AmericanLongRifles Forums
General discussion => Gun Building => Topic started by: Thom on February 07, 2014, 09:16:20 PM
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I've been wanting to learn how to braze and I think I'm ready to give it a shot. I do have a Bernzomatic oxygen- propane/mapp gas torch, but it is a PITA to use. It does not keep a consistant flame, and uses up a tank of oxygen in about fifteen minuets. Any suggestions would be appreciated.
Thanks
Thom
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You need a lot of heat to braze, and the right flux. Borax works just fine, tho' a local welding shop will have specialized brazing fluxes. They might have 'low temp' brazes that melt around 900 F. These brazes probably will have silver and other metals in them.
If you make a surround of soft fire brick, you might experience better results. The brick will reflect and concentrate the heat, and in the end, is more economical with gas.
Brazing can be done in a furnace, over a coal or charcoal fire, and with Oxy-acetylene torches.
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I know about using the fire bricks. I did not think I needed to invest in oxyacetylene all though I would. I do have a small, hand crank farrier's forge, but I think I would be more comfortable with a torch.
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I did not think I needed to invest in oxyacetylene all though I would.
It's the only way to go. Besides brazing, you will also be able to weld steel and quickly heat up metal parts to bend or harden them.
Many uses outside of gunwork too. I've used mine to weld patch panels in old cars, straightened frames with a rosebud tip, welded up lawnmowers and trailers, etc. It's an invaluable tool.
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I braze and weld using my forge. For brazing mounts, it is very easy. For large parts, you do need a lot of heat.
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Thanks much. I expect I will be purchasing a torch. I have only used my forge for annealing and hardening larger parts like lock plate and frizzen. I'll learn more about using it when it warms up.
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I have a coal forge and it works great for brazing but its a pain to fire it up just to braze a BP or Trigger guard. I have a Mapp Torch (doesn't use Oxygen) and it works fine to braze/silver braze small items but it will not get a BP/TG hot enough to use the 1/16' silver braze that I have. I made a small forge from a couple of fire bricks but can't get a BP in it nor can I get a TG positioned to suite me.
I solved my problem by hanging my BP or TG out over a small single burner camp stove to heat it up then using the Mapp torch to bring the metal up to brazing temperature. Works fine for me. I use an old can of Silver braze flux that I bought with the roll of silver braze wire. I sprinkle a little of it on the area to be brazed then then sprinkle brass shavings over that or I use the 1/16" silver braze. As soon as the flux/brass flows I take it away from the heat and quench in water. (of course the joint but be fitted and cleaned prior to brazing)
Yes an oxyacetylene torch would be great but with the cost of purchase plus the tank rental I just can't justify the expense.
Dennis
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The feline's pelt is removed in many different ways.
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What are your regs set at most people have them set way too high and cannot get a good even flame. Try settings of maybe 7 to 10 psi
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I did not think I needed to invest in oxyacetylene all though I would.
It's the only way to go. Besides brazing, you will also be able to weld steel and quickly heat up metal parts to bend or harden them.
Many uses outside of gunwork too. I've used mine to weld patch panels in old cars, straightened frames with a rosebud tip, welded up lawnmowers and trailers, etc. It's an invaluable tool.
I'll also agree with these responses.
I just use the small size tanks (B?) so they're not so cumbersome. About 2 ft high and 6" dia.
It cost IIRC $13 to refill the acet not long ago and it lasts a long time for this type work using small tips like #0 and #2. It's fast heat,, means you're not standing there for 5 minutes wishing the part would come up to brazing or welding heat wasting gas. If anything you have to learn not to over heat stuff.
I bought my own tanks, that way I just take them in and refill.
The torch kits (hoses, gauges, torch, some tips and accs) are sold quite inexpensively for about $100 and up.
I'm sure pro-welders have an opinion of brands but for what I do,,,,mine happens to be a Harris
The 'repairmans' type kits which includes the tanks (but they are the smallest ('MC' size) and a carry pack to carry everything around in can be bought for around $250-$300.
The small tanks might not be what you need if you're going to get into large welding projects in auto & fabrication type projects, ect.
I bought a small cart that fits the next up size tanks I use and it makes all the difference in the world using the unit. Plus the safety of having them secured well and not just leaning up against a wall or bench.
Just some of the options around.
