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propane brazing

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JasonB27/11/2017 18:34:00
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25215 forum posts
3105 photos
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What Burner number have you got on the Gun?

Flux will last for years in the tub, as the others have said Tenacity 5 or HT5 have a much longer working period than standard Easyflo flux so won't get exhausted before your work is upto temp

Dusty27/11/2017 20:05:33
498 forum posts
9 photos

Another trick I have employed in the past when silver brazing small steel parts is to mix the flux with methylated spirit. This prevents the steel oxidising with the water in the flux. Care is needed in that you need the meths to vaporise off before heating otherwise you can get some interesting results. Do not do it inside for obvious reasons.

fizzy27/11/2017 20:09:17
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1860 forum posts
121 photos

You havnt said what flux you are using but I dont use easyflo on anything, ever, as it burns out so much quicker that T5.

IanT27/11/2017 21:37:30
2147 forum posts
222 photos

Philip,

This is 3mm thick (laser cut) steel - the square part is about 40mm square. It was easily brazed just using propane with the 404 torch - I have also done other (larger) parts with some additional background heat. The SIF brazing material was only applied to the inside of the unit but you can see that it's penetrated through. For SIF-bronze (e.g. brass brazing) I use SIF-Flux - I'm not sure how this compares with Tenacity but it works well enough as long as you don't hang around too much (but that's the same for any flux when silver soldering). SIF-bronze is also considerably cheaper than silver solder.

So for small (steel) fabrication work I think the Bullfinch 404 is a good solution and doesn't need anything special (e.g. expensive and/or dangerous) to use.

Regards,

IanT

Drag Bar 3

Drag Bar 4

Nicholas Farr27/11/2017 22:47:57
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3988 forum posts
1799 photos
Posted by Vic on 27/11/2017 15:32:33:

When I worked in the motor trade many years ago we were told that it takes several hours for an Acetylene cylinder to explode if you get a blow back. I read a report some years back though where a cylinder exploded about 5 minutes after a blow back. Luckily no one was injured in the explosion but the building was damaged.

Hi, the state when Acetylene becomes explosive (apart from the obvious) is very unpredictable. To be reasonably sure you are safe with it, it is important to follow all the safety precautions with its use and that includes having well maintained equipment that is used with it. If there is Acetylene in a fire, there will be an automatic 200M exclusion zone around the fire, for at least 48 hours. It will only be banned from specific sites. In my day job we use Acetylene on very many sites, but it nearly always involves having to obtain a "hot work permit" before you start to use it, and all the precautions stated on the permit must be in place and adhered too.

Regards Nick.

IanT28/11/2017 10:45:26
2147 forum posts
222 photos

By the way Philip - another recent thread (brazing hearth) has reminded me of the importance of retaining/reflecting the 'heat' you do have available - as otherwise it will be much harder to get sufficient heat in place quickly.

I've mentioned the use of ceramic blanket in the other thread and you can see the ceramic I use in the background of the photo I've posted above - and it is folded around the work. Perhaps also of note - is that the part is supported on a piece of thin tin on edge - this helps circulate the heat underneath the work, doesn't conduct too much heat away and is less of a problem to remove (should an edge inadvertently brazed/soldered to the part).

Regards,

IanT

the artfull-codger28/11/2017 11:30:40
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304 forum posts
28 photos

Over the years I've gradally built up most of the sievert nozzles & a few torches & they've served me well from boilermaking to fabrication jobs both brazing & silver soldering,but since aquiring a flamefast brazing hearth it takes it too another level, they really are good,I also have a small "chance" air/gas torch for small jobs, it was for town gas & flamefast wanted £30 a torch to convert them,well that wasn't going to happen!! so I just tried them on propane & butane & they work fine except the regulators very sensitive but just as good as the town gas ones I used at school where I worked [Can't be spending money when we don't need too!!] they sometimes come up on ebay.

Philip Burley28/11/2017 11:36:49
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198 forum posts
1 photos

Hello thanks every one for the advice , I am using a sievert 2941p burner and easyflo flux

Clive Brown 128/11/2017 11:46:26
1050 forum posts
56 photos

I was interested in the earlier tip from Dusty about mixing flux with meths. I don't do much silver soldering of steel, but when I do, I have reckoned that I get better results and better solder flow by putting the dry flux powder on the joint, rather than a water mix..

Sometimes more awkward to get it to stay in position though. I'll try meths next time.

Alan Vos28/11/2017 19:30:05
162 forum posts
7 photos

Posted by SillyOldDuffer on 27/11/2017 09:16:35:

I was intrigued by that too, but it does make sense depending on the Site. For example it's not allowed at Heathrow as per this Instruction.

That document states:

"If there are absolutely no practicable alternatives then acetylene may be used subject to the
approval of an “Acetylene Justification Report” by the Heathrow Fire Safety Team."

So, like all sensible prohibitions, it has a exception clause, with an approval process that is sufficiently stringent to deter the chancers.

AFAIR, the Home Secretary can still permit ownership of a handgun.

larry Phelan29/11/2017 15:47:09
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544 forum posts
17 photos

I did that some 50 years ago,using two blowlamps,I was making a carrier for my motorbike at the time.

Took a while to get the heat up,used a few firebricks to help [all I had at the time ],but it did work.

Brian H29/11/2017 17:54:07
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2312 forum posts
112 photos

Many years ago, Rolls-Royce Aero specified surgical spirit to mix flux because it leaves no residue unlike meths.

The trick then is to gently heat the fluxed job so that the the surgical spirit catches fire and bakes the flux onto the parts being joined. The heat can then be turned up without the danger of the flux falling off, as happens with a water mix.

Brian

Mark Rand29/11/2017 20:24:06
1505 forum posts
56 photos
Posted by Brian Hutchings on 29/11/2017 17:54:07:

Many years ago, Rolls-Royce Aero specified surgical spirit to mix flux because it leaves no residue unlike meths.

Surgical spirit definitely does leave a residue. It's industrial spirit mixed with 2.5% castor oil. Industrial spirit is the one you'd want, That's ethanol with 5% methanol.

Regards

Mark 52 years a diabetic, injecting insulin

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