Brazing torch

[Bill DawesParticipant @billdawes]

I am looking to buy a gas torch for brazing/silver soldering but a bit confused with all the options of butane, propane, butane/propane mix & MAPP.

I was thinking along the lines of a torch with disposable canister attached ( I anticipate it will be occasional use only) however as we do caravanning do have larger gas bottles (both propane and butane at the moment) but any guidance welcome.

I have a camping gaz butane canister torch that I have used for many years on plumbing jobs but assume it will not be hot enough for brazing.

Bill Dawes.

[Bill DawesParticipant @billdawes]

[mgjParticipant @mgj]

Its not about occasional use or not, but how much heat you need!

 

You can’t beat the Sievert starter kit, which runs off propane. 4 bar HP regulator, plus hose and a torch. The kit has their basic nozzle, but you can buy nozzles to suit all purposes. The 4 bar regulator will feed any nozzle too.

 

Cheapest I found it was from Machine Mart (by some margin), but it is available from Reeves and CUP alloys and I think Chronos. (well if I’m honest someone on this forum found it and posted a link – grateful)

 

I had a Calor system, rated off a 2 bar regualtor. You spent half the day heating even the smallest items. The Sievert just wellies it, which is better for the flux, and the whole thing is done in one, thoroughly and with certainty. You can step braze with higher melting point alloys with ease – in fact I regularly use one of the HT alloys just because it has better fillet forming properties than Easy Flo/842. 

 

If you are talking of silver soldering jewellery sized stuff then the smaller burners could well be all you need, but I would doubt that one of the disposable canister range has enough urge to heat up model engineering stuff (at reasonable operating costs)

 

[JasonBModerator @jasonb]

Although the MAPP gas is said to have a hotter flame most of these torches will not put enough heat into larger items.

 

Given that you already have Propane cylinders I would go with a basic torch to use with them, something like this would be OK for fabrications and even a small boiler for a stationary engine

 

Jason

[Nigel McBurney 1Participant @nigelmcburney1]

hi    Buy a Sievert  kit,  torch , hoses,regulator and an assortment of burners sizes to suit your needs ,and run off your propane cylinder,reasonably economical and gives a good hot flame,with plenty of gas in reserve for those bigger jobs. Small canisters have no capacity for the medium and large jobs. Brazing needs more heat than silver soldering and there is no choice other than propane.When silver soldering to get the best results,the work and the flux needs to reach the soldering temperature quickly so use  a decent sized burner. 

[Nigel McBurney 1Participant @nigelmcburney1]

hi    Buy a Sievert  kit,  torch , hoses,regulator and an assortment of burners sizes to suit your needs ,and run off your propane cylinder,reasonably economical and gives a good hot flame,with plenty of gas in reserve for those bigger jobs. Small canisters have no capacity for the medium and large jobs. Brazing needs more heat than silver soldering and there is no choice other than propane.When silver soldering to get the best results,the work and the flux needs to reach the soldering temperature quickly so use  a decent sized burner. 

[John HaineParticipant @johnhaine32865]

For something simple, a Bernzomatic torch head with a yellow MAPP cylinder is excellent.  Far superior to all those cheap & not-so-cheerful butane torches that the DIY shops sell. 

[Les Jones 1Participant @lesjones1]

Hi Bill,

            If you choose the “Sievert” torch option I bought mine from Millhill Supplies

Millhill Supplies   But have since found that  that “Hamilton Gas Products” are cheaper

Hamilton Gas Products   I went for the 3486 handle and the 3525 cyclone burner. (10.2 KW)  I found there is a large variation in prices from different suppliers.

Les.

[CirclipParticipant @circlip]

Wonder if the O/P really wants to “Braze”?? Seems the weapons of choice in the past, ie. the five and two pint blowlamps, are long gone.

 

  Perhaps MUCH too dangerous for the elfins to allow muppets to operate.

 

  Regards  Ian.

[Ian S CParticipant @iansc]

What gas does the yellow MAPP cylinder have? The gas I use here is a mix of butane and propane, they’v got the mix right now and it even burns in the winter(few years back if the workshop was cold-no pressure). I’v got a 1/2 pt petrol blowlamp, thats the reason I got the gas! Ian S C

[JasonBModerator @jasonb]

Circlip, I was thinking that. Maybe he wants to “silver braze” as the Americans call it. I doubt propane would get upto the temps required for proper brazing unless it was very small parts as its usually done with oxy/acet or I use the carbon arc rods on a welder.

