Burner Tuning Question

[LeeHene]

Sounds like forced air might be the best direction to experiment with in the distant future.

Here in South Carolina, summers are hot and humid. We'll need to be able to use a fan inside the barn. So far this burner doesn't take kindly to even having the barn door open for long.

[Mikey98118]

What the right gas orifice diameter turns out to be is also effected by the burner deign. My 3/4" tube burners run best with a MIG tip for 0.025" welding wire. I think 3/4"Frosty "T" burners are supposed to run best with  a MIG tip for 0.035" welding wire, yes? I also think he runs them with way lower fuel gas pressures.

Also how long the MIG tip should be, changes in relation to gas pipe diameters, as well as gas orifices diameters. Orifice diameters of 0.028" and under require shorter orifice lengths; the smaller the diameter the shorter the length, because of friction. A 1/8" schedule #80 gas tube (3/16" inside diameter) will give as strong a performance with a short MIG contact tip as a schedule #40 gas tube with a long MIG tip, because the thicker pipe wall gives better streamlining into the tip.

[LeeHene]

I appreciate the insight.

The 100HT seems to have made a bit of difference overall. This weekend a small 12v blower and speed control came in. I'm going to experiment with a blown burner too for this summer. Great thing is all it takes to swap burners is loosening one bolt.

[Mikey98118]

A variable speed burner fan, could solve your problem. Usually I discourage the choice of fan blown burners. However "circumstance alters cases." Just remember that too much air is just as bad as too little

[LeeHene]

First test run with the mini blower. This thing got hot QUICK!

[Mikey98118]

The second photo shows a very good flame. The third photo shows how hot the forge is getting, without the help of forward and rear baffle plates. However, you would be better off cutting your flame lengths in half, and adding those baffle walls, would allow you to do so, without losing any appreciable heat in the forge

How can long flams become a problem? It take sufficient distance for the fuel to combust completely with the oxygen content in the burner's induced air, to prevent some of those super-heated oxygen molecules from combining with alloys on work surfaces, creating scale.

 

[LeeHene]

Forward and rear baffle plates? Please explain with a little more detail. I'm interested!

It certainly needs some modifications. Adjustments are way, way overly sensitive. (Worse than tuning a carb.)

Part of that is due to the motor not responding well to being turned way down, and the other part is that I'm only using the regulator to adjust flow of propane. Again, it's very jumpy down as low as I'm running it. I probably need to restrict the outlet some and/or add a needle valve.

 

...and yes, as you stated, there was scale-a-plenty on the steel until we got it tuned better than what you saw in the third picture.

[Frosty]

3/4" T burners I've built tend to run best between 10-18psi and max out about 24, most won't turn down much below 8. NARB on the other hand makes good stable fire stop to stop on the regulator. 

Lee: The reason your burner is so sensitive is because it belongs in a larger forge. Imagine how careful you'd need to be on the throttle with a 600hp hemi in a Honda Civic. 

The end baffles are Mike's recommended and my seconded thermal baffles. Basically refractory walls not quite closing the ends, a 1" gap to allow exhaust gasses to escape superheat and radiate IR back into the forge chamber. What works well are kiln washed Morgan k-28 IFBs laid on edge I like two on the bottom and one centered on top. The arrangement allows you to separate them to make the size and position the openings you need for the piece you're making.  

Frosty The Lucky.

[LeeHene]

Frosty, I am indeed realizing that my burner is oversized for the forge. It sure does work well once it's tuned though! -Hahaha 

I look forward to building a little larger forge (not too big) with a ribbon burner. I think I enjoy messing with the burner more than I do forging. Guess some of us are just built that way.

Do you think a diffuser of some sort in the end of my burner would help with the long flame? My biggest concern is overly restricting flow of the $10 Amazon blower. I'm not sure how much usable pressure it can produce.

Oh, and I ordered a needle valve for the propane.

[Frosty]

If you listen to that type blower when you block one end, the change is NOT it working harder pushing against the blockage, it's the motor speed increasing because it's not pushing air. An air gate restriction reduces wear on the blower motor. 

I made NARB to demonstrate the "need" for a high static pressure to run a ribbon burner is a myth. Most often they result in the videos and pictures of forges sporting blown ribbon burners shooting flame a foot or three out the openings. 

