Topic: Have You Repaired Bent Fins?

[BenelliSEI]

Looking for tried and true, best practice. This is the barrel portion of my very early engine #582. It’s out for vapour blasting tomorrow, so it will come back spotless. Have you straightened these fins on any of your projects? What worked best? Thanks in advance.

[71 V12]

Yes, successfully straightened bent fins with just pliers. I have also had broken fins repaired with pieces aluminum welded in and then filed to shape. Once they are painted you really cannot see the repair.

Given the rarity of your engine I would try these just squeezing a small section at a time.

[grcamna2]

I see those fins on your Sandcast will also need repair John.
I think I would find someone with prior experience in repairing broken fins and straightening;nothing like experienced craftsman. 

[BenelliSEI]

Thanks guys. I’m probably going to do it myself. Curious if you used heat, or did them “cold”?

[scunny]

You may find this of interest.
https://www.revzilla.com/common-tread/can-a-bent-cast-aluminum-motorcycle-wheel-be-repaired

[BenelliSEI]

You may find this of interest.
https://www.revzilla.com/common-tread/can-a-bent-cast-aluminum-motorcycle-wheel-be-repaired

Very good! Thanks.

[Don R]

    I've seen them bend right back into shape cold, but others are brittle and snap. At the time I did mine, I wasn't educated on early vs late heads and cylinders. No one here could tell me the difference either. I have seen aluminum heated and bent back into its previous form but don't know the alloy either but I can say for sure, I'd use heat. Malco sheet metal folders have a more parallel bending surface and I like the way they flatten better. I have also used the vise grip brand though. My fin repair guy welds from the edge and builds up layers rather than try to put in a piece. 

[BenelliSEI]

Use heat before bending them. It helps aneal the metal and make it more pliable. It also won’t hurt the metal because it can simply cool normally back to it’s new position.
[/quote

Makes sense, I’ll try that for sure. Dropping these parts off to be vapour blasted, so back to it in a few weeks...

[MauiK3]

Heat on fins
How much heat? It seems it would not be very much.
Maybe 500F?

[WideAWAKE]

I’ve done a few.

Heat and some flat clamps like the ones posted above.

I will say, probably best to do a rough clean, then fix em, then send to vapor blast.

Good chance you’ll scratch the surface with the clamps. unless your going to paint the head then it doesn’t matter.

[craz1]

Make sure you post your success or failure and method. Im sure you will be successful.

[BenelliSEI]

Make sure you post your success or failure and method. Im sure you will be successful.

Will post. It will get painted, so will wait until they are clean....

[Don R]

 I found my old fin straightening thread from years ago, the pics are gone now, so I didn't make a link, but I did say the earlier ones are more brittle so be sure to use heat. I was using a heat gun then but today I'd probably go with the maap gas turbo torch.  Maybe even pre heat the whole unit a little so it doesn't soak away what heat you have on the bent area.

[BenelliSEI]

I found my old fin straightening thread from years ago, the pics are gone now, so I didn't make a link, but I did say the earlier ones are more brittle so be sure to use heat. I was using a heat gun then but today I'd probably go with the maap gas turbo torch.  Maybe even pre heat the whole unit a little so it doesn't soak away what heat you have on the bent area.

Don..... I was thinking I’d have the propane BBQ outside the shop door! Thanks.

[MauiK3]

Pre heat, good idea, those iron liners would soak up a lot of heat and the fins would work against you.

[PeWe]

Cool down is what the fins do
Fix fins before vapor blast is my vote

[BenelliSEI]

Cool down is what the fins do
Fix fins before vapor blast is my vote

Will do.

[Flyin900]

John, You may already have a vapor blaster lined up, yet you may not be aware of this business. It is in Ajax,  just off the 401 and south down Wesney Rd.

I have used him a number of times (Ed owner) in the last two years when Covid19 hit and the local vapor guy in Orillia was MIA.
A really unique process where he uses the laser system to clean up any crud and old paint and oil stains etc. Then the vapor honing process to finish it off. Quite reasonably priced and open to CASH. 

Laser Clean: https://laserclean.ca/

Good luck on the fins you seem to have a handle on the process at least.

[BenelliSEI]

John, You may already have a vapor blaster lined up, yet you may not be aware of this business. It is in Ajax,  just off the 401 and south down Wesney Rd.

I have used him a number of times (Ed owner) in the last two years when Covid19 hit and the local vapor guy in Orillia was MIA.
A really unique process where he uses the laser system to clean up any crud and old paint and oil stains etc. Then the vapor honing process to finish it off. Quite reasonably priced and open to CASH. 

Laser Clean: https://laserclean.ca/

Good luck on the fins you seem to have a handle on the process at least.

Thanks for this, I will check them out! I’m not sure I do have this figured out. If it goes south, i’m sure there is an expert somewhere that can undo my mistakes!

[MRieck]

Use heat before bending them. It helps aneal the metal and make it more pliable. It also won’t hurt the metal because it can simply cool normally back to it’s new position.

Gospel. i have repaired many fins and have had my machinist weld weld many too. Aqfter painting you cannot tell they were welded.