Need some advice on brazing please?

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Asos21
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Need some advice on brazing please?

Post by Asos21 »

So after realising that my brass fittings would be unsafe for use I've finally settled on brazing copper fittings on.

I'll be brazing something copper to the stainless steel boiler for connecting the riser. And I'll be brazing 2 X 15mm copper elbows fittings to the condenser. I'll also be brazing 2 small hose barbs to the condenser.

I'm looking at using Silverflo 55 brazing rods. These apparently have a working temp of 600 to 650 degrees Celsius.

Could I get away with using a small kitchen butane blowtorch for this job? The torch can heat to 1300 degrees Celsius though the flame will of course be small as its a kitchen blow torch.

And does anyone have a rough estimate of how many Silverflo rods I'll need? They are 55% silver and 1mm X 20cm in size.

I'm completely clueless with all this but I'm going to try and make it a success as my last attempt at brazing was a complete disaster.

Thanks all
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Ben
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Re: Need some advice on brazing please?

Post by Ben »

Should be able to do it with butane, it will depend if your torch is big enough to get past the heat dissipation of your project. Buy a few, you might get it done in one, but you don't need to be stressing out about that. You will use them eventually. Clean things really well!
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Asos21
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Re: Need some advice on brazing please?

Post by Asos21 »

Ben wrote: Sun Dec 05, 2021 9:34 am Should be able to do it with butane, it will depend if your torch is big enough to get past the heat dissipation of your project. Buy a few, you might get it done in one, but you don't need to be stressing out about that. You will use them eventually. Clean things really well!
Thanks Ben. I'll buy 5 of the rods so should be plenty.

Honestly my biggest concern now is the torch.

I just don't know if a kitchen blowtorch will be big enough to do the job. Even though it heats to 2+ times the temperature that the braze rods require.

The normal brazing blow torches are just Hella expensive.
NormandieStill
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Re: Need some advice on brazing please?

Post by NormandieStill »

Copper will spread the heat around fast so you'll need to keep up with that. Stainless will be a little easier. I strongly suggest you practice on some scraps before attacking anything final. To be honest I'd be surprised if your kitchen blow torch was up to the task. I used to do phosphor bronze brazing of chromalloy with a MAPP torch and I was always near the absolute limits and it was a pain in the neck. It's been a while since I lived in the UK, but based on prices here you should be able to get a butane / propane torch for less than £30 (I just picked up one here for about 25€).
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zed255
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Re: Need some advice on brazing please?

Post by zed255 »

I doubt the kitchen torch will be enough. I have used 45% Ag food service wire with a standard propane torch on smallish fittings, say <1" / 25mm. Beyond that you need a small oxy-fuel setup to heat quickly enough to do a good job.
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quadra
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Re: Need some advice on brazing please?

Post by quadra »

I agree, go buy a benzomatic torch and a bottle of MAPP gas.
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still_stirrin
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Re: Need some advice on brazing please?

Post by still_stirrin »

Getcha’ one of these:
Oxy-Mapp torch kit
Oxy-Mapp torch kit
Get several O2 bottles tho, because they go quickly if you have a lot of brazing to do.
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NormandieStill
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Re: Need some advice on brazing please?

Post by NormandieStill »

I don't know if it's still the case, but when I was doing brazing work in the UK, oxy kits weren't available. You could go oxy-acetylene with all the paraphernalia that it entailed (Bottles needed to be locked in steel cages when not in use), but I never saw oxy-fuel consumer kits until I moved to France.

On the other hand, MAPP bottles and MAPP torches were way more readily available in the UK than over here.
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Metalking00
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Re: Need some advice on brazing please?

Post by Metalking00 »

Those oxy-mapp setups are great. Way better than a plain mapp torch.
Asos21
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Re: Need some advice on brazing please?

Post by Asos21 »

Thanks everyone for the advice. I settled on a mapp torch and some Silverflo 55 brazing rods.
Asos21
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Re: Need some advice on brazing please?

Post by Asos21 »

So I just bought 5 of these Silverflo 55 brazing rods and I'm absolutely shocked after seeing them!

They are tiny! 1mm X 20cm.

Like literally it don't even look enough to solder a single 28mm pipe!

From what I gather I'm going to need to solder 2 X 28mm joints on the boiler. Both sides of a 15mm coupler, both sides of a 28mm to 15mm reducer, 2 nipples on the condenser and 2 28mm end caps on the condenser.

These 5 rods just won't be enough will they?
IMG_20211210_130700_492.jpg
LED_ZEP
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Re: Need some advice on brazing please?

Post by LED_ZEP »

Hi
I'm no expert but I made a 2" dephlegmator and a condenser that have served me well. Not having any access to brazing or welding kit I thought I'd just try soldering. Make sure to use solder and flux that is marked for use for potable water plumbing.
Apparently I broke all the rules as you're not supposed the be able to solder SS to copper, but I did using a cheap butane blow torch (apparently they don't burn as hot as a MAP torch so can't be used with brazing rods). I think the key was to make the parts to a high tolerance so they fit tight and use plenty of flux.
If anyone wants more details just ask.
dephleg.jpg
NormandieStill
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Re: Need some advice on brazing please?

Post by NormandieStill »

Asos21 wrote: Fri Dec 10, 2021 5:07 am So I just bought 5 of these Silverflo 55 brazing rods and I'm absolutely shocked after seeing them!

They are tiny! 1mm X 20cm.

Like literally it don't even look enough to solder a single 28mm pipe!

From what I gather I'm going to need to solder 2 X 28mm joints on the boiler. Both sides of a 15mm coupler, both sides of a 28mm to 15mm reducer, 2 nipples on the condenser and 2 28mm end caps on the condenser.

These 5 rods just won't be enough will they? IMG_20211210_130700_492.jpg
You don't need a lot. If you're soldering (or brazing) you should be fitting pieces with a very fine tolerance. I think silver solder is supposed to be in the order of 0.1mm. When everything is right, the flux is where it should be, both pieces are up to the right temperature, you touch your rod to the joint and capillary action will "suck" the solder into the joint, filling that tiny gap completely. You're not building a fillet like in TIG welding, you're "glueing" together two pieces with a good mechanical fit.

You'll be amazed how strong a <0.1mm puddle of solder is. When I was doing phosphor bronze brazing of chromalloy, I tested my method by attaching a strip of steel to a tube. The strip was about 5mm wide and maybe 20mm long. The bronze flowed right through the joint and out the other side. And despite some serious effort with pliers I never managed to tear it off.
"I have a potstill that smears like a fresh plowed coon on the highway" - Jimbo

A little spoon feeding *For New & Novice Distillers
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