I'd like to improve my copper brazing technique. (refrigerant lines)

I would like some tips to improve my copper pipe/copper fitting brazing technique. I practiced yesterday afternoon on some scrap 3/4" copper pipe and fittings and my joints are leak free but there's room for continuous improvement. I'm not producing nice consistent fillets even though the joints are filled.
I'm using oxy/acet, #2 tip, about 2-3 PSI, neutral to slightly reducing flame and Sil Fos 15.
Is this configuration about right for 3/4" connections?
Do you like to start at the bottom of the joint and work your way to the top or vice versa.
I know Sil Fos on copper to copper doesn't require a flux. However can flux be used? (ie in order to better gauge temperature of the joint). Will flux help achieve better joints?
Do you like to aim the torch flame towards the pipe end or the fitting end as your sweeping back and forth? Or do you aim it perpendicular to the axis of the pipe? Or do you like to heat the joint by going up and down or figure 8?.
Do you actually touch to inner cone of the flame tip to the fitting or do you back it away a little bit to reduce any chance of burn thru?
I'm using Sil Fos 15 ribbon filler. Would round work better? What diameter?
TIA.
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This will cover most questions. http://www.copper.org/resources/pub_list/pdf/soldering_brazing_ads.pdf
The other questions are kinda like... "What does it feel like to eat Ice cream?" 10 minutes of hands-on instruction with someone who does it everyday would be invaluable.
-zero
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Thanks. That's a great link!.
What size torch tip would you use for 7/8" copper tubing and Sil Fos 15. The objective for brazing copper suggests you bring in lots of heat, do your brazing quickly and get out. Is a # 2 Victor tip too small?? Is so what's the optimum tip size for Oxy/Acet brazing of refrigeration lines?
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It depends.
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wrote:

A lot of good that does the OP!! If you don't know anything step aside.
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.pdf
Shut the fuck up, asshole.
--







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I use a number 2 tip 7psi for Acetylene 21 psi for oxygen and that will take me thru 1-1/8 easily. Even did 1-3/8 with that setup. silfos 15. your mileage may vary.
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If you want to learn how to braze you will need to find some one who have some experience, torch tips don't mean nothing it is better if you have right tools no one will denied that but good braze can be done practically with any torch that can give heat needed. Sil-Fos I use cheapest one I can purchase and I never had any problems on any size of copper pipe, if you are going to be brazing coppernickle or (cupronickel) and brass then yes you should use 15% silver you will find it much easier to work with. main thing is that joints are clean fluxed and don't over heat don't apply heat directly on to Sil-Fos applied heat in direction you want sil-fos to flow and wait for joint to be hot enough before you apply how hot well when color start to change from dark to perhaps little reddish remember I said reddish not red sil-fos, also remember sil-fos will oxidize if is over heated. From Dido

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Thanks for "most" of the replies. In hindsight I feel I was not brazing using a good systematic procedure and I also think I was being too conservative with the heat.
I like the Copper handbook method of heating pipe, then heating pipe AND fitting and then hitting the base of the fitting until Sil Phos gets sucked in from capillary action. I also like their tip of starting at the bottom of a horizontal joint in order to build a dam and then braze up on one side and then up on the other.
I'm also going to dial up the heat a bit. I think I've been too paranoid about burn thru and haven't been hitting it with enough heat. The best practice seems to bring in lots of heat, braze and get out quickly. I think I'll give a rosebud a try vs a #2 tip.
Practice makes perfect right?
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you got it Dido
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Today was practice session #3. I used Stay Brite #8, Stay Clean Flux and a propane torch. I must admit I really like this method. No need for Nitrogen and you don't need near the heat. It's also easy to tell when the solder is ready to flow. It's almost foolproof as long as your joints are clean and you pay attention to detail.
I also tried session #4 using a small rosebud and Sil Phos 15. I must admit that using a rosebud is my favorite Oxy/Acet method. I made my best joints yet. The rosebud really heats the joint to red hot fast and the Sil Phos flows like butter. I witnessed first hand what the pros suggest. (ie bring in lots of heat, braze and get the hell out).
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