Bending brass angle into a circle.

[Raygers]

I have some 1/2" x 1/2" x 1/8" brass angle I need to bend into a 6" circle, it will be silver soldered at the join. I have tried bending it around a form without much success It twists and the worst part is that the 90 degree angle decreases by several degrees, this is not good for what I need.
Does anyone have tips or ideas for me? Even if I could anneal it, I don't have a suitable amount of heat to do that, I think that the 90 degree angle will change.
I don't have the resources to build a roller which may or may not work.

Any ideas would be very appreciated.
Ray

 

[Jasonb]

Faced with needing similar shapes in the past I have resorted to fabrication, cut an oversize disc, roll or bend flat stock into a circle. Lay circle onto disc and silver solder the two together. Then tidy up the disc to size

At that diameter with 1/2" leg even rolling will be difficult as there is a lot of metal that needs shrinking and extruded angle usually comes in one of the harder brasses that don't bend well

 

[Raygers]

Faced with needing similar shapes in the past I have resorted to fabrication, cut an oversize disc, roll or bend flat stock into a circle. Lay circle onto disc and silver solder the two together. Then tidy up the disc to size

At that diameter with 1/2" leg even rolling will be difficult as there is a lot of metal that needs shrinking and extruded angle usually comes in one of the harder brasses that don't bend well

Thanks Jasonb: that's what I was thinking.

 

[larryg]

Have you considered taking a solid circle ~8" in dia and sandwiching it between two 6" dia plates and hammer forming the lip around the plates? or roll forming it if you have a lathe. What properties of the finished product are important; size, thickness, material, structural, or cosmetic?

lg
no neat sig line

 

[kiwi2]

Hi Ray,
Not sure if this would work but might be worth a try.
Step 1. Put a saw cut through one side of the angle until it reaches the flat of the other side. Repeat this 20X? (might need more) at regular intervals along the length which will give a diameter of 6".
Step 2. Bend alternate tabs up by say 15 degrees. Bend the other tabs down by the same amount.
Step 3. Anneal the brass by heating to a red heat and let cool.
Step 4. Prepare a wooden former of the correct inside diameter (6"?)
Step 5. Bend the uncut part of the angle around the former by hand and silver solder the ends to produce a 6" cylinder.
Step 6. Bend the tabs towards each other until they are touching.
Step 7. Using a very fine blade (jewellers piercing saw?) cut through the tabs and discard the overlaps.
Step 8. Hammer the flange onto the former until the tabs all line up.
Step 9. Solder the cut edges of the tabs together.
Step 10. Put in the lathe and tidy up the face of the flange.

Then, if your lucky, Bob's your Aunty.

Regards,
Alan C.

 

[Raygers]

Thanks, everyone some good ideas here. Just to clarify, the vertical lip will be on the inside. I'm putting this on the back burner for the Christmas period, I'll get back to it in the new year.
Merry Christmas.

Ray

 

[djc]

If the vertical leg is on the inside, it is much easier to do what you want.

Anneal the piece and go around it with a cross pein hammer, concentrating more on the outside of the bend.

This will reduce the 1/8" thickness a little and cause the piece to curve. I think you can work out that a thickness reduction of 0.013" at the outside of the curve will give a 3 1/2" radius to the curve.

Like this, but by hand:



More generally, look at shrinking and stretching in the context of automobile body work. Shrinking is used much more in this area because the metal is already very thin (and will tear when stretched), but stretching is not unknown. You are starting with much thicker material, so stretching is a much less traumatic process.