I am a frame builder AMA

If someone could be so kind and help me with my current issue? Thanks!

https://www.lfgss.com/conversations/351599/?offset=25

Did some practice beads.on an old scrap frame (Dawes MTB) and had a lot of cracks. Maybe only 2 beads out of 10 were uncracked. I messed about with settings but couldn't seem to shake it, which made me think it was the rusty inside :D

don't have the kit to backfill it

You don't need that to get decent welds. Buy some clean proper test tubing.
I started with 4130 plain guage. It is worth knocking out a bunch of t-joints imo

Maybe only 2 beads out of 10 were uncracked

Did the beads crack as they cooled? Thats odd. What filler are you using?

yep, the last 'dime' of each run would crack perpendicular to the direction of travel when i stopped. i even put a 5 second downslope on.

was fun to mess with pulse setting for the first time. i even tried that 1Hz pulse thing with a lay wire.

i read around but can't seem to nail down the exact problem. it's not gas coverage. anyway, it was a shitty, dirty tube to be welding on, so it's not going to be hugely instructive. i'll just try and fix that pomp crack tomorrow and whatever happens happens. the crack runs from the tube into an area of previous brazed repair, so it could be fun and games.

Thats really wierd, could be that the dawes frame is some weird alloy? Maybe the really dirty back side contributes to it, but seems odd. Could try a more ductile filler rod, 312 or maybe even 309. I have a bunch of both if youre in london and want some.

thanks, but i'm in manchester. i'm using A15 rods apparently. i did notice the welds seemed flat - almost sunken, so there's not enough material in there to fill the gap? maybe things are sagging a bit? it was weird.

hmm, strange the only time ive had a bead crack was welding a big chunk of cast iron without enough preheat. Good luck with the pomp!

good timing. i'm having a look now and have 2 quandries

a) is it a crack or just a scratch?
b) the crack is close to a previous braze repair and it's making me nervous

the crack showed up in the paint (powdercoat) and a small bit flaked away. that's how i noticed it. now i've stripped the coating back, it's a REALLY fine line. i've given it a good sanding with coarse paper and it's still there but it doesn't have the definition of a crack.

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ok in that photo it looks more like a crack!

Definitely looks cracked

wondering if a tig braze might be a better option. the rod for that is $$$$$$$

It does look fairly crack - like :(

Watch out for tigging near the braze. If it's got any zinc in it, the zinc will be vaporized, it's not good stuff to be breathing in

the pinholes and crack suggests overheating to me. I would probably bin it tbh

pinholes in the braze? interesting. i don't know much about brazing. i'm not sure the guy did a great job, but he is pretty well known for paint and frame repair/building.

do you reckon it's just gonna crack again somewhere in that BB region?

it's not good stuff to be breathing in

the tutors on my welding course loved describing the horrors of 'gal flu'

I don't wanna call out anyone at all. But that does not look like a good fillet to me.

I am no pro and I haven't had much fail. I just know that if my flame is too hot I get pinholes/craters that looks like that. Also the transistion from fillet to tubes does not look smooth and well filed.

AHA! I found a pic of the original crack

he didn't braze the entire fucking thing!

that extremity on the DT is what's still there. it's just the old crack that was never filled.

well it's done 2 seasons of cross like that and not got worse...

Well then don't attempt welding it

yeah i'll just paint it up and carry on with my dream lifestyle

ok next Q: is there anywhere to get this type of braze on simpler and cheaper than ceeway? it seems like they prefer you making larger orders.

Depending on how urgently you need them, I will be doing an order in the next couple weeks, maybe sooner
I can add them on to that and then post them on to you in an envelope?

that would be ace phil, thanks. could you get me 7 (5 practice + 2 real) of ART. 116 please?

No problem. I’ll pop you a message when I’m ordering.