I think you could build a furnace maybe 2x the size of the average microwave oven. Not that it hamstrings you into building a huge forge it just needs to be throttled down to reasonable output. A gate valve on the blower output and a needle valve on the propane and you're golden.

Were I building it I'd replace the long horizontal nipple with one that only cleared the side of the forge by an inch or two. Put a 90 elbow on it pointed downward. The blower output and gate valve would go in line with the elbow and the propane inlet directly above that. Yes, it's all right next to the forge and if it gets too hot a little heat shield is EZ PZ, just enough stainless steel sheet even looks good though aluminum foil is good enough for NASA. 

What you end up with is more compact, stable and easily tuned. 

Frosty The Lucky.

 

[Mikey98118]

What Frosty said is exactly right.

I assume that you purchased one of the low priced oval forges online; they are all about the same size. Judging by mine, one 1/2" or two 3/8" size naturally aspirated burners would be sufficient to heat yours, too; this means that you have about four times the flame you need from a burner that can't be easily turned down. Since burners and the equipment they heat are all about balance, you're stuck in an awkward situation.

[LeeHene]

I agree 1000%! From the first time we lit this forge I had a feeling 3/4" burner was oversized. I've been extremely happy with the difference adding a blower has made.

My son and I experimented a little more with tuning this evening, blower restriction included. I think that adding a damper to the intake will yield even better results.

Im also hoping to experiment with a diffuser in the burner output fairly soon.

All this is still in the experimental stage. I greatly appreciate all the great input!

[Frosty]

A damper on the blower intake works a treat, UNLESS the blower motor relies on the blower's air flow for cooling.  Some motors have vents and the rotor causes enough air flow for cooling, some have little internal fans. Some have vents into the blower housing and the impeller draws air through the motor. The last CAN cause overheating problems. Not will, CAN.

Two 3/8' burners or one 1/2" make these little forges HOT.

One last thing not forge related. I think this is the first time I've gotten a look at your setup. It may seem silly with a light-ish anvil and a boy the age of your son but your anvil stand is a stack of springs which suck energy from each blow. If you rebuild it with the lumber on end straight from anvil base to the ground your son will get more from each blow. I also looks way too high, judging by his tong hand and the position of the elbow on his hammer hand.

If this stand fits you, build him his own, moving an anvil back and forth is easy. For the general rule of thumb for height have him stand with his arms hanging relaxed at his side and make the face of the anvil about wrist high. This will let him swing naturally and the hammer face will naturally strike reasonably parallel with the anvil face. It will also let him hold stock in a more relaxed natural position. Take a look at how high he's holding his elbow you can't control things very well that out of position.

Good times being made eh?

Frosty The Lucky.

[LeeHene]

Awe man, that's a heartbreaker! I just got close to finishing that anvil stand! Each layer is anchored to the one below with 6" lags and glued with Titebond 3. The floor of our barn is working against us too. The forge has to be secured to keep it from wondering across the bench when we hammer.

As for the blower, I'll look into a way to adjust output restriction. I'm not sure how long this little $10 Amazon special will last as it is. I must say, the output is more than sufficient and it's whisper quiet! (Not that it matters with the roar of the burner.)

The idea behind that 8" run of pipe over to the 90 was to keep the plastic blower well away from the forge in case heat were to travel up the pipe.  So far everything has stayed cool to the touch. I'll continue working on improvements!

[Mikey98118]

Well, it would be better put that the stand isn't rigid enough, and therefore partially cushions each blow. There is a very successful line of commercial farrier anvils that have an inbuilt spring system on the anvil base, just to provide extra swing-back to hammer blows. I became interested in them when searching for alternate anvils for city smiths who can't afford the high pitched rings from their  first class hardened anvils. Such an arrangement could be provided between an anvil plate and the stand, easing his problem; possibly even providing a remedy for it...just a thought  

[Frosty]

Bummer, that's another reason I don't get more fancy than necessary. How high is the anvil's face in relation to your son? He's young, still developing physically and mentally, this is the time to NOT form bad habits and physical traits. If this stand fits you, fine but he needs something that fits him and worse that is going to change as he grows. Perhaps a sand filled anvil stand, then can adjust as he grows at least to a degree. Another argument for not having the anvil so high is his grip on the hammer, his hand is twisted to the point the first joint of his thumb is on top of the handle. That puts all the impact shock on the joint rather the web, this is NOT GOOD. He's holding it that way so he can strike reasonably parallel to the anvil face.

