Bending pipe

[Throbbin Rods]

Starting a project to build a steering connector for my duck boat so I can run a kicker motor in the spring for salmon fishing and steer using the main motor. I picked up the connection piece for an EZ Steer set up in a yard sale for short money, so I just need to build the pieces that connect to the two motors. They will look something like the attached picture. I will be using 1/4" steel threaded pipe for the 90 degree pieces. Wondering how small a radius I could bend by filling the pipe with sand first and thought someone here might have experience. the larger 90 degree piece will be about 7" overall length and the smaller will be about 3.5" overall length. I have no issue with using longer pieces and cutting to length after bending but can I get a tight bend using sand?
Thanks much!
Bill

 

[Throbbin Rods]

This is a better representation of what I want to build. One to fit the main motor and one to fit the auxiliary motor

 

[tjdux]

You may likely need heat as well as sand

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[matt_i]

My opinion, and its just that...is if you use a mandrel that has a half-round groove in it and a 1/2 round "forming tool" the NPT black pipe is going to be thick enough in the wall not to need sand.

If you use a flat-sided (albeit round but with no groove to support the cross-section as its bent) mandrel or "forming tool" then it will kink much easier.

The tool in my shop I would use for bending is the Diacro rotary bender.

Heating a tube has given bad results to me, it makes the cross-section weak and wanting to kink. Supporting it with the groove seems to go a lot better.

 

[MoonRise]

Does it need to be pipe? Or can you use solid round bar?

Solid bar, just bend it.

Hollow, and no kinks or wrinkles? That's the tougher one.

 

[jaysberman]

I think I would use solid aluminum rod to prevent the whole thing from rusting.

 

[tthornto]

Solid aluminum (depending on what alloy) doesn't bend very well without cracking, could you use stainless steel brake/fuel line tubing? Then you can get fairly tight radius bends using a common/cheap tubing bender, and rust won't be an issue either.

 

[harrisplumber]

I think you have got enough suggestions here, so what you have decided?

 

[Throbbin Rods]

Thanks for all the suggestions. I may end up just using solid steel bar and tapping 1/4" pipe thread on one end. Brake tubing wouldn't take the constant vibration I don't think.
thanks again

 

[The Tool Tyrant]

Thanks for all the suggestions. I may end up just using solid steel bar and tapping 1/4" pipe thread on one end. Brake tubing wouldn't take the constant vibration I don't think.
thanks again

Note that 1/4" pipe o.d. measures .540", take that into consideration if using bar.

 

[Throbbin Rods]

Note that 1/4" pipe o.d. measures .540", take that into consideration if using bar.

Yes, that is written down out in the garage so I don't forget, thanks for the reminder though!

 

[Dutch01]

Without a pipe bender you can cut slots half way through the pipe and then bend it. A smaller radius will require slots close to one another. Here I have bent 16 mm pipe with a 1.6 mm wall thickness. Slots were cut with a 0.8 mm cutting disc.
If you do not get the required angle after bending, cut again into the same slots and bend close again. Weld up slots and finish off with a grinder.