Frosty

Naturally Aspirated Ribbon Burner. Photo heavy.

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Forge is ‘melting my face off hot’ I used timgunn’s 90 jet for the Amal injector and it OLs my probe rated at 1300degC (2372degF), ran it at 10-15 psi and it melted the ceramic fibre rated at 1430degC (2606degF). Welded a couple of stainless san mai billets today, chuffed! One pic is of the billet with a drop of ceramic on it and a blob of molten ceramic next to it, after shut-off.

 

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Put a hard refractory inner liner in that thing unless you enjoy relining it every time or two you use it. 

The whole burn your face off IR is why I've taken to aiming the forge openings 90* to the anvil so I'm not being toasted while I work. 

Nice forge, well done.

Frosty The Lucky.

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Update:  My (NARB) IFB ribbon burner block with 1/8" drilled holes failed tonight.  However, it appears to me that the forge exceeded the maximum temperature of the fire brick rather than cracking or crumbling.  I had been forging billets for pattern welded blades for a couple hours at nearly white heat when I heard the change in the burner.  It looks like it slumped inwards towards the plenum.  I'll know more this weekend when I have time to remove it and examine it more closely.

This was just standard soft 2300 degree F insulating fire brick.  I'll probably get some Morgan K26 or higher rated bricks and try again.  Overall I still think the concept has merit.

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Buzz had a meltdown!  :o Your burner block was headed for China but you got her shut down in time. WHEW that was a close one! Could you feel the radiation? Have pics?

Morgan K-26 is only rated a little hotter than 2,600 f. IIRC they make IFB rated significantly hotter. 2,800 f - 2,900 f  I think?

Frosty The Lucky.

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I don't think it was quite that perilous.  It sounded like the flame started burning inside the plenum, but I did get it shut down after just a few seconds once I heard the change.  I'll try to remember to grab some pics over the weekend.  I have family stuff to deal with tonight.   I have a half dozen other things I really need to do as well, but none of them are as satisfying as heating and beating metal so we'll see whether my sense of responsibility or my desire to play with fire wins the battle.

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We have tried a few more of the K26 bricks as baffle walls and they have all crumbled in short time.  We are now experimenting with other solutions.  

One thing you might try if you are determined to use the bricks, coat the flame face with plistix.  

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I have some Matrikote I may try, but I'm thinking that if the internal forge temperature is higher than the maximum temperature the brick can withstand and maintain structural integrity it probably won't matter much if the outer surface is coated or not.  Worth a try though since it doesn't cost much to do it.

I was actually pleasantly surprised that up to this point I hadn't seen any cracking between the drilled outlet holes or any of the other normally observed failures of the bricks when they are used as forge walls or baffles.

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I have not been paying attention for quite a while, I have done quite a bit of reading to catch up. I have not seen the epiphany that solved the long use, over heating, back fire problem. Is this because it has not happened yet??  And of course the previous entry is a dead give away. My grasp of the obvious remains impeccable. 

 

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If I keep mine cranked over about 12psi it runs as long as I want to. Spent about 5 hrs at a demo yesterday and it only backfired when I shut it off. 

Nothing new though. 

Frosty The Lucky.

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Does the light brick improve the overheat at low pressure thing, I can't call this a problem really. You are using a 3/4" T burner if I recall?

 

 

 

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Yes, the original NARBs, Kastolite burner blocks, driven by 3/4" Ts. I haven't started another forge and I need to, this forge doesn't work like it should.  I'm thinking my next will be 1/8" outlets like Dan's but a really thin block, maybe 3/4" - 1" thick with a zircopax flame face. 

Frosty The Lucky.

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3 hours ago, Howling dog forge said:

I have not seen the epiphany that solved the long use, over heating, back fire problem. Is this because it has not happened yet??

Using 1/8" holes instead of crayon sized holes has solved this problem.  Look back starting on Page 22 of this post I talk about my NARB mod using 122 holes @ .125"  After a 2 hours session of forge welding I am able to turn it down to almost no pressure bringing the forge down to 1450 degreed F for heat treating.  No back fire.  I'm forging at about 4lbs using a reil burner as the injector.

Dan R

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Here's a couple pics of my soft insulating fire brick burner block meltdown.  What appears to have happened is the burner block melted (or at least sintered) in the interior of the block without significantly deforming either the plenum side or the forge side of the burner block at first.  The third picture shows the plenum side of the burner block after removing it. Eventually gravity won the battle and the weakened flame face of the burner block slumped inward towards the plenum.  My NARB is floor mounted facing upwards.  In addition to turning a portion of the IFB into a glazed maze of tubes, a portion of the side also failed and turned a small section of Superwool into a similar material.

On the bright side, the time to remove the burner, take pics, break out the old IFB, drill a new block, seal it with refractory cement, and remount in the forge was less than 2 hours.  That includes one failed burner block that I managed to break by pushing a little too hard when fitting it into the plenum.  Of course these things always break when you are nearly finished rather than when you first start out.

I have a couple 2600 F rated bricks (Greentherm is the brand I think), so I used one of those for the replacement burner block.  I ran the forge for something like 6 or 7 hours between Saturday and Sunday without mishap.  I did a little more forge welding, but I did back the temperature down a little.  So far so good with the new block.

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Yeah I think you pushed the envelope a might too hard. :ph34r: It still looks pretty cool, maybe worthy of display?

Frosty The Lucky.

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Those suckers got HOT!  

On 6/24/2019 at 11:12 AM, Buzzkill said:

I did a little more forge welding, but I did back the temperature down a little. 

