Bending Aluminum Tubing?

[Kims Robot]

Manufacturing Question...
We are trying to figure out a way to give a curved bend to some 1/16" wall 1" diameter aluminum tubing.

Anyone know any good ways to do this??

Thanks!

[Rob]

Hi Kim,

We typically have used a tubing bender in the past that has a die for the size of tube being bent and the desired radius. You can usually find these at local shops, even automotive shops (although they might not have dies for 1" tube).

If you are feeling adventurous you can get a conduit bender from the hardware store and do it by hand.

Due to the fact that we lost much of our round tube bending capabilities between last season and this one, we have had to be a bit more experimental this year. We used a conduit bender on round tube for out prototype, and could have done this for our final parts taking alot of time and caution to get it right. We ended up rolling square tube through a sheet metal roller to get the desired radius, but that only works for very large diameters (Like 40" or so...)

Good luck,

RAZ

[dlavery]

With walls that thin, you will probably also need to reinforce the tubing during the bending process (particularly if you are going to be using a hand bender). The most common way of doing this is to fill the tube with incompressible material to fill the voids. This will prevent the tube from collapsing during the bending process. There are many materials that are suitable for this. The ones most commonly used include low-melting-temperature alloys, sand or even water (if you can completely seal the tube). You can also find special springs that are used to provide the same function (insert them into the tube to the location of the bend, where they support the tubing walls during the bending process).

-dave



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[JesseK]

This isn't a suggestion, this is simply how we did it. In hindsight, we probably should have asked for better techniques to aid us in perfection. We decided to bend things for prototyping on the spot, and it worked out so well that we've used the same techniques to do the final product.

For this year, we've bent 3 radii: 20", 13", and 3.5" and none with any typical bending equipment. For the 40" bend we used 1" square tubing, and even though the final product isn't perfect it still works well since it's a low-load/stress piece.

First, we used a 2" sheet of wood at least 40" x 20", a bunch of clamps, and some muscle. Using a pencil/marker tied to one end of a string, we measured out 20" to create a radius. We put the 20" mark of the string down on a point of our 2" sheet and marked out our semi-circle. We used a bandsaw to cut out the semi-circle.

What you do from here depends on whether or not you have a blow torch. The torch is used to heat the metal while it's bent in order to let it settle to its new shape when quenched (cooled). This keeps it from springing out back to a greater radius when the clamps are removed. If you do not have a blow torch, you'll need some extra clamps & time and also to cut another ~38" semi circle from inside your 40" one. You will clamp the metal to the wood to create your bend and let it sit clamped long enough to settle.

We then clamped a scrap piece of wood directly to the right of the semi-circle, about 1 1/4" from it. This gave us something to leverage off of as we bent the tubing around the wood template. We bent the metal around the wood template, gently clamped everything in place, and used the blow torch to heat the metal as evenly as we could. We then used wet cloths to cool the metal, then threw it out in the snow for a few minutes to completely cool it. Now it's as rigid as if we had welded it.

Make sure you have one person designated with a fire extinguisher and that everyone has gloves/eyewear. It took 6 students and 1 mentor about 45 minutes to fully bend three 20" radii pieces.

[meaubry]

Kim,
Funny you should ask. We are using the same material and I have successfully been able to use the technique that Dave suggested. Taped one end shut, filled with sand, tape the other end, and used a conduit bender.

Just remember to go slow, and keep the bends small - I tried staying under 22 degrees. Do not over bend them as you don't want to straighten them after bending.

Make a template to check against as you bend.

Using that technique, I was able to create bends that pretty closely follow the contour of the ball. I used something like 7 or 8 inch spacing between the bends.

The hard part was trying to keep the sequence of bends for the ones that had multiple directions.

All in all, we are happy with the way they came out.

Mike

[Shivang1923]

If you don't have the materials for that way, you could always use all purpose steel from mcmaster carr. Our claw type thing only weighs 16 pounds, which is really a lot less than you'd think because the claw is made up of about 18 ft of steel.

We have contacts at TCNJ and they said that aluminum folds if it isn't bended properly (wont be a problem if you go with dave's idea), but if you're going to use it in a place where it will probably get hit a lot, the aluminum will get damaged. Also, it is expensive to buy an aluminum welder, so if you need to weld, you will be in for a huge problem. (Again, iff you can find one, then go ahead use aluminum, or if you don't NEED to weld, and you can bend it properly, go for it).

Just my thoughts and my experience.

[Laxphan1525]

this isnt a real pretty way but if your good at machining you can cut a slot using a mill at the "correct" angle then bend it by hand and weld the joint to restore rigidity. However if you dont have a mill i have in the past cut a slot using an angle grinder and then welded the joint after. Again neither are that pretty but i have done both in the past and it works. It all depends on what angle you need and how accurate you need to be. Obviously they sell cnc benders and several large companies with access to these benders but most people dont have access to this type of equiupment. like people have said before tube benders work extremely well with aluminum and are an excellent tool for such a process.

[Dad1279]

For the nicest bends, try an canvas awning manufacturer (commercial or nautical) or a race shop that build roll cages. They both will have a 1" die. We have bent tubing with the benders that electricians use, like sold at home depot. If you use the electrical bender, consider using steel electrical conduit for a nicer bend. It is fairly strong, thin wall, inexpensive and not too heavy.

[colin340]

hey kim try freezing it full of ice then bending it that how they bend trumpet parts

[Rob]

Just as an FYI, we have been using bent tubing of various sizes and various bend radii for years, and have never had to heat, cool, or fill it with anything to get good results. The only time you will run into issues is with large tube and tight radii. We have had great success with 1" tubing bent to a radius as small as 3".

The suggestion to find a nautical shop or a race shop that makes roll cages is exactly what you need. The guy who does this for us used to work in a nautical shop, and learned the skills by making roll cages.

You should be ably to use a conduit bender to do what you need providing that you can find one able to accommodate a 1" tube. Using the conduit itself is also a valid option, it is not nearly as heavy as you might expect and makes a god sub for aluminum.

Good luck,

RAZ

[slocynerd]

Originally Posted by Kims Robot

Manufacturing Question...
We are trying to figure out a way to give a curved bend to some 1/16" wall 1" diameter aluminum tubing.

Anyone know any good ways to do this??

Thanks!

use a vice, not the hand ones, one with a crank and just use leverage to your advantage

[Kirk]

I am not sure if you mentioned whether you are using round or square but go around to shop and ask if they have a "Ring Roller" like this http://www.vansantent.com/bending_machine_z402.htm . Call around and ask if someone has one that can bend the tube for you. If you are using square tube you can also use a large sheet metal roll but it will make the tube a little oval. I have seen both used to bend .062 wall aluminum tube.