Naturally Aspirated Ribbon Burner. Photo heavy.

[cbrianroll]

GAAAA...NO! I will look now lol. I've been really lazy lately....everything is bus. Have had no time for forging at all. Hopefully order supplies this week though...

[Greebe]

Quote

I saw Frosty mention that this burner is ideal for 300-350 cu/in. Is forge shape important? In other words can it be shorter in height and wider and work well, or does it need to be taller and more narrow? Was thinking maybe 7" wide x 4" tall x 12" deep for 336 cu/in, but not sure if that short of height would reduce burner efficiency.

On 1/30/2021 at 1:56 PM, Frosty said:

That shape should be fine, it's long and narrow that makes even heat difficult. 

Sorry, not to be daft, but I do not understand your response. If the shape I have planned should be fine, why would that make even heat difficult? Should I change the internal dimensions? Sorry for the confusion. Thanks!

[tinkertim]

3 hours ago, Greebe said:

That shape should be fine, it's long and narrow that makes even heat difficult. 

Hi Greebe,

I think it's a slight punctuation hiccup that is making it confusing.

Breaking it down into:

"That shape should be fine" because your dimensions are quite sensible.

"It's long and narrow that makes even heat difficult" which is a separate statement that doesn't apply to your dimensions.

Does that help?

Tink!

[Another FrankenBurner]

I interpret that a little differently.  

Should be fine meaning the burner would run fine and the forge would heat steel.

Difficult to heat evenly meaning you may have a hot spot wherever the burner is pointed because of the long/narrow dimensions.  With a top center down burner, the hottest area being right in the center.

If you are to be a knife smith exclusively, you might want to invest some fuss in this.  I am a general smith and I prefer to have a hot spot.  On the occasion that I make a knife, I just have to know the hot spot is there and work with it.

With a ribbon burner which is also long and narrow, your heat gradient may be a lot less than my single port burner forges.  I am not experienced with ribbon burners so I am not sure on this.  

Sounds like it could be a nice forge.

If you end up building with soft firebrick, you can build the burner, then temporarily play legos with the bricks and burner to see what configuration you like.  

[tinkertim]

9 hours ago, Greebe said:

Was thinking maybe 7" wide x 4" tall x 12" deep for 336 cu/in

Hi AFB,

These dimensions don't feel like a long and narrow forge, which is what I thought Greebe was concerned about.

Maybe Frosty can confirm what his intended meaning was, when he pops by.

Tink!

[Another FrankenBurner]

I thought the same on the dimensions but I don't know much about ribbon burner or square wall forge flow patterns. 

[Frosty]

I wasn't clear enough. Your forge should be fine as described, Greebe. 

Long and narrow being problematical, should've been a different sentence. 

Nailed it in one Tink, thanks.

Sorry for the confusion.

Frosty The Lucky.

[Another FrankenBurner]

I need to go out and forge a foot in mouth extraction pry bar.  

I try hard not to talk about things I don't know.  If I ever fully figure it out, there's a good chance I'll never speak again.  

[tinkertim]

Don't worry about it AFB, you don't need the pry-bar matey!  

But what you know about is hot NA burners!  Your burner designs and mini-forges are epic!!!

I still want to make a 1/2" hand-held one for local heating.  I'm going to try and CAD up something along the lines of your V46, just to see if I can handle the merging of complex compound curves in the free CAD package I use.

It will only be for short-time-use, so I'll probably print it in PLA and use 1/2" stainless for the mixer as it is less conductive than malleable iron. 

Funnily enough, I recently moved to the department that designs and builds Metal-Powder-Bed 3D Laser Printers, so one day I might be able to scrounge a metal print on a test run. Fingers-crossed!   

Tink!

[Greebe]

Thanks guys for the responses. At first I read it that way, but I then started to question the meaning and wanted to confirm.

K26 bricks should be fine for a forge like this, eh?

