cant get welding temp

C

custommachineman

Joined
Jan 28, 2009
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I just finished a LPG tank forge. It has 1" of 2400 deg. wool and 1" of 2700 deg. wool. There is about 3/16" of Satanite with 2 coats of ITC-100 on that. The bottom is 2.5" refractory brick with a piece of hard kiln shelf on top with ITC painted on it. The burners are 2 3/4" N.C. tool forge burners that have been modified. I flared the burners too 12 deg and made adjustable tops. The jet holes are #67 drill, thats .032".
I tried running it today and couldn't get my parts past orange even at around 18 psi. I am very disappointed with how it ran. I put a lot of work and study into it and now it doesnt seem to work right.
Does anyone have any suggestions about how to make it work better?

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You using a blower? Sounds like it's choking out maybe...
 
I can't offer much help, but I think your forge itself is more than adequate unless you don't have the openings closed down enough (hard to tell from the pics); therefore, I'd suspect something not being right with the torches.

I have a somewhat similar sized forge with 2 burners, minus one inch of kaowool and the ITC-100 as compared to yours, which reaches welding heat pretty easily. My 'doors' are stacked hard firebricks, which do not have the best insulating properties.
 
I notice you have 2 lines run in how are they joined?Maybe another pic of that,probably more efficient to run one line in and manifold the burners together,you might be losing pressure the way their set up.Regards Butch
 
Its hard to tell from the pic, is the back of the forge insulated with wool? If not, insulate it.

Make a door out of steel with wool or stack some of the light weight insulated brick up in the front to close some of the opening off. You don't really need much more than maybe 4"x4" for an opening.

What kind of flame are you getting off the burners? The flame should have a nice blue cone in the center an inch or 2 long. I notice there are no choke plates on the burners to restrict some incoming air. When I built my burners, the flame kept trying to burn inside the burner tube instead of inside the forge and that was the problem, lack of a choke plate.

I would think that with 2 burners that size, you should have no problem reaching welding heat with much less pressure on the propane.

Brad
www.AndersonKnives.ca
 
I think the problem is the curved burners, try some straight pipes. I believe the orifices should be centered as much as possible, gas shooting straight into the forge.
 
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I cant seem to get the burner to hold a flame at all until the forge is hot. There is only one line in and it splits at the edge of the picture. I am getting a lot of flame out of the door when the forge is running.
 
custommachineman said:
I cant seem to get the burner to hold a flame at all until the forge is hot. There is only one line in and it splits at the edge of the picture. I am getting a lot of flame out of the door when the forge is running.
Click to expand...


A lot of dragons breath,too rich not enough air----
 
custommachineman said:
I cant seem to get the burner to hold a flame at all until the forge is hot. There is only one line in and it splits at the edge of the picture. I am getting a lot of flame out of the door when the forge is running.
Click to expand...


That would lead me to believe it's the curved pipes. Mine did the same thing until the orifices were centered to make the gas shoot straight into the chamber. You must use the correct length and diameter of burners to make them work properly.
 
Here are more photos.
1. Complete forge
2. The jets
3. The door with Itc-100 and satanite
forge.jpg

burnerjets2.jpg

forgedoor.jpg


You can see in the photos that the jets will reduce the size of the incoming air port when they are moved forward.
 
If it isn't the curved pipe can you adjust the length of the burner going into the forge and see how it burns? Unbolt it, light it and hold it to see how they're burning outside of the forge? It may be the distance it's poking into the forge or the orifice may be too big or too small.
 
While I have only built several venturi burners I have never used needle valves on any of mine. I just regulated gas pressure with a propane regulator and usually run about 3-10psi on mine. If you cant get the forge to stay lit its probably either too high PSI on your regulator or you dont have an appropriate burner flare entering the forge.
Maybe even alittle of both. A good venturi burner will burn outside of the forge, try unbolting it from your forge and seeing if it will stay lit. Unless you are creating your burner flares using Satanite of course.
Good luck
Chris
 
"You can see in the photos that the jets will reduce the size of the incoming air port when they are moved forward".

I looks to me like the pipes for the gas are way to large and blocking the air flow.It is hard to diagnose just looking,you will have to keep fiddling with it:D
Everybody's trying to help:)Regards Butch
 
I'm bett'n on the curved tubes. Are those "modified" NC tubes from a blown or atmospheric (venturi type) setup? Seems to me there would be way to much turbulence with a bend like that. I have a side armed venturi burner and I cant even see the tip (tig tip) thru the air opening its so far in. I just got it running and moved it in and out till it ran good. Good luck.
btw- those side arm type burners are a snap to put together.

JM
 
I'd try trouble shooting one burner at a time. 1) Loosen the assembly to allow you to move your jets closer in or further out while testing. 2) Use a consistent pressure while testing. 5 psi should be good. 3) Cut out a cardboard disk about 2" in diameter that has a hole in the center with a slit leading to the hole. The hole in the center should be about 1/2" in diameter, sized to snug around your pipe leading to your jet. 4) Try different depths for your jets and move the cardboard disk close to the rear tube opening at varying distances as a choke. 5) Take notes as you do this to find out the optimum jet location along with the best choke for that location. Strive for a nice blue flame.

Once you get one burner dialed in, make the same adjustments for the other burner. Make some metal choke plates instead of the cardboard test choke plate. Then go weld some steel...
 
Guys, the NC burners are curved.

I have an NC Low Boy with three burners and it will easily reach welding temp at 10 psi.
But use my blown forge for welding, Don Fogg style, big vertical with single blown burner. Can do larger billets, reaches higher temp, uses less gas and the flux is much less of a prob. Have welded hundreds of pounds of damascus in the last 9+ years in it.

NC burners are designed to have a manifold of square tubing that fit across the burner in the square notch, this blocks the right amount of air. And the orifice (jet) is threaded into the tubing, centered over the burner. Also my NC burners don't have flared ends.

Like said, try to get the burners to burn right outside the forge and I would set up the burners like designed by NC Tool. You got some tweakin to do :)

Hope this helps
 
A friend of mine teaches blacksmithing with a 6 or 8 NC forges.
He has a couple three burners that he uses to forge weld in.
I never tried to weld in the two burner forges.

The only one on NC's site that mentions welding is the three burner!


The nc burners work great. the two burner NC forge is in a 3"x12"x6"
firebox. Do the math and figure what size firebox you have built.

It would need to be very smilar I think.
 
my forge is set up almost the exact same way as your, i used a 5 gallon propane bottle for the forge and it has pretty much the exact insulation. my door opening isnt as big as yours, but i only run 1 hybrid shorty burner in mine and i can get welding temps with no problems. so with you running 2 burners should be a none issue. the hybrid burner is also a venturi type burner. so the issue is in the burners. if you tweak the burners out of the forge to get the right flame and fire it should work inside. Also venturis are more sensitive to back pressure so be aware of that also.
 
Thanks for all your help on this. I am working on building some new burners that should work better. I have built Reil EZ burners before and they worked great. I am working on something like the T-REX burner right now. I have all the tools to make it I just dont have more than a picture to work from. I have built the whole thing except the flair. The tube is just over 3/4" and there are 4 5/8" slots on the top. I presently have a .023 tweko tip in it. It will burn now at about 5 psi without a flair and with the choke turned down about 3/4 of the way.
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