Brick Pile - Frosty T - Gas forge - Tuning help.

[ThorsHammer82]

I tried to start this on my phone but, it didn't feel like cooperating... so here goes. This is my "Brick Pile" Gas forge using a Frost T. Now that I've got it all put together it's time to start tuning it. I've already trimmed the Tip back to approximately 1/2" the run of the T and I still feel like it could do more. it's not a loud roar unless I hit it with a hair dryer. So I'm assuming that means I'm still rich, and need to trim back some more of the tip to get it a truly atmospheric burner which is the desire. 

Frosty, here are a few pics for you to judge what my next move should be. 

The T has a 6" nipple, and a SS coupler to act as the flare. The burner sits approximately 1/2"-3/4" into the chamber. Which by my calculations is 314"3 

I haven't been able to get past a bright orange heat yet.

Edited September 5, 2015 by ThorsHammer82

[Frosty]

Get rid of that blow drier, give it back to the wife or something it is flat ZERO use tuning your burner. NONE.

In truth it looks pretty good.

#1. The flame is a pretty good color and reasonably well centered if a little bushy. That color is the opaque light blue I associate with the primary cone. Compare it to a oxy acet torch flame, it's just not as bright. If this color flame were to be washing down and spreading on the forge floor it'd indicate too rich a burn and the Dragon's breath would have orange feathery edges to it's flames.

The bushy shape might be the coupler's influence, I don't think means a lot though. The flame's bushy shape is why it doesn't have a secondary burn zone, the darker more clear flame surrounding the primary cone in an oxy acet flame.

What psi are you running?

#2 The dragon's breath looks to have very little or no orange in it. I can't see any in the pic, maybe take a night pic. Orange dragon's breath means rich. Blue can mean neutral burn or lean. The leaner the burner the louder the roar. I can often tell how the burn is by the sound but I have experience, but you don't so how it sounds isn't going to help you now. Just remember how it sounds as you change psi or adjust the jet for future reference.

It MIGHT be running a little leaner than optimum but I'd put it to work for a day and see. I think it's pretty close. If you do trim the jet, only 1/8" MAX, you're close now.

Close off the forge opening some, especially on the floor and let it burn a while. Heck put it to work and see how you like it. The bricks are starting to show color in the pic about where it should after a short time burning.

Frosty The Lucky.

[ThorsHammer82]

I worked 3/8"x2" flat stock in it already. But like I said I'm only getting to a bright orange heat with it. Fine for the job at hand, but was hoping for more. Maybe blocking the opening more will help with that.

I'll slowly trim back the tip over time. I've got more if I go to far.

There is some light orange feathering on the dragons breath.

[ThorsHammer82]

ok, so I took off about 1/32" and now it's got a much more stable flame. I also narrowed the opening by about 1..5"-1.75". but I'm still not able to get to welding heat.

My regulator is a 10 PSI regulator, is it to small?

Here is a picture of the dragons breath that is more visible.

The other thing I noticed when I took off the additional 1/32" is that the cone isn't nearly as long as it used to be. In the picture on my previous post, you can see that the cone is nearly touching the bottom hard brick in the forge. Now you can't even see it looking straight into the forge. You have to look up into it to see the cone. But the cone itself is much more stable though with less feathering.

Edited September 7, 2015 by ThorsHammer82

[Frosty]

A 10psi reg is pretty low power. Is it off a BBQ or camp stove? I run a 0-20psi variable and what's most commonly seems to be a 0-30psi variable pressure. I can get one off the shelf at the Propane distributor's showroom in Wasilla ALASKA for $26.00 and change. Not only does the regulator need to supply stable pressure but it has to supply enough volume of gas to do the work. BBQ, etc. regs are generally low volume as well as pressure. A 3/4" T burner has a total BTU output that'd heat the average home in winter Alaska.

I run my burners under 10psi on occasion and they consume propane prodigiously, a crab pot reg is completely out of it's range.