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I love brazing in the forge. Your little farrier's or rivet forge is just right. I use my little mc size ox/acet. outfit a lot for small stuff. It is quicker than building a fire in the forge if you only have one thing to braze. Still I can have brazing heat in the forge in about 15 minutes. You really do need ox/acet. outfit if you want to braze with a torch. I usually set acetylene about 7# and oxygen at about 18# for brazing or welding. You need more pressure for rosebud tip. Flux coated brazing rod works well but any brass with borax for flux will work.
Brazing in the forge goes like this: Clean the parts to be joined bright. Pin them together or clamp in some manner, flux with borax. Cut strips of brass or brass wire and form it to lay near the joint. Lay it in the fire and bring up the heat slowly. When the right heat is reached it looks like magic. The brass will melt and poof you are brazed.
Brazing with the torch is easy. Again clean the parts bright and clamp or pin. With the flux coated rod you don't need any borax. Keep the torch moving in little circles ALWAYS. If you don't you will burn holes in your stuff. Start your heat at the thickest or heaviest part first and run the brass in as it melts.
I have done a lot of brazing and welding with ox/acet. as I have made my living doing commercial refrigeration. Every new guy I've ever trained (even the ones who told me they were expert at brazing or silver soldering) always burned holes in the fittings the first time I let them try.
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Thom,
There are many ways to braze I knew an old man who used a carbon arc torch and he just thought it was the only way to do it , I use an oxy aceyteline and use it a lot for shaping small parts and heat treating them.
you can get a small set up pretty reasonable I use a victor now ,and you can still rent tanks I believe .
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Hope I'm not butting in here, but I do have a question that relates to this topic:
What about brazing with a TIG Torch? You can buy filler rods specifically for brazing in various diameters.
I'm only asking because I've been meaning to try it with my TIG machine...If anything, the ability to finely control the heat surely must be better than bringing most of, if not, all of the parts up to such a high temperature.
Will
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I have been reading and watching videos about brazing for weeks and I got more practical information from this thread than everywhere else combined. Now I know enough to be confident in my decisions.
Thank You
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I don't have a lot of TIG experience, I just know that zinc can boil off while working brass. Zinc fumes are TOXIC. Also consider that color matching can be difficult when the zinc burns away, as TIG leaves a redder, copper-rich alloy in the weld.
Always have good ventilation going when taking solder/braze metals to a high temp. Some old formula silver solders carry cadmium, which makes the fumes TOXIC. I'm sure the fumes from fluxes aren't so healthy either.
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I found that some gas suppliers do not want to rent tanks to hobbyists or low-use builders. If you go to rent tanks, tell
them that you have a business, not a part-time or hobby shop. Jim
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Gosh - there really are a bunch of ways to do this.... I've even used a couple propane torches combined at opposite angles to heat up pieces enough to braze them. Recently I borrowed a friend's Acetylene torch that he uses for jewelry, and with the large torch head it was plenty of heat to braze some large pieces. An oxy-acetylene would be the best though, for a few extra bucks you have the power to weld as well.
If money weren't an issue right now (ha, when isn't it...) I'd pull the trigger on a small TIG set up, they things they can do blow me away.
-Eric
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How hot do you have to get the parts to brass with brass? I"ve a heavy duty propane torch I use to melt sterling silver to cast ingots.
Best regards
Rolf
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I just use the small size tanks (B?) so they're not so cumbersome. About 2 ft high and 6" dia.
I bought my own tanks, that way I just take them in and refill.
I also had the small tanks that I owned. Down here I ran into a problem getting them filled. There is an exchange point in town, but they never had my size. The driver would take mine and return it the following week filled. Doesn't help if you run out of gas in the middle of a project. It's a 40 mile trip to the main distribution depot, but they don't fill them there. They would exchange mine with oxygen bottles that COPD patients and ambulances used.
Finally, the driver suggested that for my tank and $28 each he would upgrade me to larger tanks. Problem solved and I still own them. YOU DO NOT HAVE TO RENT TANKS. Buy em and work you way up to the size you need. Tanks are like railroad cars, you may own them but will never see yours again.
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For smallish parts. tubing and such you can use a Map gas torch. As the parts get bigger you will need more heat. I use an old plumbers' gasoline blowtorch and additional propane torches. All brazing rod does not melt at the same temperature. If you are using the Bernzomatic rods, the white ones are tougher to melt than the blue ones. They also make a lower temp uncoated rod. Really though, get an oxy-acetelene rig. Oh, I also have the map gas/oxygen hobby torch. Absolute junk. The fitting that goes on the gas bottle makes a good flame to smoke parts for fitting to the stock.