Those are some really weird results.
What you call a pilot is sometimes called a mandrel, if we are talking about the same thing.
My guess is that tube is heat treated.
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I don’t generally bend tubes outside of a pretty safe range so I am not an expert but there are rules about how much you can bend a tube based on diameter, radius and wall thickness and you’ve exceeded those rules. The center line of the radius of the bend needs to be 3x the diameter of the tube. This would mean whatever you’re bending the tube around needs to be at least 125mm radius.
Keep in mind, those are not hard and fast rules, just rules of thumb, and they are usually skirted via mandrel bending processes, as (I think?) was used here.
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I built a steel front triangle that used a 44.45mm X0.9mm downtube, it had a bend in it that was about 25 degrees on I think a 7" CLR.
the local bending wizard was pretty weary of taking it on because he didn’t like the wallthickness- OD ratio being so extreme.
it cracked or wrinkled on a draw bender despite his best efforts, he ended up filling the tube with cerrobend (spelling?) and working it back and forth on a section roller. wasn’t /perfectly/ smooth but looks perfectly fine under a 2-layer powder.
he said “never again” like it was a bit of a nightmare, but I think he’d be up for it.
best pic thats coming to hand is here.
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Well, I’ve figured out that the location of the bend actually mattered as I wanted one part of this tube to be horizontal.
That’s the way I’ve done it, and worked pretty well. I’ve used two rulers and a welding table as an old school engineering drawing board to mark ends.
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Hi everyone,
i also need some help for a self made tube bender. I want to bend my new Chainstay standart with 22,2mm and have a bunch of bending dies in very good quality.
Radius big bending die: 77mm, radius the small bending dies 32mm
But i really don’t know how i can transform these pieces into a bending machine… My bending machine for smaller tubes is a Gressel RB15. May I can make some adapter to use this base? Or another China bender. Photos below. May some of the engineer heads in this forum can figure out… In my head are solutions like the anvil bender or something like the cobra one. Or maybe a construction for the press. like these cheap bending machines working with three dies.
Most important thing is the repeatability and a good marking for the start of the bend
Best, Janosch
For the Vevor, my idea was to weld or bolt a big chainring at the pivot and use either a manual or electric crank to spin it, small cog on the crank and big cog on the bender.
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nice but to ruff design for me 
want to built something stable.
Could one of the euro crew recommend a cost-effective small bender that would be suitable for rack and bottle cage tubing diameters?, so from ~3mm to about 10mm. Amazon is okay but it should just be available in the EU.
I have to double check, but I would like to use 4130 tubing similar to what Tubus use, I think it’s sub mm wall thickness?
no one? 
isn’t the Vevor tube bender available in EU? Or any other similar one, it’s less than $150 here on Amazon.
For a 3mm tube bender, why not making the dies with a 3D printer and then some simple laser cut pieces and build it DIY? Those diameters don’t really require a lot of pressure.
I have bent 12mm steel rods via 3D printed dies with great success
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