Just be sure it's a propane regulator, using an old acet reg, etc. isn't a good idea, Propane is very reactive with rubbers that aren't formulated for it. You really don't want propane to start shooting out of the vent holes in the sides of a regulator, it'll be leaking at tank pressure, aprox. 200psi @ 72f.

Just another detail to take care of. Life's full of the pesky things. You're almost there, hang in we're pulling for you.

Frosty The Lucky.

[ThorsHammer82]

Ok. Time to upgrade the regulator. Well maybe in a month or two. I'm onto welding projects for the time being. I'll post the finished fire rack tomorrow. For whatever reason, my phone won't let me post pictures.

[ThorsHammer82]

Well, here it its. nothing to fancy. but at least it's designed for the size of fireplace. instead of two store bought ones next to each other. 24" deep by 36" wide. Final height will be determined at the cabin, as the fire bricks in the bottom of the fire place aren't exactly level.

[cranky]

Very nice job Sir

[Frosty]

Nice, I like it. I've always liked reverse scrolls as finials on fire grates and andirons. It gives them a more organic, almost serpentine look.

Frosty The Lucky.

[ThorsHammer82]

yeah, I went with the fish tails because of the number of owners/visitors that enjoy fishing.

[Frosty]

There's a practical reason too, it's much easier to use a reverse scroll as a fulcrum and lever stubborn logs with a poker.

Typical tapered scrolls look nice but aren't as popular once folk get a look at a reverse scroll.

Frosty The Lucky.

[ThorsHammer82]

The biggest reason for making the rack was the fact that the orientation of the support bars on the rack that is in place now is counter productive to hooking and moving logs. As half the time you're hooking the rack with either the hook, or the log causing it to not want to move easily. Thus the longitudinal orientation of the support bars under the logs. It should make rolling logs, and condensing the fire much easier.

I wasn't the one who took the measurements for sizing the rack, but per the person who did, they left room for the doors/screens and what not. So hopefully it will fit in as easily as a 70+ lbs. fire rack can. I think that the height of the rack should put the bottom of the logs inline with the bottom of the doors (They have air vents under them) +/- 1/2" or so. I'll be bringing my angle grinder with me for the install so that I can get it level in the fire place. Just need to get up there before it gets to cold so that I'm not freezing trying to get the thing installed.

[Frosty]

I figured the orientation of the grate bars was customer specced, there's nothing good about it otherwise. Sometimes "Paid in Full" is all the gratitude we can realistically expect. There are times when being able to say, "I just built it" is a saving grace for our market name.

Frosty The Lucky.

[ThorsHammer82]

"Paid in full" that's funny right there. I guess you can say I was paid in full at conception on this one. Luckily the Metal didn't cost me anything. and I'm only about $65 into the forge so far.

[Alan Evans]

I do not know anything about atmospheric burners so my observations may be totally off. And I may be misreading your photos.

All of my gas forges depend on containing the heat for fuel efficiency and high temperatures. They have a heavy fire clay lining to act as a reservoir of heat which is what heats heavy metal fast.

I am not reckoning the flame does the heating... which it can do in a light insulated lining forge if you are heating light section steel. I try to avoid letting the flame play on the steel directly to avoid hot spots.

If you were getting orange temperatures with the furnace with one side as wide open as shown in your photos, you were doing extremely well. 

I pack firebrick tight around the work piece so I am unable to see into the chamber...in order to contain the heat…if I can't see in then the heat can't radiate out. The big furnace has a drop down / sliding door lifted with a trailer winch. The door rests on top of the bars being heated and any gaps between bars are filled with fire brick.

I trim the gas and air pressure until I cannot see any dragons breath, if it is burning outside the chamber then it is too gas rich. I make sure it is just on the teeter of burning outside so that I know I have a reasonably neutral atmosphere.

