brazing flux paste

[hotrodder]

It was more of a suggestion for something cheap to try than a recommendation. You may hate it from the lumpiness versus runnyness POV, should find it easy to remove the residue, doubt it'll be as nice to use as the posh premixed paste. Nothing is as nice as gasfluxing but then you've got to be selling a lot brazed products to justify the cost of that kit...

Even if everyone is in the States talking tip/nozzle sizes must still be a nightmare unless everyone is using the same torch... http://bikesmithdesign.com/Welding/tips.html Assuming you're using a Saffire then yeah, probably 3, 5 & 7 got used the most

 

[bambuko]

Thanks hotrodder,
- boric acid powder on order
- Mark Stonich's table is fine but doesn't include UK tips, I have created my own table roughly equating Victor's tips to UK tips:

Victor nozzles quote recommended plate thickness and orifice diameter, UK nozzles only list recommended plate thickness.

Also had other discussions confirming my choice of 3, 5 and 7 (btw I am using Butbro, but afaik it's the same as Saffire) for use with oxy-propane.

I have also done some "experimenting" with Sifbronze flux and after a bit of grinding it has changed from granules to powder and I was able to mix it to a nice creamy consistency paste

ps very good interview with Ron Cooper, couple of years ago:
http://thebikeshow.net/ron-cooper-on-ron-cooper/#podPressPlayerSpace_1

 

[hotrodder]

Cheers for that, brought back some memories.

 

[JDJones]

Hello bambuko At college we taught brazing, beginners started with bare filler rods heating the end and dipping into SIF powder flux, then flux coated filler rods, then impregnated flux filler rods and we also had one Oxy/Acet station fitted out with a Gas Flow fluxer here the liquid flux was carried to the flame via the Acetylene line all students had a go at all processes, also plunging their specimen into the cooling tank when very hot which cleaned it up a treat.
Braze welding is very strong and was in those days used extensively, I am talking about the 70s 80s 90s though, small MIG welding machines were pretty new then. All the Best desmo11225

 

[piman]

Hello Bambuko,

not of any use to your quest but I find that SIF aluminium flux mixes very well with tap water. I've not tried making a paste with their brazing flux however.
As another off topic, how is it that the American torches use higher recommended pressures than U.K. torches, well my BOC or Murex torches?

Alec

 

[Ped]

Hi Bambuko,
I have a bit of experience with both flux and fillet brazing. I have Sif (old and new), Tenacity, Braze Tech, Cycle Design and a gas fluxer.

Without doubt the gas fluxer is king but unless you're lucky on Ebay they're pricey. They do come up occasionally though. Out of the paste fluxes Cycle design is the best of the bunch. It soaks off in hot water without agitation and changes fluidity/state as you're brazing, giving a helpful indication of temperature. Yeah, it's more expensive but you have a choice here, either you spend hours and days struggling (and probably failing) to make something inferior work or you buy the right stuff that works day one, right out of the box.

The Sif and Tenacity powder fluxes both set like glass and can't be soaked off in water. You could probably add something to the water/use an acid but then you're reducing the saving you've made over the Cycle Design flux. if you have one you could probably use a media blaster, but do you really want the hassle? BTW, the old, red coloured Sif flux was OK, the new pink stuff is absolute rubbish. As you've discovered it won't mix into a paste unless you grind it. Throw it away.

I use a lightweight torch with a number 2 nozzle for fillet brazing frames. You need to use a soft flame and be patient. You don't need anything over that size unless you're building with lugs. Larger torches (eg Saffire 3) use larger nozzles but are numbered in the same way 1, 2, 3 etc. I only mention this because I made the mistake of thinking they were the same.

Cheers
Ped
www.eracycles.co.uk

 

[bambuko]

Thanks very much guys!
All very useful info
No, I do not have media blaster, but tend to leave my brazed bits in rain water butt overnight and it seems to make it slightly easier (but as you say Ped - new pink stuff is absolute rubbish).

I have also learned that patience is the name of the game - slowly getting better :-)
I am not using lugs - it's all fillet brazed.

thanks
Chris