First of all I want to say thank you to Frosty and all the other contributors for the amazing well of information that this thread is.

I'm going with a NARB for the new forge I'm planning and I feel that I've ready to move out of the testing phase and start building the mold for the refractory.

I'm using a 1" burner with 0.8 mm mig tip and the wooden test block has 142 4mm holes. I've tested it up to 25 psi and It is burning really stable over the whole pressure range. No back firing or other issues at all.

I feal that I've gotten as far as I can without a proper forge to play with, so that's next on the agenda.

 

This is testing at 15 psi. What do you guys think?

 

Very nice!

 Also, welcome to the forum! 

Welcome aboard Leif, glad to have you. If you put your general location in the header you'll have a much better chance of meeting up with other members within visiting distance.

Your burner looks good but be prepared for it to burn differently when you put it in a forge, it might need a little turning. What are you casting the burner block from?

Frosty The Lucky. 

Thank you, Frosty!

I have some Kastolite 30 that I bought years and years ago with this intended purpose. Never got around to it before now, though.

Thanks to this thread I've understood that it most likely will need some tuning when I mount it in the forge and I have built the burner with this in mind. I'm also playing with the idea of putting even more holes in the plinth and plug a few if I have too many. It seems easier than drilling into it or casting a new one if I have too few.

Heh, heh, heh, my two NARBs both have a couple few plugged burner outlet holes. Plugging excess is WAY easier than trying to drill out more. 

I haven't built a burner in years, I have the T burner down to hardly needing to tune them so I don't consider the couple I've put together for the NARBS as counting. 

I'd really like to see someone come up with a way to keep the burner block cool enough to prevent burn back. I don't recall specifics but the hotter the outlets the higher the rate of propagation of the flame, IIRC Flame Front Velocity. Anyway, if the outlets get hot enough to raise the flame front velocity to the same velocity as the fuel air mix in the outlets it WILL burn back. 

Of course you can just turn up the psi and keep the outlets cool enough but at a point they break contact with the burner block and it stops performing. 

It's a balancing act. Wooden burner blocks like your test burner don't absorb energy or heat up like a hard refractory so you don't run into the problem until you start casting blocks.

I discovered that tuning by ear was more effective than by eye. Unfortunately wood blocks make long primary flames as seen in yours so there are possible surprises when you start casting blocks.

Listen to the other guys on the forum who work with and build multiple outlet burners, it's really old tech and many of them have been using the things for decades. I wouldn't have gotten close, heck even thought of a home build if it weren't for the glass people and glory hole burners. I just adopted and adapted other's burners.

Keep us in the loop please.

Frosty The Lucky. 

On 6/29/2024 at 11:23 AM, Frosty said:

I'd really like to see someone come up with a way to keep the burner block cool enough to prevent burn back.

Well, so far my latest block doesn't burn back at all even after being at welding temperature and dropping back to under 1 psi.  It doesn't even pop when I turn off the gas.  However it has about 180 ports that are 1/8" diameter, and the ports are nearly 3 inches long.  It's a big heavy burner block and if I didn't have a 3d printer I wouldn't have even wanted to attempt the mold.  I think the distance between the outer burner head surface and the plenum is playing a significant role here.

I have less than 100 hours on the burner head at this point so I don't know how it will hold up long term.  Some of my previous attempts started out very promising, but showed degradation in the performance over time.

Sounds promising Buzz, may we have a look at it running?

Frosty The Lucky.

I haven't had very good luck getting pictures with accurate colors, but I'll give it another shot soon when I get a chance to fire up the forge again.

Yeah, the colors aren't worth trying to judge forges with online. I'd sure like a look at the flames though. I can generally tell how hot a well made forge will get from how the flames look.

Thanks, Frosty The Lucky.

Alas, had I only had a 3D-printer!

I've ordered some sprue wax from China that I'll try to make sense. That's one of the reasons I'm using 4 mm holes, I think 3 mm wax will be too bendy.

