Naturally Aspirated Ribbon Burner. Photo heavy.

[Jbradshaw]

Has any one figured out how many holes are needed for a 1/2" burner yet? I just picked up a helium tank that I'm going to make a smaller forge out of (I currently am using a 20 lb propane tank) and I'm thinking a 3/4" burner will be too much burner for it.

[Another FrankenBurner]

Jbradshaw - On page 6, Buzzkill posted February 18 a 1/2" version.  Forgive me if the link does not work, this is my first post on IFI.  

 

[Jbradshaw]

I looked the thread over for a 1/2"

burner before posting that question. Clearly not well enough. Thanks for pointing me to that post. 

[the2ndcashboy]

So I just want to say "thanks" to Frosty. I made my very own NARB this weekend and it's pretty sweet. Runs great from 1psi all the way up to 20psi (my regulator's max pressure). I put it in a propane bottle sized forge with 2" of wool and ~1/2" of refractory cement (hyrezist 2700 from plibrico if that matters). Internal volume is just under 300ci. It gets to a bright yellow heat at 20psi with the opening halfway blocked (opening is 4"x7"). I dunno if that's quite welding temp or not, since I'm a total noob, but I'd say it's pretty close if it isnt. The mild steel stock I was playing with wasn't sparking. I'm thinking the burner is running a little "lean". I'm running a full-length Tweco .035 welding tip for the jet, and I'm not getting anything but medium orange dragons breath even at 20psi. At 10psi there barely any dragons breath at all. There also seems to be quite a bit of forge scale on the bar I was heating. Should I ream the tip out a bit and try that? I'm not planning on forge welding right away, but I think I'd like to try it in the future.

[jlpservicesinc]

just buy and 0.040 or 0.045 tip, they are cheap enough and you can go up or down in size.. 

[the2ndcashboy]

I have extra .035 tips and the drill bits I'd need to enlarge them, so I'd rather do that than buy more tips. I guess my question was more "is my burner actually running 'lean' or am I reading the signs wrong?". 

[Buzzkill]

Based on my limited experience with NARBs, I'd be very surprised if you were in fact running lean.  Is scale forming while the stock is in the forge?  To check it take new stock or some that you have ground to a shiny surface.  Let it heat up to the same temp/color as your forge and observe the surface before you remove it.  If the surface still looks smooth chances are you are not running lean.  Of course once you remove glowing stock from the forge, scale will form almost immediately.  Orange flames don't tell you as much as you might think.  It appears that some refractories, like Kastolite, tend to influence the flame color for a while at least and orange is what I've seen.  I'm not sure if the material you used has the same effect.  You can also observe the flame cones at the burner.  Lean flames tend to be a deeper blue and can even trend towards purple when very lean.  Rich flames are a lighter blue that trend towards green when very rich.

On the other hand, if you have spare mig tips you can always drill some out and try them to see what effect that has on your forge temperature.

[the2ndcashboy]

I'll have to try grinding a bar shiny and see how it scales. I was mainly going by the amount of scale it was leaving on the anvil. I had heard the same thing about the NARB running on the rich side, so I was surprised when mine seemed lean. Mine almost acts like it could use one more hole (I used the 19 Frosty settled on). Like maybe the air velocity is borderline too high. It won't really burn at all outside of the forge, and when the forge is cold, there's a fair amount of flame standoff at 3psi and above, but it'll still stay lit from 1-20psi. As the forge heats up the standoff goes away, and then you can't see the individual flames at all when it's all the way up to temp. Never any popping or anything unless I go down to <1psi, then it will flutter and pop out. That's a more than acceptable bottom end though.

[Buzzkill]

Scale on the anvil doesn't really tell you much unfortunately.   Once you remove the piece from the forge atmosphere it is definitely exposed to oxygen and that will produce scale rapidly.

It does sound like you're at least borderline for either slightly enlarging some of the holes or an additional hole.   I'd make certain all holes are free of anything that could restrict flow before changing anything else though.

It's normal for the flames to become effectively invisible at the burner as you get up to temperature, but in the first few minutes you should be able to get an idea of their color.

I've been very pleasantly surprised with the operating range of the NARB I made.  After getting the forge up to temp I can keep a nice high orange forging temperature around 5 psi, but I do get some backfiring around 2 psi or a little lower.  At this point I really have no desire to go back to a single opening burner.

