One fin on each barrel Atlas and Dominator is chipped where, or has anyone got some cast iron pieces for repairs?
some bits of fin from my brother's spare AJS barrel. As someone once (nearly) said, what better use for an AJS than repairing a Norton?
I cut them to shape then used JB Weld to attach them. Radco, in his Vintage Morotcyclist's Workshop, says epoxy should take the heat but due to lockdown haven't tried it yet.
I did have some fins welded years ago on an A10 but it's hard to find someone with the capability.
I used some JB weld to fill unwanted holes drilled in some Model 7 crankcases. When I put these cases in an oven to warm them ready to fit new main bearing the JB Goo softened and ran.
Prior to this I had great success with the same stuff; using it to repair a broken fork mudguard stay lug. That time, when the Goo had set, it was shaped, drilled and tapped and held the stay in position for the next 12 years.
Going back to cast iron fins. I had great success repairing broken fins on three sets of barrels using Disimilar Metals welding rods with an Arc set. The only issue being the weld join material is really hard and not easy to file. See attachments but don't shout at me for leaving the followers in place.
Welding cast iron in the past was a bit trickey, But fins are not heavily stressed . Pre heating the parts helps as does a slow cool down. I once spent ages chasing cracks round a ford exhaust manifold .Better rods and welding sets now.
The Fin is the second one up from the bottom of the barrel on the right-hand side looking from the front and difficult to get to, but not impossible, I suppose!
On the Atlas barrel it's the top fin!
I have seen the proper barrel fin repair guys in action and they do not mess about to save time. In your example of the broken second fin up they quite happily chop off the lowest fin in order to gain better access and then weld both back in one session.
As Robert says, the key to success with welding cast iron fins is to get the barrel as hot as possible. I cooked mine in the oven for an hour at max heat.....250*C then placed it in an insulated box while keeping it hot with two gas torches and a blow lamp. The Disimilar Welding rods are very interesting to use. I found that the weld puddled like solder which gave a fairly level surface. Unlike normal Arc welding which causes bumps and dips along the seam.
I paid just 25p each for my welding rods and used 4 altogether.
Thanks Ian, Phil, Robert, now that you mention if Phil, I hav e heard that before they just cut off an adjacent fin off to get access!
Got to get the special slim spanner to get the Head nuts off got one arriving soonish!
I've repaired fins on cast iron barrels using silver solder. Relatively cheap and easy to use. Never had any problems.
Having a pacemaker means now keeping clear of Magnetic resonance etc. I would love to have developed my welding Skills. I convinced my son he could weld (he had no skill at all!) ,But I knew he would battle with it.I think I will buy him a MIG welder , In my life I tought myself,carpentry,bricklaying,plastering,house electrics,plumbing,central heating ,gas Installation!(don't tell anyone).Roofing,electronics (built my own TV) , Appliance repair Microwave,dishwasher,washing machine,fridge,,Car and bike mechanics,engine,gearbox,axle rebuilds,Etc,Etc. .If you think you can do it ,chances are you can. I can fly a plane, sail a boat ,Build a Kit car . Never learnt to Navigate , something for my old age. Just do it.
Over the years i have repaired several broken fins, i used a bit of mild steel of comparable thickness, well cleaned the join area, devised a "holding in place" setup ,clamps etc, oxy propane set up with a standard blowpipe, used brazing as the filler suitably dressed and painted after repair, never had one fail.
You don't need cast iron to repair cast iron fins on a barrel. It will probably be easier to use another metal and you would braze it on, not weld it. Steel or brass will be OK if it is a small area. Large areas might suffer from dissimilar expansion but fin breakages are usually small. Braze it in and hand file it to shape.