Brazing and Cutting with Propane

[vtsteam]

I found these videos interesting enough to try it.

Brazing:

Cutting:

A few additional points.

You must use a "T" Grade hose (not the usual "R" for acetylene).
I found that my regulator directly fit a standard 20 lb gas cylinder without any adapter.
Propane tips are somewhat different than acetylene tips.
I did modify a #2 Victor welding tip by counterboring slightly and it seems to work.

For complete info:

http://www.smithequipment.com/alt_fuel_faq.html

[Brass_Machine]

This is pretty cool. Only was able to skim the videos, but I will watch them again soon.

Eric

[pebbleworm]

Very neat! Demolition torches run on propane, so why not anything else?  I keep mumbling about converting a torch to run on propane and compressed air, sort of like a jewelers or laboratory blow pipe.  I live in a city apartment and might need a torch for one project a year so I don't really want to curate oxygen and acetylene cylinders.

[vtsteam]

pebbleworm, I am thinking about making an air and propane torch for brazing, too. More for reasons of economy and convenience. So happens I'm running out of oxygen this weekend, and the place where I get cylinders filled won't open until Monday.

For brazing straight propane seems very do-able  to me, and in fact, without the need for compressed air, though that might be interesting, as well. But I like to simplify things, if possible.

Seems to me a mod of some of the atmospheric forge burner designs would work for brazing. Might mess with that this weekend.

[modeng200023]

There is a torch design called the Drax Torch that is according to the literature, able to cut steel using just propane and air.
Here is a link to the literature http://www.geodyssey3.u-net.com/ that might be worth reading.

As I understand it,the design has not been marketed (I wonder why, perhaps it was bought up to stop competition?) but it looks to be quite an advance in torch technology. I also think there is a British patent for this idea.

Hope this is on topic.

John

[black85vette]

I first saw propane used with a cutting torch back in the sixties.  Worked fine just was not as hot.  Currently I use propane and oxygen for cutting but the welding tips I just use for body work, brazing, and heat treating.  Using standard tips without any mods (is that allowed here?)   Read somewhere that propane has something in it that weakens the steel at the weld.   So I don't use it for welding.   Mostly use the MIG anyway.  Also; I just use the regular hoses that came with it.  Since I don't use it often and don't leave the hose connected to the propane I figure it won't be a problem.

Another thing I do with propane is that I got a hose that adapts a 5gal / 20 lb tank to replace the little bottles used for lanterns and cook stoves.   I use it with the torch that comes with the tall cylinders of propane or mapp fuel.    It pulls air in to add with the propane and I find that it works for brazing if you don't have too much metal to heat up.

http://www.academy.com/webapp/wcs/stores/servlet/Product_10151_10051_751405_-1?kwid=ps_pla&mkid=PLA|023756711|Char-Broil%204%27%20Low-Pressure%20Propane%20Hose%20and%20Adapter

http://www.lowes.com/pd_148722-13877-334750_4294772357__?productId=4640199&Ns=p_product_qty_sales_dollar|1&pl=1&currentURL=%3FNs%3Dp_product_qty_sales_dollar%7C1&facetInfo=

I bought the conversion generator for my old Coleman stove and now run it off a 5 gal tank also.   Much higher BTU and cook time!

[vtsteam]

Great info black85vette.

I think the reason propane doesn't work for welding (weakens the joint) is that it is difficult to get the proper mix ratio with propane in the flame, so you're either oxidizing or laying down carbon in  the joint. The reason for that, I think, is that propane has a much more restricted mixing range for complete combustion than acetylene does. Therefore the flame isn't as uniform inside, and when it's playing on something. That's a guess on my part.

But it leaves me wondering if I could actually weld with it on something that isn't critical for strength like  sheet metal contraptions I sometimes build out of really high quality metal like electrical conduit, stovepipe metal, and chain link fence rails. 

On the other hand brazing works well with thin stuff and with its very high strength compared to flame welding, and all it's other advantages re. heat distortion, cast iron cracking, etc. I gotta wonder why I would even bother trying to flame weld thin sheet. Maybe just for butt joints, where braze isn't so good.

I still think I might play around with making an atmospheric burner for brazing today. If I have time.

[black85vette]

I don't think there is any problem welding with propane if there is no life or safety issue.   I have welded with propane with good results.

