Author Topic: Fin repair  (Read 1800 times)

Online Brian

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Re: Fin repair
« Reply #15 on: 03.01. 2016 04:27 »
Well I have done one fin and so far so good.

I have to wait until Monday now so I can get some more steel.

Offline Tomcat

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Re: Fin repair
« Reply #16 on: 03.01. 2016 09:45 »
It does concern me a little that maybe we still throw away parts that may one day be repairable.

Cranks are probably a good example. There has been much discussion about building cranks up with spray metal etc etc and maybe now it is not entirely successful but in 50 years time with advances in technology it may well be quite easily done.

We all have to remember there will be generations after us that will want to ride our bikes and will need parts so dont throw away anything without having a very close look first.


A friend in the BSA club who has late '20's Beezas said to me once "at least you can find good second hand parts for A7's & A10's, any part I can find for my bikes is stuffed and needs re-making".

Nice repair job Brian, and it makes for an interesting read too.
'48 A7 '59 SR '74 850 Commando TDM900

Offline coater87

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Re: Fin repair
« Reply #17 on: 04.01. 2016 03:05 »
Most of my buddies are into old Harleys. One guy found an original set of barrels from the 30s still on standard bore. Nobody ever wanted them because someone used a long reach drill bit and drilled about 100 "lightening" holes through all the fins.

 Last I knew they were cutting off each fin, repairing it and brazing them back on.

 20 minutes with a drill, 100 labor hours to repair. But it was mentioned, at the time they were considered "old junk".
Central Wisconsin in the U.S.

Online BSA_54A10

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Re: Fin repair
« Reply #18 on: 04.01. 2016 08:33 »
Then you don't want to look too close as Musky's bikes
Bike Beesa
Trevor

Offline muskrat

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Re: Fin repair
« Reply #19 on: 04.01. 2016 09:22 »
Good one Trevor. Their never standing still long enough to get a close look.
Brian, are you brazing or welding with stainless rods?
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, .
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Muskys Plunger A7

Online Brian

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Re: Fin repair
« Reply #20 on: 04.01. 2016 11:07 »
I'm using standard .6mm mild steel wire.

I have never tackled a job quite this large before but I have done quite a few smaller repairs and so far it has been very succesful.

The "secret" seems to be that the mig used in very short bursts puts very little heat into the job.

Offline nimrod650

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Re: Fin repair
« Reply #21 on: 04.01. 2016 18:09 »
i use 12 gauge cast iron rods on stick  welder worked fine for me you can reach with a rod where you can.t with a mig it takes to cast and mild  steel

Online Greybeard

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Re: Fin repair
« Reply #22 on: 04.01. 2016 18:33 »
... you can reach with a rod where you can.t with a mig...
Are there such things as narrow MIG nozzles? Thinking off the top of my head I guess a narrow silicon nozzle extension should work; it only has to guide the gas to the work point.

Online Brian

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Re: Fin repair
« Reply #23 on: 05.01. 2016 00:45 »
Finished one side, so far so good.

Online KiwiGF

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Re: Fin repair
« Reply #24 on: 05.01. 2016 02:13 »
Looks excellent, are the fins deflecting much when the weld cools?

Are you using several heavy duty tack welds on the new metal to hold it in position? (before doing the main welding).

I'm trying to fully your method before I (one day) attempt a similar job on a cylinder head  *work*
New Zealand

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Online Brian

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Re: Fin repair
« Reply #25 on: 05.01. 2016 03:21 »
They are finished.

Kiwi they didnt deflect much at all, not as much as I was expecting. I put a spot weld in about 6 places and then welded about 5mm at a time. A weld on each end then in the middle and then about 1/4 of the way along etc etc. After two welds I left it to cool for about 5 minutes and then did some more.

Online Klaus

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Re: Fin repair
« Reply #26 on: 05.01. 2016 06:31 »
After blasting and colouring it looks like new *yeah*

realy gread job, and thank you for posting

cheers Klaus


If you think, everything is under control, you are not fast enought.

Offline terryg

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Re: Fin repair
« Reply #27 on: 05.01. 2016 07:01 »
Good job, Brian.
Terry
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Online cyclobutch

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Re: Fin repair
« Reply #28 on: 05.01. 2016 08:59 »
Indeed. Good work, good post.
Various, including ...
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Online Greybeard

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Re: Fin repair
« Reply #29 on: 05.01. 2016 09:07 »
Fintastic!