Oven brazed Evaps

[PhilippF]

After some months of experimenting (and a lot of tossed away evaps), I managed to braze two evaps in an oven. They came out very nice and needed no further cleaning. I always hated having to clean the much oxidized copper only to hope that there will be no leaks. Also I did not like the idea of leaving corrosive flux behind inside the evap when brazing with silver rods.

Now I dont need any flux at all...

Regards,

Philipp

[LittleDevil]

Great, any pics how did you do that?

Regards

[killermiller]

Wow, those look great. What kind of oven did you use?

[PhilippF]

The oven is normally used for ceramics and makes up to 1100C. I use mainly CO2 as protective gas with water-free ethanol vapor below 450C and CO2 + hydrogen above 450C.

Regards,

Philipp

[Polizei]

How do you apply the brazing rod though? Use the oven to heat the evap, pull it out and then apply the rod? Or do you set the rod on the joint, put it in the oven, and then let it self braze?

[runmc]

It looks really good Tell us more..

Have you hooked one up yet and pressure tested it?

[PhilippF]

As it would bring in oxygen you can not open the oven during brazing, so the brazing rods have to be in place before. So I start the oven, when reaching 450C, I switch from CO2+Ethanol to CO2+hydrogen and at cooldown, at 450C I switch back to CO2+Ethanol for saving purposes (hydrogen is expensive here, I experimented with an elecrolytic hydrogen generator but the gas was much to damp).

Both evaps had no leaks on the first try now

[Polizei]

Good idea.

Seems like a hassle though to deal with the changing of purging gasses, but the end result is clean. If you can get a good rate of return with very few leaky evaps, you have yourself a winning process.

[{.bLanK} GoD]

Mad skills.
Well done Philip

[PhilippF]

I am very confident now (after a lot of errors) that now the evaps will come out without a leak, but even if, I can put them into the oven again as I dont have any tinder on them after brazing...

Oh man, I have experimented since November to perfect the process and now it finally works perfect

[wdrzal]

A oven will work just fine ,but if you wanted to produce evaps,I would make a Induction heating element/system for them. You would be able to complete the braze measured in seconds.

[PhilippF]

You sure are right, but this is still my hobby and I am not going to mass produce evaps. An induction heater goes into the 1000s of $ and I would still have the problem with protective gas. This is just to produce some nice looking and tight evaps for my builds (and perhaps for some other people, if needed).

Regards,

Philipp

[DetroitAC]

Nice job PhilippF, I've had the same idea and I'm using a vacuum oven for my prototype evaps. It's not my original idea really, I'm an automotive engineer and all production automotive evaps are either controlled atmosphere or vacuum brazed. Cleaning evaps after they are brazed is just such a drag... Wonderful to have them ready to go when they cool

I started out with making brazing rings from sil-phos-copper alloys, but now I'm using a paste that let's me control the alloy placement much better. What are you using?

[[XC] 2long4u]

You copied Ssilencer!!!

[wdrzal]

I'm an automotive engineer and all production automotive evaps are either controlled atmosphere or vacuum brazed.

What's the trick you guys use to get the evaps to not leak just until the the vehicle's warranty runs out ?

[[XC] 2long4u]

If its a dodge truck they will leak bofore the warranty is up.

[Polizei]

If its a dodge truck they will leak bofore the warranty is up.

My roommate owned a Dodge truck. Everything died on that truck before the warranty was up. Piece of garbage.

[[XC] 2long4u]

Depends what year. Anyway you look at it they are easier to fix then a Ford.

[[XC] gomeler]

What would you use to heat an evap in a vacuum? A large inductor? Wonder if I could build a small vacuum oven for evaps for a decent price. Does anyone know of a nice informative website on this concept? Can't find anything but food ovens or product listings.

You copied Ssilencer!!!

God I hope this is a joke from the last thread about the acrylic mounts?

[{.bLanK} GoD]

STFU 2long! You are doing nothing but spamming this thread. It's people like you that spoil this place.
Polizei, you're not helping either.

If you're seriously keen gomler, I'm sure Philip will give a few pointers.

Hey Philip, how come there is a tiny bit of oxidation at the top? Mostly noticeable on the 1/4" tube cap connecting on the left evap. Is the entire oven not purged? I'm not nit picking, that oxidation is nothing, you have done an awesome job. They look very professional.

[[XC] gomeler]

STFU 2long! You are doing nothing but spamming this thread. It's people like you that spoil this place.
Polizei, you're not helping either.

If you're seriously keen gomler, I'm sure Philip will give a few pointers.

Hey Philip, how come there is a tiny bit of oxidation at the top? Mostly noticeable on the 1/4" tube cap connecting on the left evap. Is the entire oven not purged? I'm not nit picking, that oxidation is nothing, yo have done an awesome job. They look very professional.

It sounds like Phillip is using a kiln mean for ceramics. I was more interested in what DetroitAC and Walt were talking about. I did a short google search and it turned up either cooking ovens or component/vacuum oven sales. Then I got side-tracked into algae farming

[killermiller]

I'd like to see one prepped before it goes in the oven. Phillip, if you do another, take a before pic will ya?

What are you using for braze material?

How does Gosmeyer do the cryostars?

[DetroitAC]

What's the trick you guys use to get the evaps to not leak just until the the vehicle's warranty runs out ?

It's easy, hire substandard engineers like me

@2long4u: Yes! I must have copied somehow! The Chrysler Dayton Accustar plant was legendary for it's quality control of evaps.

@gomeler: They heat by radiation, and just use electric elements (at least mine does)

[[XC] gomeler]

It's easy, hire substandard engineers like me

@2long4u: Yes! I must have copied somehow! The Chrysler Dayton Accustar plant was legendary for it's quality control of evaps.

@gomeler: They heat by radiation, and just use electric elements (at least mine does)

So a vacuum chamber and then high-temp electric coils like those found on an electric kitchen stove? Seal it in a steel box, insulate, have a pump-down port. Hrm..

[DagoDuck]

I like it very much. Excellent work, indeed.