I think it would be worth the effort to run some compressed air rather than oxygen and see how that works on a torch set using propane.  Just need to make up the adapter and try it out.  After all I am not trying to cut half inch plate or weld it back together.

[vtsteam]

Well that's good news B85V! I had a feeling it was possible to weld with propane. Just hadn't been able to try it yet.
Blacksmiths weld with some propane fired forges. Depends on the burner. I would only want to flame weld thin stuff anyway. Looking forward to doing some experiments this week.

[black85vette]

Thought it was worth a quick try.   I made a quick and dirty adapter to hook up the oxygen hose to a air pressure regulator connected to the compressor.   Tried several pressure settings but the air just blows the flame out.

[vtsteam]

Toward a propane/free air brazing torch:

I tried a few things this morning before the rain started. I found a 20' 1/4" ID propane hose I had in storage  from a boat stove, UL rated at 350PSI. Thinking about using this for a brazing torch, but I wanted to attach it to an acetylene regulator and gauge and run at maybe 15 PSI. I want a steady regulated pressure. Unfortunately the ends were  M and  F compression fittings while the regulator was B type left hand thread.

Then I found an old cracked OxyAcet twin hose, no longer useful -- I was hanging on to it for no obvious reason. But of course I now realized the end connectors were still in fine shape, and there were 2 B type left hand connectors on the red hose -- oh boy!   

I split the crimped ferrule with a Dremel tool, leaving the end swivel portion intact. As I thought, under the ferrule in the hose was a nice 1/4" hose barb end. So I figured I could mate that lefty B connector with hose barb to my 1/4" propane hose. but unfortunately I didn't have a small enough hose clamp to fit the hose. Actually I want two on this connection for security -- and they need to be the full round type. So couldn't go any further. Maybe I'll go to town and get clamps tomorrow.

Then I thought I'd try firing up my Harbor Freight weed burner and testing it as a brazing torch. It puts out massive heat.

http://www.harborfreight.com/propane-torch-91033.html

For the test, I took a piece of 3/8" plate and set a piece of 1/2" water pipe on it. I ground them both clean beforehand. I figured the torch could easily do the job, but after a couple minutes of heating -- even up to the point where the pipe was glowing red in daylight, I couldn't get the braze to flow on the plate -- not sure if it was a fluxing issue or a gas mixture issue. I hadn't used much flux in the joint and hadn't fluxed the rod. It was definitely hot enough to melt the brazing rod, but it stayed on the plate like a little worm. I'll have to repeat that again when the rain stops, with a flux coated rod.

But it was clear the flame was just too massive and spread out to be much good as a brazing torch. Very wasteful. I unscrewed the head, which measured a whopping 2-3/8" ID (!), and checked the bore of the jet, which was .060". Also huge.

I think I'd like to make a torch about 1/2" to 3/4" ID with a much more concentrated flame with a jet orifice somewhere around .040. Also, as I said, with an adjustable regulated propane supply. The weed burner is direct connected to the propane tank.

It does have a good handle, valve, wand, and trigger, so might make a good starter assembly for my brazing torch. But the head will need to be quite different.

[vtsteam]

I got a little time today to work on a brazing burner. First I did quite a bit of web research on burners -- Reill, Oliver, T-Rex/hybrids, Gypsy Tinker's Mako, etc.

For starters I'm going to try a Mako type because of its simplicity, light weight, and narrow profile (useful for what is intended to be a hand torch), plus its reported good behavior and good turn down ratio.

I'll probably modify things along the way, and I'm keeping in mind features of the other burners I've looked at, which may come in.

Plus I like working with scrap electrical conduit and fence rail tube. Don't know why! In this case though, light weight and less restrictive porting with thinner walls are small advantages, maybe.

Anyway, here's a start:

I turned a scrap of Brass down to make it a tight sliding fit in 1/2" electrical conduit, with a shoulder, and drilled it 1/4" to fit a mig contact tip. Because the piece wasn't long enough to thread the gas connection end, I rummaged around in my old plumbing fittings box and found a compression to 3/8" pipe thread bushing. I sawed off the compression side, and faced it, leaving the hex shoulder and the pipe threads.

[vtsteam]

Then I took them outside on the porch, set them on a firebrick, fluxed both parts and cut little strips of silver solder to put in the joint. I set one on top of the other with the solder sandwiched in between, heated with a handheld Mapp torch, and It was able to do the job. The pieces came together and the solder wet out very nicely.

