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Verd

Can anyone help me with my venturi torch?

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So I have been getting into metal casting the last 6 months, and I began my journey with charcoal. NowI am trying to upgrade my setup to a propane venturi setup. My problem is even after following EXACTLY the instructions my burner is not running properly. I am getting sputtering and an inefficient flame. Additionally, the end of my jet tube is getting red hot which I know is not a good thing. With that, I cant run my furnace until I know it's working as intended. I have tried running it at 5 PSI to 15 PSI and anything after 15 is pretty chaotic.

 

I took the design from Grant Thompson. -

 

This is where I am at: https://www.youtube.com/watch?v=49FCz3AGubE

 

The piping was done 1"1/2 x 1" ----> 6" 1inch nipple -----> 1"x 1"1/4 coupling as the flare. It seemed to be too much volume and the flame wasnt controllable to my standards. (I also later realized I made everything the wrong size)

 

Since it wasnt running right I switched over to a 1"1/4 x 3/4 -----> 6" 3/4 nipple -------> 3/4 x 1" as a flare. thinking the the smaller diameter pipe would increase the pressure, and I am having the same issue. I dont know what else to say that can better describe whats going on. It looks and sounds like the flame isnt oxidizing enough? Any help would be great.

 

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Welcome. These are just the first few things that came to my mind on this:

 

1) Your flame doesn't look like it is about to sputter out, so really you're doing fine.

2) You'll want a needle valve after your ball valve. The 1/4 turn ball valve is great for a quick safety shutoff, but terrible for control of flow.

3) A tapered MIG welding tip creates better flow.

4) Definitely play with different orifice sizes (0.035, 0.030, 0.023).

5) Putting a burner in a forge (or melting furnace) will create back-pressure, and thus change how the burner is running. Playing with it in open air is fine, but won't quite be the same as in the forge/furnace.

6) Definitely play with restricting the air. Getting the right balance is important.

 

Good luck.

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You don't usually want the flame to be oxidizing...... your flame holder at the tip is probably a big part of the problem, also, some burners need the back pressure of being in the forge or furnace to work properly. My advice is to take off the coupling at the tip, grind off the threads of the pipe tip, and use a pipe piece of suitable diameter to slip over the pipe (about 2 inches long) as the flame holder. Adjust by sliding in and out to get the ideal position; mark it, and use a set screw to hold the position. A choke plate at the inlet might be useful as well. Hope that helps.

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Welcome. These are just the first few things that came to my mind on this:

 

1) Your flame doesn't look like it is about to sputter out, so really you're doing fine.

2) You'll want a needle valve after your ball valve. The 1/4 turn ball valve is great for a quick safety shutoff, but terrible for control of flow.

3) A tapered MIG welding tip creates better flow.

4) Definitely play with different orifice sizes (0.035, 0.030, 0.023).

5) Putting a burner in a forge (or melting furnace) will create back-pressure, and thus change how the burner is running. Playing with it in open air is fine, but won't quite be the same as in the forge/furnace.

6) Definitely play with restricting the air. Getting the right balance is important.

 

Good luck.

Hey thanks for the reply.

 

I currently have a .60 welding tip as the nozzle. but you are saying getting the tapered one would be better? Also, if the nozzle was drilled and tapped perfectly straight could that cause an issue as well? I ask because I drilled that by hand (No drill press)

 

As far as airflow, there really is no adjustment. Once that makeshift regulator is off I cant make the set up breathe in more air, unless I increase the pressure on the tank correct?

 

I am just nervous because I dont want to blow myself up. Is there a PSI you suggest I do not go over?

 

Edit: Also I forgot to mention, you said the flame seems to be doing ok, but I need to get this to Aluminum/Brass melting temperatures efficiently

Edited by Verd

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You don't usually want the flame to be oxidizing...... your flame holder at the tip is probably a big part of the problem, also, some burners need the back pressure of being in the forge or furnace to work properly. My advice is to take off the coupling at the tip, grind off the threads of the pipe tip, and use a pipe piece of suitable diameter to slip over the pipe (about 2 inches long) as the flame holder. Adjust by sliding in and out to get the ideal position; mark it, and use a set screw to hold the position. A choke plate at the inlet might be useful as well. Hope that helps.

Ive seen that setup as well. you mean something like this ?

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You don't say where you are located. Altitude can be an issue.

 

Geoff

Oh my fault. New York. Long island specifically.

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I'd recommend getting a tapered tip of smaller orifice size. My set-up is currently running on a 0.030 tip and easily gets to welding temps at about 10 psi. The key to not blowing yourself up is eliminating excess un-burned gas build up. The most common sources of this is from leaks in the fittings (very soapy water in a spray bottle helps find those super fast), and turning your gas on before having an ignition source going. Your gas speed (a function of pressure and orifice size/shape) combined with your air port opening controls the amount of air sucked into the system. Since your orifice is fixed (unless you change out tips or add a needle valve) pressure changes are the easiest thing to control. You may even need to block air from getting in (check out Grant's video that you linked to for his version). Also, read this thread if you haven't already.

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I'd recommend getting a tapered tip of smaller orifice size. My set-up is currently running on a 0.030 tip and easily gets to welding temps at about 10 psi. The key to not blowing yourself up is eliminating excess un-burned gas build up. The most common sources of this is from leaks in the fittings (very soapy water in a spray bottle helps find those super fast), and turning your gas on before having an ignition source going. Your gas speed (a function of pressure and orifice size/shape) combined with your air port opening controls the amount of air sucked into the system. Since your orifice is fixed (unless you change out tips or add a needle valve) pressure changes are the easiest thing to control. You may even need to block air from getting in (check out Grant's video that you linked to for his version). Also, read this thread if you haven't already.

