Gas forge...once again, I know.

[Vito]

Hello everyone.

Let me first clarify WHY I am starting a new thread on this subject. I always read as much as I could BEFORE I asked question were already answered, therefore, I always tried to avoid asking things that have already been answered. I tried the same this time, many times, but it seems that I'm cursed by the digital demon of this forum...I can't open any threads of the stickies, can't open any threads in references...nothing...XXXX , I'm even scared If I'll be able to post this thread...:(
 I have been through the simmiliar threads, none of which exactly answerd my specific questions.

What I have conclued this time, is this: Will do planning BEFORE actually doing it.

Here's my plan:
I intend to do a cilindrically shaped gas forge. Basically, I have two ''pipes'' laying around, of which dimensions are:

19.7'' long,
11.8''diameter
7mm thick steel

Both ends opened. 
1) Let me ask my first ask if I'm thinking in the right direction; I choose the cilindrical shape because of the possibility of the ''swirling effect'' which should distribute the heat more evenly(and reduce wear of the bottom base) and because I already have the pipes.  Now, do you think that for some reason a square shapped forge would be somewhat supperior to cilindrical shape? Or maybe the opposite? Or it just simply doesn't matter (besides the possibility of the swirl effect, which a round shape allows)?

2) Another thing which seems incredibly important to me is: Is there some kind of a formula, which would enable me how much volume should the chamber have, regarding to the burner's BTU? I intend to buy a burner, of which link I've pasted below. It's a ''Devil's forge'' ''DFP'' burner and they claim that it spits out gas with  92,363 BTU's on 25PSI.  How I can use that data to calculate maximum efficiency of the forge, regarding the volume, while on the other hand still being able to sustain a reducing atmosphere, if needed.

ebay url removed

 

3) Ceramic wool (no, we don't have Kaowool here in Slovenia...)...I talked to local suppliers of such materials and the only thickness I can get is 1''. Do you think that 1'' is insufficient? Even if I line it with two layers one on top of each other? Also the density isn't the maximum one (it's 128kg/cubic metre); anything wrong with that? I suppose that density only contributes to higher wear resistance and ''firmness'' of the material?  But I could probably compensate that lack of density with heavy rigidizing of the lining, correct?

4) How does positioning of the burner nozzle affects the swirl effect and is there an exact position or angle, which I should take in consideration when positioning the nozzle?
 

5) Are my dimensions an overkill? (Yes I know, you want to know what I'm intending to do with it, right?)

Here are my main ''fields of work'' when I use forges: bladesmithing(I'm getting really close to becoming a full time bladesmith and knifemaker) and some ''general blacksmithing'' such as making various cutting tools for a specific job, etc. 
The reason I don't want to buy a ''pre-made'' gas forge is simply because I like tinkering and I enjoy using ''tools and hardware'' that I produce on my own.

And please excuse my poor English but I have sensed that many of you considered me being a ''rookie'' just because  I don't know proper ENGLISH terms and expressions for certain things and I therefore explain things in my own way and it offcourse sounds wrong in the end. One of you said it nicely: lack of ''proper'' vocabulary in a foreign language does not necessarilly mean lack of skills. 

Thank you and all the best, Vito

 

EDIT: I'm sorry but I got the inches wrong... Here are the real intended measurements:
Length: 15''
Dia: 11'' (outer shell) minus 2'' for ceramic wool.

 

Edited July 7, 2015 by Steve Sells
language

[Quarry Dog]

Very well thought out questions.  I will say up front that I've no experience in such matters but have asked similar questions of one Mr. Frost.  I'm sure he will correct me if I'm wrong.

  I have a feeling that if you're dead set on running a cylindrical forge the full length of that pipe, you'll need multiple burners, which does not seem to be necessary for general forging, and will use excess fuel.

  Do you know the temperature rating of this ceramic wool?  If if will handle welding temperatures it should be fine, and it may even be what we call kaowool, just a different manufacturer.  2 inches seems to be the recommended thickness.  RigidizerRigidizer on the innermost layer will help to keep the fibers from breaking up and producing dust that is rather unfriendly to the lungs in the long term, as well as make it last longer.  A flux resistant hard floor is also recommended if you plan on doing any forge welding.  

