[Shop-talk] tubing bender dies

[John Innis]

Not sure about materials, but you don't need to shape your cutting tool, IF
you are patient and careful.  You can use a thin cutting tool and remove a
very small amount of material from the center of where you want your
groove.  Then widen the groove until it is the diameter of the tubing
stock.  Then remove a small amount of material from the center of the
groove and then widen the groove until is the width of your stock MINUS the
change in radius for the depth of the groove.  You can find the change in
radius buy subtracting the dept of the groove from the width of the stock
and multiplying by 2.  Keep doing this and you get a successive
approximation of a half circle groove.  The less material you remove in
each pass, the more accurate your radius will be.  You can then clean up
with a sanding tool if needed to remove any residual ridges.


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On Wed, May 18, 2016 at 7:00 AM, Brad Kahler <bkahler1 at gmail.com> wrote:

> I was given one of these tubing benders from Harbor Freight.  By
> design it bends flat stock rather well.
>
> http://www.harborfreight.com/compact-bender-38470.html
>
> I now have a need to bend some 5/8" diameter OD 1/16" wall tubing.
> I've been shopping around for dies but the prices I'm finding are
> fairly high for a one time need to make a couple of bends.
>
> I've got a nice 13" South Bend lathe so I'm thinking I should be able
> to fabricate the dies myself.  Would a material like Delrin would be
> suitable for the dies?
>
> Assuming I do decide to try and turn the dies myself I would also need
> to figure out how to grind the cutting tool to shape the curve.
>
> I'm looking for suggestions on how to accomplish this task.
>
> Thanks!
>
> Brad
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