Author Topic: Bent Mast - Rideable?  (Read 850 times)

Rastaman3030

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Bent Mast - Rideable?
« on: October 07, 2019, 04:58:03 PM »
I have bent my aluminum Gong mast, the board got picked up in wind and slammed down on the front wing and subsequently bent the mast near the base. Do you guys think this is still rideable with this bend until my replacement arrives from France? I've tried bending it back with a vice, slamming it with a hammer, and even took it to a fabrication shop, but they couldn't help me.




PonoBill

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Re: Bent Mast - Rideable?
« Reply #1 on: October 07, 2019, 06:04:20 PM »
I'd say take it to a good motorcycle shop, one that knows how to fix bent front fork legs, not just replace them. Of course, that might be rare now, I've straightened lots of them. I could straighten that easily in a press. Or if it was kinked I'd cut out the kink and tig weld it back together. Easy. Better if you hadn't tried the vice or hammer first through. But yeah, fixable, and yes, probably rideable. You won't know until you try.
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clay

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Re: Bent Mast - Rideable?
« Reply #2 on: October 07, 2019, 07:13:24 PM »
That looks like a pretty significant bend, I suspect it'd be noticeable when trying to fly.

I've bent 2 aluminum masts, bending straight took a lot of force.  I broke 1 vice off its base, I had a bigger more secure vice mounted to a metal table and almost pulled the table over a few times before I got straight.

Something like a solid steel bumper or hitch reciever on a truck usually has a gap to stick the mast in and provide a lever to push down on.
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PonoBill

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Re: Bent Mast - Rideable?
« Reply #3 on: October 07, 2019, 08:33:27 PM »
The problem with using the mast as a lever is that a bend creates stresses in the metal, which means it's now harder than the rest of the mast (work hardening). You'll bend the rest of the mast into a curve trying to straighten the kink. The way you straighten a thing like this is to put it in a hydraulic press with supports close to the bend on each side and press directly on the bend. You localize the force to bend it in the harder spot. There's a lot of spring back, you have to push the metal to the point of yielding without going too far and reversing the bend. I suspect that's 6061 aluminum, probably treated to T6. It's fairly strong and doesn't work harden as drastically as some alloys. Don't do anything crazy like warming it up, you'll damage it to the point of hoplessness.
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Rastaman3030

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Re: Bent Mast - Rideable?
« Reply #4 on: October 07, 2019, 10:07:11 PM »
You'll bend the rest of the mast into a curve trying to straighten the kink.

Bingo. That's what I just did unintentionally. After trying the press to no avail, I decided to stomp on it right where bend appeared to be. The good news is the plate and fuselage are now level, but the mast has a noticeable curve. How do you guys think this will effect the performance? This just needs to get me by for about a week.


sflinux

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Re: Bent Mast - Rideable?
« Reply #5 on: October 08, 2019, 06:47:13 AM »
If that was my mast, I would ride it for a week.
The wing is banking one direction, so you will have to apply a force to compensate (to go straight).
I have not had luck with bending aluminum, as it becomes weaker.
To salvage the mast, assuming the base separates from the mast, I would approach it by cutting it off at the bend.  Either ride it short, or manufacture an extension, to join the salvaged mast.
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scubasteve

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Re: Bent Mast - Rideable?
« Reply #6 on: October 09, 2019, 12:57:31 AM »
HI

I have bent 2 x Axis masts no chance of straightening them with a vice and hammers.

The only thing I could do was to cut the bent part out, it normally bends just after the top collar so I ended up loosing at 120mm.

Just tap a couple of M8x1.25 threads and  off you go till the replacement arrives.

 ;D