BXProject

[Bx Bandit]

Righty ho then, I am going to extend the A frame on my trailer as it was made far too short originally and thanks so Vanny I have all the necessary bits.

The donor A frame is however too short, so in essence I am completely removing the old A frame: 75 x 50 x 5 RSA and welding it to the new A frame: [ shaped channel in 4mm. There is 500mm overlap for the [ channel to fit in and under the Angle.

My concern is two fold:
1) Whether to stitch or fully seam weld
2) How to prevent rust developing between the two inner surfaces.

Is it best to fully paint it, fully seam weld and do a really good paint job along the seam?

[mat_the_cat]

I'd be tempted to stitch weld it, as that should be strong enough I'd have thought. I usually use some polyurethane sealant such as Tigerseal over the welds anyway, so in your case I would use it to fill the seam where you haven't welded. Might also be worth putting a coat of weld through primer on the overlapping surfaces beforehand. It's designed for spot welds so you'll have to grind or wire brush it off where you're welding, otherwise it'll splatter but it stands up to heat pretty well.

[Philhod]

1 Dont cut it where the A frame joins the trailer box, do the joint at least 200 up the A frame.

2 butt weld the joint from inside grind back outside then weld outside. Flush grind the inside then weld a 4 thick bar across the joint on the inside, welded all round.

If you are just letting a piece in, fully weld it. This seals the the inner faces from the air, so no rust can form. Also, unless you are a professional welder, space welding is DANGEROUS and comes apart like a zip if stressed. dims given in mm's by the way.


Is it galvanised????????

[Fish_Botherer]

Not an area I know anything about, but what's "space welding", out of interest?

[Philhod]

the correct term for "stitch" welding.

This type, inexpertly done, comes apart dramatically when overloaded.

Also, like spot welding, allows moisture and air, to get between the two parent metals.
If you are using Galv, grind it off where your welding just before, then you can get galve paint to seal off what you've done.

[Vanny]

and drink lots of milk!

[Bx Bandit]

No it's not galvanised. I understand why not to cut the existing A frame at the trailer box - to avoid a shear stress on the weld...??

I missed some info which may be relevant:
The replacement A frame (in C section) is short and I intend to use the RSA from the existing A frame to extend it to the correct length.
The existing A frame has a different angle at the hitch point than the replacement.
So, the existing A frame (RSA) must be ground off from the trailer chassis, ground off at the hitch end to give me 2 individual lengths of RSA for the extension members.

Is a butt weld suitable Phil? The existing A frame is RSA, the new A frame is C section, both differing dimensions in width,depth and thickness (let me know if I'm wrong)

My intention was to overlap the joint with the C section fitting 'inside' the RSA. The overlap would be 500mm.

[Vanny]

picture/sketch might help

[Bx Bandit]

I tried for a bit to do that - not quite managed it. Will persevere....

[Way2go]

I tried for a bit to do that - not quite managed it. Will persevere....

Draw it freehand and use a scanner to input it as a jpeg. Easier/faster than using draw packages.

[Bx Bandit]

Probably - except it's already in a drawing package ok, I'll try now....

[Vanny]

print out where your up to and start doodlin on the sheet?!?


And you dont even need a scanner, take a picture with yar phone and email it to your self!

[Way2go]

It all goes to update & prove the old adage that "there are many ways of skinning a cat"!

[Vanny]

but if i was trying to get there, i wouldn't be starting here!

[Way2go]

A pre-satnav reply you might have got when asking directions from a rustic character in the middle of nowhere.

[docchevron132]

Bit of fucking sticky back plastic should see that alright mate,

[Vanny]

zip ties?

[Philhod]

No you would get yobbo's cutting them with Stanleys

that sounds ok Bandit, but a 250 o/lap should be plenty, as you will be fully welding it I assume?

Also weld a piece of suitable flat bar across any gaps in the RSA.

Butt welds are not suitable for this type of joint. If you read my first post, if you were joining like for like
you would need to stiffen the joint as described.

[Bx Bandit]

I have an old fashioned phone that don't do piccies so can't do what Van said!
Sticky backed plastic it is then Doc!!!! I'll add zip ties to be sure though!
That's cool then Philios, fully welded it'll be. Need to get some discs and then I can

[Vanny]

sticky back plastic, what, rape tape?