I was thinking of trying an experiment with 3d printing the NARB form instead of using Crayons. Then I could make it all one piece, and maybe create a small cone on each orifice. Not sure if that would do anything to aid in performance, but all other burner designs have a flared end.

Thanks again.

[Frosty]

If you're going to 3D print the burner block form why not taper the entire length of the outlet nozzles? Just make sure they don't exceed a 1:12 ratio. 

Keep us in the loop please. 

Frosty The Lucky.

[Greebe]

Good point. If I were to taper the entire hole length, what are you thinking would be appropriate for outlet diameter? Thinking maybe the small diameter should be 5/16", and taper to 3/8" on the outlet end? Just thinking out loud as I have know idea how the flow would react to being tapered in this type of burner. Thanks!

[Frosty]

No idea and it'd be a bear to model the way I did before. Taper the Increase a few thousandths and see what happens? 

Frosty The Lucky.

[Greebe]

I was modifingmy post above with dimensions as you were posting. LOL!

[Greebe]

Did a quick model. This has a base plate that would be removable from the plugs. That way, in theory anyways, you could pop the plate off and maybe be able to twist out the burner orifice plugs one at a time. The plugs are 2" long tapered from 5/16" diameter at the small end to 3/8" diameter at the large end. The tenon on the bottom is .500" diameter and .375" long. Spacing side to side is 1.080" and .928" diagonally. (Don't ask why I used odd spacing. LOL!)

Thoughts?

[Frosty]

Of course I have thoughts, it helps keep the voices from arguing.

Yeah, How about using tapered wooden pins with a thinnish rubber outer sheath for outlet cores. They could maybe insert into the board with a tapered head similar to your rendering so they're reasonably liquid tight. I wouldn't extend the rubber onto the tapered head you want it to come free easily.

When you make up the mold each core has a well lubed wooden pin to hold it's shape. When the refractory sets up, a pass with an air hose over the ends of the pins in the base board will break contact with the rubber skin and with the pins removed the rubber skin should just pull out. 

Another thought would be to rig a fitting to inject water under pressure into the plenum through the fuel air inlet and force the cores out of the bock hydraulically. Once the wooden pins are removed that is.

Hmmm? What do your voices think?

Frosty The Lucky.

[Greebe]

Well the voices in my head are arguing right at the moment, so it is making it hard for me to find the right thoughts. LOL!

Yes a barrier between the plug and the refractory would be a way to go. Not sure how the rubber lining would be made. Perhaps via dipping it in an aqueous solution of latex?

The thought that comes to mind is being able to make this as simple as possible. It would be nice if the tapered plug would come loose without damage. Then the whole unit can be used again. That would be another benefit of a tapered plug is that you would just barely need to break it free and then it would come out easily.

This leads me to thinking that I could make the plugs with the tenon being the same diameter as the base of the plug. So instead of having it .500" make it .375". Only problem with this and the reason I went .500" is that it allows me to have a fillet at the junction of these two points to make the casting more clean. However my reasoning behind a .375" tenon is that I can print it with a very thin and continuous spiralized wall. This would serve two functions. One is that it would essentially produce a very fine thread if you will on the outer surface which might make removal easier, maybe even screw it out. Secondly, it would be thin enough that it might be possible to twist up and remove, yet still be strong enough to hold its shape. Like twisting up a plastic straw.

Oh, too much thinking and complicating me doth do.

 

Edit:

Here I quickly changed it to what I was describing.

 

 

[Frosty]

You should buy some of the refractory you wish to use and find out how sticky the stuff is. I used Kastolite 30 and have never been able to pull anything out of it. Dowels dipped in wax wouldn't come out until the test coupon was hot enough to melt the wax. I tried coating it in stiff grease, that one is still stuck, Crisco seems to be the best release agent I've tried so far.

Not being able to pull cores is why I use crayons.

Other guys have made cores and pulled them but they don't wait till it sets completely I believe.

There are other guys who have gone way farther than I did and are much better at making multiple outlet burners. WAY BETTER at it.

