it much easier to bend to a nearly zero radius. Yes, it will be slower but it will get the job done cleanly and accurately.

be careful, you could put someone's eye out!!
especially while running with scissors...

06-10-2013, 04:09 PM
I finally got back to this jig. I increased the pivot to 2 1/4" (had a piece around). I turned a pivot to match the hole I put in the middle (~3/4 " ) and put a bearing on the other side (just one the bearing shop had, 1 1/8" o.d. The id is 1/2". It works much better. Still, the complaint is the swinging back and forth of the ends but perhaps the better half will walk one back and forth for me and I can just support the other on a long board.

I also put some grease in the pivot and using the much more substantial material, it works very well

Bending force is much better now that I am not digging into the rod....go figure, eh?


http://i1359.photobucket.com/albums/q786/ShawnR6/Aluminium%20bend%20jig/IMG_2285_zps6b3c774d.jpg (http://s1359.photobucket.com/user/ShawnR6/media/Aluminium%20bend%20jig/IMG_2285_zps6b3c774d.jpg.html)

You will notice in this image, the vertical pieces I welded on over the pivot and the bearing. I found the arm was bending a bit. I could have tried to keep a downward force on it (which I do anyways) but felt that restricting the bend here would be a good move. It helped too.

http://i1359.photobucket.com/albums/q786/ShawnR6/Aluminium%20bend%20jig/IMG_2284_zpsc6f1161b.jpg (http://s1359.photobucket.com/user/ShawnR6/media/Aluminium%20bend%20jig/IMG_2284_zpsc6f1161b.jpg.html)

http://i1359.photobucket.com/albums/q786/ShawnR6/Aluminium%20bend%20jig/IMG_2286_zps7021c35e.jpg (http://s1359.photobucket.com/user/ShawnR6/media/Aluminium%20bend%20jig/IMG_2286_zps7021c35e.jpg.html)

06-11-2013, 01:43 AM
Good to see your getting everything ironed out. Its nice to see the process and progress of a project.