 

Jason

[Pat BraveryParticipant @patbravery]

I also was interested in having some brazing facility and upon looking at the link to Machine mart decided to buy a torch at £27.01, I reaffirm the old addage that you get what you pay for. I tried to braze some 1mm steel plate and I gave up after 5 mins as there was insufficient heat. I had the regulator on the highest setting. I will use it for soldering and dig a bit deeper for a proper set up. Pat

[Steve GarnettParticipant @stevegarnett62550]

Posted by Ian S C on 24/03/2010 11:31:28:
What gas does the yellow MAPP cylinder have?

 

According to Wikipedia, the composition of the gas is: propyne 30%, propadiene 14%, propylene 43%, propane 7%, C4 (isobutane, butane) 6%. So basically it’s LPG.

 

The Bernzomatic gas (the stuff in the yellow cylinders) specifically has a combustion temperature of 1,982°C (3,600°F) in air and 2,867°C (5,193°F) in oxygen. You can’t use it for welding steel though, because the welds end up being brittle due to the hydrogen in the flame, which infuses into them.

 

So yes, it can weld (nearly as hot as acetylene with oxygen) but really it was only ever used for cutting in this context, and generally underwater at that, where it had advantages until they all started using exothermic cutters.

 

 

 

[Ian S CParticipant @iansc]

Thanks Steve, I’v used LPG for cutting(not under water), found it worked quite well, although it uses a lot of Oxygen 4.5:1 for a neutral flame compared to 1:1 for Oxy-acetylene.It gives a softer edge to the cut than Oxy-acetylene,got for brazing realy big stuff. Ordenary LPG in NZ burns at 4890F, but LPG has 2500BTU per cu ft compared to Oxy-acetylene with 1475 BTU per cu ft. Ian S C

[JohnFParticipant @johnf59703]

Hi Bill everyone seems to advocate Seivert torches; I have been using Bullfinch torches  professionally on a daily basis for over 30 years and find them superior to others I have tried. These are the auto ignition torch–a little more expensive but very convenient and you can get a range of nozzles for varying work size. Look at http://www.adamsgas.co.uk but there are many other suppliers. All the best John

[Richard ParsonsParticipant @richardparsons61721]

 

I have used Seivert torches for along time. But once in a silversmith class I used a Air propane unit. It was a Rolls Royce of torches. I have hunted for one ever since. Any one any ideas as to where I could get one?
 I think it was called a Flame-master,  but as good things go they seem to have gone.

[NilochParticipant @niloch]

It wasn’t Flame-fast by any chance?  Flamefast equipment was very popular in schools’ CDT Depts.  especially for natural gas.

Flamefast

Edited By Niloch on 05/07/2010 21:21:04

[Richard ParsonsParticipant @richardparsons61721]

 

No it was a Flame Master. I know of the Flamefast kit and this was different it was in solid cast aluminium and had an economiser trigger which you pulled in to use the torch. There was another one at the same college which had three gas supplies gas, compressed air and oxygen. It was made in Germany and was probably ‘a liberated’ item.

I have a micro flamefast burner, which is a devil to use as I have to clean out the residues left by the gas each time. I have not tried it over here yet.

[A D 1Participant @ad1]

Hello everyone,

I know I am kind of resurrecting an old thread here, sorry in advance if that's the wrong approach.

I recently got the Bullfinch Brazing torch, and I would appreciate your input with a problem I am having:

I am trying to braze some 8mm threaded bar to a section of 30x30x3mm mild steel

The steel is drilled 8mm and the threaded bar is sitting in hole. The steel is set on, and partially surrounded with fire bricks, but I am struggling badly to reach a temperature where the brass brazing rod runs into the joint.

Is the steel section too big for this torch?

Or would it be a flux issue? (I ordered brass brazing flux, but the company sent me silver solder flux-I am temporarily using this)

The steel gets red hot easily enough, but the rod doesn't melt (or at least certainly doesn't flow) by touching the steel – only when the flame is directly applied to it.

