Repair of the broken No. 9

This repair is going to take a while, so I decided to post updates here as I go along.

It might be a nuisance to those who aren't interested, but I hope you'll bear with me.





I finally acquired No. 9 by investing all the money I got from selling off a lot of my collection.

I know it's a ridiculous amount of money and you'll probably be amazed, but I don't regret it because I wanted No. 9 so badly that I even made a replica.


















I'd like to correct what I said earlier.
I regret it a little.



Yes, the fuel tank was cracked.









To ensure strength, I decided to use silver brazing.

The crack has an outward-facing edge.
Therefore, to make it a perfect circle, I will tie it from the outside.

I decided to perform the silver brazing in that state.







The result was disastrous.
I tied it too tightly, causing the heated area to deform.
It became uneven...

It seems the brass softened when it reached the melting point of the silver solder, and then deformed under the pressure of the binding.









Not only that, the crack progressed further and completely split to the edge.








I couldn't help but laugh at what happened.
I was ashamed of how ignorant I was...


I wanted to just give up, but I can't.
It was quite expensive, after all.




I was so disgusted with it that I left it alone for a few days.

Then, when I looked at No. 9 again, I noticed something.

Solder was melting and oozing out from around the crack.
I also realized it wasn't a crimped structure.

In other words, it could be disassembled.


Previously, when I made a replica of number 9, I couldn't disassemble number 10 because its radius was crimped and sealed, so I assumed number 9 couldn't be disassembled either.

https://classiccampstoves.com/threads/the-franken-stove-of-a-man-who-admired-optimus-no-9.56775/



If I had realized this structure from the beginning, I could have easily silver-soldered it from the inside.

It's frustrating, but I can't go back in time.





I immediately removed the side parts.















Silver soldering was performed from the inside.

By applying a generous amount of silver solder from the inside, the strength was increased.









This brings us to the present.
This has turned into a long post.

The content is quite embarrassing because the repair was full of failures, but
I'm posting it in the hope that it will be helpful to others who will be repairing No. 9 in the future.


I'm still working on the repair, so I'll update this if there's any progress.
Thank you.

 

Good idea tackling from the inside. Too bad about the clamp around the exterior. High on my list to obtain also, but beyond my finances.
Duane

 

@Camp numao
It’s admirable that you’ve given a full and frank account of your repair from the outset. After that initial mis-step you’re surely well on the way to creating a first-class and lasting repair.

I hope my Optimus 9 repair will last well also, but it isn’t as neat as your repair seems likely to be.

John

 

@hikerduane

Thank you.
The inside is easier because I don't have to worry about protecting the plating.

Every time I see the terrible outside, I want to punch my past self.



@presscall

Yes, of course I've read your repair instructions carefully.
Because you've already done everything I'm trying to do. Haha.

It's really educational. Thank you.
I agree with your approach of considering rigidity against internal pressure, rather than simply soldering.

Since the No. 9 I acquired has more than three cracks, I've given up on using the method you described and decided to use silver solder instead.

I don't know how far I can repair it, but I intend to at least get it into a working condition.

 

Good report.

Have you annealed the tank brass?

 

@snwcmpr

Thanks for watching.

I didn't heat-treat it because I was afraid it would reduce the material's strength.

Because of that, I had to tie it very tightly, so my method was wrong.

It was an expensive lesson. Sigh.

 

I agree that a number of stress cracks presents a different challenge and that your approach of silver-soldering the cracks from the inside of the tank.

I puts me in mind of the repair Pete Sav did on a Blanchard lamp fount, where he had many cracks to seal up!

 

Numao: I had Aircraft Sheet Metal Assembly shop in high school. A trick to stop a crack from running more, is to drill a hole at the end of the crack. Then shoot a rivet in the hole. Don't know how well this aluminum trick would work in brass, though.

 

@presscall

I read the article you recommended.
I was impressed by how well you repaired the lantern, even though it was in worse condition than the one I'm trying to fix.

I learned that if the stress isn't relieved by heat, cracks could reappear.
I learned a lot.



@SveaSizzler

Thank you for teaching me the technique to stop the cracking.
I'll remember it, as I think that knowledge will come in handy someday!

 

Is the main body material of the tank the only cracked material?
Consider replacing the cylinder part of the tank?

 

Given it’s the end caps where the fuel filler/pump/burner connections arise, that’s a sound suggestion Ken.

A nickel plated brass cylinder of the right diameter might be a difficult thing to source, but a brass cylinder of slightly oversized diameter could have a section along its length removed to generate the required diameter, then sibrazed along to join and made visibly seamless with smoothing off and polishing. A heavier gauge of brass than the original wouldn’t be a bad idea, the Opt 9’s being too flimsy, hence the stress-cracking reaction to flexing with pressurising/de-pressurisation of the tank.

Nickel-plating the polished cylinder would be a relatively simple procedure, as I found with my Optimus 123R project.

 

I pictured making the cylinder.

 

Roll sheet and join at the seam?

 

…then nickel plate.

 

If you go for the repair option-rather than replacing- I'd echo the need to anneal, or more stress cracks will most likely appear in use.

 

Yes
This member has proven that he has the skills.

Yes

 

Unless a rolling machine is available a solid cylinder of metal or wood to form the sheet around, with periodic annealing of the workpiece, would be the method.

When I repaired Doug’s Optimus No.9 I was concerned that getting the metal up to brazing temperature, or red hot to anneal it, would destroy the nickel plating. It wouldn’t be such a concern these days after dabbling succesfully with re-plating.

 

@presscall
@snwcmpr
@junior trangia master
@Pharael
@Blackdog

Thank you all for your consideration.
I also considered rolling up a brass plate and remaking it, but I'm not as dexterous as you all, so I think I'd fail.

First, I'll try to establish an airtight seal, and then see if I can hammer it back into shape.

Whether it works or fails, I intend to update you.
Thank you.

 

@presscall
A silver brazing jewelry class talked about temperature for annealing of brass to be met when the Sharpie mark when written on it disappears

 

@snwcmpr

I'll try heating it until the marker ink disappears.