Need Help!- Bending 1/4" X 1" aluminum bar

[jeffmorris]

How do I bend 1/4" X 1" aluminum bar for my CNC machine that I'm building? I don't have machines that bend metal (brakes?). Putting the bars in vises and using hammers may not work. The 3-1/2" pieces of bars have to be bent about 15 degrees in two places.

[cam1]

Hi:
Have you tried to put the bar stock in a vise.
You only need to bend 15 degrees. Without resorting to hammers, try slipping a piece of square stock over the aluminium when it's held in a vise. This will allow you to control where the bend is, and make the effrort required less (leverage).

regards

[ashurbanapol]

Hello. You need to decide how clean the metal must be when done. If you don't want marks and are using a hammer and vise, pad the jaws with some smooth material, such as some of the same aluminum or pieces of aluminum angle. Using a test piece, place a mark with, say a laundry marker or if permissible and better, a scribed mark, where you wish the bend to be. Place the piece in the vice. Using a narrow wooden or tough plastic piece against the material you can hammer a bend and get it about perfect. Bend toward the side with the scribed mark. If it bends away from the mark, not just how much to correct on ou real pieces. You can do this with just a mallet or hammer, but the wooden or tough plastic piece will allow you to make sure you are accurate. 2 bends are easy. 3 becomes more complicated. As a hint, you might contact the local high school or tech school metal shop teacher. These bends can easily be done in a sheet metal brake with perfect accuracy. The shop teacher will be an expert in this simple operation. Use a protractor and bevel gauge to make sure your bends are correct.

[jeffmorris]

I used a piece of wood and a wooden mallet to bend the aluminum bars in a metal-working vise. I may have bent the aluminum bars too much. I was using the drawing in the plans for building the CNC machine. Is it possible to bend back a little bit?

[chester1957]

Yes, unless you repeatedly bend it back and forth, your material will be no worse for wear. Good luck with your project.

[ashurbanapol]

Sure you can bend it back. a 15 degree bend is not much, and just correcting your bend will give you no problem. Best thing is always to get a little extra stock and experiment with it. I've bent metal as a blacksmith for 41 years. Aluminum comes in many varieties. Some of the harder alloys that are springy can be softened by heating them in boiling water. Typical commercial bar stock is very soft from my viewpoint. There is a little spring back, but not much.

[tirel12]

This is my first time on this forum so i appologize if this is not appropriate to post a question instead of a reply.
I would like to bend this bar by about 110 degrees in the middle. I do not have bending equipment and would rather not use a hammer. Is this possible to do by heating it and bending it over another bar to create the bend?

Thanks,
ti

[Geof]

Is this aluminum bar?

Aluminum is different to steel and you do not bend it hot, but you may need to heat iot before bending depending on the alloy and the temper.

Most aluminum alloys are tempered after extrusion to give them strength; for instance the most common aluminum alloy is 6061 T655 and the T655 describes the temper. In this condition 6061 is very difficult to bend and if you did try to bend it 110 degrees it is very likely it will crack.

Normally it is necessary to use an alloy at T0, no temper, if it is going to be bent. You can anneal 6061 T655 to get T0 and then it will bend but of course then it does not have the same strength any longer.

To anneal it you need to heat it to around 350 to 400 degrees F which is probably possible with a propane torch. A way to test the temperature is to put a drop of oil on it and if the oils smokes it is hot enough. You do not need to quench it, just let it cool down slowly and then you should be able to bend it just by holding it in a vise and sliding a length of tube over it.

[tirel12]

Thanks for the reply. i am not that concerned about the strength of the bar at the bend as I plan on making a sissy bar with it and there will be no pressure on the actual bend. I will try the heat method. that seems to be the most common advice. Thanks again.
ti

[garagefela]

To get enough temperature into aluminium without going too far and melting can be quite hard. I have heard of one method but have not tried it.

Get your oxy torch and light up a sooty yellow flame and blacken the aluminium part, now set up the torch a bit better and start to heat it up and when the soot burns off then the temp is about right.

Now I can't remember what the temp actually is and for me this is an untested method. Has anyone else tried this?

Cheers M

[ashurbanapol]

Bending 110º for a sissy bar sounds as if you want quite a radius. You really need to know what sort of aluminum you are working with. If it is aluminum from someplace like a hardware store or Home Depot it is most likely quite soft and can be easily bent without heat. The advice to slip square tubing over as a handle to focus the bend is good advice. To bend even a tough alloy of aluminum you most likely would not heat it to 400º F. That is a good temperature for forging or preheat for welding, but you may not need nearly that much for a simple bend at a large radius. A 110º sharp bend will produce a lot of stress, but if you are bending around, say, a 2" radius piece of pipe you could form most typical aluminum alloys quite easily without fracturing. The best course is usually to experiment on a short length of the material.. Clamp it with some padded vice grips against the pipe and bend a little bit agaisnt the pipe cold. If it does not fracture you will know that's the way to go. I would then clamp the stock in the middle of the bend against the pipe and, using something like the square tubing, pull both ends. Make a mark on the aluminum with a magic marker to keep the bend centered. Must manufactured goods are bent cold whenever possible to reduce cost and increase profit and speed production. The simplest methods are usually the best. If you can't pull both ends yourself at the same time get a friend to help you. Using a short piece of stock as an experiment can save you a lot of grief and expense bending the longer piece.

[Geof]

Originally Posted by garagefela ..Get your oxy torch and light up a sooty yellow flame and blacken the aluminium part, now set up the torch a bit better and start to heat it up and when the soot burns off then the temp is about right... Cheers M

I have heard about this method, the one I mentioned earlier with smoking oil and a third which is to get a piece of soft pine and when the alloy is hot enough to char the pine the temperature is correct. I reckon the temperature is quite similar in all three because in all you are just on the edge of the ignition temperature for hydrocarbons which as I recall is around 475 degrees F. This is a bit hotter than needed, I think that a few minutes at 350 degrees is enough to reduce the temper of most aluminum alloys down close to T0.