A springy floor is an issue for sure. Is this going to be a permanent location for the forge? If so you could cut the decking and fill with compacted gravel where you're going to be beating on things, the leg vise is one that benefits from good support top and bottom.

A DC blower eh, you can control the speed (output) with a rheostat or similar, say the heater fan speed control out of a vehicle. Being plastic means mounting it so high means chimney effect will channel HOT air from the forge through it. Not heat conducting through the pipe. Is that circuitry mounted directly to the blower case?

Does your forge get hot enough to boil water on the outside? A kitchen hot pad allows you to pick up a steak searing hot 400+f cast iron frying pan comfortably. A simple heat shield between blower and forge shell will be plenty of protection. You can use almost anything as a heat shield. Another benefit is having both gas and air controls next to each other.

Of course you could run the air from under the bench with some automotive heater hose or some from an old vacuum cleaner. 

All of this stuff is just tweaking, it'll get better fast.

Frosty The Lucky.

 

[LeeHene]

Thank you for pointing out an issue with the anvil stand that I wasn't even aware of.

I've not secured the top yet, so I could add vertical beams to the inside. I also bought 1.25" steel angle that I plan to put on the outside corners, bolted into each cross beam.

The height still needs some adjustment for my boy. I honestly sized it more for me since he's growing fast. I'll give that some though. Possibly a thinner top? As for the floor, ther's not much I can do aside from supporting it better underneath.

My wife is a photographer and we use the barn for Santa photo sessions before Christmas. It's a 5 day event that's booked with a waiting list each year. So no permanent visible modifications allowed. We'll figure out something better for the long run though!

(And no, I am NOT Santa!)

[Frosty]

Running angle iron down the corners won't effect the basic springiness of your stand. Even stacked solid wood has more give cross grain than end grain. That is compounded significantly by having the lumber bridging a gap. If it fits you just use it, it'll be okay till you replace it.   

You could make a platform so you son is high enough to use this set up. Too be honest though I don't care for more trip hazards in a shop than necessary.

What do you mean, no blacksmithing equipment and tools in Santa's workshop!?!?!? Santa Clause has THE BEST smithy on Earth! I could turn an anvil, elf and some colorful toys into a Christmas photo set almost without trying. Ah, then again kids don't go to the north pole to see Santa so . . . nevermind. 

Frosty The Lucky.

[LeeHene]

I didn't say no blacksmithing equipment in the barn, just no cutting a hole in the floor to anchor our anvil stand in the ground. -hahaha!

[LeeHene]

Quick update: I installed a gate valve for air and a needle valve for the propane. The picture is a low-ish flame. I had trouble balancing air/fuel for low heat before adding the valves.

It's going to take a little practice to get the hang of adjustments, but I'm pleased. Thank you Frosty and Mikey for your help!

[Mikey98118]

I don't think we have mentioned yet how much approval your first burner design deserves. The one change that I would bring up has to do with your desire to try a ribbon burner next. Why not try a slightly different version of multi-flame burner nozzle on this burner instead?

Some guys have successfully turned fan blown burners similar to yours into multi flame burner heads, by trapping a flat stainless steel disc, drilled with several small holes in it, at the end of the burner's flame nozzle. I believe that most use the drilled stainless steel disc from a shower head for this, but I think that drilling your own disc from a thicker piece of stainless sheet, will cause your work to last much longer. Just a thought.

[Frosty]

Looks much better. Now all you need to do is close this end up some and you'll have a screaming HOT forge.

Frosty The Lucky.

[LeeHene]

Thank you guys, that means a lot.

There is so much great information on this site, it really makes it easier to learn and develop a starter design.

The size of the forge is plenty sufficient for what we need right now. Next I plan to build a frame for sliding doors on the front and back. I've gotta get that anvil stand more rigid. I'll probably experiment with the burner nozzle after that.

 

As for a ribbon burner forge, that might be something for another time, but not now. My son's interest is in making knives, and this little forge seems just right for that.

We need to find someone local for some hands-on pointers on moving steel.

[Mikey98118]

I think that making knives will give him the very vest opportunity to learn a variety of skills. Even more to the point, since knife making all about quality, it will give him a chance to learn what is most lacking in our society; integrity in his work.

[LeeHene]

I was googling "forge forced air burner nozzle" for design ideas and look what I ran across. Ouch! They're taking folks to the cleaner with that burner.