  I don't know the answer for whether that insulation is an appropriate density or how those burners will work withwith the projected volume of the forge body.  You might want to look at 3/4 inch (or metric equivalent design) T-Burners.  They're easy to make, and work well at 300-350 cubic inch volume.  I'll work on metric volumes later if necessary as I'm riding in a very bumpy truck right now.

  I hope I didn't misinform you too much, and maybe spread out the question load some.

[Vito]

Thanks.

The length of the forge is not set in stone offcourse, as I've already mentioned; I'm sensing upfront that 18'' of length is an overkill for one burner, even if ''swirling'' the fire. It'll just consume too much fuel to get to working temperature and to sustain that temperature.

Somebody can offcourse propose an ''ideal'' measurements for my intended purpose (I know that there's no ''forge that does it all'')

Yes, 2 inches is the recommended thickness but I can't get a hold of that thickness, I'll have to deal with what I can get and lay one layer on top of the another to get 2'' of insulation.

I intend to lay a matching piece of hard firebrick on the floor, not fixing it. When it gets ''corroded'' and eaten away enough, I can just replace it, I have plenty.
Yes, I know the temp. rating for the wool; supplier claims it should sustain temperatures from 1000-1200 celsius for long periods of time, without any damage.

You don't have to work on metric measurements, I can convert them myself, work with what suits you most

Thank you and all the best, Vito

[basher]

There is no problem building a round forge, its easier when using K wool. However I find square forges and fibre board easier to use.

 I have seen no benefit in the swirl when building forges, none at all. I've build forges with swirl and without, I discarded it long ago.. There is a benefit when building a crucible furnace with a large  crucible taking up 80% of the furnace space I don't know if that is where the swirl myth is still coming from.......

[ThomasPowers]

Ideal length is simple: how long a section can you effectively hammer before it cools off.  For most folks its measured in inches and not feet.

[Vito]

basher, thanks for that food for thought

Just one thing...what's fibre board? Simply ceramic fibre with higher density, which makes them look and manipulate like boards instead of ''blanket-like-behaviour?

Thomas...so you're saying that I should build a forge that's about 4-5'' long? Haven't seen one like it so far...or maybe I should just build a soup can forge and call it a day?

I think that you know what I was trying to ask and there's simply no need to get sarcastic on me; I wasn't when I asked the question.

 

Thank you anyways for being my Heyoka

Best, Vito

 

[Vito]

One more thing basher...my interest for cilindrical forges (SWIRLING) comes from wish for (more) equal heat distribution. Everytime I see a burner positioned directly vertical over the workpiece, I can see localised ''heat spots''...on the other hand; when  I see a swirl, the whole workpiece is about the same temperature (and color) as the whole forge is.
Maybe that's due to bad choice of appropriate burners but anyway, I don't see that with round forges that have burners positioned in a way which enables the fire to swirl it's way around the lining and therefore dissabling localised heat.

Just some of my thoughts though...

Best, Vito
 

[ThomasPowers]

No the hot spot is about that size you will need some ramping area on either side.

[LastRonin]

Thomas wasn't really being sarcastic. (Well, maybe just a little, but I doubt he meant real offense by it. Believe me... From what I have read on here, you would have NO doubt if he were seriously bothered) Just blunt and to the point. My gas forge is only about eleven inches long. It will hear about eight to ten inches of  length IF I leave it in long enough, but the typical amount I let get to higher than Orange is about four to six inches because that is what I am comfortable with being able to seriously work. If I'm to the point of just plainsong, I'll heat more length. People with more experience and/or power hammers may very well want to heat more length becUse they can get more worked before it has lost its heat.

Edited July 6, 2015 by LastRonin

[ThomasPowers]

Heating more than you can work results in more grain growth, decarburization and scale losses.  All things you want to minimize when working a blade.

[Vito]

Ronin, thanks for explanation, will definately need to take that in consideration as this was not the first time. 
 

Oh ok, so I got the length figured out...I suppose

Thanks.

 

[Frosty]

I'm getting bounced every time I try to reply. I'll try editing my answer in AGAIN!