[the2ndcashboy]

I cast it with crayons, so my holes should be the same as the original NARB, but I also cast it a full 2" thick, and after reading back through Frostys write up, I think his was only 1.5" thick (he said he used 2x2s for the form). You'd think the extra hole length would slow the gas jet down though, not speed it up. Maybe its cause I'm near sea level, and Frosty is at a higher elevation? At any rate, the thing works fantastic, I'm just fine tuning at this point. I think if it was a smaller forge then the air velocity might start to be a problem, but mine is on the upper end of what this burner will do, so it's not really a problem.

Pics of the flames. Cold startup. 1st pic is 2psi, 2nd is 10, 3rd is 20. Ignore the orange streamer in the 1st pic. Just a bit of crayon wrapper burning off.

[Frosty]

Looks pretty good to me. Your flames look about like mine at similar psi and they're certainly not lean. Another hole might work better, maybe not. I'd have to make another test block were it  mine.

The calcium used in high temp refractories burns at the surface with an orange flame till it's done doing that.  It makes more dragon's breath than accounted for by unburned fuel. The color of the dragon's breath in your first post is the calcium, the rest it pretty clear. If it's not forming scale IN the forge it's running neutral to slightly rich. Scale will form on hot steel in open air.

Frosty The Lucky.

[the2ndcashboy]

Yeah there's basically no dragons breath until the forge is up to operating temp, so it makes sense that it's the refractory burning off. Guess I'll run it for awhile as is then. I'll revisit burner tuning if adding doors doesn't get my temps up to welding heat. Or maybe just paint on some Plistix or Matrikote. I've heard that stuff works wonders.

[Buzzkill]

From what I've seen Matrikote doesn't really raise the internal temperature noticeably.  The max temperature is, IMO, a function of how well your burner is working - assuming you have a good forge design (and it looks like you do).  What I have noticed though, is that Matrikote seems to do a great job evening out the internal temperature in the forge, and I think I use less fuel to maintain temperature as a result.  I didn't keep notes before and after applying the stuff, so I can only report my impression rather than hard data.

[Frosty]

Buzz: Reading your reply made me search out the Matrikote MSDS and it doesn't list a zirconia ingredient at all. It's 90.4% Al2O3,  1.5% SiO2, P2O5  and the remainder something proprietary. It's intended as a thin protective refractory coating. A kiln wash in ceramic and pottery kiln terms. ITC doesn't list the components for ITC 100 HT as anything but proprietary and being non health hazards with no reportable quantity, they don't have to. Chronic exposure is potentially hazardous but basic, non specialized precautions are sufficient.

It looks like I've been wrong in thinking Plastix or Matrikote contain zirconium. They are however good high temp kiln washes that'll protect your forge liner from fluxes and flame impingement effects.

Hmmmm, back to thinking about home brew high zirconium kiln washes eh? Good thing I never stopped. 

Frosty The Lucky.

[WayneCoeArtistBlacksmith]

I can say that when I added Metrikote or Plistix it cut the heating time in half to get a piece of 1" square up to forging temps.

Let me know if I can help you.

Wayne Coe

[Buzzkill]

No doubt there is an improvement in that area.  To me it seems that's a result of the improved radiant oven effect.  In other words it's making better use of the heat that is available, but I'm not yet convinced that there is a significant increase in maximum temperature with everything else about a well-built forge being the same.  Again my opinions are not based on hard data, but rather my observations before and after applying Matrikote.  It would be interesting to me to see the temperature readings before and after application using the same forge, burner, amount of time since ignition, and pressure (or fuel/air settings for a blown burner).  I don't have a good way to accurately record the temperatures, but if someone does have that data or checks it out in the future I'd like to know to satisfy my curiosity if nothing else.

I guess all I'm saying here is that while I believe that there is some fuel efficiency to be gained with Matrikote, I'm not sure that it can help you get to forge welding temperatures if your burner will only bring you up into the high orange range or something similar without the coating.

[Exo313]

I think Wayne and Buzz both make sense, in that there's an observable improvement in cycle time. 

Being worse than a novice in this area, I would hazard a guess that, with Matrikote, more fuel is going towards heating the steel as opposed to heating the liner.

I don't know if this is realistic. Someone with a better understanding of the science may be able to assist. It just seems like a cold glass of water in a drafty room that is "on average" at 68F will take longer to reach the ambient temperature than a room that is insulated and held at 68F.