FYI: I've successfully forge welded without flux down to 2250 on my pyrometer (using reducing flame).  I usually weld around 2350 just to make sure.  2250 looks pretty cool to me, but the welds were perfect.  As long as I clean the surfaces anally and use known steel, I have a nearly 100% success rate.  It's not about heat, it's about cleanliness and pressure.

DanR

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I agree that prep and technique are key to getting good welds.  Extra heat is kind of extra insurance for me.  Since I was planning to (and did) twist the billet 3 full turns I wanted to ensure I had no poor welds or delaminations at all. I've had some in the past that appeared good even when cut or ground, but split in a couple places during the twists.  And, to be honest, sometimes I can't resist seeing just how hot I can get the forge.   It's kind of like having a 4 barrel carburetor.  If you have it, you will use it at least occasionally. :)

 

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I'm not criticizing. Its fun to test the limits.  But respectfully, I just did a nice twist with two billets of 1095 and 15n20 @125 layers that was all welded at 2300 or so.  I think I did at least 5 twists in opposite directions on them.  Just saying you don't need the high heat to weld...and it saves on rebuilding the forge :)  But I admit, now and again I do like to let it rip!  Especially when working with Wrought Iron. 

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I'm a perfectionist at seeing things in my mind and sharing the information as I see it.

Problem is created when what i write is missing tidbits of information dismissed as unimportant or unnecessary. 

I've found as pointed out you can certainly weld at lower temperatures and have no delams or defects. 

I've also found that the temperature at which the bars are twisted depending on billet makeup (carbon steels, alloys, wrought iron,  nickle etc,etc)  as some move at different speeds for a given temperature.  Twisted at to low a temperature and the weld shears again depending on what the billet is made from.

 

I think it's one of the largest faults I see with newer Smith's that dont finish out a billet completely smooth and have stress risers coupled with the lower than needed temps.

 

To high can also be bad, but it's usually the other way around.

 

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An update on my progress:

I have my first burner running but it backfires unless I turn it up past 12 psi after about an hour.  I determined the probable cause of my problem.  I thought I followed the original directions implicitly but I did one thing differently.  I made the burner head 2.25 inches deep rather than 2”.  I believe my thinking at the time was to make it fit my forge perfectly while rationalizing an increase in the potential for heat conduction.  This was obviously wrong in all ways.  The significant increase in friction was my problem.

 

On another note, I decided to make another burner with 1/8” holes.  I cast it yesterday and figured I would share what I did construction wise.  I used Azek to make the form since I had scrap of it from building a front step.  It was very easy to work with and, best of all, the refractory simply can’t stick to it.  I used crisco as a release agent anyway, but mainly for the next part.  Instead of wax I used 1/8” round acrylic rods and same sized steel rods slathered in crisco.  After about 14 hours the block was hard enough to release from the mould and I pulled the rods out.  I knew there was a chance I would have trouble and scrap the whole thing but I wanted to see if it would work.  I found that the steel rod was superior in every way.  It was rigid and made casting in that area quite easy.  It also pulled out almost effortlessly.  The acrylic was flexible and made casting tedious.  I struggled to keep the pattern of holes and spacing true.  Also, some of the acrylic rods were difficult to remove likely because they were slightly canted and their flexibility was again an issue.  Point is, steel rods, in my opinion, are superior to crayons or any other medium if you want holes without flares in them.  It would have taken me about three minutes to pull all 97 rods if they were all steel and the holes were all perfect.  The burner is back in its bag with a wet rag in it and I’ll be testing it out in no time.

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Lou: When you say you made your burner 2.25" rather than 2" deep, do you mean the burner block with the outlet holes?

The longer the holes the more friction and more it slows the fuel air mix, too slow and it burns back. 

I'm going to try 3/4" thick for my next burner block to see if it stays cooler. It'll probably have 1/8" outlets. I'll give steel wire some thought, these outlets are going to be angled so it might be an issue. 

Frosty The Lucky.

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You are correct, I was referring to the depth of the cast block.  I made this latest one 2” dead on.  I’m going to test run it a bit and then decide if the next one could be even narrower.  Any chance you intend on making the 3/4” block really really soon so I can learn from your results ;) 

If you drill your pilot holes at the desired angles you will seriously enjoy using the steel rods.  They almost fall out of the holes.  It was a satisfying success. This makes sizing the holes in your stock as simple as having various sizes of stock on hand.  I admit that it is a bit tedious cutting and then grinding a small bevel on every rod, but then you can make burners for a long time with them.

Another aside:  I’m liking the ideas of the possible cooling benefits of a thinner block, but I’m concerned that it will be difficult to configure/set up in the standard kaowool and refractory lined forge.  You will get great clearance from the inside of the forge but it will almost necessarily have to point straight into the bottom of the forge.  It will work fine, I think, for your stacked brick forges, but on round forges it kinda defeats the purpose of the roundness.

Lou

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I don't know when I'll get off my butt and build the next forge. I certainly don't like my last one. 

Your assumption that you have to have the face with the burner outlets at the inside of the liner. I intend to hold mine back and shape the opening through the liner to keep as much reflected heat off the burner face. I'm not sure how I'm going to do it or if it'll work. Maybe someday I'll build a burner or forge that isn't an experiment.

Frosty The Lucky.

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Here’s how mine fits inside, roughly tangent to the top of the forge interior and with Kastolite molded around the opening in the kaowool. 

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Have you been using it or is the backbirning still a problem?

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