I still have thoughts, can't seem to help it.

Frosty The Lucky.

[D.Rotblatt]

Hey guys!  Still around, and still playing around .  Was browsing Amazon and found a extruded honeycomb heat resistant ceramic plate for a gas BBQ oven, 7.8x5.5", about $20.  Lots of tiny holes, refractory, made for a gas flame.... HMMMM.

So I bought one.  I had a test plenum sitting around, and I worked up a mold, and made a NARB.  I've only test fired it once, but it looks really promising!  My only concern is that it is only 1/2" thick.  The flash point of propane is 1100F, so if the back gets up to that heat it'll backfire.  Here's some pics, I'll do a 4lb Damascus billet this week and see how it works over a long hot 2350F+ run.  

After curing the burner, it seemed to be about 150F or so hotter at the same pressures I usually use on my 1/8" holed NARB.  Quiet burning, no organ sound except for a little momentary note the moment it first ignited.  

Construction was really easy.  The ceramic cut with an angle grinder and cutting disc like a hot knife on butter.  Actually I felt no resistance at all when I cut, so easy to form. The mold worked great, and it only took a few minutes to mortar the honeycomb into the burner.

I made the mold with my 3D printer, but it would be really easy to make out of wood, just have to cut some draft on the pieces so it will release from the refractory.

The bottom temperature is phenomenal!  After bringing up to heat and warming up the forge, I was able to turn it down to 1400F.  Just barely holding a flame.  Pure awesomeness!  It'll be great for HT!

 

Closeup of the extruded ceramic to get an idea of the hole size.

 

The plenum and mold for the refractory.

 

The mold in place.

 

Ready for the refractory.  I used Mizzou.  A lot easier than trying to get it around all those little rods.

 

The cast and the Ceramic Honeycomb cut and ready to be mortared into place.  I used a 3000F refractory mortar (Meeco's Red Devil 610) that I got for doing hamons on blades.  

 

Mortared in place.

 

Compared to my NARB with 120 @ 1/8" holes.  

 

The first burn, just curing.  At 5 lbs (this is a NARB). 

 

At heat.  The gas seems to keep the honeycomb cooler than the forge.  We'll see if that's enough at 2350F.

 

[JHCC]

That certainly looks lovely. Keep us posted on its performance. 

[Rojo Pedro]

Super cool Dan. Watching with great interest. 

What is the function of the refractory and its shape? Is it just to hold the ceramic or insulation, flow?

How is the refractory fastened to the plenum?

[Another FrankenBurner]

Very cool.  I see these plates used in burners at work a lot.  I have a pile of them I planned on playing with.  Most manufacturers call them ceramic radiant burners or high efficiency burners.  Both naturally aspirated and powered air varieties.  The powered air versions usually use 3 of these blocks for a large, high output burner.  The naturally aspirated sometimes run a low enough output that the flame just barely covers the plate and the plate runs into the orange temperature ranges for radiant heat transfer.

I wondered about the cooling factor when run in the higher temperatures of a forge.  Your pictures make it look like there is enough flow through the block to keep it cool.  Makes sense, the connecting refractory being only as wide as the ports themselves.  Little refractory with lots of flow.

I like it.  I will have to start tinkering too.

 

[D.Rotblatt]

3 hours ago, Rojo Pedro said:

What is the function of the refractory and its shape? Is it just to hold the ceramic or insulation, flow?

How is the refractory fastened to the plenum?

Correct, the refractory is just a way to hold the ceramic plate.  It's also to allow the plate to extend 1" or so from the plenum so the plenum doesn't get hot.  The shape of the plastic mold, i.e. the slope of the pieces is just so it will release from the refractory easily.  

When I cut the square tube (rectangular) for the plenum I left some lips, the metal extends over the refractory 1/2". It's the same way we always do ribbon burners.

1 hour ago, Another FrankenBurner said:

ceramic radiant burners or high efficiency burners

Yes, I think that was mentioned.  Probably a better google search.