I'll try to go as thick as possible. Hopefully I'm have enough refractory to get close to 3".

You can chill the wax before casting the burner head so they don't bend so easily. 

Frosty The Lucky.

2 hours ago, Frosty said:

You can chill the wax before casting the burner head so they don't bend so easily. 

Frosty The Lucky.

My thoughts, exactly 

So I finally cast the burner. Our two week family holiday in Italy delayed the process.

I ended up doing 132 holes. Even though the sprue wax said 4.0 mm on the package, it was actually a lot closer to 4.5 mm. 

 

Here's what it looked like with all the pins in place. The mold is 240 mm by 90 mm and 70 mm deep.

 

I've never really used Kast-o-lite 30 before and I had to go on YouTube to find some visual aid on what it should look like when mixed correctly. It really funny how it well it flows when vibrated. My power drill has a high pitched hammer function and this was the perfect tool for the job. I got the mold completely full.

 

Here's a look at the new forge I'm building. The shell is only 1.2 mm thick so I need to make an external fram to support the burner. I don't think the shell will be able to support it in the long run.

 

This has to be the weirdest thing I've ever barbequed. 

What do you think? Low and slow on indirect heat to cure the refractory and melt out the wax?

Looks like a good idea. Wouldn't recommend cooking anything else at the same time, unless it were in some kind of airtight wrapping; you don't know what kind of nastiness might be off-gassing from the burner.

Looks good for the initial melt of the wax. It will need a full burnout or residual wax will burn out when you use the burner and that's problematical on a couple levels. 

I brought my burner blocks to well above waxes ignition temp and let it roast. I asked a caster who burns out wax as a matter of course and did it his way. I made a brick furnace around it and used a propane burner on it for a couple hours.

It sounds extreme but wax can be very persistent.

Frosty The Lucky.

It's ALIVE!

Melting out the wax on the barbecue worked really well

This running at 15 psi with a 1.0 mm mig tip.

Ooh, pretty. 

Nice. The flames are pretty even. She's in easy tuning range. They will improve considerably if you lean it up, all the tertiary flames floating above are wasted fuel. Well done.

Pro tip. Make any changes one at a time and evaluate the results before making another. Keep notes.

Frosty The Lucky.

Looks a pretty even flame pattern, but it looks like the burner is fully choked down.

Maybe it's just the angle of the camera.

It's not fully choked down, but pretty close. When I open it up more the flames lift of the block and it can even extinguish itself. I've decided to leave it like this for now and and time it once it's mounted on the forge.

Turn the psi down to keep the flames in contact with the burner block. Forget what some guy on the internet says is the "right" psi to run burners, it's all BS. Home built burners are always individualist machines even if you buy the important component like yours. Tune your own and it'll work properly. Running this rich it might not even light in the forge, all the flame will be outside the doorways.

A MAJOR safety issue running any burner is carbon monoxide production. They all produce it unless run dangerously lean but you can make burners into CO machines and yours is WAY over the line right now.

Frosty The Lucky.

Don’t listen to any Internet advice.  Especially this Frosty character. If that is his real name. What could he possibly know about a NARB? 

It’s a good looking burner. Thank you for sharing.

CURSES FOILED AGAIN! You impudent irregular stream of electrons aspiring to form lucid communications. BAH!

Frosty Whiplash.

Hi all, I'm trying to learn how to make a NARB and there's been a wealth of knowledge in here but I have a question or two that i couldn't find an answer for.

Mainly, what kind of tip/nozzle do I want to use for the injection of propane? I see MIG tips are used and my current propane forge is a NA single burner, could I use that very tip or would I want a smaller orifice? And, how would I want to connect it to a black iron pipe T?

I understand that a wood block is good to test but not a hard and fast idea as the actual cast of the burner is where the work is at. Would I want to use like, mizzou or kastolit? All my experience has been satinite so far. Im sure I have other questions but they currently escape me. Thanks all.