Author Topic: Broken fin on barrel  (Read 379 times)

Offline Oggers

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Broken fin on barrel
« on: February 20, 2021, 02:55:46 PM »
Just managed to break a fin on the aluminium alloy barrel of the Velo. I was heating it trying to bend it back and then snap! Much profanity followed. Piece is around 40mm by 15mm.

Forget welding it for the moment - looks very difficult and besides I am rubbish at it and there are no welders round here in the immediate vicinity.

Thoughts therefore are

Epoxy putty/plastic metal, JB weld or Belzona or something.
Solder?

Comments welcome 

Offline R

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Re: Broken fin on barrel
« Reply #1 on: February 20, 2021, 11:02:59 PM »
JB weld might hold it. Emphasis on MIGHT.
You are going to need a big lump to support it though, so its not going to be pretty.

Lumiweld low temp rod was mentioned here in connection with low temp gas welding of zinc/alloy.
You could probably get away with doing on the bike, assembled.
Its more like soldering than welding.

Remove petrol tank and all trace of petrol fumes - FIRST !!
Practice welding on a coke can first.
When you have it down to a fine art, move onto the real thing.
Its still going to show.

Most small airports will have an alloy welder, or someone they can recommend.
Folks lives can depend on the weld quality, so they are GOOD.
Should be a quick easy repair for them.
The engine is going to have to be dismantled though.

Offline mini-me

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Re: Broken fin on barrel
« Reply #2 on: February 21, 2021, 08:21:24 AM »
Araldite if applied properly. I done the following many times on cast iron fins

clean the break with solvent, brake cleaner good enough.

use small diameter pins, I used needle rollers ;  drill matching holes in each part, for these pins, glue and then fix together.

lay barrel down with the fixed part uppermost, then over it put some kind of lamp, anglepoise in my shed, and not with a LED bulb, near enough to warm the item, then just leave it a few hours,araldite cures best under gentle heat, it should turn brown.
After cleanin up it should be permanent,   

On black painted barrels its invisible.

Offline Oggers

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Re: Broken fin on barrel
« Reply #3 on: February 22, 2021, 08:15:35 AM »
Thanks both. Yes - I was going to drill in both sides and add reinforecement wire. Interesting about araldite - may be better than JB weld on reflection...

Offline mini-me

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Re: Broken fin on barrel
« Reply #4 on: February 22, 2021, 10:27:50 AM »
good pegs, silver steel or old needle rollers. only needtobe thin,just for reinforcement.
Secret with aradlite is gentle heat such as you get frfom a 100w bulb about 4-6 inches over it.

Offline iansoady

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Re: Broken fin on barrel
« Reply #5 on: March 07, 2021, 04:02:46 PM »
JB weld worked very well for the (cast iron) fins on my Norton ES2. Stay in place despite getting well up to temperature. Of course you don't get the full cooling effect.

I supported it with a thin bit of alloy either side and made sure it was well held in position while it cured. I used bits of fin chopped off a scrap AJS head which gave a good shape, although I also used a bit of mild steel for a smaller repair. This pic shows the first fin in place - I let it set before doing the next one.



This is with a coat of cylinder black (which isn't as shiny as it looks):



Ian
1952 Norton ES2
1955 Francis Barnett Cruiser 75

Offline Rex

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Re: Broken fin on barrel
« Reply #6 on: March 09, 2021, 11:07:27 AM »
I hear a lot on the Net about how good JB Weld is, but I've never really trusted sticky goo to fix things like this, though having an excellent welder available for such repairs makes things easier for me.
How long has the repair lasted for?

Offline iansoady

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Re: Broken fin on barrel
« Reply #7 on: March 09, 2021, 11:21:31 AM »
Well over a year but obviously my riding has been seriously curtailed this year......
Ian
1952 Norton ES2
1955 Francis Barnett Cruiser 75

Offline john.k

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Re: Broken fin on barrel
« Reply #8 on: March 11, 2021, 10:52:10 AM »
ES2 s seem to have much problem with fin breakage both head and barrel.....the iron seems to be particularly brittle.

Offline iansoady

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Re: Broken fin on barrel
« Reply #9 on: March 11, 2021, 11:59:11 AM »
Don't know about that - the A10 I pictured her a little while ago had several broken fins. I did have them welded however.
Ian
1952 Norton ES2
1955 Francis Barnett Cruiser 75