[vtsteam]

The silver brazed part:

[vtsteam]

I cleaned up a piece of 1/2" conduit and fitted the end in. It was a tight sliding fit.

[vtsteam]

Then I drilled for tapping for a #6 set screw right through both the outer casing and the brass fitting. The set screw will allow adjusting the position the MIG tip in the brass fitting, as well as lock the outer casing to the steel tube shell.

This was as far as I got today.

[vtsteam]

I tapped the burner base and installed a .030" mig tip.  I also milled two 3/8" x 1" air ports lengthwise on the barrel. That's different than a Mako burner which as radially milled ports, so I wasn't sure what to expect for performance. I guessed that the open area was roughly equal to that in the Mako design. The slots are similar to the Hybrid burners like the T-rex, but those feature a much larger barrel and venturi, and the nozzle orifice is forward of the slots.

[vtsteam]

I connected the propane hose to the tank and regulator hose barb using 2 new proper size hose clamps, and connected the other end to a gas ball valve and then to the burner base.

Here's the complete assembly (minus a burner flare):

[vtsteam]

I tried a lot of experiments today with the new burner.

I tried it with and without a flare, with different amounts of flare in the flare (!) with different mig tip positions, and lengths, and with and without the three 1/4" holes in the end of the main barrel, which appear on the Mako design. Pressures ranged from 2 to 15 PSI.

To summarize, the burner definitely requires a flare in free air, and the flare should be flared. The tip position was best with this design placed far forward near the end of the air slots. That is different than the Mako design which positions the orifice in the middle of the air slots. But, of course those slots run radially, not axially.

The burner worked very well, though I think the flare needs more flare currently to increase stability at the higher pressure end of the range, and in wind (It was very blustery today -- not actually a good day for testing).

It puts out a lot of heat, but it is diffuse heat compared to a hand held torch, which really focuses a flame. For that reason, it never was able to do more than soften brazing rod rather than really fuse it to base metal despite the fact that it was producing lots of heat and flame. I'm sure it would be a fine burner in a forge or foundry where insulation could allow a rapid temperature rise, radiant wall heating, and contain  the flame.

But in open air playing against metal it was just too big a flame to reach good brazing temperature. I'd rate this burner as a success as a massive and efficient heat source, but a failure as a hand held brazing torch.

Focusing an atmospheric flame is something I want to find out about.

Sorry I don't have pictures of the torch with flare today., and the flame produced.  I'll try to get some tomorrow

[vtsteam]

I'm going to open a new topic in the "Metal Stuff" board for this since it started as a "Neat Stuff" link to oxy-propane videos, and has now become an ongoing atmospheric propane burner construction project.


New Thread Link:

http://madmodder.net/index.php/topic,8633

[PTsideshow]

One word of caution your home owners insurance will not cover damage to your house or shop with a home made torch.

Yes you can weld with oxy/fuel it isn't recommend , Due to the contamination of the weld joint melt and in theory you can not adjust it to a neutral flame! but then again I have seen a lot of people that can't adjust oxy/acetylene to a neutral flame.

For the rest it works great for cutting it takes longer to pre heat the work, and the tip configuration is completely different.

working end for acetylene they are one piece

This is the other end of acetylene tip


This is the working end of a Victor Propane cutting tip

It is a two piece tip.

My oxy propane set up

I beam cut with the propane tip, It is slower since you will have to adjust your travel speed and how you cut. Which means it will get a lot hotter on the gloved hands.

Victor torch

This is my craftsman 1967 regulator they use to have in on the name plate that it could be used for LP/propane. Now they would rather sell you another regulator.

 This is a Harbor Freight regulator that I use as I picked it up never used but the guy never checked the cost of the cylinders. Didn't want to spend the money   
I also use the quick connectors on the propane rig since my acetylene set has them.

For the fuel air torches you have three basic choices:

Home version canned propane cylinder, a MC (motorcycle)cylinder and a B (bus) cylinder
carry over from the olden days. that is why the MC has the angled valve from being clamp on the cross bar.

Commonly called a prest-o-lite torch There are probably 14/17 brand names most have interchangeable parts.


Same air fuel torch



A new generation propane/mapp air fuel torch that will develop heat to silver braze they have become very popular with the silver smithing jewelry/beader crowd. Also sold as the shark comes with a bulk cylinder fitting.