Cylinder forge is fine. 2 layers of 1" ceramic blank preferable it wears out and it's easier and cheaper to change the inside layer than the whole thing.

Split hard fire brick or kiln shelf for the floor.

9" +/- length with the 7" inside dia your forge will have is a good volume.

Frosty with Fingers CROSSED.

Edited July 6, 2015 by Frosty

[Frosty]

Devil forge site is under construction but found a Youtube video. It looks like a competent 3/4" burner but nothing special. One should be enough to bring a 7" dia. x 9-10" long forge to welding temp. Partially blocking the ends will really help.

Vortexing the flame only HELPS even temps in the chamber. More significantly it helps slow flame wear of the ceramic blanket.

Frosty the finger crossed.

Edited July 6, 2015 by Frosty

[Vito]

Frosty, I can completely relate to that 

Ok, so now I'm  getting there (length wise and height wise)  
Frosty, to which burner of theirs are you reffering to exactly? They have quite a few burners on disposal. Is it one of their DF burners, DFC, DFPROF? 
Here's a video that you may be interested in...https://www.youtube.com/watch?v=rqcPJEAl2-E ...what do you think? Is it worth 150 USD?

Well, if it helps, why not do it if I can...:) 
Thank you for all your advices

 

All the best, Vito

[Vito]

I'm sorry, I have re-read my post and noticed how wrong that question sounded (about ''being worth'' of the asking price). I'm truly, honestly sorry. It wont repeat again. Although I didn't mean nothing bad when I was asking it.

 

Thanks for understanding.

Best, Vito

[Frosty]

I'm sorry, I have re-read my post and noticed how wrong that question sounded (about ''being worth'' of the asking price). I'm truly, honestly sorry. It wont repeat again. Although I didn't mean nothing bad when I was asking it.

 

Thanks for understanding.

Best, Vito

 

Vito: It's a good question, it's not wrong to ask for evaluations of a commercial product. These are burners up for sale on the public market so they're a commercial product, Heck that's a commercial.

I'll give you my opinion as my answer. I wouldn't pay that much but I make a burner just as effective if not more so for around $10 USD. I say just as effective but I don't understand his testing or criteria. I judge a burner by putting it in a forge, lighting it up and seeing how long it takes to bring the forge volume to welding temperature. THEN I put a piece of steel in it and see how long it takes to come to welding temperature.

I didn't see the point to his couch talk other than to try convincing you he makes a good product. Watching him tig welding things that should be screw fittings or milling air intake slots is another attempt to impress customers. I think the whole video is a clumsy attempt at a commercial.

I use a drill press, taps and dies to make a T burner in about 20 minutes. Tuning takes about 5-10 minutes depending on how good a job I did on the drill press. With increasing prices of pipe and such a burner costs me about $10-$12. USD

I suppose if I wanted to make a buck off a machine shop I'd modify a Mike Porter burner, sell kits and finished burners like Rex Price.

If you aren't confident in your skills to make a T or Side Arm burner then buy one. If I had to I'd probably buy the one with the White choke sleeve, it's an ejector type and a little more efficient as a type. All in all I'm not impressed with any of it.

Frosty The Lucky.

 

Edited July 7, 2015 by Frosty

[Vito]

and again I cant post....this is getting a bit tiring, really...

[BANAN]

Vito, you write that you're from Slovenia, it may be easier for you to move Slavic blacksmith forum. We've got a lot of experience in the construction of gas furnaces, and is different from local. http://forumkowalskie.pl/viewtopic.php?t=76  Of course, we started from the burners naturally aspirated, but everyone still wants to have an effective and economical tool.

[Vito]

Banan thanks for an idea but I've checked your page out and I can't speak your language...what is that? Polish, Czech?
We started with naturally aspirated burners...? So you're basically saying that naturally aspirated burners are inefficient and not economical? Or have I got this wrong?
Best, Vito

[BANAN]

Forum is in Polish. Aspirated burners are ineffective. I lost three years to experiment with burners to develop its own model of working with fans and giving full control of the flame atmosphere. They convinced them Polish blacksmiths, even those who could not imagine working at another hearth than Coke. My burners work in more than 200 forges, and it speaks for itself.