Stainless steel A-Frame for boat - bend or cut+weld?

[David Pye]

Hi guys,

My first project (after mastering TIG on plenty of scraps etc) is going to be to weld up an A-Frame for our diving RIB (rigid inflatable boat).

What I am after needs to look vaguely like the attached pictures.

It needs to be made of quite thick SS tubing, which is thicker than I am able to bend at home. It will be made of two lengths of SS tubing, with cross-braces to make it into a single frame.

The thing I'm not sure about is whether I am best off paying a company to bend the tubing into the basic shape, leaving me just to weld the cross-pieces on, or whether I should cut the SS tubing at an angle and weld the next sections together at appropriate angles to make the shape.

I'd be interested in particular whether there is a great cost in terms of strength with cut+weld as opposed to welding. Advice very welcome!

Thanks,

David

 

[astro_al]

Get it bent, it'll look so much better. It'll be strong enough, provided your welds are good, either way.

Al.

 

[Drains]

What Al said. Strength won't be an issue if the welds are sound (but you might want to purge if you want it to last forever), but it'll look soooo DIY if you cut and weld it.

 

[Ed.]

What everybody else said, definitely get it bent, doing cuts and welding them will look so amaturish and back yard like it will be a constant eyesore. You will regret it!

 

[Delgado]

As said, the easiest way is to get it professionally bent, failing that you could use elbows cut to the angles you want (draw it out on wood first), welded and ground flush. Which if done right could look just as good, but is obviously more work. Looking at it, I think that you could do it with 6 elbows, and It doesn't look like it needs to hold much weight, so would have thought that 16 or maybe 14 swg 316L tube would be fine being as it's all tied together with cross braces.

 

[David Pye]

Thanks for the replies guys - It looks like I will end up paying to get it bent then just TIG in the cross-braces and brackets for all the things I want to mount onto it.

It needs to be 316L marine stainless - re thickness, well, no it doesnt have a HUGE amount of weight to take but it needs to be as robust as is possible as it is sometimes used for towing another boat etc. It needs to be as thick as possible within the criteria of not being so heavy it's unmanageable.

What I would probably end up doing is measuring the details of the existing one re tube diameter and thickness as I know his one is strong enough!

Cheers,

David