Alan

[ThorsHammer82]

First I want to say that I'm not trying to be rude, or insulting. But if you have no idea what you're talking about, why say anything?

now, just for my own questioning. if there is air and fuel being drawn into a forge, but there is no exit/opening, what's going to keep the forge running? Eventually you'd have no airflow which = no fire. forced air is one thing, but on an atmospheric burner, it requires air flow. or draw, to bring in enough Oxygen to burn (correct me if I'm wrong)

I can understand closing the opening as much as possible to still allow access to the work piece. but not entirely. I think the biggest issue I have right now is the regulator. once I've upgraded that I will move on to other potential culprits, but I don't think that  the opening is the primary problem at this point as 90% of the gas forges I've looked at have all been open.

As for the dragons breath, my thoughts on how far it reaches out side the forge are not so much gasses burning outside of the forge, so much as burning gas being forced outside of the forge due to the draw/pressure induced by the cone (where the real heat is). For example, an A/O torch has multiple flames. each level of flame has a different heat, but it's all directed by the flow of the gasses being introduced to the atmosphere. a short hot cone shaped blue flame/s and a long after flame. both are required for the torch to work properly. but once tuned properly they still maintain different lengths. Regardless of where you point the flame, the length of the different types of flame remain the same. Some shoot out away from the obstruction. In the case of the forge burner, the forge chamber directs the dragons breath out the opening.

[Frosty]

Ease up there a bit. Alan says he doesn't use "atmospheric" (naturally aspirated) burners so back pressure isn't an issue. What he's describing as properly tuned is right for a gun (blown) burner, especially for a large furnace.

A large forge furnace works better with a hard refractory liner for a few reasons: First, larger forges usually mean larger work or large quantity so the hard brick radiates more heat because it has a higher specific heat think reservoir. Secondly you don't light a large forge up for a few hours or half day at a time, they're often lit and left running for weeks with a low flame to keep them hot over the weekend to prevent thermal checking. Lastly a large forge, large size or quantity of work means the interiors tend to get beat up more than a small forge.

For a hobbyist our side of the pond insulating a small chamber is more economical because we're only lighting it up for a couple few hours at a time. We don't need the thermal mass because even if we're heating 1" sq. stock we aren't doing enough to need the higher output of a hard refractory "reverberative" liner. Our forges are also more susceptible to thermal cycling because they're hot for a while then cool down. That's why you're going to be buying soft brick pretty often and I use Kaowool.

I'm assuming Alan's is a commercial operation. Unless things have changed most hobbyists using gas are using "chip forges." A whole different breed of forge and they too require a gun burner there's too much back pressure to work with a naturally aspirated burner.

What we use for small forges in the States is pretty uncommon for the UK and naturally aspirated burners are even more rare.

Nothing Alan passed on is in error. Your forge is WAY too wide open, the door can be 1/4 brick size and be larger than it really needs to be. I've already said as much. His perspective on well tuned is aimed at a neutral flame and naturally aspirated burners tend to actually be oxidizing when the outside cues say it's neutral. Heck, unless I'm mistaken I believe folk in the UK use methane rather than propane so dragon's breath would be a BAD thing.

Frosty The Lucky.

[ThorsHammer82]

like I said, I wasn't trying to be rude, and I knew it would come off that way. But that was not the intention. 

I guess I'm a visual type. I can't see working with a closed forge, as how would you be able to tell when the metal is ready? 

the only other gas forge I've worked with at all was one time, and it was an open ribbon burner forced air forge, it had a secondary "invisible wall" blower that kept the dragons breath in check.

[Frosty]

Closed for a naturally aspirated forge is wide open for a gun. He keeps the forge as close to as possible and keeps the flame off the stock. It's a whole different thing. You gauge the stock's temperature by pulling it just like a solid fuel forge. After a while you have a good idea of how long it's going to take to come to heat.

I know how long it's going to take my steels to heat, I don't stand there watching them I do other things and only glance when they're should be close to ready.

Same same, just different machines.

Frosty The Lucky.

