Trying to get my propane forge built

[Brandon Buford 0]

Okay, so after four months of inactivity, I am finally able to get back to swinging a hammer. I am wanting to start my propane furnace build and I have a few questions. I will provide pictures as well to help explain.

 

I have two furnaces that I can build. I have a box type furnace that was given to me that has two burners and is a venturi burner. I don't know if I want to fix it up (needs insulation) because the design seems to be inefficent.

 

I am leaning more towards a freon tank or propane tank build.

 

I was given this burner by one you.

I assume that the long black pipe going left would be inserted into the forge.

 

The Top opening would have a pipe with a blower attached to it

 

and the nipple on the left would be somehow connected to the propane hose.

 

Is this correct?

 

Here are closeups of the nipple.

[GBrackett 18]

Looks like a venturi burner, no blower needed. Nipple screws into the back of burner and supply hose connects to it. To control the air mix you can make a sliding cover for the top hole. Add a needle valve to the supply line to control gas flow.

Edited April 27, 2014 by GBrackett

[Gary LT 107]

You can look up Larry Zoeller and/or Ron Reil. This looks like Larry's side arm venturi. Both have a lot of information about what's needed and what to expect, especially safety-wise. I made one similar in concept to this and it worked very well. Make sure you install a regulator at the tank and a 1/4 trun shut-off in the line!~

 

Gary T

[Brandon Buford 0]

Thank you all. Can this be a blown air design?

 

Can a properly set up venturi forge get to welding heat?

[GBrackett 18]

I've seen venturi based forges get to forging heat. We have done it at Bola Custom Knives before. He has a dual burner unit that gets there with no problem.

[Wayne Coe 56]

You should change the mig tip to a Tweeko T tip, available at your welding supply store. T stands for tapered. That is a side arm venture burner and not suited for a blown forge. It looks like the long pipe is 3/4" and will get a properly constructed forge with an interior volume of 350 cu in or less up to forge welding temps. A Freon bottle will build a forge with less than 350 cu in.

 

Look at my tutorial on my web site at the Forge Supplies page.

 

Let me know if I can help you.

[Brandon Buford 0]

Wayne, Thank you for that info. I do plan on giving you a call and finally purchasing the insulation and refractory maybe as soon as next week.

 

I have a welding store right next to my work and I will go check them out on the tip.

[Jerrod Miller 445]

You should change the mig tip to a Tweeko T tip, available at your welding supply store. T stands for tapered.

 

OK, I have to ask: Why? What does that do for you?

[Doug Lester 281]

No, you cannot change that to a blown design. Actually a blown burner is simpler with no internal parts. You can see from the photo what's there, except for the blower which is off frame to the right. The gas comes in through the line with the regulator and pressure gauge at the tank. The gas line attaches to a ball valve which aids in lighting the burner and provides a quick turn-off. Then to a needle valve for fine adjustment. That attaches to a brass nipple which threads into a plug in a cap that is threaded into a T connector. I would use a shorter nipple and If I had the tap needed for the fine thread on the nipple I would drill it into a black pipe cap. but I check the connection and it's good.

 

The air line comes up from the bottom. I have two forges that share a blower so I use the black flexible tubing to switch it from one to the other. The hose attaches to a matching nipple which goes to a reducer, to a gate valve to control the air flow, to a nipple, to the T connector, to a longer nipple, to an 90° connector, ending up with the burner tube which is inserted into the forge.. How you connect it to the forge body will depend on what you are using and the equipment that you have. Do not bring the burner pipe all the way through into the fire chamber or you will slowly burn it away. Keep it back inside the wall or build up a coating of refractory around it. Just make sure that every thing from the elbow to the forge is black pipe and not galvanized.

 

Of course, if you have a problem with a power supply out to your forge then a venturi burner is about the only way to go.