[Frosty]

Exo: What we use as a gas forge is a reverberatory furnace, I don't know the etymology of the term but it means. The flame heats the furnace walls and infra red radiation emanating from the walls heats the contents. The fuel heats the forge, the forge heats the steel. Okay, I should've done this years ago, YahooFu says. http://uotechnology.edu.iq/dep-production/branch5_files/reverberatory furnace.pdf

The first paragraph covers how it works and where the name comes from. 

I am NOT saying Matrikote or Plistex don't improve forge performance, they obviously do. I've known Wayne online for I can't remember how long and by reputation longer. Other than typos or differences of opinion I haven't known him to be anything but an upright guy. I haven't  known Buzz nearly as long but I've never heard him say anything to find fault with.

Worse, I've never used either kiln wash, I've had to make my own. I have no first hand opinion of how either product works, just testimony from folks who have, my opinion is hearsay. I still have no doubts they work as our guys say or I wouldn't have been recommending them. I'm just surprised they don't contain zirconium which means zirconium isn't as necessary to an effective kiln wash as I thought.

Frosty The Lucky.

[Daguy]

I'm in agreement with Frosty et al.  I'm a Machine Maintenance Mechanic professionally.  Read that as "Jack of All Trades, Master of  None".  For guys at our levels of, for want of a better turn of phrase, "The Art", we are more interested in results than in formulae.  The Formulae on these matters help us determine a direction, but just as with Frosty's NARB (or whatever we end up calling it), experimentation ultimately gets us there.  If we're not willing to put the time, money, effort, and thought into finding out, we weren't THAT curious in the first place.  Sometimes we talk technical, sometimes we talk expirimentation.

Kudos to the thinkers here.  Kudos to the grunts.  I for one am so happy thatI have found a community with both, and each respects the other.  What it all comes down to is that there really is no GOOD industrialy produced, out-of-the-box forge out there.  But, Man, what a treasure that there's a place to find simple instructions on how to build an exceptional forge / burner combo for less money than those commercially available.

Thank you all for being here and being willing to FREELY share your knowledge/experience.

Daguy 

[the2ndcashboy]

Ok, y'all have me curious now. I'm going to rig up a thermocouple of some sort and do a before/after temp check with either plistix or matrikote. Might even try to find a pid with datalogging, that would be really informative to see the whole warmup curve instead of just the end result. I'll report back in a few weeks with my findings (honey-do list permitting).

[Buzzkill]

Thanks for taking that on.  I'm very interested in what you find.

[the2ndcashboy]

So the thermocouple and Matrikote are on order. Meanwhile, I've been playing around with the forge. I've never tried to forge weld, so I decided to try a fluxless weld with some mild 1/2" square stock (may as well aim high, right?). I can state with confidence that my forge does indeed get to welding temps. It wasn't a perfect weld, but it *did* weld in the center of the bar. I quenched it in water and tried to separate the pieces with a big chisel and they wouldn't move, so then I cut it across the weld and there's a cold shut about 1/3rd of the way across but the rest is welded solid. Shouldn't have any problem at all welding higher carbon steel with flux.

[WayneCoeArtistBlacksmith]

On 7/10/2018 at 1:31 PM, Frosty said:

I am NOT saying Matrikote or Plistex don't improve forge performance, they obviously do. I've known Wayne online for I can't remember how long and by reputation longer. Other than typos or differences of opinion I haven't known him to be anything but an upright guy. 

Frosty, you are to kind.  I will send you a pint of Metrikote if you will test it and give your (honest, which is the only opinion that I've known you to give) opinion here.  I don't think that I have your mailing address so e-mail me.

the2ndcashbooy the way you did the forge weld is not the best way to test a weld.  There is no scarf shown there.  It is good that you did get a weld there but it would be better if you did a proper scarf for a test.

Let me know when I can help you.

Wayne

[the2ndcashboy]

Yeah, I know that wasn't the proper way to do it, but I wasn't trying to actually make anything. I just sanded the mill scale off both pieces and tossed it into the fire to see what would happen. More of a temperature test than anything else. I figured if the pieces of mild would stick together then I can weld anything (once I have the skill to do so).

[Frosty]

I wasn't bucking for anything Wayne, I just calls them like I sees them. Sure, I'll give some a test I even have a good opportunity coming up. Our club is holding a forge build clinic for the new guys. Small, 150 cu/n +/-, clamp together K-26 brick pile forges with a single 1/2" T burner. Nothing elaborate a main part of the point is to show how little is involved in making a good forge. It'll be the perfect place to do some testing on kiln washes.

Heck, it'll be good loss leader marketing. Include a handful of cards and we have a deal. 

Thank you. Frosty The Lucky.