[Alan Evans]

First I want to say that I'm not trying to be rude, or insulting. But if you have no idea what you're talking about, why say anything?

now, just for my own questioning. if there is air and fuel being drawn into a forge, but there is no exit/opening, what's going to keep the forge running? Eventually you'd have no airflow which = no fire. forced air is one thing, but on an atmospheric burner, it requires air flow. or draw, to bring in enough Oxygen to burn (correct me if I'm wrong)

I can understand closing the opening as much as possible to still allow access to the work piece. but not entirely. I think the biggest issue I have right now is the regulator. once I've upgraded that I will move on to other potential culprits, but I don't think that  the opening is the primary problem at this point as 90% of the gas forges I've looked at have all been open.

As for the dragons breath, my thoughts on how far it reaches out side the forge are not so much gasses burning outside of the forge, so much as burning gas being forced outside of the forge due to the draw/pressure induced by the cone (where the real heat is). For example, an A/O torch has multiple flames. each level of flame has a different heat, but it's all directed by the flow of the gasses being introduced to the atmosphere. a short hot cone shaped blue flame/s and a long after flame. both are required for the torch to work properly. but once tuned properly they still maintain different lengths. Regardless of where you point the flame, the length of the different types of flame remain the same. Some shoot out away from the obstruction. In the case of the forge burner, the forge chamber directs the dragons breath out the opening.

You may not want to be rude, or insulting but yours is not a positive response to somebody who took the time and trouble to try and help give you an insight into the problem you described in your OP.

I am not quite sure how you extrapolate that I "have no idea what I am talking about" from what I said. It may well be true of course. 

You are perfectly at liberty to take or leave anything you read on the internet if it doesn't speak to your condition... including my posts and especially the following:-

To answer your question "why say anything?" I do have over 40 years of full-time professional blacksmithing experience which has involved lots of different ways of trying to get bits of metal hot. I have also been lucky to have learned much from others who shared information with me and wished to do likewise.

My comment about my lack of atmospheric burner knowledge was a précis of….not having actually built or tuned one of the T burners, or knowing why you had made your furnace in that form… I apologise if you misunderstood.

I have however built a few furnaces with atmospheric burners but they used either commercial T burners by Amal, or, for my first foray (30 odd years ago) a big Sievert propane hand torch. The sievert torch pointed in to a section of a 45 gallon drum which had ceramic fibre blanket strips packed into the arc masonry style. This was to give 24" heats on 6' x 2" square Aluminum bars to forge for grille panels to hang in a fashion house window. I mention this aluminium project to try and explain that one of the advantages of gas furnaces over coke or coal or charcoal fires is that the temperature can be readily controlled, without the intense hot spot which would burn the workpiece. 

It therefore follows that... by being able to control the temperature you do not need to be able to see the entire chamber.The most you need is to look alongside the workpiece to see when it is up to temperature.

Being able to see into the entire furnace at all times is counter productive to one's goal of getting the metal hot. Your wish to see the complete interior of your furnace is fine by me…but it is contributing to your perceived problem of "only being able to get to bright orange heat".

The elephant in the room of your OP is that despite a not unsatisfactory looking flame you are losing a large percentage of your heat by only having a five sided box. A huge loss through direct and radiant heat. The tuning of your burner was of minor relevance in this case.

The basic principle of preventing heat loss is what underlies all furnaces. It is why you can heat so much more effectively in a furnace than with a similar torch/burner in the open air. 

The more heat you contain then the less energy required for a given temperature of a given size of workpiece. The more energy/heat you can retain; the higher the temperature generated by a given burner. The more you contain the quicker the workpiece will reach working temperature and the less the heat will travel along the handle end. The quicker the workpiece heats the less opportunity for it to oxidise and form heat scale. Containment is good.

I moved on to heavier constructed furnaces with fan pressured burners (designed and made by me) because I had more atmospheric control and I could heat bigger bars quicker. I built different format boxes to contain the heat for given projects.