Will do. The only reason im nervous is because the jet tube from my understanding is not supposed to get hot, but mine is. and Idk why is doing that.

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Mine is connected to my forge via a black iron coupler. Before I got it fine-tuned, the coupler would get glowing hot. Major problem? No. Very inefficient? Yes. After getting the right tip in there and properly forming my burner cone (via the ceramic in the forge) I now have zero problems. Other than lack of time and energy to forge; but the forge runs great.

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Mine is connected to my forge via a black iron coupler. Before I got it fine-tuned, the coupler would get glowing hot. Major problem? No. Very inefficient? Yes. After getting the right tip in there and properly forming my burner cone (via the ceramic in the forge) I now have zero problems. Other than lack of time and energy to forge; but the forge runs great.

Interesting. I had read that if you nozzle gets hot it can be dangerous, hence why I was nervous. I have barely let the thing run more than 5 mins so far lol. I read the link you posted and I see he has the inlet for the air on top instead of behind. Is that a better setup? What PSI from the tank do you run usually? I

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I seem to recall a discussion about air inlet orientation and the general consensus being that it didn't really matter that much, just whether it is obstructed or not. I run from 5 to 15 psi, depending on what I'm doing. General forging is often at 10 psi with the needle valve turned down a bit. That is all highly dependent on forge and burner sizing and configuration.

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Seems to me that your orifice size is way too big at .060

I have found that .030 or .035 work very well for me

having the orifice well centered makes a lot of difference

and as Jarrod said a tapered one improves the air flow some also.

On another note I prefer the side burner for it's ease of building and it's ease of

changing over to a blown burner set up, see Geoff Keyes sticky on

the care and feeding of blown burners here on this site.

As for the end glow put It just inside the outside edge of the refractory

and it will make it's own flame holder there instead of the tube I melt

aluminum with a 1" side burning venturi for my foundry furnace and it works great.... B)

Edited by Clifford Brewer

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Ok So i just came inside from fiddlin with it. I ground down the threads on the air inlet for smoother air flow, and did the same for the flare end since its what I had. still having the same issue more or less, but at 18 seconds it was the best ive ever gotten this thing to run... @ 10 PSI.

 

https://www.youtube.com/watch?v=mi_x_2_lKN0

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Ive seen that setup as well. you mean something like this ?

Yes...... also the idea of your choke is good, just do it from a non flammable material. The burner tube should not project all the way into your furnace but be protected a bit by the insulation. I would also install some pipe between your valve and the burner tube to make sure the valve does not heat up.

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There have been a couple of comments on the jet size that seem to suggest confusion over units. The link to Grant Thompson's video in the OP shows a .6mm tip, which is about .024". Probably about a .030" hole, as the hole is bigger than the nominal wire size it is intended to pass.

 

If anything, it looks like it's too small to me.

 

It's hard to tell what's going on with the choke in the last video, but I get the impression it is going too lean and going out when the choke is opened?

 

If so, and it's a .6mm mig tip, I might try a .8mm mig tip and see if it improves things, but only if it is going to be used in open air.

 

I would not try tapering the present tip. It looks like there's too much air at the moment and anything that increases the amount of air drawn in, relative to the gas flow, seems likely to make things worse.

 

If you stick it in a forge with some back-pressure, that will reduce the amount of air. Grant's setup looks like it probably has quite a lot of back-pressure, so putting it in the furnace, with a crucible, seems like the thing to do if that's how you are intending to use it.

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There have been a couple of comments on the jet size that seem to suggest confusion over units. The link to Grant Thompson's video in the OP shows a .6mm tip, which is about .024". Probably about a .030" hole, as the hole is bigger than the nominal wire size it is intended to pass.

 

If anything, it looks like it's too small to me.

 

It's hard to tell what's going on with the choke in the last video, but I get the impression it is going too lean and going out when the choke is opened?

 

If so, and it's a .6mm mig tip, I might try a .8mm mig tip and see if it improves things, but only if it is going to be used in open air.

 

I would not try tapering the present tip. It looks like there's too much air at the moment and anything that increases the amount of air drawn in, relative to the gas flow, seems likely to make things worse.

 

If you stick it in a forge with some back-pressure, that will reduce the amount of air. Grant's setup looks like it probably has quite a lot of back-pressure, so putting it in the furnace, with a crucible, seems like the thing to do if that's how you are intending to use it.

I have not tried changing the tip yet But I did change out the flare to the one mentioned above. :

 

https://www.youtube.com/watch?v=eOFqCUFKVQk

 

It seems to be running MUCH better, but it stil feels like im not getting the desired pressure, On Grants video the flame is shooting close to 12 inches out the barrel. Does this seem better now? Possibly good enough to melt aluminum and brass?

 

I am under the assumption you want the flame to be igniting close to the tip of the barrel not towards the middle, I think thats where im concerned.

Edited by Verd

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I think you're overthinking. Try to melt some stuff, if it works, ta da! You're golden. If not, then you've got a basis to tinker. RIght now your don't really know anything.

 

Geoff

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UPDATE

 

So I took the advice and gave it a go. Gotta say it worked pretty good. Whats more, It worked great at keeping my metal hot so I ccan pour more reliable molds with less imperfections. Just wanted to say thanks to you that answered my noob questions. I just completed this for a cousin of mine. Shes a bartender on the weekends and it was her birthday.

 

4982407671.jpg

 

Thanks again guys.

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