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Gallery, Projects and General => How do I?? => Topic started by: SemiSkilled on March 15, 2011, 06:33:32 PM

Title: Brazing with brass rod, will forced air do it?
Post by: SemiSkilled on March 15, 2011, 06:33:32 PM

I have a Flamefast brazing hearth, propane torch with a blower, the torch is rated at 80,000 btu.

I'm trying to braze mild steel 16mm dia with brass rods as they're a bit stronger than silver solder and cheaper too,n from what I've read the job needs to be really hot, red heat, can't seem to get it to red heat and have the rod melt on the job.

do I need Oxy/ Acet ?

Any experts out there ?

thanks

Lee.

Title: Re: Brazing with brass rod, will forced air do it?
Post by: Troutsqueezer on March 16, 2011, 01:00:22 AM

I'm not an expert but I have brazed with brass rods a number of times. I use a MAPP torch.

Title: Re: Brazing with brass rod, will forced air do it?
Post by: picclock on March 16, 2011, 04:02:42 AM

You may be better off borrowing an additional torch. I'm not familiar with your Flamefast brazing hearth, but higher temperatures require low heat losses from the work being heated. 

I use refractive insulation bricks stacked around, over and under the work so that any radiated heat is reflected back. A std propane torch has a flame temperature of around 1900C, and brass melts below 1000, so if you can keep the thermal losses down it should get there easily.

So no drafts and strategically placed extra refractive insulation should resolve the issue.

Hope this helps

Best regards

picclock

Title: Re: Brazing with brass rod, will forced air do it?
Post by: mike os on March 16, 2011, 09:05:55 AM

needs to be quite hot...almost 900c iirc. maybe oxy prop?... done small thin sections that way but not sure if it will have enough heat for larger pieces...without heating the whole piece to near brazing temps

Title: Re: Brazing with brass rod, will forced air do it?
Post by: tonybraz on March 17, 2011, 06:33:55 AM

  I have a Bullfinch 4100 this runs its own regulator at 4 bar and  gives out a lot of heat with a smaller flame

   http://www.bullfinch-gas.co.uk/index.php?page=shop.browse&category_id=43&option=com_virtuemart&Itemid=1

   Tony

Title: Re: Brazing with brass rod, will forced air do it?
Post by: SemiSkilled on March 17, 2011, 03:34:17 PM

Picclock nailed it, I thought I had enough fire brick around the job but I hadn't put a roof on .

Once I had nowhere for the heat to go, within 5 mins my test pieces were up to red and brazed up OK. this does make getting the rod in a bit difficult but reading one of the workshop practice series

http://www.amazon.co.uk/Soldering-Brazing-Workshop-Practice-Tubal/dp/0852428456

I could place the rod as a preformed ring or cut up pieces of rod or even spelter grains, which seem to be brass filings.


So, "Brazing with brass rod, will forced air do it?" easy.

Lee