Having studied the glory holes and the glass melting furnace designs of glass blowers, I did start off by building in a sub floor level flue (not a bright idea to vent the hottest part at the top of the furnace). I realised very soon that given the nature of the construction and my inability to seal the door/access completely that a flue was unnecessary.

The commercial atmospheric burner forges I have used (mainly Cecil Swan's Portaforges) have a sealable door at the front and a small flue at front or back. All the later atmospheric burner furnaces I built were able to cope with the back pressure by using the gaps in the construction and around the workpieces...you are only reducing the heat escape not hermetically sealing it in. My pressurised air burner furnaces for instance do not explode with pressure even with out a dedicated flue.

I did wonder, being stung by your response to my initial post, whether to shrug my shoulders or tell you to go boil your head. ...But then I thought that even if you are not able to find anything of relevance in my shared experiences others following the thread may.

Alan

 

[fergy]

Thanks Alan that was a very interesting read 

im sure a lot of people will gain knowledge from that post 

a lot of people would have shrugged there shoulders and ignored the OP and not bothered helping

but you have replied with a post that should not only help the OP but also anyone else interested 

one day I will build a gas forge and it will be you and Crusty I ask for advice

fergy

[ThorsHammer82]

First and foremost I want to apologize for my rude gruff "Merican" nature. I assure you that was not my intent. I will attribute it to my lack of linguistic skill, and more than likely being at least a little "Hangry" at the time of my response. Both of which I take full responsibility for.

Alan,

I want to thank you for clarifying your response. As you obviously know far more than I probably ever will in regards to Blacksmithing. I feel that I read to much into your opening statement and didn't follow along clearly there after.

so close up the opening. Got it!

But I do have one question. how do you maintain the heat when the work piece is to big for the forge? Is it a matter of packing the opening around the work piece during heats and removing it right before it's time to forge? For example a Damascus billet on a handle. Or a larger cross section work piece like scrolls and rings?

I know in many forges people make "pass throughs" for longer stock. From what I've seen these can be anywhere from small flap type openings, to the whole back side of the forge opening up. how does one accommodate this with a brick pile forge?

Is it just a matter of stacking bricks in such a way that the least amount of heat possible escapes while still fitting the work piece through?

 

[Alan Evans]

 

Is it just a matter of stacking bricks in such a way that the least amount of heat possible escapes while still fitting the work piece through?

 

Yes.

Radiant heat loss is reduced by you not begin able to see a glow. Or rather I should say by less of the chamber interior being able to "radiate" through the opening. 

You can see less glow/furnace interior if your 1" square flue is through a 6" chamber wall than if it is the same cross sectional area flue through a 1" chamber wall. Think camera Obscura/pinhole camera. The smaller the hole or the longer the "tube" the narrower the angle. Same back pressure release with less heat loss.

Alan

But I do have one question. how do you maintain the heat when the work piece is to big for the forge? 

 

I moved on to heavier constructed furnaces with fan pressured burners (designed and made by me) because I had more atmospheric control and I could heat bigger bars quicker. I built different format boxes to contain the heat for given projects.

 

 

One of the disadvantages of gas furnaces over a coke fire is just that, if you want to heat part of a large object you have problems. It is one reason why Rosebud Oxy-acetylene/propane nozzles were invented….and why I have never got rid of my coke hearth even though I have not lit it for a decade.

Alan

Edited September 10, 2015 by Alan Evans

[ThorsHammer82]

so in theory, for a billet, if I left enough room for the handle to pass through that would be the best case scenario.

[Alan Evans]

so in theory, for a billet, if I left enough room for the handle to pass through that would be the best case scenario.

Yes, plus any gap needed for your back pressure issue.

If you are just heating a billet without a fixed handle constructing the flue can be done in such a way as to reduce the radiant heat. My friend  Cecil's portaforges have an exhaust about the same as the diameter of the burner look up Swan portaforge to see some images. You will need to experiment to find what size flue yours requires. Consult Frosty.

I attach a sketch showing the theory of the flue length advantage in case my text description earlier was not clear.

Alan