Would appreciate your thought,

Thanks,

Á D

[JasonBModerator @jasonb]

If it is the 404 that you have then all the videos I have seen of it are with quite thin material so probably not getting hot enough

[A D 1Participant @ad1]

Thanks for the quick reply.

Do you have any experience brass brazing with propane only? I am wondering if the Sievert would give better results, or would an oxy- or air-gas torch be needed for that size of steel?

Thanks

[Bill PhinnParticipant @billphinn90025]

A D, I wouldn't want to be trying to brass braze with a flux designed for silver solder personally; the likely lower temperature tolerance of the silver solder flux may render it useless by the time your brass solder is ready to flow.

Also, do you have a compelling reason to want to brass braze here rather than silver braze?

It's hard to tell if your torch is too small. The job doesn't sound a particularly big one.The standard burner with the 404 is, I believe, 4.76 kW, which is a relative tiddler in the propane torch world. Reassuringly, you do say the steel is getting red hot easily. But do you know that to successfully brass braze, the steel has to get considerably hotter and redder than when silver brazing with typical silver solders?

Even if you do know this, we come back to your present flux and its probable inadequacy for brass brazing.

[IanTParticipant @iant]

Hi AD,

The Bullfinch should handle that work with no problems, provided the work is clean, you use the right flux (?) and you can 'contain' the heat (I use a simple hearth inside).

This is a similar sized part (3mm laser cut steel – base being about 35mm square) and the only problem I had (at first) was not allowing any gap for the Sifbronze to flow into. Second attempt worked fine – just a problem of my technique, not the torch.

Here is the finished part – not perfect perhaps but very strong. If you look in my 'Brazing' photo folder, you will see some larger items I brazed with the Bullfinch. Only when trying to join the very large plate to its base (it's about 180 x 120 x 100mm) did it struggle with the Sifbronze – and I had to use silver solder to complete it. These days, I would have just added some more heat from one of my other (disposable) propane.butane mix torches (as the metal radiant area was quite large) – and shielded it better.

.

The Bullfinch 404 is not a replacement for Oxy/A but works very well for small ferrous fabrications. There are many users of Sievert torches here (I have a similar (non-Sievert) torch myself) and they are certainly good where I want large volumes of heat (e.g. for boiler work). However, the Bullfinch is very good for the work I use it for – and Sifbronze is at least an order of magnitude cheaper than silver solder (which I still use of course for non-ferrous brazing).

So I'd suggest you practice with Sifbronze and the right flux – making sure that the work is correctly shielded and the filler can flow into a slight gap in the parts (similar to silver soldering really).

Have a look here – I use the 1.6mm rod by the way (£26.85 for 1kg ! ). They also do the correct Sifbronze Flux – 500gm for £13.75 (inc VAT) which will last you some time.

Sifbronze No 1

Regards,

IanT

[A D 1Participant @ad1]

Hi Bill,

I was thinking the flux might be causing problems.

As for brass brazing- no I have no objection to using silver solder-which I might end up doing yet.

I was mainly making long drill bits with silver steel and for that purpose bought some brass rods believing them to be stronger and cheaper than silver, and it worked on those. So I suppose my reason for brass brazing on this occasion is really because that's what I've got at the minute. And since it failed I want to know whether the torch is at/past its limit with this size of steel.

Hi IanT

Looking at what you have brazed there I think the torch should definitely be able for what I was doing.

When you say the work should be properly shielded – what would you suggest using? I'm using fire bricks to insulate for now but I'm not sure how effective these are.

I will try again once I get the correct flux.

Thanks both for your advice!

[JohnFParticipant @johnf59703]

I have had a Bullfinch torch for close to 50 years now, only once have I had a fault the auto ignition failed and the company fixed it and charged only return postage ! As far as the job in hand is concerned it should handle it comfortably but as already said you will need to make up a hearth, however beware some "fire bricks" are designed to absorb heat not reflect it, e.g. the ones from storage heaters, so make sure you have the correct bricks or other material.

Almost all my work is silver solder but for brazing you can use Borax, old fashioned yes but it was used pretty exclusively until better fluxes were developed.

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