BRAZING

[Repair man]

Hello All,

I am restoring my 50 Year Old Claud Butler road bike and I wanted to fill a small patch of corrosion on one of the Steel Reynolds 531 tubes, with brass ready for re painting.

I still have some very old brazing rods, probably at least 50 years old, but not sure if they used to be Flux coated or not, I have a vague recollection the small surface indentations used to be full of pale blue flux. I have not done any brazing for many years and I can't remember using a paste flux with these rods as seen on Youtube.

The Original tube they are in is labelled EUROBRAZE AND UNIBRAZE. see pictures.

Can any one tell me if these are still any good or perhaps the best flux to use wit them, or should I just try them without any additional flux on some scrap.

Thanks if anyone can advise me.

Trevor

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[Seadog]

Ah, blue flux. We used that at school in the 60s. The rods had no flux on them. Borax should do the job.

 

[500e]

They are fluxed rods. Cant find the names you put up though.
Bit of an expensive trial on the CB frame, try on some thin tube first.
Personally I would ask if anyone has a new rod or 2 they can let you have for tokens.
@Seadog I have some nub ends of rods like shown they are fluxed in groves but red flux used one last week, they are 50/60 years old held with long pliers.
Yes I am a tight B*****d and had run out of Argon and wanted the job finished, they were in the bottom of a airtight tube.
Don't we have a cycle frame man on here ?

 

[voipio]

Borax, on its own, applied as a paste, will do the job. Other brazing fluxes are still basically borax, or sodium borate, with additional ingredients, such as ammonium chloride, and can improve the properties of the flux, but can also cost quite a bit.

However, it's worth considering the area, depth and nature of the corrosion. Although brazed joints can be very strong, the braze itself is no match, and therefore no substitute for 531 in terms of tensile strength.

 

[Cobbler]

Not sure you can buy borax anymore, I wanted some for brazing years ago & got some from the chemist for pence, l wanted some recently, but I understood it was on the no-no list.

 

[brightspark]

get some sifbronze flux. the impregenated ones might not be suficient now i have loads of old ones and just dip the heated rod in to the flux shop around price wize https://www.zoro.co.uk/shop/welding...MInrKrnPjvhwMVaoBQBh2Fay7PEAQYAyABEgK9ovD_BwE

 

[Seadog]

Not sure you can buy borax anymore, I wanted some for brazing years ago & got some from the chemist for pence, l wanted some recently, but I understood it was on the no-no list.

Borax 1kg (also known as sodium borate)

www.naturalenzymes.co.uk

 

[Cobbler]

Borax 1kg (also known as sodium borate)

www.naturalenzymes.co.uk

According to the web, it can’t be sold to the general public……. So you can get it mail order off the web!

 

[Repair man]

Hi All,

Thank you all for sharing your knowledge, I was not expecting such an amazing response.
I have had a closer look at the Brazing Rods under a Microscope and some of the surface indentations do still contain a ligt bluey coloured solid, which I dont think is Copper Sulphate corrosion as the rest of the plain surface is fairly shiny.

Here is a picture of the bike Tube Corrosion, this is the worst bit adjacent to the rear tyre area on the inner face of the Left Hand Chain Stay. I did not Sand Blast the old paint off I spent about 5 Hours scraping it by hand.
I have had a good scrape at this bit and I dont think it is not corroded right through at any point but there is a shallow depression and quite a few other tily pit corrosion marks down this tube that will probably fill with Primer. My Dad bought this bike for me in June 1974,


I have tried to photograph the tube lables again but it is hard to get the whole wording in one picture, so there are three and the tube rolled around.

I think if I tried to Mig Weld it may well bun a hole.

I shall go back now and study all your replies. Thank you so much.

Kind Regards
Trevor

 

[brightspark]

id just fill that with cataloy paste and sand it. looks strong enough. would take a lot of work cleaning out the pitting to brazing over that lot and grinding back

 

[dave h 2]

Sand blast the pits or don't get it wet again. If you still have that 70's favourite a carbon arc torch it will burn the rust off and not melt the tube. 531 cannot be welded

 

[Repair man]

Hi Dave and Sparky,

I could scratch the majority clean with the point of a Stanley blade or something, I don't think that would be too difficult.

I did not realise 531 could not be welded, I shall have to google that, strange you mentiom the Carbon Ark torch, I had two of those. Bright Yellow plastic with sliding Carbon Electrodes sticking out. not seen them for a long time I shall have a search.

There is stuff called Industrial Metal Epoxy which is extremely expensive £100s. then there is this cheap stuff £20 on ebay.

JENOLITE Epoxy Putty Repair Stick | TITANIUM | Industrial Strength Epoxy | & All | eBay

FAST ACTING: Functional in just 60 minutes - cured colour is steel grey.

www.ebay.co.uk

This method would be the simplest I suppose, but like Dave say's it would have to be well protected from weather, when I was scraping off the old paint I found tiny patch of paint chipped and rust had got in and made its's way several inches under what looked to be perfectly undamaged paint just like a fungus under tree bark.

Regards
Trevor.

 

[Seadog]

https://www.amazon.co.uk/JB-Weld-Original-Cold-Formula/dp/B0044US7SY/ref=asc_df_B0044US7SY/

 

[Repair man]

Hi,
Thank You -
I shall send for some of this it sounds like good stuff, I don't need that much, if I bought 500gm of the Professional stuff it would just go to waste. --

I have been scratching away in the pin holes of the rusty patch usind the point of a strong modeling knife blade You are right about it being not to bad, I tried to pierce through with the point and was unable to do so, and if I tap it it sounds solid, so I think this epoxy repair should do, although I still like the idea of brazing it and having a nice shiny brass tube. It's not urgent so I think before I do anything, I will get new brazing rods and flux and practice on a bit of thin tube (with a bit of rust on) and see what I can do. Whatever I end up doing I will send in a picture.
Regards
Trevor
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