 

Doug

 

 

[Wayne Coe 56]

Jerrod, I'm not sure. When I was first introduced to inline burners the Tweeko T tips were specified, then I had a student who had built a burner and used as standard tip and the forge would not burn properly. I got him to get a T tip. When he replaced the tip it burned properly. That was the only change. I imagine that the T tip allows more room for air flow and better mixing.

[Jerrod Miller 445]

Thanks Wayne, I'll give it a try on mine some time and see if it gives me better control.

 

Doug - I must admit I don't see the problem with converting his set-up to blown. Just thread in a gate valve and blower to what is currently the venturi air inlet and you have essentially the same thing. Alternatively, he can move the reducer to that side so his gas comes in that side then add the gate valve and blower and he has the exact same thing. Also, safety note: Propane is heavier than air and may pool in your blower if the piping is done like yours and the gate valve is left open prior to the blower being turned on. When the blower turns on the motor may spark and go "boom". Geoff Keyes notes that here (post #4): http://www.bladesmithsforum.com/index.php?showtopic=25573 (great thread on blown designs BTW)

[Pelallito1 0]

You can convert the tip he has to a taper. Put it in a drill chuck and put a file against the end until you have the taper you want. Then follow that up with different grit sandpapers to make it smooth.

Fred

[Jerrod Miller 445]

So for a variety of reasons I haven't been able to fire up the forge for a while (mid April!). I finally got a chance last night and was still having the issues getting it to run right. I had been playing with the venturi set-up (gas nozzle--wire-feed welder tip, size and location), but the flame kept going up into my inlet pipe. I decided to quickly turn down my 0.030" tip in the lathe and put it back in the assembly. I had no idea I would be able to run so smoothly. Thank you Wayne for the tip (pun not intended, but I'll go with it). Not sure why it works so much better, but it is the same tip I started with that was having problems and after a minute in the lathe it performs PERFECTLY. Ran it at various psi ranges and valve openings, all without the flame going up in the pipe. Nothing beats a well running forge.

[James Spurgeon 22]

So for a variety of reasons I haven't been able to fire up the forge for a while (mid April!). I finally got a chance last night and was still having the issues getting it to run right. I had been playing with the venturi set-up (gas nozzle--wire-feed welder tip, size and location), but the flame kept going up into my inlet pipe. I decided to quickly turn down my 0.030" tip in the lathe and put it back in the assembly. I had no idea I would be able to run so smoothly. Thank you Wayne for the tip (pun not intended, but I'll go with it). Not sure why it works so much better, but it is the same tip I started with that was having problems and after a minute in the lathe it performs PERFECTLY. Ran it at various psi ranges and valve openings, all without the flame going up in the pipe. Nothing beats a well running forge.

 

Wow, fascinating that the outside shape of the tip makes that big of a difference for your burner, really wonder what the reason is, but smoother air flow around the tip makes sense.

I have never had a problem with mine, but I wonder if that is due to burner tube diameter. IIRC, your burner has a 1" tube while mine uses a 1.25" tube, which might simply give it more clearance for the air flow.

 

I may have to experiment with the idea... but a RR track / RR Spike PW Damascus might need to come first.

 

And, to second what Jerrod said in an earlier post, you can indeed change this to a Blown design by simply plumbing in a gate valve and blower line to the T fitting. You may want to remove the MIG tip if you add the blower, just to allow it to operate at a lower propane pressure than required when operated as a venturi.

James

[Jerrod Miller 445]

I may have to experiment with the idea... but a RR track / RR Spike PW Damascus might need to come first.

Yes it does need to come first! I've got a spike with inset leaf spring chunk I am working on now. Need to be more patient/thorough in my insert prep though.

 

And yes, my pipe is 1". I also tried 0.035" and 0.023" MIG tips (all turned down to have the taper. In fact, I was wrong when I posted my last comment; that one was the 0.035" tip. All worked, but the 0.030" seems to get me the best temp range I'm looking for with 2-15 psi (1550-forge welding, my T/C only goes to 2000F which was about 10 psi). I still need a better valve for the gas though, needle vs my current ball valve.