1 hour ago, Another FrankenBurner said:

The naturally aspirated sometimes run a low enough output that the flame just barely covers the plate and the plate runs into the orange temperature ranges for radiant heat transfer.

Yea, it's pretty cool .  Earlier in this thread we talked about the FAM not being able to burn back into small holes with examples of the screens on old kerosene mine lamps. That's why I'm only worried about the back of the plate getting hot. The other factor with NARBs in turning them down is the back pressure.  The gas coming out of the jet is, I think, the main thing pulling air into the intake.  At really low pressures if it meets any resistance air just doesn't get pulled in and you get orange pure propane flame. These perforated plates don't have much resistance which allows me to turn it down so there's barely any flames coming out.  Just little nubs of blue if at all.  I have to look at it again, but I don't think it does that glowing orange thing, went to orange propane flame first.  Our burners are made to perform at high output, not low.  Even so... 1400F and seemed stable.

I'll play with it more later!  I'll keep you posted and if it works post the Amazon site for getting the ceramic plate.

[Another FrankenBurner]

Good stuff.  I like tinkering with the turn down range as well.  I am curious, if you turn it down to what you consider your lowest end with still clean burning, will the FAM flow through be enough to keep the block cool enough?  Or like Frosty experienced, will it run well for a while until the block slowly heats too high and then boom ignition inside the plenum?  Your long running stable low end may be determined by having enough FAM flow for cooling more so than just pulling in enough air.  

If you had more than enough high end, you could sacrifice some high end to gain low end if you needed lower capabilities for some reason.  You are liking low end for heat treat purposes?  In which case, you are more than happy with 1400°F?

Did you run some tests for the surface area of the initial block or did you just size it based on the available space in your forge from the previous burner?  

[D.Rotblatt]

25 minutes ago, Another FrankenBurner said:

I am curious, if you turn it down to what you consider your lowest end with still clean burning, will the FAM flow through be enough to keep the block cool enough?

Should be.  They are made to run at low temps like that.  They are, after all, mostly used as infra red heater blocks.  Some specs say 1000-1200C.  I saw one video showing the burner in use, was red on one side and when he picked it up the other side was not red. In addition, the small holes will not allow the FAM to burn back into the block. At HT temps, which is 1450 to 1650 for normalizing that's in the range of it's normal specs. It should be fine at low temps.  It's the high ones that I'm concerned about.

30 minutes ago, Another FrankenBurner said:

If you had more than enough high end, you could sacrifice some high end to gain low end if you needed lower capabilities for some reason.  You are liking low end for heat treat purposes?  In which case, you are more than happy with 1400°F?

First, I have no idea how to re-tune our burners to get a lower end. We've worked so hard to get the most out of them. It's a different burner design, (pic below).  The jet has air intakes, and is far from the mixing tube.  I could pull back the jet for more air entrapment.  My burners have some adjustment there and a thumb screw, so that's easy.

1400 is great!  I'm only looking at hardening (tempering goes in the oven or an oil bath for swords), so the minimum is 1450F and some alloys go up to 1550F.  If I'm doing stainless I'll use the oven with stainless HT wrap, but that's a whole different beast with ramp schedules and all.  Some people do sub-critical soak for grain refinement, down to 1300, but 1400 should be fine even for that. I didn't try the low temps with a reducing flame, so I might be able to get it lower.  We'll see

36 minutes ago, Another FrankenBurner said:

did you just size it based on the available space in your forge from the previous burner?  

Yup. Basically I just made the largest opening I could for the sized plenum I had. If this works well, I have an 18" forge that I had two NARBs on, but just couldn't get them to work right, so I just reconverted it to a gun ribbon burner.  I'll try these on that forge as well as it's primarily for HT of longer blades.  Something about the back pressure caused that loud organ sound when I turned on the second NARB.  Wouldn't go away, and it's loud as sin.  I finally gave up, but these don't have any organ sound.

Great bouncing around ideas with you, and great being on again, it's been too long .