Filler for Reynolds 531

[Garreth]

One for the bike lads !

Our apprentice at work has an old Cyclocross bike which he is in love with ! Unfortunately the tube that goes between the bottom bracket and the headstock has cracked about an inch away from the lug at the headstock end (apologies for the terminology but I know nothing about bikes !).

He's buying a new frame.

He wants us to weld the old one up for him to use on an indoor trainer (I think he called it a Turbotrainer ??) 'cos basically he can't bear to throw it away !

The weld just needs to stop the crack getting worse. It looks like the frame might be brazed ? We were also going to put a steel gusset in the triangle between this tube, the top tube and the headstock.

I APPRECIATE THAT THE WELD WILL NOT BE STRONG OR SAFE ENOUGH TO RIDE WITH HENCE THE FRAME WILL ONLY BE USED STATIONARY IN THE GARAGE !

Anyway after all that is it possible to Tig Reynolds 531 and if so what's the best filler to use. We'll have a variety of mild and stainless steel filler wires at work.

Thanks in advance !

Garreth

 

[CKJDJK]

If I remember right from my bike shop days, Renolds 531 was nicle/bronze welded/brazed to reduce the heat affected zone. It was done using flux so I guess brazing is the better description. It was used on high spec racing bikes ( including Joe Waughs) so must have been strong enough

 

[Garreth]

Have been looking on t'net.

Looks like you can't TIG 531 tubing

I'll try and persuade him to bin it !

 

[gordon stephenson]

How about making a thin walled split sleeve and silver soldering it over the break/crack.

 

[Drains]

You can Tig it - as in, it will weld. It's designed for brazing though, so there will probably be strength issues. A15 wire will do it. Drill the ends of the crack, weld up, use the frame and keep an eye on it. The worst that will happen is it'll break again in the same place, which is somewhere very unlikely to be catastrophic.

It'll almost certainly be rideable on the road. There are lots of bikes used by certain members here (and their friends) which are made from more unlikely material/weld combinations (check out http://www.artinsteel.co.uk/page19.htm and http://www.rat-patrol.org/Bikes.html)

 

[schnappi]

How about making a thin walled split sleeve and silver soldering it over the break/crack.

Seems like the best option to me. 531 is usually double butted (ie. thicker at the ends where it's brazed) and is very thin in the middle.

If I were to try anything then it would be to drill the ends of the crack to keyhole them and stop the crack growing then sleeve the crack and braze / silver solder.

If it's only an inch away you could possibly do it in such a way as to make the lug look like a long pointed lug for aesthetics.

531 is usually very strong though so I'm surprised it's cracked unless the frame has bent. I'd check for creases!!

I wouldn't try and weld it, that's why 531 has been superceeded by 631.

 

[hotrodder]

I think 0.9/0.6/0.9mm was as light as a 531 downtube got and unless it's a tiny frame and/or the builder shortened the tube from the wrong end i'm thinking a crack 1" from the lug should still be within the thicker wall zone.

If he can't bear to part with it a decent framebuilder would be able to replace the downtube although obviously that won't be dirt cheap. If he's only planning to use it for the soul destroying pastime that is a turbotrainer* i'd just weld/braze the crack or even snot a patch over it



* Can't watch telly/listen to music properly because even the magnetic resistance ones are noisy so after what feels like hours (as you're pouring with sweat cause you're not moving and staring at a wall) you look at a clock and realise you've only been at it for 10mins.