Need help on machining process for tubing bender dies

I'm trying to make some tubing bender dies for 1 1/2" tubing and am trying to figure out the best way to do it. I have casted some out of aluminum, but I would like to make them from steel. Basically I needed to cut a 1 1/2" diameter groove along the outside of a 1 3/4" thick, 10" dia. steel blank. I have a lathe and mill that can handle this size material, but what kind of tooling is needed? The mill is CNC and the lathe will be shortly. Thanks for any help!

Reply to
DVN
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The blank is put into a rotating table/fixture under a 1-1/2" round nose end mill. Depending on the tubing you are bending, aluminum maybe alright. Also depending on the tube material and wall thickness, you might find that a 5" radius is too tight and the tubing will crinkle. Let us know how it turns out. Lane

Reply to
lane

I would mount the material on a faceplate and use a radius attachment to cut the groove. Well, I'd hog it out first using a parting tool. If you don't have a radius attachment then you can use Lautard's method to approximate the groove using very fine steps, and then use a file.

Grant

DVN wrote:

Reply to
Grant Erwin

This can be done with a long standard milling cutter and the stock mounted on a vertical rotary table. The cut is made with the side of the cutter as the stock is turned.

Reply to
Clark Werner

I have done lots of them. One 20" in diameter for a 6" pipe. The best way is to use a lathe with a radius turner. I built one about 15 years ago that's simalar to the Holdridge radii cutter in the MSC catalog. This is the best way to do it. I have seen people do it with the side of an endmill and a rotary table. I have also seen it done with a boring bar and a rotary table on the mill. I prefer to do it on the lathe. I usually use either acrolloy or ETD 150. About 32 RC. I have made them for a pipe bending shop. I haven't made any for several years, so I don't remember exactly how many bends they could get from a die. But it was in the 100,000's of bends.

Richard W.

Reply to
Richard W.

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